blob: f4d14d76724274aab496177abcf84aac48952c12 [file] [log] [blame]
This is /home/vagrant/rpmbuild/BUILD/build-eglibc/manual/libc.info,
produced by makeinfo version 4.13 from libc.texinfo.
INFO-DIR-SECTION Software libraries
START-INFO-DIR-ENTRY
* Libc: (libc). C library.
END-INFO-DIR-ENTRY
INFO-DIR-SECTION GNU C library functions and macros
START-INFO-DIR-ENTRY
* ALTWERASE: (libc)Local Modes.
* ARGP_ERR_UNKNOWN: (libc)Argp Parser Functions.
* ARG_MAX: (libc)General Limits.
* BC_BASE_MAX: (libc)Utility Limits.
* BC_DIM_MAX: (libc)Utility Limits.
* BC_SCALE_MAX: (libc)Utility Limits.
* BC_STRING_MAX: (libc)Utility Limits.
* BRKINT: (libc)Input Modes.
* BUFSIZ: (libc)Controlling Buffering.
* CCTS_OFLOW: (libc)Control Modes.
* CHILD_MAX: (libc)General Limits.
* CIGNORE: (libc)Control Modes.
* CLK_TCK: (libc)Processor Time.
* CLOCAL: (libc)Control Modes.
* CLOCKS_PER_SEC: (libc)CPU Time.
* COLL_WEIGHTS_MAX: (libc)Utility Limits.
* CPU_CLR: (libc)CPU Affinity.
* CPU_ISSET: (libc)CPU Affinity.
* CPU_SET: (libc)CPU Affinity.
* CPU_SETSIZE: (libc)CPU Affinity.
* CPU_ZERO: (libc)CPU Affinity.
* CREAD: (libc)Control Modes.
* CRTS_IFLOW: (libc)Control Modes.
* CS5: (libc)Control Modes.
* CS6: (libc)Control Modes.
* CS7: (libc)Control Modes.
* CS8: (libc)Control Modes.
* CSIZE: (libc)Control Modes.
* CSTOPB: (libc)Control Modes.
* DES_FAILED: (libc)DES Encryption.
* DTTOIF: (libc)Directory Entries.
* E2BIG: (libc)Error Codes.
* EACCES: (libc)Error Codes.
* EADDRINUSE: (libc)Error Codes.
* EADDRNOTAVAIL: (libc)Error Codes.
* EADV: (libc)Error Codes.
* EAFNOSUPPORT: (libc)Error Codes.
* EAGAIN: (libc)Error Codes.
* EALREADY: (libc)Error Codes.
* EAUTH: (libc)Error Codes.
* EBACKGROUND: (libc)Error Codes.
* EBADE: (libc)Error Codes.
* EBADF: (libc)Error Codes.
* EBADFD: (libc)Error Codes.
* EBADMSG: (libc)Error Codes.
* EBADR: (libc)Error Codes.
* EBADRPC: (libc)Error Codes.
* EBADRQC: (libc)Error Codes.
* EBADSLT: (libc)Error Codes.
* EBFONT: (libc)Error Codes.
* EBUSY: (libc)Error Codes.
* ECANCELED: (libc)Error Codes.
* ECHILD: (libc)Error Codes.
* ECHO: (libc)Local Modes.
* ECHOCTL: (libc)Local Modes.
* ECHOE: (libc)Local Modes.
* ECHOK: (libc)Local Modes.
* ECHOKE: (libc)Local Modes.
* ECHONL: (libc)Local Modes.
* ECHOPRT: (libc)Local Modes.
* ECHRNG: (libc)Error Codes.
* ECOMM: (libc)Error Codes.
* ECONNABORTED: (libc)Error Codes.
* ECONNREFUSED: (libc)Error Codes.
* ECONNRESET: (libc)Error Codes.
* ED: (libc)Error Codes.
* EDEADLK: (libc)Error Codes.
* EDEADLOCK: (libc)Error Codes.
* EDESTADDRREQ: (libc)Error Codes.
* EDIED: (libc)Error Codes.
* EDOM: (libc)Error Codes.
* EDOTDOT: (libc)Error Codes.
* EDQUOT: (libc)Error Codes.
* EEXIST: (libc)Error Codes.
* EFAULT: (libc)Error Codes.
* EFBIG: (libc)Error Codes.
* EFTYPE: (libc)Error Codes.
* EGRATUITOUS: (libc)Error Codes.
* EGREGIOUS: (libc)Error Codes.
* EHOSTDOWN: (libc)Error Codes.
* EHOSTUNREACH: (libc)Error Codes.
* EHWPOISON: (libc)Error Codes.
* EIDRM: (libc)Error Codes.
* EIEIO: (libc)Error Codes.
* EILSEQ: (libc)Error Codes.
* EINPROGRESS: (libc)Error Codes.
* EINTR: (libc)Error Codes.
* EINVAL: (libc)Error Codes.
* EIO: (libc)Error Codes.
* EISCONN: (libc)Error Codes.
* EISDIR: (libc)Error Codes.
* EISNAM: (libc)Error Codes.
* EKEYEXPIRED: (libc)Error Codes.
* EKEYREJECTED: (libc)Error Codes.
* EKEYREVOKED: (libc)Error Codes.
* EL2HLT: (libc)Error Codes.
* EL2NSYNC: (libc)Error Codes.
* EL3HLT: (libc)Error Codes.
* EL3RST: (libc)Error Codes.
* ELIBACC: (libc)Error Codes.
* ELIBBAD: (libc)Error Codes.
* ELIBEXEC: (libc)Error Codes.
* ELIBMAX: (libc)Error Codes.
* ELIBSCN: (libc)Error Codes.
* ELNRNG: (libc)Error Codes.
* ELOOP: (libc)Error Codes.
* EMEDIUMTYPE: (libc)Error Codes.
* EMFILE: (libc)Error Codes.
* EMLINK: (libc)Error Codes.
* EMSGSIZE: (libc)Error Codes.
* EMULTIHOP: (libc)Error Codes.
* ENAMETOOLONG: (libc)Error Codes.
* ENAVAIL: (libc)Error Codes.
* ENEEDAUTH: (libc)Error Codes.
* ENETDOWN: (libc)Error Codes.
* ENETRESET: (libc)Error Codes.
* ENETUNREACH: (libc)Error Codes.
* ENFILE: (libc)Error Codes.
* ENOANO: (libc)Error Codes.
* ENOBUFS: (libc)Error Codes.
* ENOCSI: (libc)Error Codes.
* ENODATA: (libc)Error Codes.
* ENODEV: (libc)Error Codes.
* ENOENT: (libc)Error Codes.
* ENOEXEC: (libc)Error Codes.
* ENOKEY: (libc)Error Codes.
* ENOLCK: (libc)Error Codes.
* ENOLINK: (libc)Error Codes.
* ENOMEDIUM: (libc)Error Codes.
* ENOMEM: (libc)Error Codes.
* ENOMSG: (libc)Error Codes.
* ENONET: (libc)Error Codes.
* ENOPKG: (libc)Error Codes.
* ENOPROTOOPT: (libc)Error Codes.
* ENOSPC: (libc)Error Codes.
* ENOSR: (libc)Error Codes.
* ENOSTR: (libc)Error Codes.
* ENOSYS: (libc)Error Codes.
* ENOTBLK: (libc)Error Codes.
* ENOTCONN: (libc)Error Codes.
* ENOTDIR: (libc)Error Codes.
* ENOTEMPTY: (libc)Error Codes.
* ENOTNAM: (libc)Error Codes.
* ENOTRECOVERABLE: (libc)Error Codes.
* ENOTSOCK: (libc)Error Codes.
* ENOTSUP: (libc)Error Codes.
* ENOTTY: (libc)Error Codes.
* ENOTUNIQ: (libc)Error Codes.
* ENXIO: (libc)Error Codes.
* EOF: (libc)EOF and Errors.
* EOPNOTSUPP: (libc)Error Codes.
* EOVERFLOW: (libc)Error Codes.
* EOWNERDEAD: (libc)Error Codes.
* EPERM: (libc)Error Codes.
* EPFNOSUPPORT: (libc)Error Codes.
* EPIPE: (libc)Error Codes.
* EPROCLIM: (libc)Error Codes.
* EPROCUNAVAIL: (libc)Error Codes.
* EPROGMISMATCH: (libc)Error Codes.
* EPROGUNAVAIL: (libc)Error Codes.
* EPROTO: (libc)Error Codes.
* EPROTONOSUPPORT: (libc)Error Codes.
* EPROTOTYPE: (libc)Error Codes.
* EQUIV_CLASS_MAX: (libc)Utility Limits.
* ERANGE: (libc)Error Codes.
* EREMCHG: (libc)Error Codes.
* EREMOTE: (libc)Error Codes.
* EREMOTEIO: (libc)Error Codes.
* ERESTART: (libc)Error Codes.
* ERFKILL: (libc)Error Codes.
* EROFS: (libc)Error Codes.
* ERPCMISMATCH: (libc)Error Codes.
* ESHUTDOWN: (libc)Error Codes.
* ESOCKTNOSUPPORT: (libc)Error Codes.
* ESPIPE: (libc)Error Codes.
* ESRCH: (libc)Error Codes.
* ESRMNT: (libc)Error Codes.
* ESTALE: (libc)Error Codes.
* ESTRPIPE: (libc)Error Codes.
* ETIME: (libc)Error Codes.
* ETIMEDOUT: (libc)Error Codes.
* ETOOMANYREFS: (libc)Error Codes.
* ETXTBSY: (libc)Error Codes.
* EUCLEAN: (libc)Error Codes.
* EUNATCH: (libc)Error Codes.
* EUSERS: (libc)Error Codes.
* EWOULDBLOCK: (libc)Error Codes.
* EXDEV: (libc)Error Codes.
* EXFULL: (libc)Error Codes.
* EXIT_FAILURE: (libc)Exit Status.
* EXIT_SUCCESS: (libc)Exit Status.
* EXPR_NEST_MAX: (libc)Utility Limits.
* FD_CLOEXEC: (libc)Descriptor Flags.
* FD_CLR: (libc)Waiting for I/O.
* FD_ISSET: (libc)Waiting for I/O.
* FD_SET: (libc)Waiting for I/O.
* FD_SETSIZE: (libc)Waiting for I/O.
* FD_ZERO: (libc)Waiting for I/O.
* FILENAME_MAX: (libc)Limits for Files.
* FLUSHO: (libc)Local Modes.
* FOPEN_MAX: (libc)Opening Streams.
* FP_ILOGB0: (libc)Exponents and Logarithms.
* FP_ILOGBNAN: (libc)Exponents and Logarithms.
* F_DUPFD: (libc)Duplicating Descriptors.
* F_GETFD: (libc)Descriptor Flags.
* F_GETFL: (libc)Getting File Status Flags.
* F_GETLK: (libc)File Locks.
* F_GETOWN: (libc)Interrupt Input.
* F_OK: (libc)Testing File Access.
* F_SETFD: (libc)Descriptor Flags.
* F_SETFL: (libc)Getting File Status Flags.
* F_SETLK: (libc)File Locks.
* F_SETLKW: (libc)File Locks.
* F_SETOWN: (libc)Interrupt Input.
* HUGE_VAL: (libc)Math Error Reporting.
* HUGE_VALF: (libc)Math Error Reporting.
* HUGE_VALL: (libc)Math Error Reporting.
* HUPCL: (libc)Control Modes.
* I: (libc)Complex Numbers.
* ICANON: (libc)Local Modes.
* ICRNL: (libc)Input Modes.
* IEXTEN: (libc)Local Modes.
* IFNAMSIZ: (libc)Interface Naming.
* IFTODT: (libc)Directory Entries.
* IGNBRK: (libc)Input Modes.
* IGNCR: (libc)Input Modes.
* IGNPAR: (libc)Input Modes.
* IMAXBEL: (libc)Input Modes.
* INADDR_ANY: (libc)Host Address Data Type.
* INADDR_BROADCAST: (libc)Host Address Data Type.
* INADDR_LOOPBACK: (libc)Host Address Data Type.
* INADDR_NONE: (libc)Host Address Data Type.
* INFINITY: (libc)Infinity and NaN.
* INLCR: (libc)Input Modes.
* INPCK: (libc)Input Modes.
* IPPORT_RESERVED: (libc)Ports.
* IPPORT_USERRESERVED: (libc)Ports.
* ISIG: (libc)Local Modes.
* ISTRIP: (libc)Input Modes.
* IXANY: (libc)Input Modes.
* IXOFF: (libc)Input Modes.
* IXON: (libc)Input Modes.
* LINE_MAX: (libc)Utility Limits.
* LINK_MAX: (libc)Limits for Files.
* L_ctermid: (libc)Identifying the Terminal.
* L_cuserid: (libc)Who Logged In.
* L_tmpnam: (libc)Temporary Files.
* MAXNAMLEN: (libc)Limits for Files.
* MAXSYMLINKS: (libc)Symbolic Links.
* MAX_CANON: (libc)Limits for Files.
* MAX_INPUT: (libc)Limits for Files.
* MB_CUR_MAX: (libc)Selecting the Conversion.
* MB_LEN_MAX: (libc)Selecting the Conversion.
* MDMBUF: (libc)Control Modes.
* MSG_DONTROUTE: (libc)Socket Data Options.
* MSG_OOB: (libc)Socket Data Options.
* MSG_PEEK: (libc)Socket Data Options.
* NAME_MAX: (libc)Limits for Files.
* NAN: (libc)Infinity and NaN.
* NCCS: (libc)Mode Data Types.
* NGROUPS_MAX: (libc)General Limits.
* NOFLSH: (libc)Local Modes.
* NOKERNINFO: (libc)Local Modes.
* NSIG: (libc)Standard Signals.
* NULL: (libc)Null Pointer Constant.
* ONLCR: (libc)Output Modes.
* ONOEOT: (libc)Output Modes.
* OPEN_MAX: (libc)General Limits.
* OPOST: (libc)Output Modes.
* OXTABS: (libc)Output Modes.
* O_ACCMODE: (libc)Access Modes.
* O_APPEND: (libc)Operating Modes.
* O_ASYNC: (libc)Operating Modes.
* O_CREAT: (libc)Open-time Flags.
* O_EXCL: (libc)Open-time Flags.
* O_EXEC: (libc)Access Modes.
* O_EXLOCK: (libc)Open-time Flags.
* O_FSYNC: (libc)Operating Modes.
* O_IGNORE_CTTY: (libc)Open-time Flags.
* O_NDELAY: (libc)Operating Modes.
* O_NOATIME: (libc)Operating Modes.
* O_NOCTTY: (libc)Open-time Flags.
* O_NOLINK: (libc)Open-time Flags.
* O_NONBLOCK: (libc)Open-time Flags.
* O_NONBLOCK: (libc)Operating Modes.
* O_NOTRANS: (libc)Open-time Flags.
* O_RDONLY: (libc)Access Modes.
* O_RDWR: (libc)Access Modes.
* O_READ: (libc)Access Modes.
* O_SHLOCK: (libc)Open-time Flags.
* O_SYNC: (libc)Operating Modes.
* O_TRUNC: (libc)Open-time Flags.
* O_WRITE: (libc)Access Modes.
* O_WRONLY: (libc)Access Modes.
* PARENB: (libc)Control Modes.
* PARMRK: (libc)Input Modes.
* PARODD: (libc)Control Modes.
* PATH_MAX: (libc)Limits for Files.
* PA_FLAG_MASK: (libc)Parsing a Template String.
* PENDIN: (libc)Local Modes.
* PF_FILE: (libc)Local Namespace Details.
* PF_INET6: (libc)Internet Namespace.
* PF_INET: (libc)Internet Namespace.
* PF_LOCAL: (libc)Local Namespace Details.
* PF_UNIX: (libc)Local Namespace Details.
* PIPE_BUF: (libc)Limits for Files.
* P_tmpdir: (libc)Temporary Files.
* RAND_MAX: (libc)ISO Random.
* RE_DUP_MAX: (libc)General Limits.
* RLIM_INFINITY: (libc)Limits on Resources.
* R_OK: (libc)Testing File Access.
* SA_NOCLDSTOP: (libc)Flags for Sigaction.
* SA_ONSTACK: (libc)Flags for Sigaction.
* SA_RESTART: (libc)Flags for Sigaction.
* SEEK_CUR: (libc)File Positioning.
* SEEK_END: (libc)File Positioning.
* SEEK_SET: (libc)File Positioning.
* SIGABRT: (libc)Program Error Signals.
* SIGALRM: (libc)Alarm Signals.
* SIGBUS: (libc)Program Error Signals.
* SIGCHLD: (libc)Job Control Signals.
* SIGCLD: (libc)Job Control Signals.
* SIGCONT: (libc)Job Control Signals.
* SIGEMT: (libc)Program Error Signals.
* SIGFPE: (libc)Program Error Signals.
* SIGHUP: (libc)Termination Signals.
* SIGILL: (libc)Program Error Signals.
* SIGINFO: (libc)Miscellaneous Signals.
* SIGINT: (libc)Termination Signals.
* SIGIO: (libc)Asynchronous I/O Signals.
* SIGIOT: (libc)Program Error Signals.
* SIGKILL: (libc)Termination Signals.
* SIGLOST: (libc)Operation Error Signals.
* SIGPIPE: (libc)Operation Error Signals.
* SIGPOLL: (libc)Asynchronous I/O Signals.
* SIGPROF: (libc)Alarm Signals.
* SIGQUIT: (libc)Termination Signals.
* SIGSEGV: (libc)Program Error Signals.
* SIGSTOP: (libc)Job Control Signals.
* SIGSYS: (libc)Program Error Signals.
* SIGTERM: (libc)Termination Signals.
* SIGTRAP: (libc)Program Error Signals.
* SIGTSTP: (libc)Job Control Signals.
* SIGTTIN: (libc)Job Control Signals.
* SIGTTOU: (libc)Job Control Signals.
* SIGURG: (libc)Asynchronous I/O Signals.
* SIGUSR1: (libc)Miscellaneous Signals.
* SIGUSR2: (libc)Miscellaneous Signals.
* SIGVTALRM: (libc)Alarm Signals.
* SIGWINCH: (libc)Miscellaneous Signals.
* SIGXCPU: (libc)Operation Error Signals.
* SIGXFSZ: (libc)Operation Error Signals.
* SIG_ERR: (libc)Basic Signal Handling.
* SOCK_DGRAM: (libc)Communication Styles.
* SOCK_RAW: (libc)Communication Styles.
* SOCK_RDM: (libc)Communication Styles.
* SOCK_SEQPACKET: (libc)Communication Styles.
* SOCK_STREAM: (libc)Communication Styles.
* SOL_SOCKET: (libc)Socket-Level Options.
* SSIZE_MAX: (libc)General Limits.
* STREAM_MAX: (libc)General Limits.
* SUN_LEN: (libc)Local Namespace Details.
* SV_INTERRUPT: (libc)BSD Handler.
* SV_ONSTACK: (libc)BSD Handler.
* SV_RESETHAND: (libc)BSD Handler.
* S_IFMT: (libc)Testing File Type.
* S_ISBLK: (libc)Testing File Type.
* S_ISCHR: (libc)Testing File Type.
* S_ISDIR: (libc)Testing File Type.
* S_ISFIFO: (libc)Testing File Type.
* S_ISLNK: (libc)Testing File Type.
* S_ISREG: (libc)Testing File Type.
* S_ISSOCK: (libc)Testing File Type.
* S_TYPEISMQ: (libc)Testing File Type.
* S_TYPEISSEM: (libc)Testing File Type.
* S_TYPEISSHM: (libc)Testing File Type.
* TMP_MAX: (libc)Temporary Files.
* TOSTOP: (libc)Local Modes.
* TZNAME_MAX: (libc)General Limits.
* VDISCARD: (libc)Other Special.
* VDSUSP: (libc)Signal Characters.
* VEOF: (libc)Editing Characters.
* VEOL2: (libc)Editing Characters.
* VEOL: (libc)Editing Characters.
* VERASE: (libc)Editing Characters.
* VINTR: (libc)Signal Characters.
* VKILL: (libc)Editing Characters.
* VLNEXT: (libc)Other Special.
* VMIN: (libc)Noncanonical Input.
* VQUIT: (libc)Signal Characters.
* VREPRINT: (libc)Editing Characters.
* VSTART: (libc)Start/Stop Characters.
* VSTATUS: (libc)Other Special.
* VSTOP: (libc)Start/Stop Characters.
* VSUSP: (libc)Signal Characters.
* VTIME: (libc)Noncanonical Input.
* VWERASE: (libc)Editing Characters.
* WCHAR_MAX: (libc)Extended Char Intro.
* WCHAR_MIN: (libc)Extended Char Intro.
* WCOREDUMP: (libc)Process Completion Status.
* WEOF: (libc)EOF and Errors.
* WEOF: (libc)Extended Char Intro.
* WEXITSTATUS: (libc)Process Completion Status.
* WIFEXITED: (libc)Process Completion Status.
* WIFSIGNALED: (libc)Process Completion Status.
* WIFSTOPPED: (libc)Process Completion Status.
* WSTOPSIG: (libc)Process Completion Status.
* WTERMSIG: (libc)Process Completion Status.
* W_OK: (libc)Testing File Access.
* X_OK: (libc)Testing File Access.
* _Complex_I: (libc)Complex Numbers.
* _Exit: (libc)Termination Internals.
* _IOFBF: (libc)Controlling Buffering.
* _IOLBF: (libc)Controlling Buffering.
* _IONBF: (libc)Controlling Buffering.
* _Imaginary_I: (libc)Complex Numbers.
* _PATH_UTMP: (libc)Manipulating the Database.
* _PATH_WTMP: (libc)Manipulating the Database.
* _POSIX2_C_DEV: (libc)System Options.
* _POSIX2_C_VERSION: (libc)Version Supported.
* _POSIX2_FORT_DEV: (libc)System Options.
* _POSIX2_FORT_RUN: (libc)System Options.
* _POSIX2_LOCALEDEF: (libc)System Options.
* _POSIX2_SW_DEV: (libc)System Options.
* _POSIX_CHOWN_RESTRICTED: (libc)Options for Files.
* _POSIX_JOB_CONTROL: (libc)System Options.
* _POSIX_NO_TRUNC: (libc)Options for Files.
* _POSIX_SAVED_IDS: (libc)System Options.
* _POSIX_VDISABLE: (libc)Options for Files.
* _POSIX_VERSION: (libc)Version Supported.
* __fbufsize: (libc)Controlling Buffering.
* __flbf: (libc)Controlling Buffering.
* __fpending: (libc)Controlling Buffering.
* __fpurge: (libc)Flushing Buffers.
* __freadable: (libc)Opening Streams.
* __freading: (libc)Opening Streams.
* __fsetlocking: (libc)Streams and Threads.
* __fwritable: (libc)Opening Streams.
* __fwriting: (libc)Opening Streams.
* __gconv_end_fct: (libc)glibc iconv Implementation.
* __gconv_fct: (libc)glibc iconv Implementation.
* __gconv_init_fct: (libc)glibc iconv Implementation.
* __ppc_get_timebase: (libc)PowerPC.
* __ppc_get_timebase_freq: (libc)PowerPC.
* __ppc_mdoio: (libc)PowerPC.
* __ppc_mdoom: (libc)PowerPC.
* __ppc_set_ppr_low: (libc)PowerPC.
* __ppc_set_ppr_med: (libc)PowerPC.
* __ppc_set_ppr_med_low: (libc)PowerPC.
* __ppc_yield: (libc)PowerPC.
* __va_copy: (libc)Argument Macros.
* _exit: (libc)Termination Internals.
* _flushlbf: (libc)Flushing Buffers.
* _tolower: (libc)Case Conversion.
* _toupper: (libc)Case Conversion.
* a64l: (libc)Encode Binary Data.
* abort: (libc)Aborting a Program.
* abs: (libc)Absolute Value.
* accept: (libc)Accepting Connections.
* access: (libc)Testing File Access.
* acos: (libc)Inverse Trig Functions.
* acosf: (libc)Inverse Trig Functions.
* acosh: (libc)Hyperbolic Functions.
* acoshf: (libc)Hyperbolic Functions.
* acoshl: (libc)Hyperbolic Functions.
* acosl: (libc)Inverse Trig Functions.
* addmntent: (libc)mtab.
* addseverity: (libc)Adding Severity Classes.
* adjtime: (libc)High-Resolution Calendar.
* adjtimex: (libc)High-Resolution Calendar.
* aio_cancel64: (libc)Cancel AIO Operations.
* aio_cancel: (libc)Cancel AIO Operations.
* aio_error64: (libc)Status of AIO Operations.
* aio_error: (libc)Status of AIO Operations.
* aio_fsync64: (libc)Synchronizing AIO Operations.
* aio_fsync: (libc)Synchronizing AIO Operations.
* aio_init: (libc)Configuration of AIO.
* aio_read64: (libc)Asynchronous Reads/Writes.
* aio_read: (libc)Asynchronous Reads/Writes.
* aio_return64: (libc)Status of AIO Operations.
* aio_return: (libc)Status of AIO Operations.
* aio_suspend64: (libc)Synchronizing AIO Operations.
* aio_suspend: (libc)Synchronizing AIO Operations.
* aio_write64: (libc)Asynchronous Reads/Writes.
* aio_write: (libc)Asynchronous Reads/Writes.
* alarm: (libc)Setting an Alarm.
* alloca: (libc)Variable Size Automatic.
* alphasort64: (libc)Scanning Directory Content.
* alphasort: (libc)Scanning Directory Content.
* argp_error: (libc)Argp Helper Functions.
* argp_failure: (libc)Argp Helper Functions.
* argp_help: (libc)Argp Help.
* argp_parse: (libc)Argp.
* argp_state_help: (libc)Argp Helper Functions.
* argp_usage: (libc)Argp Helper Functions.
* argz_add: (libc)Argz Functions.
* argz_add_sep: (libc)Argz Functions.
* argz_append: (libc)Argz Functions.
* argz_count: (libc)Argz Functions.
* argz_create: (libc)Argz Functions.
* argz_create_sep: (libc)Argz Functions.
* argz_delete: (libc)Argz Functions.
* argz_extract: (libc)Argz Functions.
* argz_insert: (libc)Argz Functions.
* argz_next: (libc)Argz Functions.
* argz_replace: (libc)Argz Functions.
* argz_stringify: (libc)Argz Functions.
* asctime: (libc)Formatting Calendar Time.
* asctime_r: (libc)Formatting Calendar Time.
* asin: (libc)Inverse Trig Functions.
* asinf: (libc)Inverse Trig Functions.
* asinh: (libc)Hyperbolic Functions.
* asinhf: (libc)Hyperbolic Functions.
* asinhl: (libc)Hyperbolic Functions.
* asinl: (libc)Inverse Trig Functions.
* asprintf: (libc)Dynamic Output.
* assert: (libc)Consistency Checking.
* assert_perror: (libc)Consistency Checking.
* atan2: (libc)Inverse Trig Functions.
* atan2f: (libc)Inverse Trig Functions.
* atan2l: (libc)Inverse Trig Functions.
* atan: (libc)Inverse Trig Functions.
* atanf: (libc)Inverse Trig Functions.
* atanh: (libc)Hyperbolic Functions.
* atanhf: (libc)Hyperbolic Functions.
* atanhl: (libc)Hyperbolic Functions.
* atanl: (libc)Inverse Trig Functions.
* atexit: (libc)Cleanups on Exit.
* atof: (libc)Parsing of Floats.
* atoi: (libc)Parsing of Integers.
* atol: (libc)Parsing of Integers.
* atoll: (libc)Parsing of Integers.
* backtrace: (libc)Backtraces.
* backtrace_symbols: (libc)Backtraces.
* backtrace_symbols_fd: (libc)Backtraces.
* basename: (libc)Finding Tokens in a String.
* basename: (libc)Finding Tokens in a String.
* bcmp: (libc)String/Array Comparison.
* bcopy: (libc)Copying and Concatenation.
* bind: (libc)Setting Address.
* bind_textdomain_codeset: (libc)Charset conversion in gettext.
* bindtextdomain: (libc)Locating gettext catalog.
* brk: (libc)Resizing the Data Segment.
* bsearch: (libc)Array Search Function.
* btowc: (libc)Converting a Character.
* bzero: (libc)Copying and Concatenation.
* cabs: (libc)Absolute Value.
* cabsf: (libc)Absolute Value.
* cabsl: (libc)Absolute Value.
* cacos: (libc)Inverse Trig Functions.
* cacosf: (libc)Inverse Trig Functions.
* cacosh: (libc)Hyperbolic Functions.
* cacoshf: (libc)Hyperbolic Functions.
* cacoshl: (libc)Hyperbolic Functions.
* cacosl: (libc)Inverse Trig Functions.
* calloc: (libc)Allocating Cleared Space.
* canonicalize_file_name: (libc)Symbolic Links.
* carg: (libc)Operations on Complex.
* cargf: (libc)Operations on Complex.
* cargl: (libc)Operations on Complex.
* casin: (libc)Inverse Trig Functions.
* casinf: (libc)Inverse Trig Functions.
* casinh: (libc)Hyperbolic Functions.
* casinhf: (libc)Hyperbolic Functions.
* casinhl: (libc)Hyperbolic Functions.
* casinl: (libc)Inverse Trig Functions.
* catan: (libc)Inverse Trig Functions.
* catanf: (libc)Inverse Trig Functions.
* catanh: (libc)Hyperbolic Functions.
* catanhf: (libc)Hyperbolic Functions.
* catanhl: (libc)Hyperbolic Functions.
* catanl: (libc)Inverse Trig Functions.
* catclose: (libc)The catgets Functions.
* catgets: (libc)The catgets Functions.
* catopen: (libc)The catgets Functions.
* cbc_crypt: (libc)DES Encryption.
* cbrt: (libc)Exponents and Logarithms.
* cbrtf: (libc)Exponents and Logarithms.
* cbrtl: (libc)Exponents and Logarithms.
* ccos: (libc)Trig Functions.
* ccosf: (libc)Trig Functions.
* ccosh: (libc)Hyperbolic Functions.
* ccoshf: (libc)Hyperbolic Functions.
* ccoshl: (libc)Hyperbolic Functions.
* ccosl: (libc)Trig Functions.
* ceil: (libc)Rounding Functions.
* ceilf: (libc)Rounding Functions.
* ceill: (libc)Rounding Functions.
* cexp: (libc)Exponents and Logarithms.
* cexpf: (libc)Exponents and Logarithms.
* cexpl: (libc)Exponents and Logarithms.
* cfgetispeed: (libc)Line Speed.
* cfgetospeed: (libc)Line Speed.
* cfmakeraw: (libc)Noncanonical Input.
* cfree: (libc)Freeing after Malloc.
* cfsetispeed: (libc)Line Speed.
* cfsetospeed: (libc)Line Speed.
* cfsetspeed: (libc)Line Speed.
* chdir: (libc)Working Directory.
* chmod: (libc)Setting Permissions.
* chown: (libc)File Owner.
* cimag: (libc)Operations on Complex.
* cimagf: (libc)Operations on Complex.
* cimagl: (libc)Operations on Complex.
* clearenv: (libc)Environment Access.
* clearerr: (libc)Error Recovery.
* clearerr_unlocked: (libc)Error Recovery.
* clock: (libc)CPU Time.
* clog10: (libc)Exponents and Logarithms.
* clog10f: (libc)Exponents and Logarithms.
* clog10l: (libc)Exponents and Logarithms.
* clog: (libc)Exponents and Logarithms.
* clogf: (libc)Exponents and Logarithms.
* clogl: (libc)Exponents and Logarithms.
* close: (libc)Opening and Closing Files.
* closedir: (libc)Reading/Closing Directory.
* closelog: (libc)closelog.
* confstr: (libc)String Parameters.
* conj: (libc)Operations on Complex.
* conjf: (libc)Operations on Complex.
* conjl: (libc)Operations on Complex.
* connect: (libc)Connecting.
* copysign: (libc)FP Bit Twiddling.
* copysignf: (libc)FP Bit Twiddling.
* copysignl: (libc)FP Bit Twiddling.
* cos: (libc)Trig Functions.
* cosf: (libc)Trig Functions.
* cosh: (libc)Hyperbolic Functions.
* coshf: (libc)Hyperbolic Functions.
* coshl: (libc)Hyperbolic Functions.
* cosl: (libc)Trig Functions.
* cpow: (libc)Exponents and Logarithms.
* cpowf: (libc)Exponents and Logarithms.
* cpowl: (libc)Exponents and Logarithms.
* cproj: (libc)Operations on Complex.
* cprojf: (libc)Operations on Complex.
* cprojl: (libc)Operations on Complex.
* creal: (libc)Operations on Complex.
* crealf: (libc)Operations on Complex.
* creall: (libc)Operations on Complex.
* creat64: (libc)Opening and Closing Files.
* creat: (libc)Opening and Closing Files.
* crypt: (libc)crypt.
* crypt_r: (libc)crypt.
* csin: (libc)Trig Functions.
* csinf: (libc)Trig Functions.
* csinh: (libc)Hyperbolic Functions.
* csinhf: (libc)Hyperbolic Functions.
* csinhl: (libc)Hyperbolic Functions.
* csinl: (libc)Trig Functions.
* csqrt: (libc)Exponents and Logarithms.
* csqrtf: (libc)Exponents and Logarithms.
* csqrtl: (libc)Exponents and Logarithms.
* ctan: (libc)Trig Functions.
* ctanf: (libc)Trig Functions.
* ctanh: (libc)Hyperbolic Functions.
* ctanhf: (libc)Hyperbolic Functions.
* ctanhl: (libc)Hyperbolic Functions.
* ctanl: (libc)Trig Functions.
* ctermid: (libc)Identifying the Terminal.
* ctime: (libc)Formatting Calendar Time.
* ctime_r: (libc)Formatting Calendar Time.
* cuserid: (libc)Who Logged In.
* dcgettext: (libc)Translation with gettext.
* dcngettext: (libc)Advanced gettext functions.
* des_setparity: (libc)DES Encryption.
* dgettext: (libc)Translation with gettext.
* difftime: (libc)Elapsed Time.
* dirfd: (libc)Opening a Directory.
* dirname: (libc)Finding Tokens in a String.
* div: (libc)Integer Division.
* dngettext: (libc)Advanced gettext functions.
* drand48: (libc)SVID Random.
* drand48_r: (libc)SVID Random.
* drem: (libc)Remainder Functions.
* dremf: (libc)Remainder Functions.
* dreml: (libc)Remainder Functions.
* dup2: (libc)Duplicating Descriptors.
* dup: (libc)Duplicating Descriptors.
* ecb_crypt: (libc)DES Encryption.
* ecvt: (libc)System V Number Conversion.
* ecvt_r: (libc)System V Number Conversion.
* encrypt: (libc)DES Encryption.
* encrypt_r: (libc)DES Encryption.
* endfsent: (libc)fstab.
* endgrent: (libc)Scanning All Groups.
* endhostent: (libc)Host Names.
* endmntent: (libc)mtab.
* endnetent: (libc)Networks Database.
* endnetgrent: (libc)Lookup Netgroup.
* endprotoent: (libc)Protocols Database.
* endpwent: (libc)Scanning All Users.
* endservent: (libc)Services Database.
* endutent: (libc)Manipulating the Database.
* endutxent: (libc)XPG Functions.
* envz_add: (libc)Envz Functions.
* envz_entry: (libc)Envz Functions.
* envz_get: (libc)Envz Functions.
* envz_merge: (libc)Envz Functions.
* envz_strip: (libc)Envz Functions.
* erand48: (libc)SVID Random.
* erand48_r: (libc)SVID Random.
* erf: (libc)Special Functions.
* erfc: (libc)Special Functions.
* erfcf: (libc)Special Functions.
* erfcl: (libc)Special Functions.
* erff: (libc)Special Functions.
* erfl: (libc)Special Functions.
* err: (libc)Error Messages.
* errno: (libc)Checking for Errors.
* error: (libc)Error Messages.
* error_at_line: (libc)Error Messages.
* errx: (libc)Error Messages.
* execl: (libc)Executing a File.
* execle: (libc)Executing a File.
* execlp: (libc)Executing a File.
* execv: (libc)Executing a File.
* execve: (libc)Executing a File.
* execvp: (libc)Executing a File.
* exit: (libc)Normal Termination.
* exp10: (libc)Exponents and Logarithms.
* exp10f: (libc)Exponents and Logarithms.
* exp10l: (libc)Exponents and Logarithms.
* exp2: (libc)Exponents and Logarithms.
* exp2f: (libc)Exponents and Logarithms.
* exp2l: (libc)Exponents and Logarithms.
* exp: (libc)Exponents and Logarithms.
* expf: (libc)Exponents and Logarithms.
* expl: (libc)Exponents and Logarithms.
* expm1: (libc)Exponents and Logarithms.
* expm1f: (libc)Exponents and Logarithms.
* expm1l: (libc)Exponents and Logarithms.
* fabs: (libc)Absolute Value.
* fabsf: (libc)Absolute Value.
* fabsl: (libc)Absolute Value.
* fchdir: (libc)Working Directory.
* fchmod: (libc)Setting Permissions.
* fchown: (libc)File Owner.
* fclose: (libc)Closing Streams.
* fcloseall: (libc)Closing Streams.
* fcntl: (libc)Control Operations.
* fcvt: (libc)System V Number Conversion.
* fcvt_r: (libc)System V Number Conversion.
* fdatasync: (libc)Synchronizing I/O.
* fdim: (libc)Misc FP Arithmetic.
* fdimf: (libc)Misc FP Arithmetic.
* fdiml: (libc)Misc FP Arithmetic.
* fdopen: (libc)Descriptors and Streams.
* fdopendir: (libc)Opening a Directory.
* feclearexcept: (libc)Status bit operations.
* fedisableexcept: (libc)Control Functions.
* feenableexcept: (libc)Control Functions.
* fegetenv: (libc)Control Functions.
* fegetexcept: (libc)Control Functions.
* fegetexceptflag: (libc)Status bit operations.
* fegetround: (libc)Rounding.
* feholdexcept: (libc)Control Functions.
* feof: (libc)EOF and Errors.
* feof_unlocked: (libc)EOF and Errors.
* feraiseexcept: (libc)Status bit operations.
* ferror: (libc)EOF and Errors.
* ferror_unlocked: (libc)EOF and Errors.
* fesetenv: (libc)Control Functions.
* fesetexceptflag: (libc)Status bit operations.
* fesetround: (libc)Rounding.
* fetestexcept: (libc)Status bit operations.
* feupdateenv: (libc)Control Functions.
* fflush: (libc)Flushing Buffers.
* fflush_unlocked: (libc)Flushing Buffers.
* fgetc: (libc)Character Input.
* fgetc_unlocked: (libc)Character Input.
* fgetgrent: (libc)Scanning All Groups.
* fgetgrent_r: (libc)Scanning All Groups.
* fgetpos64: (libc)Portable Positioning.
* fgetpos: (libc)Portable Positioning.
* fgetpwent: (libc)Scanning All Users.
* fgetpwent_r: (libc)Scanning All Users.
* fgets: (libc)Line Input.
* fgets_unlocked: (libc)Line Input.
* fgetwc: (libc)Character Input.
* fgetwc_unlocked: (libc)Character Input.
* fgetws: (libc)Line Input.
* fgetws_unlocked: (libc)Line Input.
* fileno: (libc)Descriptors and Streams.
* fileno_unlocked: (libc)Descriptors and Streams.
* finite: (libc)Floating Point Classes.
* finitef: (libc)Floating Point Classes.
* finitel: (libc)Floating Point Classes.
* flockfile: (libc)Streams and Threads.
* floor: (libc)Rounding Functions.
* floorf: (libc)Rounding Functions.
* floorl: (libc)Rounding Functions.
* fma: (libc)Misc FP Arithmetic.
* fmaf: (libc)Misc FP Arithmetic.
* fmal: (libc)Misc FP Arithmetic.
* fmax: (libc)Misc FP Arithmetic.
* fmaxf: (libc)Misc FP Arithmetic.
* fmaxl: (libc)Misc FP Arithmetic.
* fmemopen: (libc)String Streams.
* fmin: (libc)Misc FP Arithmetic.
* fminf: (libc)Misc FP Arithmetic.
* fminl: (libc)Misc FP Arithmetic.
* fmod: (libc)Remainder Functions.
* fmodf: (libc)Remainder Functions.
* fmodl: (libc)Remainder Functions.
* fmtmsg: (libc)Printing Formatted Messages.
* fnmatch: (libc)Wildcard Matching.
* fopen64: (libc)Opening Streams.
* fopen: (libc)Opening Streams.
* fopencookie: (libc)Streams and Cookies.
* fork: (libc)Creating a Process.
* forkpty: (libc)Pseudo-Terminal Pairs.
* fpathconf: (libc)Pathconf.
* fpclassify: (libc)Floating Point Classes.
* fprintf: (libc)Formatted Output Functions.
* fputc: (libc)Simple Output.
* fputc_unlocked: (libc)Simple Output.
* fputs: (libc)Simple Output.
* fputs_unlocked: (libc)Simple Output.
* fputwc: (libc)Simple Output.
* fputwc_unlocked: (libc)Simple Output.
* fputws: (libc)Simple Output.
* fputws_unlocked: (libc)Simple Output.
* fread: (libc)Block Input/Output.
* fread_unlocked: (libc)Block Input/Output.
* free: (libc)Freeing after Malloc.
* freopen64: (libc)Opening Streams.
* freopen: (libc)Opening Streams.
* frexp: (libc)Normalization Functions.
* frexpf: (libc)Normalization Functions.
* frexpl: (libc)Normalization Functions.
* fscanf: (libc)Formatted Input Functions.
* fseek: (libc)File Positioning.
* fseeko64: (libc)File Positioning.
* fseeko: (libc)File Positioning.
* fsetpos64: (libc)Portable Positioning.
* fsetpos: (libc)Portable Positioning.
* fstat64: (libc)Reading Attributes.
* fstat: (libc)Reading Attributes.
* fsync: (libc)Synchronizing I/O.
* ftell: (libc)File Positioning.
* ftello64: (libc)File Positioning.
* ftello: (libc)File Positioning.
* ftruncate64: (libc)File Size.
* ftruncate: (libc)File Size.
* ftrylockfile: (libc)Streams and Threads.
* ftw64: (libc)Working with Directory Trees.
* ftw: (libc)Working with Directory Trees.
* funlockfile: (libc)Streams and Threads.
* futimes: (libc)File Times.
* fwide: (libc)Streams and I18N.
* fwprintf: (libc)Formatted Output Functions.
* fwrite: (libc)Block Input/Output.
* fwrite_unlocked: (libc)Block Input/Output.
* fwscanf: (libc)Formatted Input Functions.
* gamma: (libc)Special Functions.
* gammaf: (libc)Special Functions.
* gammal: (libc)Special Functions.
* gcvt: (libc)System V Number Conversion.
* get_avphys_pages: (libc)Query Memory Parameters.
* get_current_dir_name: (libc)Working Directory.
* get_nprocs: (libc)Processor Resources.
* get_nprocs_conf: (libc)Processor Resources.
* get_phys_pages: (libc)Query Memory Parameters.
* getauxval: (libc)Auxiliary Vector.
* getc: (libc)Character Input.
* getc_unlocked: (libc)Character Input.
* getchar: (libc)Character Input.
* getchar_unlocked: (libc)Character Input.
* getcontext: (libc)System V contexts.
* getcwd: (libc)Working Directory.
* getdate: (libc)General Time String Parsing.
* getdate_r: (libc)General Time String Parsing.
* getdelim: (libc)Line Input.
* getdomainnname: (libc)Host Identification.
* getegid: (libc)Reading Persona.
* getenv: (libc)Environment Access.
* geteuid: (libc)Reading Persona.
* getfsent: (libc)fstab.
* getfsfile: (libc)fstab.
* getfsspec: (libc)fstab.
* getgid: (libc)Reading Persona.
* getgrent: (libc)Scanning All Groups.
* getgrent_r: (libc)Scanning All Groups.
* getgrgid: (libc)Lookup Group.
* getgrgid_r: (libc)Lookup Group.
* getgrnam: (libc)Lookup Group.
* getgrnam_r: (libc)Lookup Group.
* getgrouplist: (libc)Setting Groups.
* getgroups: (libc)Reading Persona.
* gethostbyaddr: (libc)Host Names.
* gethostbyaddr_r: (libc)Host Names.
* gethostbyname2: (libc)Host Names.
* gethostbyname2_r: (libc)Host Names.
* gethostbyname: (libc)Host Names.
* gethostbyname_r: (libc)Host Names.
* gethostent: (libc)Host Names.
* gethostid: (libc)Host Identification.
* gethostname: (libc)Host Identification.
* getitimer: (libc)Setting an Alarm.
* getline: (libc)Line Input.
* getloadavg: (libc)Processor Resources.
* getlogin: (libc)Who Logged In.
* getmntent: (libc)mtab.
* getmntent_r: (libc)mtab.
* getnetbyaddr: (libc)Networks Database.
* getnetbyname: (libc)Networks Database.
* getnetent: (libc)Networks Database.
* getnetgrent: (libc)Lookup Netgroup.
* getnetgrent_r: (libc)Lookup Netgroup.
* getopt: (libc)Using Getopt.
* getopt_long: (libc)Getopt Long Options.
* getopt_long_only: (libc)Getopt Long Options.
* getpagesize: (libc)Query Memory Parameters.
* getpass: (libc)getpass.
* getpeername: (libc)Who is Connected.
* getpgid: (libc)Process Group Functions.
* getpgrp: (libc)Process Group Functions.
* getpgrp: (libc)Process Group Functions.
* getpid: (libc)Process Identification.
* getppid: (libc)Process Identification.
* getpriority: (libc)Traditional Scheduling Functions.
* getprotobyname: (libc)Protocols Database.
* getprotobynumber: (libc)Protocols Database.
* getprotoent: (libc)Protocols Database.
* getpt: (libc)Allocation.
* getpwent: (libc)Scanning All Users.
* getpwent_r: (libc)Scanning All Users.
* getpwnam: (libc)Lookup User.
* getpwnam_r: (libc)Lookup User.
* getpwuid: (libc)Lookup User.
* getpwuid_r: (libc)Lookup User.
* getrlimit64: (libc)Limits on Resources.
* getrlimit: (libc)Limits on Resources.
* getrusage: (libc)Resource Usage.
* gets: (libc)Line Input.
* getservbyname: (libc)Services Database.
* getservbyport: (libc)Services Database.
* getservent: (libc)Services Database.
* getsid: (libc)Process Group Functions.
* getsockname: (libc)Reading Address.
* getsockopt: (libc)Socket Option Functions.
* getsubopt: (libc)Suboptions.
* gettext: (libc)Translation with gettext.
* gettimeofday: (libc)High-Resolution Calendar.
* getuid: (libc)Reading Persona.
* getumask: (libc)Setting Permissions.
* getutent: (libc)Manipulating the Database.
* getutent_r: (libc)Manipulating the Database.
* getutid: (libc)Manipulating the Database.
* getutid_r: (libc)Manipulating the Database.
* getutline: (libc)Manipulating the Database.
* getutline_r: (libc)Manipulating the Database.
* getutmp: (libc)XPG Functions.
* getutmpx: (libc)XPG Functions.
* getutxent: (libc)XPG Functions.
* getutxid: (libc)XPG Functions.
* getutxline: (libc)XPG Functions.
* getw: (libc)Character Input.
* getwc: (libc)Character Input.
* getwc_unlocked: (libc)Character Input.
* getwchar: (libc)Character Input.
* getwchar_unlocked: (libc)Character Input.
* getwd: (libc)Working Directory.
* glob64: (libc)Calling Glob.
* glob: (libc)Calling Glob.
* globfree64: (libc)More Flags for Globbing.
* globfree: (libc)More Flags for Globbing.
* gmtime: (libc)Broken-down Time.
* gmtime_r: (libc)Broken-down Time.
* grantpt: (libc)Allocation.
* gsignal: (libc)Signaling Yourself.
* gtty: (libc)BSD Terminal Modes.
* hasmntopt: (libc)mtab.
* hcreate: (libc)Hash Search Function.
* hcreate_r: (libc)Hash Search Function.
* hdestroy: (libc)Hash Search Function.
* hdestroy_r: (libc)Hash Search Function.
* hsearch: (libc)Hash Search Function.
* hsearch_r: (libc)Hash Search Function.
* htonl: (libc)Byte Order.
* htons: (libc)Byte Order.
* hypot: (libc)Exponents and Logarithms.
* hypotf: (libc)Exponents and Logarithms.
* hypotl: (libc)Exponents and Logarithms.
* iconv: (libc)Generic Conversion Interface.
* iconv_close: (libc)Generic Conversion Interface.
* iconv_open: (libc)Generic Conversion Interface.
* if_freenameindex: (libc)Interface Naming.
* if_indextoname: (libc)Interface Naming.
* if_nameindex: (libc)Interface Naming.
* if_nametoindex: (libc)Interface Naming.
* ilogb: (libc)Exponents and Logarithms.
* ilogbf: (libc)Exponents and Logarithms.
* ilogbl: (libc)Exponents and Logarithms.
* imaxabs: (libc)Absolute Value.
* imaxdiv: (libc)Integer Division.
* in6addr_any: (libc)Host Address Data Type.
* in6addr_loopback: (libc)Host Address Data Type.
* index: (libc)Search Functions.
* inet_addr: (libc)Host Address Functions.
* inet_aton: (libc)Host Address Functions.
* inet_lnaof: (libc)Host Address Functions.
* inet_makeaddr: (libc)Host Address Functions.
* inet_netof: (libc)Host Address Functions.
* inet_network: (libc)Host Address Functions.
* inet_ntoa: (libc)Host Address Functions.
* inet_ntop: (libc)Host Address Functions.
* inet_pton: (libc)Host Address Functions.
* initgroups: (libc)Setting Groups.
* initstate: (libc)BSD Random.
* initstate_r: (libc)BSD Random.
* innetgr: (libc)Netgroup Membership.
* ioctl: (libc)IOCTLs.
* isalnum: (libc)Classification of Characters.
* isalpha: (libc)Classification of Characters.
* isascii: (libc)Classification of Characters.
* isatty: (libc)Is It a Terminal.
* isblank: (libc)Classification of Characters.
* iscntrl: (libc)Classification of Characters.
* isdigit: (libc)Classification of Characters.
* isfinite: (libc)Floating Point Classes.
* isgraph: (libc)Classification of Characters.
* isgreater: (libc)FP Comparison Functions.
* isgreaterequal: (libc)FP Comparison Functions.
* isinf: (libc)Floating Point Classes.
* isinff: (libc)Floating Point Classes.
* isinfl: (libc)Floating Point Classes.
* isless: (libc)FP Comparison Functions.
* islessequal: (libc)FP Comparison Functions.
* islessgreater: (libc)FP Comparison Functions.
* islower: (libc)Classification of Characters.
* isnan: (libc)Floating Point Classes.
* isnan: (libc)Floating Point Classes.
* isnanf: (libc)Floating Point Classes.
* isnanl: (libc)Floating Point Classes.
* isnormal: (libc)Floating Point Classes.
* isprint: (libc)Classification of Characters.
* ispunct: (libc)Classification of Characters.
* issignaling: (libc)Floating Point Classes.
* isspace: (libc)Classification of Characters.
* isunordered: (libc)FP Comparison Functions.
* isupper: (libc)Classification of Characters.
* iswalnum: (libc)Classification of Wide Characters.
* iswalpha: (libc)Classification of Wide Characters.
* iswblank: (libc)Classification of Wide Characters.
* iswcntrl: (libc)Classification of Wide Characters.
* iswctype: (libc)Classification of Wide Characters.
* iswdigit: (libc)Classification of Wide Characters.
* iswgraph: (libc)Classification of Wide Characters.
* iswlower: (libc)Classification of Wide Characters.
* iswprint: (libc)Classification of Wide Characters.
* iswpunct: (libc)Classification of Wide Characters.
* iswspace: (libc)Classification of Wide Characters.
* iswupper: (libc)Classification of Wide Characters.
* iswxdigit: (libc)Classification of Wide Characters.
* isxdigit: (libc)Classification of Characters.
* j0: (libc)Special Functions.
* j0f: (libc)Special Functions.
* j0l: (libc)Special Functions.
* j1: (libc)Special Functions.
* j1f: (libc)Special Functions.
* j1l: (libc)Special Functions.
* jn: (libc)Special Functions.
* jnf: (libc)Special Functions.
* jnl: (libc)Special Functions.
* jrand48: (libc)SVID Random.
* jrand48_r: (libc)SVID Random.
* kill: (libc)Signaling Another Process.
* killpg: (libc)Signaling Another Process.
* l64a: (libc)Encode Binary Data.
* labs: (libc)Absolute Value.
* lcong48: (libc)SVID Random.
* lcong48_r: (libc)SVID Random.
* ldexp: (libc)Normalization Functions.
* ldexpf: (libc)Normalization Functions.
* ldexpl: (libc)Normalization Functions.
* ldiv: (libc)Integer Division.
* lfind: (libc)Array Search Function.
* lgamma: (libc)Special Functions.
* lgamma_r: (libc)Special Functions.
* lgammaf: (libc)Special Functions.
* lgammaf_r: (libc)Special Functions.
* lgammal: (libc)Special Functions.
* lgammal_r: (libc)Special Functions.
* link: (libc)Hard Links.
* lio_listio64: (libc)Asynchronous Reads/Writes.
* lio_listio: (libc)Asynchronous Reads/Writes.
* listen: (libc)Listening.
* llabs: (libc)Absolute Value.
* lldiv: (libc)Integer Division.
* llrint: (libc)Rounding Functions.
* llrintf: (libc)Rounding Functions.
* llrintl: (libc)Rounding Functions.
* llround: (libc)Rounding Functions.
* llroundf: (libc)Rounding Functions.
* llroundl: (libc)Rounding Functions.
* localeconv: (libc)The Lame Way to Locale Data.
* localtime: (libc)Broken-down Time.
* localtime_r: (libc)Broken-down Time.
* log10: (libc)Exponents and Logarithms.
* log10f: (libc)Exponents and Logarithms.
* log10l: (libc)Exponents and Logarithms.
* log1p: (libc)Exponents and Logarithms.
* log1pf: (libc)Exponents and Logarithms.
* log1pl: (libc)Exponents and Logarithms.
* log2: (libc)Exponents and Logarithms.
* log2f: (libc)Exponents and Logarithms.
* log2l: (libc)Exponents and Logarithms.
* log: (libc)Exponents and Logarithms.
* logb: (libc)Exponents and Logarithms.
* logbf: (libc)Exponents and Logarithms.
* logbl: (libc)Exponents and Logarithms.
* logf: (libc)Exponents and Logarithms.
* login: (libc)Logging In and Out.
* login_tty: (libc)Logging In and Out.
* logl: (libc)Exponents and Logarithms.
* logout: (libc)Logging In and Out.
* logwtmp: (libc)Logging In and Out.
* longjmp: (libc)Non-Local Details.
* lrand48: (libc)SVID Random.
* lrand48_r: (libc)SVID Random.
* lrint: (libc)Rounding Functions.
* lrintf: (libc)Rounding Functions.
* lrintl: (libc)Rounding Functions.
* lround: (libc)Rounding Functions.
* lroundf: (libc)Rounding Functions.
* lroundl: (libc)Rounding Functions.
* lsearch: (libc)Array Search Function.
* lseek64: (libc)File Position Primitive.
* lseek: (libc)File Position Primitive.
* lstat64: (libc)Reading Attributes.
* lstat: (libc)Reading Attributes.
* lutimes: (libc)File Times.
* madvise: (libc)Memory-mapped I/O.
* makecontext: (libc)System V contexts.
* mallinfo: (libc)Statistics of Malloc.
* malloc: (libc)Basic Allocation.
* mallopt: (libc)Malloc Tunable Parameters.
* mblen: (libc)Non-reentrant Character Conversion.
* mbrlen: (libc)Converting a Character.
* mbrtowc: (libc)Converting a Character.
* mbsinit: (libc)Keeping the state.
* mbsnrtowcs: (libc)Converting Strings.
* mbsrtowcs: (libc)Converting Strings.
* mbstowcs: (libc)Non-reentrant String Conversion.
* mbtowc: (libc)Non-reentrant Character Conversion.
* mcheck: (libc)Heap Consistency Checking.
* memalign: (libc)Aligned Memory Blocks.
* memccpy: (libc)Copying and Concatenation.
* memchr: (libc)Search Functions.
* memcmp: (libc)String/Array Comparison.
* memcpy: (libc)Copying and Concatenation.
* memfrob: (libc)Trivial Encryption.
* memmem: (libc)Search Functions.
* memmove: (libc)Copying and Concatenation.
* mempcpy: (libc)Copying and Concatenation.
* memrchr: (libc)Search Functions.
* memset: (libc)Copying and Concatenation.
* mkdir: (libc)Creating Directories.
* mkdtemp: (libc)Temporary Files.
* mkfifo: (libc)FIFO Special Files.
* mknod: (libc)Making Special Files.
* mkstemp: (libc)Temporary Files.
* mktemp: (libc)Temporary Files.
* mktime: (libc)Broken-down Time.
* mlock: (libc)Page Lock Functions.
* mlockall: (libc)Page Lock Functions.
* mmap64: (libc)Memory-mapped I/O.
* mmap: (libc)Memory-mapped I/O.
* modf: (libc)Rounding Functions.
* modff: (libc)Rounding Functions.
* modfl: (libc)Rounding Functions.
* mount: (libc)Mount-Unmount-Remount.
* mprobe: (libc)Heap Consistency Checking.
* mrand48: (libc)SVID Random.
* mrand48_r: (libc)SVID Random.
* mremap: (libc)Memory-mapped I/O.
* msync: (libc)Memory-mapped I/O.
* mtrace: (libc)Tracing malloc.
* munlock: (libc)Page Lock Functions.
* munlockall: (libc)Page Lock Functions.
* munmap: (libc)Memory-mapped I/O.
* muntrace: (libc)Tracing malloc.
* nan: (libc)FP Bit Twiddling.
* nanf: (libc)FP Bit Twiddling.
* nanl: (libc)FP Bit Twiddling.
* nanosleep: (libc)Sleeping.
* nearbyint: (libc)Rounding Functions.
* nearbyintf: (libc)Rounding Functions.
* nearbyintl: (libc)Rounding Functions.
* nextafter: (libc)FP Bit Twiddling.
* nextafterf: (libc)FP Bit Twiddling.
* nextafterl: (libc)FP Bit Twiddling.
* nexttoward: (libc)FP Bit Twiddling.
* nexttowardf: (libc)FP Bit Twiddling.
* nexttowardl: (libc)FP Bit Twiddling.
* nftw64: (libc)Working with Directory Trees.
* nftw: (libc)Working with Directory Trees.
* ngettext: (libc)Advanced gettext functions.
* nice: (libc)Traditional Scheduling Functions.
* nl_langinfo: (libc)The Elegant and Fast Way.
* nrand48: (libc)SVID Random.
* nrand48_r: (libc)SVID Random.
* ntohl: (libc)Byte Order.
* ntohs: (libc)Byte Order.
* ntp_adjtime: (libc)High Accuracy Clock.
* ntp_gettime: (libc)High Accuracy Clock.
* obstack_1grow: (libc)Growing Objects.
* obstack_1grow_fast: (libc)Extra Fast Growing.
* obstack_alignment_mask: (libc)Obstacks Data Alignment.
* obstack_alloc: (libc)Allocation in an Obstack.
* obstack_base: (libc)Status of an Obstack.
* obstack_blank: (libc)Growing Objects.
* obstack_blank_fast: (libc)Extra Fast Growing.
* obstack_chunk_size: (libc)Obstack Chunks.
* obstack_copy0: (libc)Allocation in an Obstack.
* obstack_copy: (libc)Allocation in an Obstack.
* obstack_finish: (libc)Growing Objects.
* obstack_free: (libc)Freeing Obstack Objects.
* obstack_grow0: (libc)Growing Objects.
* obstack_grow: (libc)Growing Objects.
* obstack_init: (libc)Preparing for Obstacks.
* obstack_int_grow: (libc)Growing Objects.
* obstack_int_grow_fast: (libc)Extra Fast Growing.
* obstack_next_free: (libc)Status of an Obstack.
* obstack_object_size: (libc)Growing Objects.
* obstack_object_size: (libc)Status of an Obstack.
* obstack_printf: (libc)Dynamic Output.
* obstack_ptr_grow: (libc)Growing Objects.
* obstack_ptr_grow_fast: (libc)Extra Fast Growing.
* obstack_room: (libc)Extra Fast Growing.
* obstack_vprintf: (libc)Variable Arguments Output.
* offsetof: (libc)Structure Measurement.
* on_exit: (libc)Cleanups on Exit.
* open64: (libc)Opening and Closing Files.
* open: (libc)Opening and Closing Files.
* open_memstream: (libc)String Streams.
* opendir: (libc)Opening a Directory.
* openlog: (libc)openlog.
* openpty: (libc)Pseudo-Terminal Pairs.
* parse_printf_format: (libc)Parsing a Template String.
* pathconf: (libc)Pathconf.
* pause: (libc)Using Pause.
* pclose: (libc)Pipe to a Subprocess.
* perror: (libc)Error Messages.
* pipe: (libc)Creating a Pipe.
* popen: (libc)Pipe to a Subprocess.
* posix_memalign: (libc)Aligned Memory Blocks.
* pow10: (libc)Exponents and Logarithms.
* pow10f: (libc)Exponents and Logarithms.
* pow10l: (libc)Exponents and Logarithms.
* pow: (libc)Exponents and Logarithms.
* powf: (libc)Exponents and Logarithms.
* powl: (libc)Exponents and Logarithms.
* pread64: (libc)I/O Primitives.
* pread: (libc)I/O Primitives.
* printf: (libc)Formatted Output Functions.
* printf_size: (libc)Predefined Printf Handlers.
* printf_size_info: (libc)Predefined Printf Handlers.
* psignal: (libc)Signal Messages.
* pthread_getattr_default_np: (libc)Default Thread Attributes.
* pthread_getattr_default_np: (libc)Default Thread Attributes.
* ptsname: (libc)Allocation.
* ptsname_r: (libc)Allocation.
* putc: (libc)Simple Output.
* putc_unlocked: (libc)Simple Output.
* putchar: (libc)Simple Output.
* putchar_unlocked: (libc)Simple Output.
* putenv: (libc)Environment Access.
* putpwent: (libc)Writing a User Entry.
* puts: (libc)Simple Output.
* pututline: (libc)Manipulating the Database.
* pututxline: (libc)XPG Functions.
* putw: (libc)Simple Output.
* putwc: (libc)Simple Output.
* putwc_unlocked: (libc)Simple Output.
* putwchar: (libc)Simple Output.
* putwchar_unlocked: (libc)Simple Output.
* pwrite64: (libc)I/O Primitives.
* pwrite: (libc)I/O Primitives.
* qecvt: (libc)System V Number Conversion.
* qecvt_r: (libc)System V Number Conversion.
* qfcvt: (libc)System V Number Conversion.
* qfcvt_r: (libc)System V Number Conversion.
* qgcvt: (libc)System V Number Conversion.
* qsort: (libc)Array Sort Function.
* raise: (libc)Signaling Yourself.
* rand: (libc)ISO Random.
* rand_r: (libc)ISO Random.
* random: (libc)BSD Random.
* random_r: (libc)BSD Random.
* rawmemchr: (libc)Search Functions.
* read: (libc)I/O Primitives.
* readdir64: (libc)Reading/Closing Directory.
* readdir64_r: (libc)Reading/Closing Directory.
* readdir: (libc)Reading/Closing Directory.
* readdir_r: (libc)Reading/Closing Directory.
* readlink: (libc)Symbolic Links.
* readv: (libc)Scatter-Gather.
* realloc: (libc)Changing Block Size.
* realpath: (libc)Symbolic Links.
* recv: (libc)Receiving Data.
* recvfrom: (libc)Receiving Datagrams.
* recvmsg: (libc)Receiving Datagrams.
* regcomp: (libc)POSIX Regexp Compilation.
* regerror: (libc)Regexp Cleanup.
* regexec: (libc)Matching POSIX Regexps.
* regfree: (libc)Regexp Cleanup.
* register_printf_function: (libc)Registering New Conversions.
* remainder: (libc)Remainder Functions.
* remainderf: (libc)Remainder Functions.
* remainderl: (libc)Remainder Functions.
* remove: (libc)Deleting Files.
* rename: (libc)Renaming Files.
* rewind: (libc)File Positioning.
* rewinddir: (libc)Random Access Directory.
* rindex: (libc)Search Functions.
* rint: (libc)Rounding Functions.
* rintf: (libc)Rounding Functions.
* rintl: (libc)Rounding Functions.
* rmdir: (libc)Deleting Files.
* round: (libc)Rounding Functions.
* roundf: (libc)Rounding Functions.
* roundl: (libc)Rounding Functions.
* rpmatch: (libc)Yes-or-No Questions.
* sbrk: (libc)Resizing the Data Segment.
* scalb: (libc)Normalization Functions.
* scalbf: (libc)Normalization Functions.
* scalbl: (libc)Normalization Functions.
* scalbln: (libc)Normalization Functions.
* scalblnf: (libc)Normalization Functions.
* scalblnl: (libc)Normalization Functions.
* scalbn: (libc)Normalization Functions.
* scalbnf: (libc)Normalization Functions.
* scalbnl: (libc)Normalization Functions.
* scandir64: (libc)Scanning Directory Content.
* scandir: (libc)Scanning Directory Content.
* scanf: (libc)Formatted Input Functions.
* sched_get_priority_max: (libc)Basic Scheduling Functions.
* sched_get_priority_min: (libc)Basic Scheduling Functions.
* sched_getaffinity: (libc)CPU Affinity.
* sched_getparam: (libc)Basic Scheduling Functions.
* sched_getscheduler: (libc)Basic Scheduling Functions.
* sched_rr_get_interval: (libc)Basic Scheduling Functions.
* sched_setaffinity: (libc)CPU Affinity.
* sched_setparam: (libc)Basic Scheduling Functions.
* sched_setscheduler: (libc)Basic Scheduling Functions.
* sched_yield: (libc)Basic Scheduling Functions.
* secure_getenv: (libc)Environment Access.
* seed48: (libc)SVID Random.
* seed48_r: (libc)SVID Random.
* seekdir: (libc)Random Access Directory.
* select: (libc)Waiting for I/O.
* send: (libc)Sending Data.
* sendmsg: (libc)Receiving Datagrams.
* sendto: (libc)Sending Datagrams.
* setbuf: (libc)Controlling Buffering.
* setbuffer: (libc)Controlling Buffering.
* setcontext: (libc)System V contexts.
* setdomainname: (libc)Host Identification.
* setegid: (libc)Setting Groups.
* setenv: (libc)Environment Access.
* seteuid: (libc)Setting User ID.
* setfsent: (libc)fstab.
* setgid: (libc)Setting Groups.
* setgrent: (libc)Scanning All Groups.
* setgroups: (libc)Setting Groups.
* sethostent: (libc)Host Names.
* sethostid: (libc)Host Identification.
* sethostname: (libc)Host Identification.
* setitimer: (libc)Setting an Alarm.
* setjmp: (libc)Non-Local Details.
* setkey: (libc)DES Encryption.
* setkey_r: (libc)DES Encryption.
* setlinebuf: (libc)Controlling Buffering.
* setlocale: (libc)Setting the Locale.
* setlogmask: (libc)setlogmask.
* setmntent: (libc)mtab.
* setnetent: (libc)Networks Database.
* setnetgrent: (libc)Lookup Netgroup.
* setpgid: (libc)Process Group Functions.
* setpgrp: (libc)Process Group Functions.
* setpriority: (libc)Traditional Scheduling Functions.
* setprotoent: (libc)Protocols Database.
* setpwent: (libc)Scanning All Users.
* setregid: (libc)Setting Groups.
* setreuid: (libc)Setting User ID.
* setrlimit64: (libc)Limits on Resources.
* setrlimit: (libc)Limits on Resources.
* setservent: (libc)Services Database.
* setsid: (libc)Process Group Functions.
* setsockopt: (libc)Socket Option Functions.
* setstate: (libc)BSD Random.
* setstate_r: (libc)BSD Random.
* settimeofday: (libc)High-Resolution Calendar.
* setuid: (libc)Setting User ID.
* setutent: (libc)Manipulating the Database.
* setutxent: (libc)XPG Functions.
* setvbuf: (libc)Controlling Buffering.
* shutdown: (libc)Closing a Socket.
* sigaction: (libc)Advanced Signal Handling.
* sigaddset: (libc)Signal Sets.
* sigaltstack: (libc)Signal Stack.
* sigblock: (libc)Blocking in BSD.
* sigdelset: (libc)Signal Sets.
* sigemptyset: (libc)Signal Sets.
* sigfillset: (libc)Signal Sets.
* siginterrupt: (libc)BSD Handler.
* sigismember: (libc)Signal Sets.
* siglongjmp: (libc)Non-Local Exits and Signals.
* sigmask: (libc)Blocking in BSD.
* signal: (libc)Basic Signal Handling.
* signbit: (libc)FP Bit Twiddling.
* significand: (libc)Normalization Functions.
* significandf: (libc)Normalization Functions.
* significandl: (libc)Normalization Functions.
* sigpause: (libc)Blocking in BSD.
* sigpending: (libc)Checking for Pending Signals.
* sigprocmask: (libc)Process Signal Mask.
* sigsetjmp: (libc)Non-Local Exits and Signals.
* sigsetmask: (libc)Blocking in BSD.
* sigstack: (libc)Signal Stack.
* sigsuspend: (libc)Sigsuspend.
* sigvec: (libc)BSD Handler.
* sin: (libc)Trig Functions.
* sincos: (libc)Trig Functions.
* sincosf: (libc)Trig Functions.
* sincosl: (libc)Trig Functions.
* sinf: (libc)Trig Functions.
* sinh: (libc)Hyperbolic Functions.
* sinhf: (libc)Hyperbolic Functions.
* sinhl: (libc)Hyperbolic Functions.
* sinl: (libc)Trig Functions.
* sleep: (libc)Sleeping.
* snprintf: (libc)Formatted Output Functions.
* socket: (libc)Creating a Socket.
* socketpair: (libc)Socket Pairs.
* sprintf: (libc)Formatted Output Functions.
* sqrt: (libc)Exponents and Logarithms.
* sqrtf: (libc)Exponents and Logarithms.
* sqrtl: (libc)Exponents and Logarithms.
* srand48: (libc)SVID Random.
* srand48_r: (libc)SVID Random.
* srand: (libc)ISO Random.
* srandom: (libc)BSD Random.
* srandom_r: (libc)BSD Random.
* sscanf: (libc)Formatted Input Functions.
* ssignal: (libc)Basic Signal Handling.
* stat64: (libc)Reading Attributes.
* stat: (libc)Reading Attributes.
* stime: (libc)Simple Calendar Time.
* stpcpy: (libc)Copying and Concatenation.
* stpncpy: (libc)Copying and Concatenation.
* strcasecmp: (libc)String/Array Comparison.
* strcasestr: (libc)Search Functions.
* strcat: (libc)Copying and Concatenation.
* strchr: (libc)Search Functions.
* strchrnul: (libc)Search Functions.
* strcmp: (libc)String/Array Comparison.
* strcoll: (libc)Collation Functions.
* strcpy: (libc)Copying and Concatenation.
* strcspn: (libc)Search Functions.
* strdup: (libc)Copying and Concatenation.
* strdupa: (libc)Copying and Concatenation.
* strerror: (libc)Error Messages.
* strerror_r: (libc)Error Messages.
* strfmon: (libc)Formatting Numbers.
* strfry: (libc)strfry.
* strftime: (libc)Formatting Calendar Time.
* strlen: (libc)String Length.
* strncasecmp: (libc)String/Array Comparison.
* strncat: (libc)Copying and Concatenation.
* strncmp: (libc)String/Array Comparison.
* strncpy: (libc)Copying and Concatenation.
* strndup: (libc)Copying and Concatenation.
* strndupa: (libc)Copying and Concatenation.
* strnlen: (libc)String Length.
* strpbrk: (libc)Search Functions.
* strptime: (libc)Low-Level Time String Parsing.
* strrchr: (libc)Search Functions.
* strsep: (libc)Finding Tokens in a String.
* strsignal: (libc)Signal Messages.
* strspn: (libc)Search Functions.
* strstr: (libc)Search Functions.
* strtod: (libc)Parsing of Floats.
* strtof: (libc)Parsing of Floats.
* strtoimax: (libc)Parsing of Integers.
* strtok: (libc)Finding Tokens in a String.
* strtok_r: (libc)Finding Tokens in a String.
* strtol: (libc)Parsing of Integers.
* strtold: (libc)Parsing of Floats.
* strtoll: (libc)Parsing of Integers.
* strtoq: (libc)Parsing of Integers.
* strtoul: (libc)Parsing of Integers.
* strtoull: (libc)Parsing of Integers.
* strtoumax: (libc)Parsing of Integers.
* strtouq: (libc)Parsing of Integers.
* strverscmp: (libc)String/Array Comparison.
* strxfrm: (libc)Collation Functions.
* stty: (libc)BSD Terminal Modes.
* swapcontext: (libc)System V contexts.
* swprintf: (libc)Formatted Output Functions.
* swscanf: (libc)Formatted Input Functions.
* symlink: (libc)Symbolic Links.
* sync: (libc)Synchronizing I/O.
* syscall: (libc)System Calls.
* sysconf: (libc)Sysconf Definition.
* sysctl: (libc)System Parameters.
* syslog: (libc)syslog; vsyslog.
* system: (libc)Running a Command.
* sysv_signal: (libc)Basic Signal Handling.
* tan: (libc)Trig Functions.
* tanf: (libc)Trig Functions.
* tanh: (libc)Hyperbolic Functions.
* tanhf: (libc)Hyperbolic Functions.
* tanhl: (libc)Hyperbolic Functions.
* tanl: (libc)Trig Functions.
* tcdrain: (libc)Line Control.
* tcflow: (libc)Line Control.
* tcflush: (libc)Line Control.
* tcgetattr: (libc)Mode Functions.
* tcgetpgrp: (libc)Terminal Access Functions.
* tcgetsid: (libc)Terminal Access Functions.
* tcsendbreak: (libc)Line Control.
* tcsetattr: (libc)Mode Functions.
* tcsetpgrp: (libc)Terminal Access Functions.
* tdelete: (libc)Tree Search Function.
* tdestroy: (libc)Tree Search Function.
* telldir: (libc)Random Access Directory.
* tempnam: (libc)Temporary Files.
* textdomain: (libc)Locating gettext catalog.
* tfind: (libc)Tree Search Function.
* tgamma: (libc)Special Functions.
* tgammaf: (libc)Special Functions.
* tgammal: (libc)Special Functions.
* time: (libc)Simple Calendar Time.
* timegm: (libc)Broken-down Time.
* timelocal: (libc)Broken-down Time.
* times: (libc)Processor Time.
* tmpfile64: (libc)Temporary Files.
* tmpfile: (libc)Temporary Files.
* tmpnam: (libc)Temporary Files.
* tmpnam_r: (libc)Temporary Files.
* toascii: (libc)Case Conversion.
* tolower: (libc)Case Conversion.
* toupper: (libc)Case Conversion.
* towctrans: (libc)Wide Character Case Conversion.
* towlower: (libc)Wide Character Case Conversion.
* towupper: (libc)Wide Character Case Conversion.
* trunc: (libc)Rounding Functions.
* truncate64: (libc)File Size.
* truncate: (libc)File Size.
* truncf: (libc)Rounding Functions.
* truncl: (libc)Rounding Functions.
* tsearch: (libc)Tree Search Function.
* ttyname: (libc)Is It a Terminal.
* ttyname_r: (libc)Is It a Terminal.
* twalk: (libc)Tree Search Function.
* tzset: (libc)Time Zone Functions.
* ulimit: (libc)Limits on Resources.
* umask: (libc)Setting Permissions.
* umount2: (libc)Mount-Unmount-Remount.
* umount: (libc)Mount-Unmount-Remount.
* uname: (libc)Platform Type.
* ungetc: (libc)How Unread.
* ungetwc: (libc)How Unread.
* unlink: (libc)Deleting Files.
* unlockpt: (libc)Allocation.
* unsetenv: (libc)Environment Access.
* updwtmp: (libc)Manipulating the Database.
* utime: (libc)File Times.
* utimes: (libc)File Times.
* utmpname: (libc)Manipulating the Database.
* utmpxname: (libc)XPG Functions.
* va_arg: (libc)Argument Macros.
* va_copy: (libc)Argument Macros.
* va_end: (libc)Argument Macros.
* va_start: (libc)Argument Macros.
* valloc: (libc)Aligned Memory Blocks.
* vasprintf: (libc)Variable Arguments Output.
* verr: (libc)Error Messages.
* verrx: (libc)Error Messages.
* versionsort64: (libc)Scanning Directory Content.
* versionsort: (libc)Scanning Directory Content.
* vfork: (libc)Creating a Process.
* vfprintf: (libc)Variable Arguments Output.
* vfscanf: (libc)Variable Arguments Input.
* vfwprintf: (libc)Variable Arguments Output.
* vfwscanf: (libc)Variable Arguments Input.
* vlimit: (libc)Limits on Resources.
* vprintf: (libc)Variable Arguments Output.
* vscanf: (libc)Variable Arguments Input.
* vsnprintf: (libc)Variable Arguments Output.
* vsprintf: (libc)Variable Arguments Output.
* vsscanf: (libc)Variable Arguments Input.
* vswprintf: (libc)Variable Arguments Output.
* vswscanf: (libc)Variable Arguments Input.
* vsyslog: (libc)syslog; vsyslog.
* vtimes: (libc)Resource Usage.
* vwarn: (libc)Error Messages.
* vwarnx: (libc)Error Messages.
* vwprintf: (libc)Variable Arguments Output.
* vwscanf: (libc)Variable Arguments Input.
* wait3: (libc)BSD Wait Functions.
* wait4: (libc)Process Completion.
* wait: (libc)Process Completion.
* waitpid: (libc)Process Completion.
* warn: (libc)Error Messages.
* warnx: (libc)Error Messages.
* wcpcpy: (libc)Copying and Concatenation.
* wcpncpy: (libc)Copying and Concatenation.
* wcrtomb: (libc)Converting a Character.
* wcscasecmp: (libc)String/Array Comparison.
* wcscat: (libc)Copying and Concatenation.
* wcschr: (libc)Search Functions.
* wcschrnul: (libc)Search Functions.
* wcscmp: (libc)String/Array Comparison.
* wcscoll: (libc)Collation Functions.
* wcscpy: (libc)Copying and Concatenation.
* wcscspn: (libc)Search Functions.
* wcsdup: (libc)Copying and Concatenation.
* wcsftime: (libc)Formatting Calendar Time.
* wcslen: (libc)String Length.
* wcsncasecmp: (libc)String/Array Comparison.
* wcsncat: (libc)Copying and Concatenation.
* wcsncmp: (libc)String/Array Comparison.
* wcsncpy: (libc)Copying and Concatenation.
* wcsnlen: (libc)String Length.
* wcsnrtombs: (libc)Converting Strings.
* wcspbrk: (libc)Search Functions.
* wcsrchr: (libc)Search Functions.
* wcsrtombs: (libc)Converting Strings.
* wcsspn: (libc)Search Functions.
* wcsstr: (libc)Search Functions.
* wcstod: (libc)Parsing of Floats.
* wcstof: (libc)Parsing of Floats.
* wcstoimax: (libc)Parsing of Integers.
* wcstok: (libc)Finding Tokens in a String.
* wcstol: (libc)Parsing of Integers.
* wcstold: (libc)Parsing of Floats.
* wcstoll: (libc)Parsing of Integers.
* wcstombs: (libc)Non-reentrant String Conversion.
* wcstoq: (libc)Parsing of Integers.
* wcstoul: (libc)Parsing of Integers.
* wcstoull: (libc)Parsing of Integers.
* wcstoumax: (libc)Parsing of Integers.
* wcstouq: (libc)Parsing of Integers.
* wcswcs: (libc)Search Functions.
* wcsxfrm: (libc)Collation Functions.
* wctob: (libc)Converting a Character.
* wctomb: (libc)Non-reentrant Character Conversion.
* wctrans: (libc)Wide Character Case Conversion.
* wctype: (libc)Classification of Wide Characters.
* wmemchr: (libc)Search Functions.
* wmemcmp: (libc)String/Array Comparison.
* wmemcpy: (libc)Copying and Concatenation.
* wmemmove: (libc)Copying and Concatenation.
* wmempcpy: (libc)Copying and Concatenation.
* wmemset: (libc)Copying and Concatenation.
* wordexp: (libc)Calling Wordexp.
* wordfree: (libc)Calling Wordexp.
* wprintf: (libc)Formatted Output Functions.
* write: (libc)I/O Primitives.
* writev: (libc)Scatter-Gather.
* wscanf: (libc)Formatted Input Functions.
* y0: (libc)Special Functions.
* y0f: (libc)Special Functions.
* y0l: (libc)Special Functions.
* y1: (libc)Special Functions.
* y1f: (libc)Special Functions.
* y1l: (libc)Special Functions.
* yn: (libc)Special Functions.
* ynf: (libc)Special Functions.
* ynl: (libc)Special Functions.
END-INFO-DIR-ENTRY
This file documents the GNU C Library.
This is `The GNU C Library Reference Manual', for version
2.18-2013.10 (EGLIBC).
Copyright (C) 1993-2013 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version
1.3 or any later version published by the Free Software Foundation;
with the Invariant Sections being "Free Software Needs Free
Documentation" and "GNU Lesser General Public License", the Front-Cover
texts being "A GNU Manual", and with the Back-Cover Texts as in (a)
below. A copy of the license is included in the section entitled "GNU
Free Documentation License".
(a) The FSF's Back-Cover Text is: "You have the freedom to copy and
modify this GNU manual. Buying copies from the FSF supports it in
developing GNU and promoting software freedom."

File: libc.info, Node: Sockets, Next: Low-Level Terminal Interface, Prev: Pipes and FIFOs, Up: Top
16 Sockets
**********
This chapter describes the GNU facilities for interprocess
communication using sockets.
A "socket" is a generalized interprocess communication channel.
Like a pipe, a socket is represented as a file descriptor. Unlike pipes
sockets support communication between unrelated processes, and even
between processes running on different machines that communicate over a
network. Sockets are the primary means of communicating with other
machines; `telnet', `rlogin', `ftp', `talk' and the other familiar
network programs use sockets.
Not all operating systems support sockets. In the GNU C Library, the
header file `sys/socket.h' exists regardless of the operating system,
and the socket functions always exist, but if the system does not
really support sockets these functions always fail.
*Incomplete:* We do not currently document the facilities for
broadcast messages or for configuring Internet interfaces. The
reentrant functions and some newer functions that are related to IPv6
aren't documented either so far.
* Menu:
* Socket Concepts:: Basic concepts you need to know about.
* Communication Styles::Stream communication, datagrams and other styles.
* Socket Addresses:: How socket names (``addresses'') work.
* Interface Naming:: Identifying specific network interfaces.
* Local Namespace:: Details about the local namespace.
* Internet Namespace:: Details about the Internet namespace.
* Misc Namespaces:: Other namespaces not documented fully here.
* Open/Close Sockets:: Creating sockets and destroying them.
* Connections:: Operations on sockets with connection state.
* Datagrams:: Operations on datagram sockets.
* Inetd:: Inetd is a daemon that starts servers on request.
The most convenient way to write a server
is to make it work with Inetd.
* Socket Options:: Miscellaneous low-level socket options.
* Networks Database:: Accessing the database of network names.

File: libc.info, Node: Socket Concepts, Next: Communication Styles, Up: Sockets
16.1 Socket Concepts
====================
When you create a socket, you must specify the style of communication
you want to use and the type of protocol that should implement it. The
"communication style" of a socket defines the user-level semantics of
sending and receiving data on the socket. Choosing a communication
style specifies the answers to questions such as these:
* *What are the units of data transmission?* Some communication
styles regard the data as a sequence of bytes with no larger
structure; others group the bytes into records (which are known in
this context as "packets").
* *Can data be lost during normal operation?* Some communication
styles guarantee that all the data sent arrives in the order it was
sent (barring system or network crashes); other styles occasionally
lose data as a normal part of operation, and may sometimes deliver
packets more than once or in the wrong order.
Designing a program to use unreliable communication styles usually
involves taking precautions to detect lost or misordered packets
and to retransmit data as needed.
* *Is communication entirely with one partner?* Some communication
styles are like a telephone call--you make a "connection" with one
remote socket and then exchange data freely. Other styles are
like mailing letters--you specify a destination address for each
message you send.
You must also choose a "namespace" for naming the socket. A socket
name ("address") is meaningful only in the context of a particular
namespace. In fact, even the data type to use for a socket name may
depend on the namespace. Namespaces are also called "domains", but we
avoid that word as it can be confused with other usage of the same
term. Each namespace has a symbolic name that starts with `PF_'. A
corresponding symbolic name starting with `AF_' designates the address
format for that namespace.
Finally you must choose the "protocol" to carry out the
communication. The protocol determines what low-level mechanism is used
to transmit and receive data. Each protocol is valid for a particular
namespace and communication style; a namespace is sometimes called a
"protocol family" because of this, which is why the namespace names
start with `PF_'.
The rules of a protocol apply to the data passing between two
programs, perhaps on different computers; most of these rules are
handled by the operating system and you need not know about them. What
you do need to know about protocols is this:
* In order to have communication between two sockets, they must
specify the _same_ protocol.
* Each protocol is meaningful with particular style/namespace
combinations and cannot be used with inappropriate combinations.
For example, the TCP protocol fits only the byte stream style of
communication and the Internet namespace.
* For each combination of style and namespace there is a "default
protocol", which you can request by specifying 0 as the protocol
number. And that's what you should normally do--use the default.
Throughout the following description at various places
variables/parameters to denote sizes are required. And here the trouble
starts. In the first implementations the type of these variables was
simply `int'. On most machines at that time an `int' was 32 bits wide,
which created a _de facto_ standard requiring 32-bit variables. This
is important since references to variables of this type are passed to
the kernel.
Then the POSIX people came and unified the interface with the words
"all size values are of type `size_t'". On 64-bit machines `size_t' is
64 bits wide, so pointers to variables were no longer possible.
The Unix98 specification provides a solution by introducing a type
`socklen_t'. This type is used in all of the cases that POSIX changed
to use `size_t'. The only requirement of this type is that it be an
unsigned type of at least 32 bits. Therefore, implementations which
require that references to 32-bit variables be passed can be as happy
as implementations which use 64-bit values.

File: libc.info, Node: Communication Styles, Next: Socket Addresses, Prev: Socket Concepts, Up: Sockets
16.2 Communication Styles
=========================
The GNU C Library includes support for several different kinds of
sockets, each with different characteristics. This section describes
the supported socket types. The symbolic constants listed here are
defined in `sys/socket.h'.
-- Macro: int SOCK_STREAM
The `SOCK_STREAM' style is like a pipe (*note Pipes and FIFOs::).
It operates over a connection with a particular remote socket and
transmits data reliably as a stream of bytes.
Use of this style is covered in detail in *note Connections::.
-- Macro: int SOCK_DGRAM
The `SOCK_DGRAM' style is used for sending individually-addressed
packets unreliably. It is the diametrical opposite of
`SOCK_STREAM'.
Each time you write data to a socket of this kind, that data
becomes one packet. Since `SOCK_DGRAM' sockets do not have
connections, you must specify the recipient address with each
packet.
The only guarantee that the system makes about your requests to
transmit data is that it will try its best to deliver each packet
you send. It may succeed with the sixth packet after failing with
the fourth and fifth packets; the seventh packet may arrive before
the sixth, and may arrive a second time after the sixth.
The typical use for `SOCK_DGRAM' is in situations where it is
acceptable to simply re-send a packet if no response is seen in a
reasonable amount of time.
*Note Datagrams::, for detailed information about how to use
datagram sockets.
-- Macro: int SOCK_RAW
This style provides access to low-level network protocols and
interfaces. Ordinary user programs usually have no need to use
this style.

File: libc.info, Node: Socket Addresses, Next: Interface Naming, Prev: Communication Styles, Up: Sockets
16.3 Socket Addresses
=====================
The name of a socket is normally called an "address". The functions
and symbols for dealing with socket addresses were named
inconsistently, sometimes using the term "name" and sometimes using
"address". You can regard these terms as synonymous where sockets are
concerned.
A socket newly created with the `socket' function has no address.
Other processes can find it for communication only if you give it an
address. We call this "binding" the address to the socket, and the way
to do it is with the `bind' function.
You need be concerned with the address of a socket if other processes
are to find it and start communicating with it. You can specify an
address for other sockets, but this is usually pointless; the first time
you send data from a socket, or use it to initiate a connection, the
system assigns an address automatically if you have not specified one.
Occasionally a client needs to specify an address because the server
discriminates based on address; for example, the rsh and rlogin
protocols look at the client's socket address and only bypass password
checking if it is less than `IPPORT_RESERVED' (*note Ports::).
The details of socket addresses vary depending on what namespace you
are using. *Note Local Namespace::, or *note Internet Namespace::, for
specific information.
Regardless of the namespace, you use the same functions `bind' and
`getsockname' to set and examine a socket's address. These functions
use a phony data type, `struct sockaddr *', to accept the address. In
practice, the address lives in a structure of some other data type
appropriate to the address format you are using, but you cast its
address to `struct sockaddr *' when you pass it to `bind'.
* Menu:
* Address Formats:: About `struct sockaddr'.
* Setting Address:: Binding an address to a socket.
* Reading Address:: Reading the address of a socket.

File: libc.info, Node: Address Formats, Next: Setting Address, Up: Socket Addresses
16.3.1 Address Formats
----------------------
The functions `bind' and `getsockname' use the generic data type
`struct sockaddr *' to represent a pointer to a socket address. You
can't use this data type effectively to interpret an address or
construct one; for that, you must use the proper data type for the
socket's namespace.
Thus, the usual practice is to construct an address of the proper
namespace-specific type, then cast a pointer to `struct sockaddr *'
when you call `bind' or `getsockname'.
The one piece of information that you can get from the `struct
sockaddr' data type is the "address format designator". This tells you
which data type to use to understand the address fully.
The symbols in this section are defined in the header file
`sys/socket.h'.
-- Data Type: struct sockaddr
The `struct sockaddr' type itself has the following members:
`short int sa_family'
This is the code for the address format of this address. It
identifies the format of the data which follows.
`char sa_data[14]'
This is the actual socket address data, which is
format-dependent. Its length also depends on the format, and
may well be more than 14. The length 14 of `sa_data' is
essentially arbitrary.
Each address format has a symbolic name which starts with `AF_'.
Each of them corresponds to a `PF_' symbol which designates the
corresponding namespace. Here is a list of address format names:
`AF_LOCAL'
This designates the address format that goes with the local
namespace. (`PF_LOCAL' is the name of that namespace.) *Note
Local Namespace Details::, for information about this address
format.
`AF_UNIX'
This is a synonym for `AF_LOCAL'. Although `AF_LOCAL' is mandated
by POSIX.1g, `AF_UNIX' is portable to more systems. `AF_UNIX' was
the traditional name stemming from BSD, so even most POSIX systems
support it. It is also the name of choice in the Unix98
specification. (The same is true for `PF_UNIX' vs. `PF_LOCAL').
`AF_FILE'
This is another synonym for `AF_LOCAL', for compatibility.
(`PF_FILE' is likewise a synonym for `PF_LOCAL'.)
`AF_INET'
This designates the address format that goes with the Internet
namespace. (`PF_INET' is the name of that namespace.) *Note
Internet Address Formats::.
`AF_INET6'
This is similar to `AF_INET', but refers to the IPv6 protocol.
(`PF_INET6' is the name of the corresponding namespace.)
`AF_UNSPEC'
This designates no particular address format. It is used only in
rare cases, such as to clear out the default destination address
of a "connected" datagram socket. *Note Sending Datagrams::.
The corresponding namespace designator symbol `PF_UNSPEC' exists
for completeness, but there is no reason to use it in a program.
`sys/socket.h' defines symbols starting with `AF_' for many
different kinds of networks, most or all of which are not actually
implemented. We will document those that really work as we receive
information about how to use them.

File: libc.info, Node: Setting Address, Next: Reading Address, Prev: Address Formats, Up: Socket Addresses
16.3.2 Setting the Address of a Socket
--------------------------------------
Use the `bind' function to assign an address to a socket. The
prototype for `bind' is in the header file `sys/socket.h'. For
examples of use, see *note Local Socket Example::, or see *note Inet
Example::.
-- Function: int bind (int SOCKET, struct sockaddr *ADDR, socklen_t
LENGTH)
The `bind' function assigns an address to the socket SOCKET. The
ADDR and LENGTH arguments specify the address; the detailed format
of the address depends on the namespace. The first part of the
address is always the format designator, which specifies a
namespace, and says that the address is in the format of that
namespace.
The return value is `0' on success and `-1' on failure. The
following `errno' error conditions are defined for this function:
`EBADF'
The SOCKET argument is not a valid file descriptor.
`ENOTSOCK'
The descriptor SOCKET is not a socket.
`EADDRNOTAVAIL'
The specified address is not available on this machine.
`EADDRINUSE'
Some other socket is already using the specified address.
`EINVAL'
The socket SOCKET already has an address.
`EACCES'
You do not have permission to access the requested address.
(In the Internet domain, only the super-user is allowed to
specify a port number in the range 0 through
`IPPORT_RESERVED' minus one; see *note Ports::.)
Additional conditions may be possible depending on the particular
namespace of the socket.

File: libc.info, Node: Reading Address, Prev: Setting Address, Up: Socket Addresses
16.3.3 Reading the Address of a Socket
--------------------------------------
Use the function `getsockname' to examine the address of an Internet
socket. The prototype for this function is in the header file
`sys/socket.h'.
-- Function: int getsockname (int SOCKET, struct sockaddr *ADDR,
socklen_t *LENGTH-PTR)
The `getsockname' function returns information about the address
of the socket SOCKET in the locations specified by the ADDR and
LENGTH-PTR arguments. Note that the LENGTH-PTR is a pointer; you
should initialize it to be the allocation size of ADDR, and on
return it contains the actual size of the address data.
The format of the address data depends on the socket namespace.
The length of the information is usually fixed for a given
namespace, so normally you can know exactly how much space is
needed and can provide that much. The usual practice is to
allocate a place for the value using the proper data type for the
socket's namespace, then cast its address to `struct sockaddr *'
to pass it to `getsockname'.
The return value is `0' on success and `-1' on error. The
following `errno' error conditions are defined for this function:
`EBADF'
The SOCKET argument is not a valid file descriptor.
`ENOTSOCK'
The descriptor SOCKET is not a socket.
`ENOBUFS'
There are not enough internal buffers available for the
operation.
You can't read the address of a socket in the file namespace. This
is consistent with the rest of the system; in general, there's no way to
find a file's name from a descriptor for that file.

File: libc.info, Node: Interface Naming, Next: Local Namespace, Prev: Socket Addresses, Up: Sockets
16.4 Interface Naming
=====================
Each network interface has a name. This usually consists of a few
letters that relate to the type of interface, which may be followed by a
number if there is more than one interface of that type. Examples
might be `lo' (the loopback interface) and `eth0' (the first Ethernet
interface).
Although such names are convenient for humans, it would be clumsy to
have to use them whenever a program needs to refer to an interface. In
such situations an interface is referred to by its "index", which is an
arbitrarily-assigned small positive integer.
The following functions, constants and data types are declared in the
header file `net/if.h'.
-- Constant: size_t IFNAMSIZ
This constant defines the maximum buffer size needed to hold an
interface name, including its terminating zero byte.
-- Function: unsigned int if_nametoindex (const char *IFNAME)
This function yields the interface index corresponding to a
particular name. If no interface exists with the name given, it
returns 0.
-- Function: char * if_indextoname (unsigned int IFINDEX, char *IFNAME)
This function maps an interface index to its corresponding name.
The returned name is placed in the buffer pointed to by `ifname',
which must be at least `IFNAMSIZ' bytes in length. If the index
was invalid, the function's return value is a null pointer,
otherwise it is `ifname'.
-- Data Type: struct if_nameindex
This data type is used to hold the information about a single
interface. It has the following members:
`unsigned int if_index;'
This is the interface index.
`char *if_name'
This is the null-terminated index name.
-- Function: struct if_nameindex * if_nameindex (void)
This function returns an array of `if_nameindex' structures, one
for every interface that is present. The end of the list is
indicated by a structure with an interface of 0 and a null name
pointer. If an error occurs, this function returns a null pointer.
The returned structure must be freed with `if_freenameindex' after
use.
-- Function: void if_freenameindex (struct if_nameindex *PTR)
This function frees the structure returned by an earlier call to
`if_nameindex'.

File: libc.info, Node: Local Namespace, Next: Internet Namespace, Prev: Interface Naming, Up: Sockets
16.5 The Local Namespace
========================
This section describes the details of the local namespace, whose
symbolic name (required when you create a socket) is `PF_LOCAL'. The
local namespace is also known as "Unix domain sockets". Another name
is file namespace since socket addresses are normally implemented as
file names.
* Menu:
* Concepts: Local Namespace Concepts. What you need to understand.
* Details: Local Namespace Details. Address format, symbolic names, etc.
* Example: Local Socket Example. Example of creating a socket.

File: libc.info, Node: Local Namespace Concepts, Next: Local Namespace Details, Up: Local Namespace
16.5.1 Local Namespace Concepts
-------------------------------
In the local namespace socket addresses are file names. You can specify
any file name you want as the address of the socket, but you must have
write permission on the directory containing it. It's common to put
these files in the `/tmp' directory.
One peculiarity of the local namespace is that the name is only used
when opening the connection; once open the address is not meaningful and
may not exist.
Another peculiarity is that you cannot connect to such a socket from
another machine-not even if the other machine shares the file system
which contains the name of the socket. You can see the socket in a
directory listing, but connecting to it never succeeds. Some programs
take advantage of this, such as by asking the client to send its own
process ID, and using the process IDs to distinguish between clients.
However, we recommend you not use this method in protocols you design,
as we might someday permit connections from other machines that mount
the same file systems. Instead, send each new client an identifying
number if you want it to have one.
After you close a socket in the local namespace, you should delete
the file name from the file system. Use `unlink' or `remove' to do
this; see *note Deleting Files::.
The local namespace supports just one protocol for any communication
style; it is protocol number `0'.

File: libc.info, Node: Local Namespace Details, Next: Local Socket Example, Prev: Local Namespace Concepts, Up: Local Namespace
16.5.2 Details of Local Namespace
---------------------------------
To create a socket in the local namespace, use the constant `PF_LOCAL'
as the NAMESPACE argument to `socket' or `socketpair'. This constant
is defined in `sys/socket.h'.
-- Macro: int PF_LOCAL
This designates the local namespace, in which socket addresses are
local names, and its associated family of protocols. `PF_Local'
is the macro used by Posix.1g.
-- Macro: int PF_UNIX
This is a synonym for `PF_LOCAL', for compatibility's sake.
-- Macro: int PF_FILE
This is a synonym for `PF_LOCAL', for compatibility's sake.
The structure for specifying socket names in the local namespace is
defined in the header file `sys/un.h':
-- Data Type: struct sockaddr_un
This structure is used to specify local namespace socket
addresses. It has the following members:
`short int sun_family'
This identifies the address family or format of the socket
address. You should store the value `AF_LOCAL' to designate
the local namespace. *Note Socket Addresses::.
`char sun_path[108]'
This is the file name to use.
*Incomplete:* Why is 108 a magic number? RMS suggests making
this a zero-length array and tweaking the following example
to use `alloca' to allocate an appropriate amount of storage
based on the length of the filename.
You should compute the LENGTH parameter for a socket address in the
local namespace as the sum of the size of the `sun_family' component
and the string length (_not_ the allocation size!) of the file name
string. This can be done using the macro `SUN_LEN':
-- Macro: int SUN_LEN (_struct sockaddr_un *_ PTR)
The macro computes the length of socket address in the local
namespace.

File: libc.info, Node: Local Socket Example, Prev: Local Namespace Details, Up: Local Namespace
16.5.3 Example of Local-Namespace Sockets
-----------------------------------------
Here is an example showing how to create and name a socket in the local
namespace.
#include <stddef.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/un.h>
int
make_named_socket (const char *filename)
{
struct sockaddr_un name;
int sock;
size_t size;
/* Create the socket. */
sock = socket (PF_LOCAL, SOCK_DGRAM, 0);
if (sock < 0)
{
perror ("socket");
exit (EXIT_FAILURE);
}
/* Bind a name to the socket. */
name.sun_family = AF_LOCAL;
strncpy (name.sun_path, filename, sizeof (name.sun_path));
name.sun_path[sizeof (name.sun_path) - 1] = '\0';
/* The size of the address is
the offset of the start of the filename,
plus its length (not including the terminating null byte).
Alternatively you can just do:
size = SUN_LEN (&name);
*/
size = (offsetof (struct sockaddr_un, sun_path)
+ strlen (name.sun_path));
if (bind (sock, (struct sockaddr *) &name, size) < 0)
{
perror ("bind");
exit (EXIT_FAILURE);
}
return sock;
}

File: libc.info, Node: Internet Namespace, Next: Misc Namespaces, Prev: Local Namespace, Up: Sockets
16.6 The Internet Namespace
===========================
This section describes the details of the protocols and socket naming
conventions used in the Internet namespace.
Originally the Internet namespace used only IP version 4 (IPv4).
With the growing number of hosts on the Internet, a new protocol with a
larger address space was necessary: IP version 6 (IPv6). IPv6
introduces 128-bit addresses (IPv4 has 32-bit addresses) and other
features, and will eventually replace IPv4.
To create a socket in the IPv4 Internet namespace, use the symbolic
name `PF_INET' of this namespace as the NAMESPACE argument to `socket'
or `socketpair'. For IPv6 addresses you need the macro `PF_INET6'.
These macros are defined in `sys/socket.h'.
-- Macro: int PF_INET
This designates the IPv4 Internet namespace and associated family
of protocols.
-- Macro: int PF_INET6
This designates the IPv6 Internet namespace and associated family
of protocols.
A socket address for the Internet namespace includes the following
components:
* The address of the machine you want to connect to. Internet
addresses can be specified in several ways; these are discussed in
*note Internet Address Formats::, *note Host Addresses:: and *note
Host Names::.
* A port number for that machine. *Note Ports::.
You must ensure that the address and port number are represented in a
canonical format called "network byte order". *Note Byte Order::, for
information about this.
* Menu:
* Internet Address Formats:: How socket addresses are specified in the
Internet namespace.
* Host Addresses:: All about host addresses of Internet host.
* Ports:: Internet port numbers.
* Services Database:: Ports may have symbolic names.
* Byte Order:: Different hosts may use different byte
ordering conventions; you need to
canonicalize host address and port number.
* Protocols Database:: Referring to protocols by name.
* Inet Example:: Putting it all together.

File: libc.info, Node: Internet Address Formats, Next: Host Addresses, Up: Internet Namespace
16.6.1 Internet Socket Address Formats
--------------------------------------
In the Internet namespace, for both IPv4 (`AF_INET') and IPv6
(`AF_INET6'), a socket address consists of a host address and a port on
that host. In addition, the protocol you choose serves effectively as
a part of the address because local port numbers are meaningful only
within a particular protocol.
The data types for representing socket addresses in the Internet
namespace are defined in the header file `netinet/in.h'.
-- Data Type: struct sockaddr_in
This is the data type used to represent socket addresses in the
Internet namespace. It has the following members:
`sa_family_t sin_family'
This identifies the address family or format of the socket
address. You should store the value `AF_INET' in this member.
*Note Socket Addresses::.
`struct in_addr sin_addr'
This is the Internet address of the host machine. *Note Host
Addresses::, and *note Host Names::, for how to get a value
to store here.
`unsigned short int sin_port'
This is the port number. *Note Ports::.
When you call `bind' or `getsockname', you should specify `sizeof
(struct sockaddr_in)' as the LENGTH parameter if you are using an IPv4
Internet namespace socket address.
-- Data Type: struct sockaddr_in6
This is the data type used to represent socket addresses in the
IPv6 namespace. It has the following members:
`sa_family_t sin6_family'
This identifies the address family or format of the socket
address. You should store the value of `AF_INET6' in this
member. *Note Socket Addresses::.
`struct in6_addr sin6_addr'
This is the IPv6 address of the host machine. *Note Host
Addresses::, and *note Host Names::, for how to get a value
to store here.
`uint32_t sin6_flowinfo'
This is a currently unimplemented field.
`uint16_t sin6_port'
This is the port number. *Note Ports::.

File: libc.info, Node: Host Addresses, Next: Ports, Prev: Internet Address Formats, Up: Internet Namespace
16.6.2 Host Addresses
---------------------
Each computer on the Internet has one or more "Internet addresses",
numbers which identify that computer among all those on the Internet.
Users typically write IPv4 numeric host addresses as sequences of four
numbers, separated by periods, as in `128.52.46.32', and IPv6 numeric
host addresses as sequences of up to eight numbers separated by colons,
as in `5f03:1200:836f:c100::1'.
Each computer also has one or more "host names", which are strings
of words separated by periods, as in `www.gnu.org'.
Programs that let the user specify a host typically accept both
numeric addresses and host names. To open a connection a program needs
a numeric address, and so must convert a host name to the numeric
address it stands for.
* Menu:
* Abstract Host Addresses:: What a host number consists of.
* Data type: Host Address Data Type. Data type for a host number.
* Functions: Host Address Functions. Functions to operate on them.
* Names: Host Names. Translating host names to host numbers.

File: libc.info, Node: Abstract Host Addresses, Next: Host Address Data Type, Up: Host Addresses
16.6.2.1 Internet Host Addresses
................................
Each computer on the Internet has one or more Internet addresses,
numbers which identify that computer among all those on the Internet.
An IPv4 Internet host address is a number containing four bytes of data.
Historically these are divided into two parts, a "network number" and a
"local network address number" within that network. In the mid-1990s
classless addresses were introduced which changed this behavior. Since
some functions implicitly expect the old definitions, we first describe
the class-based network and will then describe classless addresses.
IPv6 uses only classless addresses and therefore the following
paragraphs don't apply.
The class-based IPv4 network number consists of the first one, two or
three bytes; the rest of the bytes are the local address.
IPv4 network numbers are registered with the Network Information
Center (NIC), and are divided into three classes--A, B and C. The local
network address numbers of individual machines are registered with the
administrator of the particular network.
Class A networks have single-byte numbers in the range 0 to 127.
There are only a small number of Class A networks, but they can each
support a very large number of hosts. Medium-sized Class B networks
have two-byte network numbers, with the first byte in the range 128 to
191. Class C networks are the smallest; they have three-byte network
numbers, with the first byte in the range 192-255. Thus, the first 1,
2, or 3 bytes of an Internet address specify a network. The remaining
bytes of the Internet address specify the address within that network.
The Class A network 0 is reserved for broadcast to all networks. In
addition, the host number 0 within each network is reserved for
broadcast to all hosts in that network. These uses are obsolete now
but for compatibility reasons you shouldn't use network 0 and host
number 0.
The Class A network 127 is reserved for loopback; you can always use
the Internet address `127.0.0.1' to refer to the host machine.
Since a single machine can be a member of multiple networks, it can
have multiple Internet host addresses. However, there is never
supposed to be more than one machine with the same host address.
There are four forms of the "standard numbers-and-dots notation" for
Internet addresses:
`A.B.C.D'
This specifies all four bytes of the address individually and is
the commonly used representation.
`A.B.C'
The last part of the address, C, is interpreted as a 2-byte
quantity. This is useful for specifying host addresses in a Class
B network with network address number `A.B'.
`A.B'
The last part of the address, B, is interpreted as a 3-byte
quantity. This is useful for specifying host addresses in a Class
A network with network address number A.
`A'
If only one part is given, this corresponds directly to the host
address number.
Within each part of the address, the usual C conventions for
specifying the radix apply. In other words, a leading `0x' or `0X'
implies hexadecimal radix; a leading `0' implies octal; and otherwise
decimal radix is assumed.
Classless Addresses
...................
IPv4 addresses (and IPv6 addresses also) are now considered classless;
the distinction between classes A, B and C can be ignored. Instead an
IPv4 host address consists of a 32-bit address and a 32-bit mask. The
mask contains set bits for the network part and cleared bits for the
host part. The network part is contiguous from the left, with the
remaining bits representing the host. As a consequence, the netmask can
simply be specified as the number of set bits. Classes A, B and C are
just special cases of this general rule. For example, class A addresses
have a netmask of `255.0.0.0' or a prefix length of 8.
Classless IPv4 network addresses are written in numbers-and-dots
notation with the prefix length appended and a slash as separator. For
example the class A network 10 is written as `10.0.0.0/8'.
IPv6 Addresses
..............
IPv6 addresses contain 128 bits (IPv4 has 32 bits) of data. A host
address is usually written as eight 16-bit hexadecimal numbers that are
separated by colons. Two colons are used to abbreviate strings of
consecutive zeros. For example, the IPv6 loopback address
`0:0:0:0:0:0:0:1' can just be written as `::1'.

File: libc.info, Node: Host Address Data Type, Next: Host Address Functions, Prev: Abstract Host Addresses, Up: Host Addresses
16.6.2.2 Host Address Data Type
...............................
IPv4 Internet host addresses are represented in some contexts as
integers (type `uint32_t'). In other contexts, the integer is packaged
inside a structure of type `struct in_addr'. It would be better if the
usage were made consistent, but it is not hard to extract the integer
from the structure or put the integer into a structure.
You will find older code that uses `unsigned long int' for IPv4
Internet host addresses instead of `uint32_t' or `struct in_addr'.
Historically `unsigned long int' was a 32-bit number but with 64-bit
machines this has changed. Using `unsigned long int' might break the
code if it is used on machines where this type doesn't have 32 bits.
`uint32_t' is specified by Unix98 and guaranteed to have 32 bits.
IPv6 Internet host addresses have 128 bits and are packaged inside a
structure of type `struct in6_addr'.
The following basic definitions for Internet addresses are declared
in the header file `netinet/in.h':
-- Data Type: struct in_addr
This data type is used in certain contexts to contain an IPv4
Internet host address. It has just one field, named `s_addr',
which records the host address number as an `uint32_t'.
-- Macro: uint32_t INADDR_LOOPBACK
You can use this constant to stand for "the address of this
machine," instead of finding its actual address. It is the IPv4
Internet address `127.0.0.1', which is usually called `localhost'.
This special constant saves you the trouble of looking up the
address of your own machine. Also, the system usually implements
`INADDR_LOOPBACK' specially, avoiding any network traffic for the
case of one machine talking to itself.
-- Macro: uint32_t INADDR_ANY
You can use this constant to stand for "any incoming address" when
binding to an address. *Note Setting Address::. This is the usual
address to give in the `sin_addr' member of `struct sockaddr_in'
when you want to accept Internet connections.
-- Macro: uint32_t INADDR_BROADCAST
This constant is the address you use to send a broadcast message.
-- Macro: uint32_t INADDR_NONE
This constant is returned by some functions to indicate an error.
-- Data Type: struct in6_addr
This data type is used to store an IPv6 address. It stores 128
bits of data, which can be accessed (via a union) in a variety of
ways.
-- Constant: struct in6_addr in6addr_loopback
This constant is the IPv6 address `::1', the loopback address. See
above for a description of what this means. The macro
`IN6ADDR_LOOPBACK_INIT' is provided to allow you to initialize your
own variables to this value.
-- Constant: struct in6_addr in6addr_any
This constant is the IPv6 address `::', the unspecified address.
See above for a description of what this means. The macro
`IN6ADDR_ANY_INIT' is provided to allow you to initialize your own
variables to this value.

File: libc.info, Node: Host Address Functions, Next: Host Names, Prev: Host Address Data Type, Up: Host Addresses
16.6.2.3 Host Address Functions
...............................
These additional functions for manipulating Internet addresses are
declared in the header file `arpa/inet.h'. They represent Internet
addresses in network byte order, and network numbers and
local-address-within-network numbers in host byte order. *Note Byte
Order::, for an explanation of network and host byte order.
-- Function: int inet_aton (const char *NAME, struct in_addr *ADDR)
This function converts the IPv4 Internet host address NAME from
the standard numbers-and-dots notation into binary data and stores
it in the `struct in_addr' that ADDR points to. `inet_aton'
returns nonzero if the address is valid, zero if not.
-- Function: uint32_t inet_addr (const char *NAME)
This function converts the IPv4 Internet host address NAME from the
standard numbers-and-dots notation into binary data. If the input
is not valid, `inet_addr' returns `INADDR_NONE'. This is an
obsolete interface to `inet_aton', described immediately above. It
is obsolete because `INADDR_NONE' is a valid address
(255.255.255.255), and `inet_aton' provides a cleaner way to
indicate error return.
-- Function: uint32_t inet_network (const char *NAME)
This function extracts the network number from the address NAME,
given in the standard numbers-and-dots notation. The returned
address is in host order. If the input is not valid,
`inet_network' returns `-1'.
The function works only with traditional IPv4 class A, B and C
network types. It doesn't work with classless addresses and
shouldn't be used anymore.
-- Function: char * inet_ntoa (struct in_addr ADDR)
This function converts the IPv4 Internet host address ADDR to a
string in the standard numbers-and-dots notation. The return
value is a pointer into a statically-allocated buffer. Subsequent
calls will overwrite the same buffer, so you should copy the
string if you need to save it.
In multi-threaded programs each thread has an own
statically-allocated buffer. But still subsequent calls of
`inet_ntoa' in the same thread will overwrite the result of the
last call.
Instead of `inet_ntoa' the newer function `inet_ntop' which is
described below should be used since it handles both IPv4 and IPv6
addresses.
-- Function: struct in_addr inet_makeaddr (uint32_t NET, uint32_t
LOCAL)
This function makes an IPv4 Internet host address by combining the
network number NET with the local-address-within-network number
LOCAL.
-- Function: uint32_t inet_lnaof (struct in_addr ADDR)
This function returns the local-address-within-network part of the
Internet host address ADDR.
The function works only with traditional IPv4 class A, B and C
network types. It doesn't work with classless addresses and
shouldn't be used anymore.
-- Function: uint32_t inet_netof (struct in_addr ADDR)
This function returns the network number part of the Internet host
address ADDR.
The function works only with traditional IPv4 class A, B and C
network types. It doesn't work with classless addresses and
shouldn't be used anymore.
-- Function: int inet_pton (int AF, const char *CP, void *BUF)
This function converts an Internet address (either IPv4 or IPv6)
from presentation (textual) to network (binary) format. AF should
be either `AF_INET' or `AF_INET6', as appropriate for the type of
address being converted. CP is a pointer to the input string, and
BUF is a pointer to a buffer for the result. It is the caller's
responsibility to make sure the buffer is large enough.
-- Function: const char * inet_ntop (int AF, const void *CP, char
*BUF, socklen_t LEN)
This function converts an Internet address (either IPv4 or IPv6)
from network (binary) to presentation (textual) form. AF should be
either `AF_INET' or `AF_INET6', as appropriate. CP is a pointer
to the address to be converted. BUF should be a pointer to a
buffer to hold the result, and LEN is the length of this buffer.
The return value from the function will be this buffer address.

File: libc.info, Node: Host Names, Prev: Host Address Functions, Up: Host Addresses
16.6.2.4 Host Names
...................
Besides the standard numbers-and-dots notation for Internet addresses,
you can also refer to a host by a symbolic name. The advantage of a
symbolic name is that it is usually easier to remember. For example,
the machine with Internet address `158.121.106.19' is also known as
`alpha.gnu.org'; and other machines in the `gnu.org' domain can refer
to it simply as `alpha'.
Internally, the system uses a database to keep track of the mapping
between host names and host numbers. This database is usually either
the file `/etc/hosts' or an equivalent provided by a name server. The
functions and other symbols for accessing this database are declared in
`netdb.h'. They are BSD features, defined unconditionally if you
include `netdb.h'.
-- Data Type: struct hostent
This data type is used to represent an entry in the hosts
database. It has the following members:
`char *h_name'
This is the "official" name of the host.
`char **h_aliases'
These are alternative names for the host, represented as a
null-terminated vector of strings.
`int h_addrtype'
This is the host address type; in practice, its value is
always either `AF_INET' or `AF_INET6', with the latter being
used for IPv6 hosts. In principle other kinds of addresses
could be represented in the database as well as Internet
addresses; if this were done, you might find a value in this
field other than `AF_INET' or `AF_INET6'. *Note Socket
Addresses::.
`int h_length'
This is the length, in bytes, of each address.
`char **h_addr_list'
This is the vector of addresses for the host. (Recall that
the host might be connected to multiple networks and have
different addresses on each one.) The vector is terminated
by a null pointer.
`char *h_addr'
This is a synonym for `h_addr_list[0]'; in other words, it is
the first host address.
As far as the host database is concerned, each address is just a
block of memory `h_length' bytes long. But in other contexts there is
an implicit assumption that you can convert IPv4 addresses to a `struct
in_addr' or an `uint32_t'. Host addresses in a `struct hostent'
structure are always given in network byte order; see *note Byte
Order::.
You can use `gethostbyname', `gethostbyname2' or `gethostbyaddr' to
search the hosts database for information about a particular host. The
information is returned in a statically-allocated structure; you must
copy the information if you need to save it across calls. You can also
use `getaddrinfo' and `getnameinfo' to obtain this information.
-- Function: struct hostent * gethostbyname (const char *NAME)
The `gethostbyname' function returns information about the host
named NAME. If the lookup fails, it returns a null pointer.
-- Function: struct hostent * gethostbyname2 (const char *NAME, int AF)
The `gethostbyname2' function is like `gethostbyname', but allows
the caller to specify the desired address family (e.g. `AF_INET'
or `AF_INET6') of the result.
-- Function: struct hostent * gethostbyaddr (const void *ADDR,
socklen_t LENGTH, int FORMAT)
The `gethostbyaddr' function returns information about the host
with Internet address ADDR. The parameter ADDR is not really a
pointer to char - it can be a pointer to an IPv4 or an IPv6
address. The LENGTH argument is the size (in bytes) of the address
at ADDR. FORMAT specifies the address format; for an IPv4
Internet address, specify a value of `AF_INET'; for an IPv6
Internet address, use `AF_INET6'.
If the lookup fails, `gethostbyaddr' returns a null pointer.
If the name lookup by `gethostbyname' or `gethostbyaddr' fails, you
can find out the reason by looking at the value of the variable
`h_errno'. (It would be cleaner design for these functions to set
`errno', but use of `h_errno' is compatible with other systems.)
Here are the error codes that you may find in `h_errno':
`HOST_NOT_FOUND'
No such host is known in the database.
`TRY_AGAIN'
This condition happens when the name server could not be
contacted. If you try again later, you may succeed then.
`NO_RECOVERY'
A non-recoverable error occurred.
`NO_ADDRESS'
The host database contains an entry for the name, but it doesn't
have an associated Internet address.
The lookup functions above all have one in common: they are not
reentrant and therefore unusable in multi-threaded applications.
Therefore provides the GNU C Library a new set of functions which can be
used in this context.
-- Function: int gethostbyname_r (const char *restrict NAME, struct
hostent *restrict RESULT_BUF, char *restrict BUF, size_t
BUFLEN, struct hostent **restrict RESULT, int *restrict
H_ERRNOP)
The `gethostbyname_r' function returns information about the host
named NAME. The caller must pass a pointer to an object of type
`struct hostent' in the RESULT_BUF parameter. In addition the
function may need extra buffer space and the caller must pass an
pointer and the size of the buffer in the BUF and BUFLEN
parameters.
A pointer to the buffer, in which the result is stored, is
available in `*RESULT' after the function call successfully
returned. If an error occurs or if no entry is found, the pointer
`*RESULT' is a null pointer. Success is signalled by a zero
return value. If the function failed the return value is an error
number. In addition to the errors defined for `gethostbyname' it
can also be `ERANGE'. In this case the call should be repeated
with a larger buffer. Additional error information is not stored
in the global variable `h_errno' but instead in the object pointed
to by H_ERRNOP.
Here's a small example:
struct hostent *
gethostname (char *host)
{
struct hostent hostbuf, *hp;
size_t hstbuflen;
char *tmphstbuf;
int res;
int herr;
hstbuflen = 1024;
/* Allocate buffer, remember to free it to avoid memory leakage. */
tmphstbuf = malloc (hstbuflen);
while ((res = gethostbyname_r (host, &hostbuf, tmphstbuf, hstbuflen,
&hp, &herr)) == ERANGE)
{
/* Enlarge the buffer. */
hstbuflen *= 2;
tmphstbuf = realloc (tmphstbuf, hstbuflen);
}
/* Check for errors. */
if (res || hp == NULL)
return NULL;
return hp;
}
-- Function: int gethostbyname2_r (const char *NAME, int AF, struct
hostent *restrict RESULT_BUF, char *restrict BUF, size_t
BUFLEN, struct hostent **restrict RESULT, int *restrict
H_ERRNOP)
The `gethostbyname2_r' function is like `gethostbyname_r', but
allows the caller to specify the desired address family (e.g.
`AF_INET' or `AF_INET6') for the result.
-- Function: int gethostbyaddr_r (const void *ADDR, socklen_t LENGTH,
int FORMAT, struct hostent *restrict RESULT_BUF, char
*restrict BUF, size_t BUFLEN, struct hostent **restrict
RESULT, int *restrict H_ERRNOP)
The `gethostbyaddr_r' function returns information about the host
with Internet address ADDR. The parameter ADDR is not really a
pointer to char - it can be a pointer to an IPv4 or an IPv6
address. The LENGTH argument is the size (in bytes) of the address
at ADDR. FORMAT specifies the address format; for an IPv4
Internet address, specify a value of `AF_INET'; for an IPv6
Internet address, use `AF_INET6'.
Similar to the `gethostbyname_r' function, the caller must provide
buffers for the result and memory used internally. In case of
success the function returns zero. Otherwise the value is an
error number where `ERANGE' has the special meaning that the
caller-provided buffer is too small.
You can also scan the entire hosts database one entry at a time using
`sethostent', `gethostent' and `endhostent'. Be careful when using
these functions because they are not reentrant.
-- Function: void sethostent (int STAYOPEN)
This function opens the hosts database to begin scanning it. You
can then call `gethostent' to read the entries.
If the STAYOPEN argument is nonzero, this sets a flag so that
subsequent calls to `gethostbyname' or `gethostbyaddr' will not
close the database (as they usually would). This makes for more
efficiency if you call those functions several times, by avoiding
reopening the database for each call.
-- Function: struct hostent * gethostent (void)
This function returns the next entry in the hosts database. It
returns a null pointer if there are no more entries.
-- Function: void endhostent (void)
This function closes the hosts database.

File: libc.info, Node: Ports, Next: Services Database, Prev: Host Addresses, Up: Internet Namespace
16.6.3 Internet Ports
---------------------
A socket address in the Internet namespace consists of a machine's
Internet address plus a "port number" which distinguishes the sockets
on a given machine (for a given protocol). Port numbers range from 0
to 65,535.
Port numbers less than `IPPORT_RESERVED' are reserved for standard
servers, such as `finger' and `telnet'. There is a database that keeps
track of these, and you can use the `getservbyname' function to map a
service name onto a port number; see *note Services Database::.
If you write a server that is not one of the standard ones defined in
the database, you must choose a port number for it. Use a number
greater than `IPPORT_USERRESERVED'; such numbers are reserved for
servers and won't ever be generated automatically by the system.
Avoiding conflicts with servers being run by other users is up to you.
When you use a socket without specifying its address, the system
generates a port number for it. This number is between
`IPPORT_RESERVED' and `IPPORT_USERRESERVED'.
On the Internet, it is actually legitimate to have two different
sockets with the same port number, as long as they never both try to
communicate with the same socket address (host address plus port
number). You shouldn't duplicate a port number except in special
circumstances where a higher-level protocol requires it. Normally, the
system won't let you do it; `bind' normally insists on distinct port
numbers. To reuse a port number, you must set the socket option
`SO_REUSEADDR'. *Note Socket-Level Options::.
These macros are defined in the header file `netinet/in.h'.
-- Macro: int IPPORT_RESERVED
Port numbers less than `IPPORT_RESERVED' are reserved for
superuser use.
-- Macro: int IPPORT_USERRESERVED
Port numbers greater than or equal to `IPPORT_USERRESERVED' are
reserved for explicit use; they will never be allocated
automatically.

File: libc.info, Node: Services Database, Next: Byte Order, Prev: Ports, Up: Internet Namespace
16.6.4 The Services Database
----------------------------
The database that keeps track of "well-known" services is usually
either the file `/etc/services' or an equivalent from a name server.
You can use these utilities, declared in `netdb.h', to access the
services database.
-- Data Type: struct servent
This data type holds information about entries from the services
database. It has the following members:
`char *s_name'
This is the "official" name of the service.
`char **s_aliases'
These are alternate names for the service, represented as an
array of strings. A null pointer terminates the array.
`int s_port'
This is the port number for the service. Port numbers are
given in network byte order; see *note Byte Order::.
`char *s_proto'
This is the name of the protocol to use with this service.
*Note Protocols Database::.
To get information about a particular service, use the
`getservbyname' or `getservbyport' functions. The information is
returned in a statically-allocated structure; you must copy the
information if you need to save it across calls.
-- Function: struct servent * getservbyname (const char *NAME, const
char *PROTO)
The `getservbyname' function returns information about the service
named NAME using protocol PROTO. If it can't find such a service,
it returns a null pointer.
This function is useful for servers as well as for clients; servers
use it to determine which port they should listen on (*note
Listening::).
-- Function: struct servent * getservbyport (int PORT, const char
*PROTO)
The `getservbyport' function returns information about the service
at port PORT using protocol PROTO. If it can't find such a
service, it returns a null pointer.
You can also scan the services database using `setservent',
`getservent' and `endservent'. Be careful when using these functions
because they are not reentrant.
-- Function: void setservent (int STAYOPEN)
This function opens the services database to begin scanning it.
If the STAYOPEN argument is nonzero, this sets a flag so that
subsequent calls to `getservbyname' or `getservbyport' will not
close the database (as they usually would). This makes for more
efficiency if you call those functions several times, by avoiding
reopening the database for each call.
-- Function: struct servent * getservent (void)
This function returns the next entry in the services database. If
there are no more entries, it returns a null pointer.
-- Function: void endservent (void)
This function closes the services database.

File: libc.info, Node: Byte Order, Next: Protocols Database, Prev: Services Database, Up: Internet Namespace
16.6.5 Byte Order Conversion
----------------------------
Different kinds of computers use different conventions for the ordering
of bytes within a word. Some computers put the most significant byte
within a word first (this is called "big-endian" order), and others put
it last ("little-endian" order).
So that machines with different byte order conventions can
communicate, the Internet protocols specify a canonical byte order
convention for data transmitted over the network. This is known as
"network byte order".
When establishing an Internet socket connection, you must make sure
that the data in the `sin_port' and `sin_addr' members of the
`sockaddr_in' structure are represented in network byte order. If you
are encoding integer data in the messages sent through the socket, you
should convert this to network byte order too. If you don't do this,
your program may fail when running on or talking to other kinds of
machines.
If you use `getservbyname' and `gethostbyname' or `inet_addr' to get
the port number and host address, the values are already in network
byte order, and you can copy them directly into the `sockaddr_in'
structure.
Otherwise, you have to convert the values explicitly. Use `htons'
and `ntohs' to convert values for the `sin_port' member. Use `htonl'
and `ntohl' to convert IPv4 addresses for the `sin_addr' member.
(Remember, `struct in_addr' is equivalent to `uint32_t'.) These
functions are declared in `netinet/in.h'.
-- Function: uint16_t htons (uint16_t HOSTSHORT)
This function converts the `uint16_t' integer HOSTSHORT from host
byte order to network byte order.
-- Function: uint16_t ntohs (uint16_t NETSHORT)
This function converts the `uint16_t' integer NETSHORT from
network byte order to host byte order.
-- Function: uint32_t htonl (uint32_t HOSTLONG)
This function converts the `uint32_t' integer HOSTLONG from host
byte order to network byte order.
This is used for IPv4 Internet addresses.
-- Function: uint32_t ntohl (uint32_t NETLONG)
This function converts the `uint32_t' integer NETLONG from network
byte order to host byte order.
This is used for IPv4 Internet addresses.

File: libc.info, Node: Protocols Database, Next: Inet Example, Prev: Byte Order, Up: Internet Namespace
16.6.6 Protocols Database
-------------------------
The communications protocol used with a socket controls low-level
details of how data are exchanged. For example, the protocol implements
things like checksums to detect errors in transmissions, and routing
instructions for messages. Normal user programs have little reason to
mess with these details directly.
The default communications protocol for the Internet namespace
depends on the communication style. For stream communication, the
default is TCP ("transmission control protocol"). For datagram
communication, the default is UDP ("user datagram protocol"). For
reliable datagram communication, the default is RDP ("reliable datagram
protocol"). You should nearly always use the default.
Internet protocols are generally specified by a name instead of a
number. The network protocols that a host knows about are stored in a
database. This is usually either derived from the file
`/etc/protocols', or it may be an equivalent provided by a name server.
You look up the protocol number associated with a named protocol in the
database using the `getprotobyname' function.
Here are detailed descriptions of the utilities for accessing the
protocols database. These are declared in `netdb.h'.
-- Data Type: struct protoent
This data type is used to represent entries in the network
protocols database. It has the following members:
`char *p_name'
This is the official name of the protocol.
`char **p_aliases'
These are alternate names for the protocol, specified as an
array of strings. The last element of the array is a null
pointer.
`int p_proto'
This is the protocol number (in host byte order); use this
member as the PROTOCOL argument to `socket'.
You can use `getprotobyname' and `getprotobynumber' to search the
protocols database for a specific protocol. The information is
returned in a statically-allocated structure; you must copy the
information if you need to save it across calls.
-- Function: struct protoent * getprotobyname (const char *NAME)
The `getprotobyname' function returns information about the
network protocol named NAME. If there is no such protocol, it
returns a null pointer.
-- Function: struct protoent * getprotobynumber (int PROTOCOL)
The `getprotobynumber' function returns information about the
network protocol with number PROTOCOL. If there is no such
protocol, it returns a null pointer.
You can also scan the whole protocols database one protocol at a
time by using `setprotoent', `getprotoent' and `endprotoent'. Be
careful when using these functions because they are not reentrant.
-- Function: void setprotoent (int STAYOPEN)
This function opens the protocols database to begin scanning it.
If the STAYOPEN argument is nonzero, this sets a flag so that
subsequent calls to `getprotobyname' or `getprotobynumber' will
not close the database (as they usually would). This makes for
more efficiency if you call those functions several times, by
avoiding reopening the database for each call.
-- Function: struct protoent * getprotoent (void)
This function returns the next entry in the protocols database. It
returns a null pointer if there are no more entries.
-- Function: void endprotoent (void)
This function closes the protocols database.

File: libc.info, Node: Inet Example, Prev: Protocols Database, Up: Internet Namespace
16.6.7 Internet Socket Example
------------------------------
Here is an example showing how to create and name a socket in the
Internet namespace. The newly created socket exists on the machine that
the program is running on. Rather than finding and using the machine's
Internet address, this example specifies `INADDR_ANY' as the host
address; the system replaces that with the machine's actual address.
#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
int
make_socket (uint16_t port)
{
int sock;
struct sockaddr_in name;
/* Create the socket. */
sock = socket (PF_INET, SOCK_STREAM, 0);
if (sock < 0)
{
perror ("socket");
exit (EXIT_FAILURE);
}
/* Give the socket a name. */
name.sin_family = AF_INET;
name.sin_port = htons (port);
name.sin_addr.s_addr = htonl (INADDR_ANY);
if (bind (sock, (struct sockaddr *) &name, sizeof (name)) < 0)
{
perror ("bind");
exit (EXIT_FAILURE);
}
return sock;
}
Here is another example, showing how you can fill in a `sockaddr_in'
structure, given a host name string and a port number:
#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
void
init_sockaddr (struct sockaddr_in *name,
const char *hostname,
uint16_t port)
{
struct hostent *hostinfo;
name->sin_family = AF_INET;
name->sin_port = htons (port);
hostinfo = gethostbyname (hostname);
if (hostinfo == NULL)
{
fprintf (stderr, "Unknown host %s.\n", hostname);
exit (EXIT_FAILURE);
}
name->sin_addr = *(struct in_addr *) hostinfo->h_addr;
}

File: libc.info, Node: Misc Namespaces, Next: Open/Close Sockets, Prev: Internet Namespace, Up: Sockets
16.7 Other Namespaces
=====================
Certain other namespaces and associated protocol families are supported
but not documented yet because they are not often used. `PF_NS' refers
to the Xerox Network Software protocols. `PF_ISO' stands for Open
Systems Interconnect. `PF_CCITT' refers to protocols from CCITT.
`socket.h' defines these symbols and others naming protocols not
actually implemented.
`PF_IMPLINK' is used for communicating between hosts and Internet
Message Processors. For information on this and `PF_ROUTE', an
occasionally-used local area routing protocol, see the GNU Hurd Manual
(to appear in the future).

File: libc.info, Node: Open/Close Sockets, Next: Connections, Prev: Misc Namespaces, Up: Sockets
16.8 Opening and Closing Sockets
================================
This section describes the actual library functions for opening and
closing sockets. The same functions work for all namespaces and
connection styles.
* Menu:
* Creating a Socket:: How to open a socket.
* Closing a Socket:: How to close a socket.
* Socket Pairs:: These are created like pipes.

File: libc.info, Node: Creating a Socket, Next: Closing a Socket, Up: Open/Close Sockets
16.8.1 Creating a Socket
------------------------
The primitive for creating a socket is the `socket' function, declared
in `sys/socket.h'.
-- Function: int socket (int NAMESPACE, int STYLE, int PROTOCOL)
This function creates a socket and specifies communication style
STYLE, which should be one of the socket styles listed in *note
Communication Styles::. The NAMESPACE argument specifies the
namespace; it must be `PF_LOCAL' (*note Local Namespace::) or
`PF_INET' (*note Internet Namespace::). PROTOCOL designates the
specific protocol (*note Socket Concepts::); zero is usually right
for PROTOCOL.
The return value from `socket' is the file descriptor for the new
socket, or `-1' in case of error. The following `errno' error
conditions are defined for this function:
`EPROTONOSUPPORT'
The PROTOCOL or STYLE is not supported by the NAMESPACE
specified.
`EMFILE'
The process already has too many file descriptors open.
`ENFILE'
The system already has too many file descriptors open.
`EACCES'
The process does not have the privilege to create a socket of
the specified STYLE or PROTOCOL.
`ENOBUFS'
The system ran out of internal buffer space.
The file descriptor returned by the `socket' function supports both
read and write operations. However, like pipes, sockets do not
support file positioning operations.
For examples of how to call the `socket' function, see *note Local
Socket Example::, or *note Inet Example::.

File: libc.info, Node: Closing a Socket, Next: Socket Pairs, Prev: Creating a Socket, Up: Open/Close Sockets
16.8.2 Closing a Socket
-----------------------
When you have finished using a socket, you can simply close its file
descriptor with `close'; see *note Opening and Closing Files::. If
there is still data waiting to be transmitted over the connection,
normally `close' tries to complete this transmission. You can control
this behavior using the `SO_LINGER' socket option to specify a timeout
period; see *note Socket Options::.
You can also shut down only reception or transmission on a
connection by calling `shutdown', which is declared in `sys/socket.h'.
-- Function: int shutdown (int SOCKET, int HOW)
The `shutdown' function shuts down the connection of socket
SOCKET. The argument HOW specifies what action to perform:
`0'
Stop receiving data for this socket. If further data arrives,
reject it.
`1'
Stop trying to transmit data from this socket. Discard any
data waiting to be sent. Stop looking for acknowledgement of
data already sent; don't retransmit it if it is lost.
`2'
Stop both reception and transmission.
The return value is `0' on success and `-1' on failure. The
following `errno' error conditions are defined for this function:
`EBADF'
SOCKET is not a valid file descriptor.
`ENOTSOCK'
SOCKET is not a socket.
`ENOTCONN'
SOCKET is not connected.

File: libc.info, Node: Socket Pairs, Prev: Closing a Socket, Up: Open/Close Sockets
16.8.3 Socket Pairs
-------------------
A "socket pair" consists of a pair of connected (but unnamed) sockets.
It is very similar to a pipe and is used in much the same way. Socket
pairs are created with the `socketpair' function, declared in
`sys/socket.h'. A socket pair is much like a pipe; the main difference
is that the socket pair is bidirectional, whereas the pipe has one
input-only end and one output-only end (*note Pipes and FIFOs::).
-- Function: int socketpair (int NAMESPACE, int STYLE, int PROTOCOL,
int FILEDES[2])
This function creates a socket pair, returning the file
descriptors in `FILEDES[0]' and `FILEDES[1]'. The socket pair is
a full-duplex communications channel, so that both reading and
writing may be performed at either end.
The NAMESPACE, STYLE and PROTOCOL arguments are interpreted as for
the `socket' function. STYLE should be one of the communication
styles listed in *note Communication Styles::. The NAMESPACE
argument specifies the namespace, which must be `AF_LOCAL' (*note
Local Namespace::); PROTOCOL specifies the communications
protocol, but zero is the only meaningful value.
If STYLE specifies a connectionless communication style, then the
two sockets you get are not _connected_, strictly speaking, but
each of them knows the other as the default destination address,
so they can send packets to each other.
The `socketpair' function returns `0' on success and `-1' on
failure. The following `errno' error conditions are defined for
this function:
`EMFILE'
The process has too many file descriptors open.
`EAFNOSUPPORT'
The specified namespace is not supported.
`EPROTONOSUPPORT'
The specified protocol is not supported.
`EOPNOTSUPP'
The specified protocol does not support the creation of
socket pairs.

File: libc.info, Node: Connections, Next: Datagrams, Prev: Open/Close Sockets, Up: Sockets
16.9 Using Sockets with Connections
===================================
The most common communication styles involve making a connection to a
particular other socket, and then exchanging data with that socket over
and over. Making a connection is asymmetric; one side (the "client")
acts to request a connection, while the other side (the "server") makes
a socket and waits for the connection request.
* Menu:
* Connecting:: What the client program must do.
* Listening:: How a server program waits for requests.
* Accepting Connections:: What the server does when it gets a request.
* Who is Connected:: Getting the address of the
other side of a connection.
* Transferring Data:: How to send and receive data.
* Byte Stream Example:: An example program: a client for communicating
over a byte stream socket in the Internet namespace.
* Server Example:: A corresponding server program.
* Out-of-Band Data:: This is an advanced feature.

File: libc.info, Node: Connecting, Next: Listening, Up: Connections
16.9.1 Making a Connection
--------------------------
In making a connection, the client makes a connection while the server
waits for and accepts the connection. Here we discuss what the client
program must do with the `connect' function, which is declared in
`sys/socket.h'.
-- Function: int connect (int SOCKET, struct sockaddr *ADDR, socklen_t
LENGTH)
The `connect' function initiates a connection from the socket with
file descriptor SOCKET to the socket whose address is specified by
the ADDR and LENGTH arguments. (This socket is typically on
another machine, and it must be already set up as a server.)
*Note Socket Addresses::, for information about how these
arguments are interpreted.
Normally, `connect' waits until the server responds to the request
before it returns. You can set nonblocking mode on the socket
SOCKET to make `connect' return immediately without waiting for
the response. *Note File Status Flags::, for information about
nonblocking mode.
The normal return value from `connect' is `0'. If an error
occurs, `connect' returns `-1'. The following `errno' error
conditions are defined for this function:
`EBADF'
The socket SOCKET is not a valid file descriptor.
`ENOTSOCK'
File descriptor SOCKET is not a socket.
`EADDRNOTAVAIL'
The specified address is not available on the remote machine.
`EAFNOSUPPORT'
The namespace of the ADDR is not supported by this socket.
`EISCONN'
The socket SOCKET is already connected.
`ETIMEDOUT'
The attempt to establish the connection timed out.
`ECONNREFUSED'
The server has actively refused to establish the connection.
`ENETUNREACH'
The network of the given ADDR isn't reachable from this host.
`EADDRINUSE'
The socket address of the given ADDR is already in use.
`EINPROGRESS'
The socket SOCKET is non-blocking and the connection could
not be established immediately. You can determine when the
connection is completely established with `select'; *note
Waiting for I/O::. Another `connect' call on the same
socket, before the connection is completely established, will
fail with `EALREADY'.
`EALREADY'
The socket SOCKET is non-blocking and already has a pending
connection in progress (see `EINPROGRESS' above).
This function is defined as a cancellation point in multi-threaded
programs, so one has to be prepared for this and make sure that
allocated resources (like memory, files descriptors, semaphores or
whatever) are freed even if the thread is canceled.

File: libc.info, Node: Listening, Next: Accepting Connections, Prev: Connecting, Up: Connections
16.9.2 Listening for Connections
--------------------------------
Now let us consider what the server process must do to accept
connections on a socket. First it must use the `listen' function to
enable connection requests on the socket, and then accept each incoming
connection with a call to `accept' (*note Accepting Connections::).
Once connection requests are enabled on a server socket, the `select'
function reports when the socket has a connection ready to be accepted
(*note Waiting for I/O::).
The `listen' function is not allowed for sockets using
connectionless communication styles.
You can write a network server that does not even start running
until a connection to it is requested. *Note Inetd Servers::.
In the Internet namespace, there are no special protection mechanisms
for controlling access to a port; any process on any machine can make a
connection to your server. If you want to restrict access to your
server, make it examine the addresses associated with connection
requests or implement some other handshaking or identification protocol.
In the local namespace, the ordinary file protection bits control
who has access to connect to the socket.
-- Function: int listen (int SOCKET, int N)
The `listen' function enables the socket SOCKET to accept
connections, thus making it a server socket.
The argument N specifies the length of the queue for pending
connections. When the queue fills, new clients attempting to
connect fail with `ECONNREFUSED' until the server calls `accept' to
accept a connection from the queue.
The `listen' function returns `0' on success and `-1' on failure.
The following `errno' error conditions are defined for this
function:
`EBADF'
The argument SOCKET is not a valid file descriptor.
`ENOTSOCK'
The argument SOCKET is not a socket.
`EOPNOTSUPP'
The socket SOCKET does not support this operation.

File: libc.info, Node: Accepting Connections, Next: Who is Connected, Prev: Listening, Up: Connections
16.9.3 Accepting Connections
----------------------------
When a server receives a connection request, it can complete the
connection by accepting the request. Use the function `accept' to do
this.
A socket that has been established as a server can accept connection
requests from multiple clients. The server's original socket _does not
become part of the connection_; instead, `accept' makes a new socket
which participates in the connection. `accept' returns the descriptor
for this socket. The server's original socket remains available for
listening for further connection requests.
The number of pending connection requests on a server socket is
finite. If connection requests arrive from clients faster than the
server can act upon them, the queue can fill up and additional requests
are refused with an `ECONNREFUSED' error. You can specify the maximum
length of this queue as an argument to the `listen' function, although
the system may also impose its own internal limit on the length of this
queue.
-- Function: int accept (int SOCKET, struct sockaddr *ADDR, socklen_t
*LENGTH_PTR)
This function is used to accept a connection request on the server
socket SOCKET.
The `accept' function waits if there are no connections pending,
unless the socket SOCKET has nonblocking mode set. (You can use
`select' to wait for a pending connection, with a nonblocking
socket.) *Note File Status Flags::, for information about
nonblocking mode.
The ADDR and LENGTH-PTR arguments are used to return information
about the name of the client socket that initiated the connection.
*Note Socket Addresses::, for information about the format of the
information.
Accepting a connection does not make SOCKET part of the
connection. Instead, it creates a new socket which becomes
connected. The normal return value of `accept' is the file
descriptor for the new socket.
After `accept', the original socket SOCKET remains open and
unconnected, and continues listening until you close it. You can
accept further connections with SOCKET by calling `accept' again.
If an error occurs, `accept' returns `-1'. The following `errno'
error conditions are defined for this function:
`EBADF'
The SOCKET argument is not a valid file descriptor.
`ENOTSOCK'
The descriptor SOCKET argument is not a socket.
`EOPNOTSUPP'
The descriptor SOCKET does not support this operation.
`EWOULDBLOCK'
SOCKET has nonblocking mode set, and there are no pending
connections immediately available.
This function is defined as a cancellation point in multi-threaded
programs, so one has to be prepared for this and make sure that
allocated resources (like memory, files descriptors, semaphores or
whatever) are freed even if the thread is canceled.
The `accept' function is not allowed for sockets using
connectionless communication styles.

File: libc.info, Node: Who is Connected, Next: Transferring Data, Prev: Accepting Connections, Up: Connections
16.9.4 Who is Connected to Me?
------------------------------
-- Function: int getpeername (int SOCKET, struct sockaddr *ADDR,
socklen_t *LENGTH-PTR)
The `getpeername' function returns the address of the socket that
SOCKET is connected to; it stores the address in the memory space
specified by ADDR and LENGTH-PTR. It stores the length of the
address in `*LENGTH-PTR'.
*Note Socket Addresses::, for information about the format of the
address. In some operating systems, `getpeername' works only for
sockets in the Internet domain.
The return value is `0' on success and `-1' on error. The
following `errno' error conditions are defined for this function:
`EBADF'
The argument SOCKET is not a valid file descriptor.
`ENOTSOCK'
The descriptor SOCKET is not a socket.
`ENOTCONN'
The socket SOCKET is not connected.
`ENOBUFS'
There are not enough internal buffers available.

File: libc.info, Node: Transferring Data, Next: Byte Stream Example, Prev: Who is Connected, Up: Connections
16.9.5 Transferring Data
------------------------
Once a socket has been connected to a peer, you can use the ordinary
`read' and `write' operations (*note I/O Primitives::) to transfer
data. A socket is a two-way communications channel, so read and write
operations can be performed at either end.
There are also some I/O modes that are specific to socket operations.
In order to specify these modes, you must use the `recv' and `send'
functions instead of the more generic `read' and `write' functions.
The `recv' and `send' functions take an additional argument which you
can use to specify various flags to control special I/O modes. For
example, you can specify the `MSG_OOB' flag to read or write
out-of-band data, the `MSG_PEEK' flag to peek at input, or the
`MSG_DONTROUTE' flag to control inclusion of routing information on
output.
* Menu:
* Sending Data:: Sending data with `send'.
* Receiving Data:: Reading data with `recv'.
* Socket Data Options:: Using `send' and `recv'.

File: libc.info, Node: Sending Data, Next: Receiving Data, Up: Transferring Data
16.9.5.1 Sending Data
.....................
The `send' function is declared in the header file `sys/socket.h'. If
your FLAGS argument is zero, you can just as well use `write' instead
of `send'; see *note I/O Primitives::. If the socket was connected but
the connection has broken, you get a `SIGPIPE' signal for any use of
`send' or `write' (*note Miscellaneous Signals::).
-- Function: ssize_t send (int SOCKET, const void *BUFFER, size_t
SIZE, int FLAGS)
The `send' function is like `write', but with the additional flags
FLAGS. The possible values of FLAGS are described in *note Socket
Data Options::.
This function returns the number of bytes transmitted, or `-1' on
failure. If the socket is nonblocking, then `send' (like `write')
can return after sending just part of the data. *Note File Status
Flags::, for information about nonblocking mode.
Note, however, that a successful return value merely indicates that
the message has been sent without error, not necessarily that it
has been received without error.
The following `errno' error conditions are defined for this
function:
`EBADF'
The SOCKET argument is not a valid file descriptor.
`EINTR'
The operation was interrupted by a signal before any data was
sent. *Note Interrupted Primitives::.
`ENOTSOCK'
The descriptor SOCKET is not a socket.
`EMSGSIZE'
The socket type requires that the message be sent atomically,
but the message is too large for this to be possible.
`EWOULDBLOCK'
Nonblocking mode has been set on the socket, and the write
operation would block. (Normally `send' blocks until the
operation can be completed.)
`ENOBUFS'
There is not enough internal buffer space available.
`ENOTCONN'
You never connected this socket.
`EPIPE'
This socket was connected but the connection is now broken.
In this case, `send' generates a `SIGPIPE' signal first; if
that signal is ignored or blocked, or if its handler returns,
then `send' fails with `EPIPE'.
This function is defined as a cancellation point in multi-threaded
programs, so one has to be prepared for this and make sure that
allocated resources (like memory, files descriptors, semaphores or
whatever) are freed even if the thread is canceled.

File: libc.info, Node: Receiving Data, Next: Socket Data Options, Prev: Sending Data, Up: Transferring Data
16.9.5.2 Receiving Data
.......................
The `recv' function is declared in the header file `sys/socket.h'. If
your FLAGS argument is zero, you can just as well use `read' instead of
`recv'; see *note I/O Primitives::.
-- Function: ssize_t recv (int SOCKET, void *BUFFER, size_t SIZE, int
FLAGS)
The `recv' function is like `read', but with the additional flags
FLAGS. The possible values of FLAGS are described in *note Socket
Data Options::.
If nonblocking mode is set for SOCKET, and no data are available to
be read, `recv' fails immediately rather than waiting. *Note File
Status Flags::, for information about nonblocking mode.
This function returns the number of bytes received, or `-1' on
failure. The following `errno' error conditions are defined for
this function:
`EBADF'
The SOCKET argument is not a valid file descriptor.
`ENOTSOCK'
The descriptor SOCKET is not a socket.
`EWOULDBLOCK'
Nonblocking mode has been set on the socket, and the read
operation would block. (Normally, `recv' blocks until there
is input available to be read.)
`EINTR'
The operation was interrupted by a signal before any data was
read. *Note Interrupted Primitives::.
`ENOTCONN'
You never connected this socket.
This function is defined as a cancellation point in multi-threaded
programs, so one has to be prepared for this and make sure that
allocated resources (like memory, files descriptors, semaphores or
whatever) are freed even if the thread is canceled.

File: libc.info, Node: Socket Data Options, Prev: Receiving Data, Up: Transferring Data
16.9.5.3 Socket Data Options
............................
The FLAGS argument to `send' and `recv' is a bit mask. You can
bitwise-OR the values of the following macros together to obtain a
value for this argument. All are defined in the header file
`sys/socket.h'.
-- Macro: int MSG_OOB
Send or receive out-of-band data. *Note Out-of-Band Data::.
-- Macro: int MSG_PEEK
Look at the data but don't remove it from the input queue. This is
only meaningful with input functions such as `recv', not with
`send'.
-- Macro: int MSG_DONTROUTE
Don't include routing information in the message. This is only
meaningful with output operations, and is usually only of interest
for diagnostic or routing programs. We don't try to explain it
here.

File: libc.info, Node: Byte Stream Example, Next: Server Example, Prev: Transferring Data, Up: Connections
16.9.6 Byte Stream Socket Example
---------------------------------
Here is an example client program that makes a connection for a byte
stream socket in the Internet namespace. It doesn't do anything
particularly interesting once it has connected to the server; it just
sends a text string to the server and exits.
This program uses `init_sockaddr' to set up the socket address; see
*note Inet Example::.
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#define PORT 5555
#define MESSAGE "Yow!!! Are we having fun yet?!?"
#define SERVERHOST "www.gnu.org"
void
write_to_server (int filedes)
{
int nbytes;
nbytes = write (filedes, MESSAGE, strlen (MESSAGE) + 1);
if (nbytes < 0)
{
perror ("write");
exit (EXIT_FAILURE);
}
}
int
main (void)
{
extern void init_sockaddr (struct sockaddr_in *name,
const char *hostname,
uint16_t port);
int sock;
struct sockaddr_in servername;
/* Create the socket. */
sock = socket (PF_INET, SOCK_STREAM, 0);
if (sock < 0)
{
perror ("socket (client)");
exit (EXIT_FAILURE);
}
/* Connect to the server. */
init_sockaddr (&servername, SERVERHOST, PORT);
if (0 > connect (sock,
(struct sockaddr *) &servername,
sizeof (servername)))
{
perror ("connect (client)");
exit (EXIT_FAILURE);
}
/* Send data to the server. */
write_to_server (sock);
close (sock);
exit (EXIT_SUCCESS);
}

File: libc.info, Node: Server Example, Next: Out-of-Band Data, Prev: Byte Stream Example, Up: Connections
16.9.7 Byte Stream Connection Server Example
--------------------------------------------
The server end is much more complicated. Since we want to allow
multiple clients to be connected to the server at the same time, it
would be incorrect to wait for input from a single client by simply
calling `read' or `recv'. Instead, the right thing to do is to use
`select' (*note Waiting for I/O::) to wait for input on all of the open
sockets. This also allows the server to deal with additional
connection requests.
This particular server doesn't do anything interesting once it has
gotten a message from a client. It does close the socket for that
client when it detects an end-of-file condition (resulting from the
client shutting down its end of the connection).
This program uses `make_socket' to set up the socket address; see
*note Inet Example::.
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#define PORT 5555
#define MAXMSG 512
int
read_from_client (int filedes)
{
char buffer[MAXMSG];
int nbytes;
nbytes = read (filedes, buffer, MAXMSG);
if (nbytes < 0)
{
/* Read error. */
perror ("read");
exit (EXIT_FAILURE);
}
else if (nbytes == 0)
/* End-of-file. */
return -1;
else
{
/* Data read. */
fprintf (stderr, "Server: got message: `%s'\n", buffer);
return 0;
}
}
int
main (void)
{
extern int make_socket (uint16_t port);
int sock;
fd_set active_fd_set, read_fd_set;
int i;
struct sockaddr_in clientname;
size_t size;
/* Create the socket and set it up to accept connections. */
sock = make_socket (PORT);
if (listen (sock, 1) < 0)
{
perror ("listen");
exit (EXIT_FAILURE);
}
/* Initialize the set of active sockets. */
FD_ZERO (&active_fd_set);
FD_SET (sock, &active_fd_set);
while (1)
{
/* Block until input arrives on one or more active sockets. */
read_fd_set = active_fd_set;
if (select (FD_SETSIZE, &read_fd_set, NULL, NULL, NULL) < 0)
{
perror ("select");
exit (EXIT_FAILURE);
}
/* Service all the sockets with input pending. */
for (i = 0; i < FD_SETSIZE; ++i)
if (FD_ISSET (i, &read_fd_set))
{
if (i == sock)
{
/* Connection request on original socket. */
int new;
size = sizeof (clientname);
new = accept (sock,
(struct sockaddr *) &clientname,
&size);
if (new < 0)
{
perror ("accept");
exit (EXIT_FAILURE);
}
fprintf (stderr,
"Server: connect from host %s, port %hd.\n",
inet_ntoa (clientname.sin_addr),
ntohs (clientname.sin_port));
FD_SET (new, &active_fd_set);
}
else
{
/* Data arriving on an already-connected socket. */
if (read_from_client (i) < 0)
{
close (i);
FD_CLR (i, &active_fd_set);
}
}
}
}
}

File: libc.info, Node: Out-of-Band Data, Prev: Server Example, Up: Connections
16.9.8 Out-of-Band Data
-----------------------
Streams with connections permit "out-of-band" data that is delivered
with higher priority than ordinary data. Typically the reason for
sending out-of-band data is to send notice of an exceptional condition.
To send out-of-band data use `send', specifying the flag `MSG_OOB'
(*note Sending Data::).
Out-of-band data are received with higher priority because the
receiving process need not read it in sequence; to read the next
available out-of-band data, use `recv' with the `MSG_OOB' flag (*note
Receiving Data::). Ordinary read operations do not read out-of-band
data; they read only ordinary data.
When a socket finds that out-of-band data are on their way, it sends
a `SIGURG' signal to the owner process or process group of the socket.
You can specify the owner using the `F_SETOWN' command to the `fcntl'
function; see *note Interrupt Input::. You must also establish a
handler for this signal, as described in *note Signal Handling::, in
order to take appropriate action such as reading the out-of-band data.
Alternatively, you can test for pending out-of-band data, or wait
until there is out-of-band data, using the `select' function; it can
wait for an exceptional condition on the socket. *Note Waiting for
I/O::, for more information about `select'.
Notification of out-of-band data (whether with `SIGURG' or with
`select') indicates that out-of-band data are on the way; the data may
not actually arrive until later. If you try to read the out-of-band
data before it arrives, `recv' fails with an `EWOULDBLOCK' error.
Sending out-of-band data automatically places a "mark" in the stream
of ordinary data, showing where in the sequence the out-of-band data
"would have been". This is useful when the meaning of out-of-band data
is "cancel everything sent so far". Here is how you can test, in the
receiving process, whether any ordinary data was sent before the mark:
success = ioctl (socket, SIOCATMARK, &atmark);
The `integer' variable ATMARK is set to a nonzero value if the
socket's read pointer has reached the "mark".
Here's a function to discard any ordinary data preceding the
out-of-band mark:
int
discard_until_mark (int socket)
{
while (1)
{
/* This is not an arbitrary limit; any size will do. */
char buffer[1024];
int atmark, success;
/* If we have reached the mark, return. */
success = ioctl (socket, SIOCATMARK, &atmark);
if (success < 0)
perror ("ioctl");
if (result)
return;
/* Otherwise, read a bunch of ordinary data and discard it.
This is guaranteed not to read past the mark
if it starts before the mark. */
success = read (socket, buffer, sizeof buffer);
if (success < 0)
perror ("read");
}
}
If you don't want to discard the ordinary data preceding the mark,
you may need to read some of it anyway, to make room in internal system
buffers for the out-of-band data. If you try to read out-of-band data
and get an `EWOULDBLOCK' error, try reading some ordinary data (saving
it so that you can use it when you want it) and see if that makes room.
Here is an example:
struct buffer
{
char *buf;
int size;
struct buffer *next;
};
/* Read the out-of-band data from SOCKET and return it
as a `struct buffer', which records the address of the data
and its size.
It may be necessary to read some ordinary data
in order to make room for the out-of-band data.
If so, the ordinary data are saved as a chain of buffers
found in the `next' field of the value. */
struct buffer *
read_oob (int socket)
{
struct buffer *tail = 0;
struct buffer *list = 0;
while (1)
{
/* This is an arbitrary limit.
Does anyone know how to do this without a limit? */
#define BUF_SZ 1024
char *buf = (char *) xmalloc (BUF_SZ);
int success;
int atmark;
/* Try again to read the out-of-band data. */
success = recv (socket, buf, BUF_SZ, MSG_OOB);
if (success >= 0)
{
/* We got it, so return it. */
struct buffer *link
= (struct buffer *) xmalloc (sizeof (struct buffer));
link->buf = buf;
link->size = success;
link->next = list;
return link;
}
/* If we fail, see if we are at the mark. */
success = ioctl (socket, SIOCATMARK, &atmark);
if (success < 0)
perror ("ioctl");
if (atmark)
{
/* At the mark; skipping past more ordinary data cannot help.
So just wait a while. */
sleep (1);
continue;
}
/* Otherwise, read a bunch of ordinary data and save it.
This is guaranteed not to read past the mark
if it starts before the mark. */
success = read (socket, buf, BUF_SZ);
if (success < 0)
perror ("read");
/* Save this data in the buffer list. */
{
struct buffer *link
= (struct buffer *) xmalloc (sizeof (struct buffer));
link->buf = buf;
link->size = success;
/* Add the new link to the end of the list. */
if (tail)
tail->next = link;
else