posix/unistd.h

   1 /* Copyright (C) 1991, 92, 93, 94, 95, 96 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.
   3
   4 The GNU C Library is free software; you can redistribute it and/or
   5 modify it under the terms of the GNU Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 License, or (at your option) any later version.
   8
   9 The GNU C Library is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 /*
  20  *      POSIX Standard: 2.10 Symbolic Constants         <unistd.h>
  21  */
  22
  23 #ifndef _UNISTD_H
  24
  25 #define _UNISTD_H       1
  26 #include <features.h>
  27
  28 __BEGIN_DECLS
  29
  30 /* These may be used to determine what facilities are present at compile time.
  31    Their values can be obtained at run time from sysconf.  */
  32
  33 /* POSIX Standard approved as IEEE Std 1003.1 as of August, 1988 and
  34    extended by P1003.1b (aka POSIX.4).  */
  35 #define _POSIX_VERSION  199309L
  36
  37 /* These are not #ifdef __USE_POSIX2 because they are
  38    in the theoretically application-owned namespace.  */
  39
  40 #define _POSIX2_C_VERSION       199912L /* Invalid until 1003.2 is done.  */
  41
  42 /* If defined, the implementation supports the
  43    C Language Bindings Option.  */
  44 #define _POSIX2_C_BIND  1
  45
  46 /* If defined, the implementation supports the
  47    C Language Development Utilities Option.  */
  48 #define _POSIX2_C_DEV   1
  49
  50 /* If defined, the implementation supports the
  51    Software Development Utilities Option.  */
  52 #define _POSIX2_SW_DEV  1
  53
  54 /* If defined, the implementation supports the
  55    creation of locales with the localedef utility.  */
  56 #define _POSIX2_LOCALEDEF       1
  57
  58
  59 /* Get values of POSIX options:
  60
  61    If these symbols are defined, the corresponding features are
  62    always available.  If not, they may be available sometimes.
  63    The current values can be obtained with `sysconf'.
  64
  65    _POSIX_JOB_CONTROL           Job control is supported.
  66    _POSIX_SAVED_IDS             Processes have a saved set-user-ID
  67                                 and a saved set-group-ID.
  68    _POSIX_REALTIME_SIGNALS      Real-time, queued signals are supported.
  69    _POSIX_PRIORITY_SCHEDULING   Priority scheduling is supported.
  70    _POSIX_TIMERS                POSIX.4 clocks and timers are supported.
  71    _POSIX_ASYNCHRONOUS_IO       Asynchronous I/O is supported.
  72    _POSIX_PRIORITIZED_IO        Prioritized asynchronous I/O is supported.
  73    _POSIX_SYNCHRONIZED_IO       Synchronizing file data is supported.
  74    _POSIX_FSYNC                 The fsync function is present.
  75    _POSIX_MAPPED_FILES          Mapping of files to memory is supported.
  76    _POSIX_MEMLOCK               Locking of all memory is supported.
  77    _POSIX_MEMLOCK_RANGE         Locking of ranges of memory is supported.
  78    _POSIX_MEMORY_PROTECTION     Setting of memory protections is supported.
  79    _POSIX_MESSAGE_PASSING       POSIX.4 message queues are supported.
  80    _POSIX_SEMAPHORES            POSIX.4 counting semaphores are supported.
  81    _POSIX_SHARED_MEMORY_OBJECTS POSIX.4 shared memory objects are supported.
  82
  83    If any of these symbols is defined as -1, the corresponding option is not
  84    true for any file.  If any is defined as other than -1, the corresponding
  85    option is true for all files.  If a symbol is not defined at all, the value
  86    for a specific file can be obtained from `pathconf' and `fpathconf'.
  87
  88    _POSIX_CHOWN_RESTRICTED      Only the super user can use `chown' to change
  89                                 the owner of a file.  `chown' can only be used
  90                                 to change the group ID of a file to a group of
  91                                 which the calling process is a member.
  92    _POSIX_NO_TRUNC              Pathname components longer than
  93                                 NAME_MAX generate an error.
  94    _POSIX_VDISABLE              If defined, if the value of an element of the
  95                                 `c_cc' member of `struct termios' is
  96                                 _POSIX_VDISABLE, no character will have the
  97                                 effect associated with that element.
  98    _POSIX_SYNC_IO               Synchronous I/O may be performed.
  99    _POSIX_ASYNC_IO              Asynchronous I/O may be performed.
 100    _POSIX_PRIO_IO               Prioritized Asynchronous I/O may be performed.
 101    */
 102
 103 #include <posix_opt.h>
 104
 105
 106 /* Standard file descriptors.  */
 107 #define STDIN_FILENO    0       /* Standard input.  */
 108 #define STDOUT_FILENO   1       /* Standard output.  */
 109 #define STDERR_FILENO   2       /* Standard error output.  */
 110
 111
 112 /* All functions that are not declared anywhere else.  */
 113
 114 #include <gnu/types.h>
 115
 116 #ifndef ssize_t
 117 #define ssize_t __ssize_t
 118 #endif
 119
 120 #define __need_size_t
 121 #define __need_NULL
 122 #include <stddef.h>
 123
 124
 125 /* Values for the second argument to access.
 126    These may be OR'd together.  */
 127 #define R_OK    4               /* Test for read permission.  */
 128 #define W_OK    2               /* Test for write permission.  */
 129 #define X_OK    1               /* Test for execute permission.  */
 130 #define F_OK    0               /* Test for existence.  */
 131
 132 /* Test for access to NAME using the real UID and real GID.  */
 133 extern int __access __P ((__const char *__name, int __type));
 134 extern int access __P ((__const char *__name, int __type));
 135
 136 #ifdef __USE_GNU
 137 /* Test for access to NAME using the effective UID and GID
 138    (as normal file operations use).  */
 139 extern int euidaccess __P ((__const char *__name, int __type));
 140 #endif
 141
 142
 143 /* Values for the WHENCE argument to lseek.  */
 144 #ifndef _STDIO_H                /* <stdio.h> has the same definitions.  */
 145 #define SEEK_SET        0       /* Seek from beginning of file.  */
 146 #define SEEK_CUR        1       /* Seek from current position.  */
 147 #define SEEK_END        2       /* Seek from end of file.  */
 148 #endif
 149
 150 #if defined (__USE_BSD) && !defined (L_SET)
 151 /* Old BSD names for the same constants; just for compatibility.  */
 152 #define L_SET           SEEK_SET
 153 #define L_INCR          SEEK_CUR
 154 #define L_XTND          SEEK_END
 155 #endif
 156
 157
 158 /* Move FD's file position to OFFSET bytes from the
 159    beginning of the file (if WHENCE is SEEK_SET),
 160    the current position (if WHENCE is SEEK_CUR),
 161    or the end of the file (if WHENCE is SEEK_END).
 162    Return the new file position.  */
 163 extern __off_t __lseek __P ((int __fd, __off_t __offset, int __whence));
 164 extern __off_t lseek __P ((int __fd, __off_t __offset, int __whence));
 165
 166 /* Close the file descriptor FD.  */
 167 extern int __close __P ((int __fd));
 168 extern int close __P ((int __fd));
 169
 170 /* Read NBYTES into BUF from FD.  Return the
 171    number read, -1 for errors or 0 for EOF.  */
 172 extern ssize_t __read __P ((int __fd, __ptr_t __buf, size_t __nbytes));
 173 extern ssize_t read __P ((int __fd, __ptr_t __buf, size_t __nbytes));
 174
 175 /* Write N bytes of BUF to FD.  Return the number written, or -1.  */
 176 extern ssize_t __write __P ((int __fd, __const __ptr_t __buf, size_t __n));
 177 extern ssize_t write __P ((int __fd, __const __ptr_t __buf, size_t __n));
 178
 179
 180 /* Create a one-way communication channel (pipe).
 181    If successul, two file descriptors are stored in PIPEDES;
 182    bytes written on PIPEDES[1] can be read from PIPEDES[0].
 183    Returns 0 if successful, -1 if not.  */
 184 extern int __pipe __P ((int __pipedes[2]));
 185 extern int pipe __P ((int __pipedes[2]));
 186
 187 /* Schedule an alarm.  In SECONDS seconds, the process will get a SIGALRM.
 188    If SECONDS is zero, any currently scheduled alarm will be cancelled.
 189    The function returns the number of seconds remaining until the last
 190    alarm scheduled would have signaled, or zero if there wasn't one.
 191    There is no return value to indicate an error, but you can set `errno'
 192    to 0 and check its value after calling `alarm', and this might tell you.
 193    The signal may come late due to processor scheduling.  */
 194 extern unsigned int alarm __P ((unsigned int __seconds));
 195
 196 /* Make the process sleep for SECONDS seconds, or until a signal arrives
 197    and is not ignored.  The function returns the number of seconds less
 198    than SECONDS which it actually slept (thus zero if it slept the full time).
 199    If a signal handler does a `longjmp' or modifies the handling of the
 200    SIGALRM signal while inside `sleep' call, the handling of the SIGALRM
 201    signal afterwards is undefined.  There is no return value to indicate
 202    error, but if `sleep' returns SECONDS, it probably didn't work.  */
 203 extern unsigned int sleep __P ((unsigned int __seconds));
 204
 205 #ifdef __USE_BSD
 206 /* Sleep USECONDS microseconds, or until a signal arrives that is not blocked
 207    or ignored.  Return value is not necessarily useful.  */
 208 extern unsigned int usleep __P ((unsigned __useconds));
 209 #endif
 210
 211
 212 /* Suspend the process until a signal arrives.
 213    This always returns -1 and sets `errno' to EINTR.  */
 214 extern int pause __P ((void));
 215
 216
 217 /* Change the owner and group of FILE.  */
 218 extern int __chown __P ((__const char *__file,
 219                          __uid_t __owner, __gid_t __group));
 220 extern int chown __P ((__const char *__file,
 221                        __uid_t __owner, __gid_t __group));
 222
 223 #ifdef  __USE_BSD
 224 /* Change the owner and group of the file that FD is open on.  */
 225 extern int __fchown __P ((int __fd,
 226                           __uid_t __owner, __gid_t __group));
 227 extern int fchown __P ((int __fd,
 228                         __uid_t __owner, __gid_t __group));
 229 #endif /* Use BSD.  */
 230
 231 /* Change the process's working directory to PATH.  */
 232 extern int __chdir __P ((__const char *__path));
 233 extern int chdir __P ((__const char *__path));
 234
 235 #ifdef __USE_BSD
 236 /* Change the process's working directory to the one FD is open on.  */
 237 extern int fchdir __P ((int __fd));
 238 #endif
 239
 240 /* Get the pathname of the current working directory,
 241    and put it in SIZE bytes of BUF.  Returns NULL if the
 242    directory couldn't be determined or SIZE was too small.
 243    If successful, returns BUF.  In GNU, if BUF is NULL,
 244    an array is allocated with `malloc'; the array is SIZE
 245    bytes long, unless SIZE <= 0, in which case it is as
 246    big as necessary.  */
 247 extern char *__getcwd __P ((char *__buf, size_t __size));
 248 extern char *getcwd __P ((char *__buf, size_t __size));
 249
 250 #ifdef  __USE_GNU
 251 /* Return a malloc'd string containing the current directory name.
 252    If the environment variable `PWD' is set, and its value is correct,
 253    that value is used.  */
 254 extern char *get_current_dir_name __P ((void));
 255 #endif
 256
 257 #ifdef  __USE_BSD
 258 /* Put the absolute pathname of the current working directory in BUF.
 259    If successful, return BUF.  If not, put an error message in
 260    BUF and return NULL.  BUF should be at least PATH_MAX bytes long.  */
 261 extern char *getwd __P ((char *__buf));
 262 #endif
 263
 264
 265 /* Duplicate FD, returning a new file descriptor on the same file.  */
 266 extern int __dup __P ((int __fd));
 267 extern int dup __P ((int __fd));
 268
 269 /* Duplicate FD to FD2, closing FD2 and making it open on the same file.  */
 270 extern int __dup2 __P ((int __fd, int __fd2));
 271 extern int dup2 __P ((int __fd, int __fd2));
 272
 273 /* NULL-terminated array of "NAME=VALUE" environment variables.  */
 274 extern char **__environ;
 275 extern char **environ;
 276
 277
 278 /* Replace the current process, executing PATH with arguments ARGV and
 279    environment ENVP.  ARGV and ENVP are terminated by NULL pointers.  */
 280 extern int __execve __P ((__const char *__path, char *__const __argv[],
 281                           char *__const __envp[]));
 282 extern int execve __P ((__const char *__path, char *__const __argv[],
 283                         char *__const __envp[]));
 284
 285 #ifdef __USE_GNU
 286 /* Execute the file FD refers to, overlaying the running program image.
 287    ARGV and ENVP are passed to the new program, as for `execve'.  */
 288 extern int fexecve __P ((int __fd,
 289                          char *const __argv[], char *const __envp[]));
 290
 291 #endif
 292
 293
 294 /* Execute PATH with arguments ARGV and environment from `environ'.  */
 295 extern int execv __P ((__const char *__path, char *__const __argv[]));
 296
 297 /* Execute PATH with all arguments after PATH until a NULL pointer,
 298    and the argument after that for environment.  */
 299 extern int execle __P ((__const char *__path, __const char *__arg,...));
 300
 301 /* Execute PATH with all arguments after PATH until
 302    a NULL pointer and environment from `environ'.  */
 303 extern int execl __P ((__const char *__path, __const char *__arg,...));
 304
 305 /* Execute FILE, searching in the `PATH' environment variable if it contains
 306    no slashes, with arguments ARGV and environment from `environ'.  */
 307 extern int execvp __P ((__const char *__file, char *__const __argv[]));
 308
 309 /* Execute FILE, searching in the `PATH' environment variable if
 310    it contains no slashes, with all arguments after FILE until a
 311    NULL pointer and environment from `environ'.  */
 312 extern int execlp __P ((__const char *__file, ...));
 313
 314
 315 /* Terminate program execution with the low-order 8 bits of STATUS.  */
 316 extern void _exit __P ((int __status)) __attribute__ ((__noreturn__));
 317
 318
 319 /* Get the `_PC_*' symbols for the NAME argument to `pathconf' and `fpathconf';
 320    the `_SC_*' symbols for the NAME argument to `sysconf';
 321    and the `_CS_*' symbols for the NAME argument to `confstr'.  */
 322 #include <confname.h>
 323
 324 /* Get file-specific configuration information about PATH.  */
 325 extern long int __pathconf __P ((__const char *__path, int __name));
 326 extern long int pathconf __P ((__const char *__path, int __name));
 327
 328 /* Get file-specific configuration about descriptor FD.  */
 329 extern long int __fpathconf __P ((int __fd, int __name));
 330 extern long int fpathconf __P ((int __fd, int __name));
 331
 332 /* Get the value of the system variable NAME.  */
 333 extern long int __sysconf __P ((int __name));
 334 extern long int sysconf __P ((int __name));
 335
 336 #ifdef  __USE_POSIX2
 337 /* Get the value of the string-valued system variable NAME.  */
 338 extern size_t confstr __P ((int __name, char *__buf, size_t __len));
 339 #endif
 340
 341
 342 /* Get the process ID of the calling process.  */
 343 extern __pid_t __getpid __P ((void));
 344 extern __pid_t getpid __P ((void));
 345
 346 /* Get the process ID of the calling process's parent.  */
 347 extern __pid_t __getppid __P ((void));
 348 extern __pid_t getppid __P ((void));
 349
 350 /* Get the process group ID of the calling process.  */
 351 extern __pid_t getpgrp __P ((void));
 352
 353 /* Set the process group ID of the process matching PID to PGID.
 354    If PID is zero, the current process's process group ID is set.
 355    If PGID is zero, the process ID of the process is used.  */
 356 extern int setpgid __P ((__pid_t __pid, __pid_t __pgid));
 357
 358 /* Get the process group ID of process PID.  */
 359 extern __pid_t __getpgid __P ((__pid_t __pid));
 360 #ifdef __USE_GNU
 361 extern __pid_t getpgid __P ((__pid_t __pid));
 362 #endif
 363
 364 #if defined (__USE_SVID) || defined (__USE_BSD)
 365 /* Both System V and BSD have `setpgrp' functions, but with different
 366    calling conventions.  The BSD function is the same as POSIX.1 `setpgid'
 367    (above).  The System V function takes no arguments and puts the calling
 368    process in its on group like `setpgid (0, 0)'.
 369
 370    New programs should always use `setpgid' instead.
 371
 372    The default in GNU is to provide the System V function.  The BSD
 373    function is available under -D_BSD_SOURCE with -lbsd-compat.  */
 374
 375 #ifndef __FAVOR_BSD
 376
 377 /* Set the process group ID of the calling process to its own PID.
 378    This is exactly the same as `setpgid (0, 0)'.  */
 379 extern int setpgrp __P ((void));
 380
 381 #else
 382
 383 /* Another name for `setpgid' (above).  */
 384 extern int setpgrp __P ((__pid_t __pid, __pid_t __pgrp));
 385
 386 #endif  /* Favor BSD.  */
 387 #endif  /* Use SVID or BSD.  */
 388
 389 /* Create a new session with the calling process as its leader.
 390    The process group IDs of the session and the calling process
 391    are set to the process ID of the calling process, which is returned.  */
 392 extern __pid_t __setsid __P ((void));
 393 extern __pid_t setsid __P ((void));
 394
 395 #ifdef __USE_GNU
 396 /* Return the session ID of the given process.  */
 397 extern __pid_t getsid __P ((__pid_t));
 398 #endif
 399
 400 /* Get the real user ID of the calling process.  */
 401 extern __uid_t __getuid __P ((void));
 402 extern __uid_t getuid __P ((void));
 403
 404 /* Get the effective user ID of the calling process.  */
 405 extern __uid_t __geteuid __P ((void));
 406 extern __uid_t geteuid __P ((void));
 407
 408 /* Get the real group ID of the calling process.  */
 409 extern __gid_t __getgid __P ((void));
 410 extern __gid_t getgid __P ((void));
 411
 412 /* Get the effective group ID of the calling process.  */
 413 extern __gid_t __getegid __P ((void));
 414 extern __gid_t getegid __P ((void));
 415
 416 /* If SIZE is zero, return the number of supplementary groups
 417    the calling process is in.  Otherwise, fill in the group IDs
 418    of its supplementary groups in LIST and return the number written.  */
 419 extern int __getgroups __P ((int __size, __gid_t __list[]));
 420 extern int getgroups __P ((int __size, __gid_t __list[]));
 421
 422 #ifdef  __USE_GNU
 423 /* Return nonzero iff the calling process is in group GID.  */
 424 extern int __group_member __P ((__gid_t __gid));
 425 extern int group_member __P ((__gid_t __gid));
 426 #endif
 427
 428 /* Set the user ID of the calling process to UID.
 429    If the calling process is the super-user, set the real
 430    and effective user IDs, and the saved set-user-ID to UID;
 431    if not, the effective user ID is set to UID.  */
 432 extern int __setuid __P ((__uid_t __uid));
 433 extern int setuid __P ((__uid_t __uid));
 434
 435 #ifdef  __USE_BSD
 436 /* Set the real user ID of the calling process to RUID,
 437    and the effective user ID of the calling process to EUID.  */
 438 extern int __setreuid __P ((__uid_t __ruid, __uid_t __euid));
 439 extern int setreuid __P ((__uid_t __ruid, __uid_t __euid));
 440
 441 /* Set the effective user ID of the calling process to UID.  */
 442 extern int seteuid __P ((__uid_t __uid));
 443 #endif /* Use BSD.  */
 444
 445 /* Set the group ID of the calling process to GID.
 446    If the calling process is the super-user, set the real
 447    and effective group IDs, and the saved set-group-ID to GID;
 448    if not, the effective group ID is set to GID.  */
 449 extern int __setgid __P ((__gid_t __gid));
 450 extern int setgid __P ((__gid_t __gid));
 451
 452 #ifdef  __USE_BSD
 453 /* Set the real group ID of the calling process to RGID,
 454    and the effective group ID of the calling process to EGID.  */
 455 extern int __setregid __P ((__gid_t __rgid, __gid_t __egid));
 456 extern int setregid __P ((__gid_t __rgid, __gid_t __egid));
 457
 458 /* Set the effective group ID of the calling process to GID.  */
 459 extern int setegid __P ((__gid_t __gid));
 460 #endif /* Use BSD.  */
 461
 462
 463 /* Clone the calling process, creating an exact copy.
 464    Return -1 for errors, 0 to the new process,
 465    and the process ID of the new process to the old process.  */
 466 extern __pid_t __fork __P ((void));
 467 extern __pid_t fork __P ((void));
 468
 469 #ifdef  __USE_BSD
 470 /* Clone the calling process, but without copying the whole address space.
 471    The the calling process is suspended until the the new process exits or is
 472    replaced by a call to `execve'.  Return -1 for errors, 0 to the new process,
 473    and the process ID of the new process to the old process.  */
 474 extern __pid_t __vfork __P ((void));
 475 extern __pid_t vfork __P ((void));
 476 #endif /* Use BSD. */
 477
 478
 479 /* Return the pathname of the terminal FD is open on, or NULL on errors.
 480    The returned storage is good only until the next call to this function.  */
 481 extern char *ttyname __P ((int __fd));
 482 #ifdef __USE_REENTRANT
 483 /* Store at most BUFLEN characters of the pathname of the terminal FD is
 484    open on in BUF.  Return 0 on success, -1 otherwise.  */
 485 extern int ttyname_r __P ((int __fd, char *__buf, int __buflen));
 486 #endif
 487
 488 /* Return 1 if FD is a valid descriptor associated
 489    with a terminal, zero if not.  */
 490 extern int __isatty __P ((int __fd));
 491 extern int isatty __P ((int __fd));
 492
 493 #ifdef __USE_BSD
 494 /* Return the index into the active-logins file (utmp) for
 495    the controlling terminal.  */
 496 extern int ttyslot __P ((void));
 497 #endif
 498
 499
 500 /* Make a link to FROM named TO.  */
 501 extern int __link __P ((__const char *__from, __const char *__to));
 502 extern int link __P ((__const char *__from, __const char *__to));
 503
 504 #ifdef  __USE_BSD
 505 /* Make a symbolic link to FROM named TO.  */
 506 extern int __symlink __P ((__const char *__from, __const char *__to));
 507 extern int symlink __P ((__const char *__from, __const char *__to));
 508
 509 /* Read the contents of the symbolic link PATH into no more than
 510    LEN bytes of BUF.  The contents are not null-terminated.
 511    Returns the number of characters read, or -1 for errors.  */
 512 extern int __readlink __P ((__const char *__path, char *__buf, size_t __len));
 513 extern int readlink __P ((__const char *__path, char *__buf, size_t __len));
 514 #endif /* Use BSD.  */
 515
 516 /* Remove the link NAME.  */
 517 extern int __unlink __P ((__const char *__name));
 518 extern int unlink __P ((__const char *__name));
 519
 520 /* Remove the directory PATH.  */
 521 extern int __rmdir __P ((__const char *__path));
 522 extern int rmdir __P ((__const char *__path));
 523
 524
 525 /* Return the foreground process group ID of FD.  */
 526 extern __pid_t tcgetpgrp __P ((int __fd));
 527
 528 /* Set the foreground process group ID of FD set PGRP_ID.  */
 529 extern int tcsetpgrp __P ((int __fd, __pid_t __pgrp_id));
 530
 531
 532 /* Return the login name of the user.  */
 533 extern char *getlogin __P ((void));
 534
 535 #ifdef  __USE_BSD
 536 /* Set the login name returned by `getlogin'.  */
 537 extern int setlogin __P ((__const char *__name));
 538 #endif
 539
 540
 541 #ifdef  __USE_POSIX2
 542 /* Process the arguments in ARGV (ARGC of them, minus
 543    the program name) for options given in OPTS.
 544
 545    If `opterr' is zero, no messages are generated
 546    for invalid options; it defaults to 1.
 547    `optind' is the current index into ARGV.
 548    `optarg' is the argument corresponding to the current option.
 549    Return the option character from OPTS just read.
 550    Return -1 when there are no more options.
 551    For unrecognized options, or options missing arguments,
 552    `optopt' is set to the option letter, and '?' is returned.
 553
 554    The OPTS string is a list of characters which are recognized option
 555    letters, optionally followed by colons, specifying that that letter
 556    takes an argument, to be placed in `optarg'.
 557
 558    If a letter in OPTS is followed by two colons, its argument is optional.
 559    This behavior is specific to the GNU `getopt'.
 560
 561    The argument `--' causes premature termination of argument scanning,
 562    explicitly telling `getopt' that there are no more options.
 563
 564    If OPTS begins with `--', then non-option arguments
 565    are treated as arguments to the option '\0'.
 566    This behavior is specific to the GNU `getopt'.  */
 567 extern int getopt __P ((int __argc, char *__const * __argv,
 568                         __const char *__opts));
 569 extern int opterr;
 570 extern int optind;
 571 extern int optopt;
 572 extern char *optarg;
 573 #endif
 574
 575
 576 #ifdef  __USE_BSD
 577
 578 /* Put the name of the current host in no more than LEN bytes of NAME.
 579    The result is null-terminated if LEN is large enough for the full
 580    name and the terminator.  */
 581 extern int __gethostname __P ((char *__name, size_t __len));
 582 extern int gethostname __P ((char *__name, size_t __len));
 583
 584 /* Set the name of the current host to NAME, which is LEN bytes long.
 585    This call is restricted to the super-user.  */
 586 extern int sethostname __P ((__const char *__name, size_t __len));
 587
 588 /* Return the current machine's Internet number.  */
 589 extern long int gethostid __P ((void));
 590
 591 /* Set the current machine's Internet number to ID.
 592    This call is restricted to the super-user.  */
 593 extern int sethostid __P ((long int __id));
 594
 595
 596 /* Return the number of bytes in a page.  This is the system's page size,
 597    which is not necessarily the same as the hardware page size.  */
 598 extern size_t __getpagesize __P ((void));
 599 extern size_t getpagesize __P ((void));
 600
 601
 602 /* Return the maximum number of file descriptors
 603    the current process could possibly have.  */
 604 extern int __getdtablesize __P ((void));
 605 extern int getdtablesize __P ((void));
 606
 607
 608 /* Truncate FILE to LENGTH bytes.  */
 609 extern int truncate __P ((__const char *__file, __off_t __length));
 610
 611 /* Truncate the file FD is open on to LENGTH bytes.  */
 612 extern int ftruncate __P ((int __fd, __off_t __length));
 613
 614
 615 /* Make all changes done to FD actually appear on disk.  */
 616 extern int fsync __P ((int __fd));
 617
 618 /* Make all changes done to all files actually appear on disk.  */
 619 extern int sync __P ((void));
 620
 621
 622 /* Revoke access permissions to all processes currently communicating
 623    with the control terminal, and then send a SIGHUP signal to the process
 624    group of the control terminal.  */
 625 extern int vhangup __P ((void));
 626
 627 /* Revoke the access of all descriptors currently open on FILE.  */
 628 extern int revoke __P ((const char *__file));
 629
 630
 631 /* Enable statistical profiling, writing samples of the PC into at most
 632    SIZE bytes of SAMPLE_BUFFER; every processor clock tick while profiling
 633    is enabled, the system examines the user PC and increments
 634    SAMPLE_BUFFER[((PC - OFFSET) / 2) * SCALE / 65536].  If SCALE is zero,
 635    disable profiling.  Returns zero on success, -1 on error.  */
 636 extern int profil __P ((unsigned short int *__sample_buffer, size_t __size,
 637                         size_t __offset, unsigned int __scale));
 638
 639
 640 /* Turn accounting on if NAME is an existing file.  The system will then write
 641    a record for each process as it terminates, to this file.  If NAME is NULL,
 642    turn accounting off.  This call is restricted to the super-user.  */
 643 extern int acct __P ((__const char *__name));
 644
 645 /* Make PATH be the root directory (the starting point for absolute paths).
 646    This call is restricted to the super-user.  */
 647 extern int chroot __P ((__const char *__path));
 648
 649 /* Make the block special device PATH available to the system for swapping.
 650    This call is restricted to the super-user.  */
 651 extern int swapon __P ((__const char *__path));
 652
 653 /* Stop using block special device PATH for swapping.  */
 654 extern int swapoff __P ((__const char *__path));
 655
 656 /* Reboot or halt the system.  */
 657 extern int reboot __P ((int __howto));
 658
 659
 660 /* Successive calls return the shells listed in `/etc/shells'.  */
 661 extern char *getusershell __P ((void));
 662 extern void endusershell __P ((void)); /* Discard cached info.  */
 663 extern void setusershell __P ((void)); /* Rewind and re-read the file.  */
 664
 665
 666 /* Prompt with PROMPT and read a string from the terminal without echoing.
 667    Uses /dev/tty if possible; otherwise stderr and stdin.  */
 668 extern char *getpass __P ((const char *__prompt));
 669
 670 /* Put the program in the background, and dissociate from the controlling
 671    terminal.  If NOCHDIR is zero, do `chdir ("/")'.  If NOCLOSE is zero,
 672    redirects stdin, stdout, and stderr to /dev/null.  */
 673 extern int daemon __P ((int __nochdir, int __noclose));
 674
 675 #endif /* Use BSD.  */
 676
 677
 678 #ifdef __USE_MISC
 679
 680 /* Generate a unique temporary file name from TEMPLATE.
 681    The last six characters of TEMPLATE must be "XXXXXX";
 682    they are replaced with a string that makes the file name unique.
 683    Returns TEMPLATE, or a null pointer if it cannot get a unique file name.  */
 684 extern char *mktemp __P ((char *__template));
 685
 686 /* Generate a unique temporary file name from TEMPLATE.
 687    The last six characters of TEMPLATE must be "XXXXXX";
 688    they are replaced with a string that makes the filename unique.
 689    Returns a file descriptor open on the file for reading and writing,
 690    or -1 if it cannot create a uniquely-named file.  */
 691 extern int mkstemp __P ((char *__template));
 692
 693
 694 /* Set the end of accessible data space (aka "the break") to ADDR.
 695    Returns zero on success and -1 for errors (with errno set).  */
 696 extern int __brk __P ((__ptr_t __addr));
 697 extern int brk __P ((__ptr_t __addr));
 698
 699 #define __need_ptrdiff_t
 700 #include <stddef.h>
 701
 702 /* Increase or decrease the end of accessible data space by DELTA bytes.
 703    If successful, returns the address the previous end of data space
 704    (i.e. the beginning of the new space, if DELTA > 0);
 705    returns (void *) -1 for errors (with errno set).  */
 706 extern __ptr_t __sbrk __P ((ptrdiff_t __delta));
 707 extern __ptr_t sbrk __P ((ptrdiff_t __delta));
 708
 709
 710 /* Invoke `system call' number SYSNO, passing it the remaining arguments.
 711    This is completely system-dependent, and not often useful.
 712
 713    In Unix, `syscall' sets `errno' for all errors and most calls return -1
 714    for errors; in many systems you cannot pass arguments or get return
 715    values for all system calls (`pipe', `fork', and `getppid' typically
 716    among them).
 717
 718    In Mach, all system calls take normal arguments and always return an
 719    error code (zero for success).  */
 720 extern int syscall __P ((int __sysno, ...));
 721
 722 #endif  /* Use misc.  */
 723
 724
 725 #if defined (__USE_MISC) && !defined (F_LOCK)
 726 /* NOTE: These declarations also appear in <fcntl.h>; be sure to keep both
 727    files consistent.  Some systems have them there and some here, and some
 728    software depends on the macros being defined without including both.  */
 729
 730 /* `lockf' is a simpler interface to the locking facilities of `fcntl'.
 731    LEN is always relative to the current file position.
 732    The CMD argument is one of the following.  */
 733
 734 #define F_ULOCK 0       /* Unlock a previously locked region.  */
 735 #define F_LOCK  1       /* Lock a region for exclusive use.  */
 736 #define F_TLOCK 2       /* Test and lock a region for exclusive use.  */
 737 #define F_TEST  3       /* Test a region for other processes locks.  */
 738
 739 extern int lockf __P ((int __fd, int __cmd, __off_t __len));
 740 #endif /* Use misc and F_LOCK not already defined.  */
 741
 742
 743 #ifdef __USE_GNU
 744
 745 /* Evaluate EXPRESSION, and repeat as long as it returns -1 with `errno'
 746    set to EINTR.  */
 747
 748 #define TEMP_FAILURE_RETRY(expression) \
 749   ({ long int __result;                                                       \
 750        do __result = (long int) (expression);                                 \
 751        while (__result == -1L && errno == EINTR);                             \
 752        __result; })
 753
 754 #endif
 755
 756 #ifdef __USE_POSIX
 757 /* Synchronize at least the data part of a file with the underlying
 758    media.  */
 759 extern int fdatasync __P ((int __fildes));
 760 #endif /* Use POSIX */
 761
 762 __END_DECLS
 763
 764 #endif /* unistd.h  */