posix/unistd.h

   1 /* Copyright (C) 1991, 1992, 1993, 1994, 1995 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.  */
  34 #define _POSIX_VERSION  199009L
  35
  36 /* These are not #ifdef __USE_POSIX2 because they are
  37    in the theoretically application-owned namespace.  */
  38
  39 #define _POSIX2_C_VERSION       199912L /* Invalid until 1003.2 is done.  */
  40
  41 /* If defined, the implementation supports the
  42    C Language Bindings Option.  */
  43 #define _POSIX2_C_BIND  1
  44
  45 /* If defined, the implementation supports the
  46    C Language Development Utilities Option.  */
  47 #define _POSIX2_C_DEV   1
  48
  49 /* If defined, the implementation supports the
  50    Software Development Utilities Option.  */
  51 #define _POSIX2_SW_DEV  1
  52
  53
  54 /* Get values of POSIX options:
  55
  56    If these symbols are defined, the corresponding features are
  57    always available.  If not, they may be available sometimes.
  58    The current values can be obtained with `sysconf'.
  59
  60    _POSIX_JOB_CONTROL   Job control is supported.
  61    _POSIX_SAVED_IDS     Processes have a saved set-user-ID
  62                         and a saved set-group-ID.
  63
  64    If any of these symbols is defined as -1, the corresponding option is not
  65    true for any file.  If any is defined as other than -1, the corresponding
  66    option is true for all files.  If a symbol is not defined at all, the value
  67    for a specific file can be obtained from `pathconf' and `fpathconf'.
  68
  69    _POSIX_CHOWN_RESTRICTED      Only the super user can use `chown' to change
  70                                 the owner of a file.  `chown' can only be used
  71                                 to change the group ID of a file to a group of
  72                                 which the calling process is a member.
  73    _POSIX_NO_TRUNC              Pathname components longer than
  74                                 NAME_MAX generate an error.
  75    _POSIX_VDISABLE              If defined, if the value of an element of the
  76                                 `c_cc' member of `struct termios' is
  77                                 _POSIX_VDISABLE, no character will have the
  78                                 effect associated with that element.
  79    */
  80
  81 #include <posix_opt.h>
  82
  83
  84 /* Standard file descriptors.  */
  85 #define STDIN_FILENO    0       /* Standard input.  */
  86 #define STDOUT_FILENO   1       /* Standard output.  */
  87 #define STDERR_FILENO   2       /* Standard error output.  */
  88
  89
  90 /* All functions that are not declared anywhere else.  */
  91
  92 #include <gnu/types.h>
  93
  94 #ifndef ssize_t
  95 #define ssize_t __ssize_t
  96 #endif
  97
  98 #define __need_size_t
  99 #define __need_NULL
 100 #include <stddef.h>
 101
 102
 103 /* Values for the second argument to access.
 104    These may be OR'd together.  */
 105 #define R_OK    4               /* Test for read permission.  */
 106 #define W_OK    2               /* Test for write permission.  */
 107 #define X_OK    1               /* Test for execute permission.  */
 108 #define F_OK    0               /* Test for existence.  */
 109
 110 /* Test for access to NAME using the real UID and real GID.  */
 111 extern int __access __P ((__const char *__name, int __type));
 112 extern int access __P ((__const char *__name, int __type));
 113
 114 #ifdef __USE_GNU
 115 /* Test for access to NAME using the effective UID and GID
 116    (as normal file operations use).  */
 117 extern int euidaccess __P ((__const char *__name, int __type));
 118 #endif
 119
 120
 121 /* Values for the WHENCE argument to lseek.  */
 122 #ifndef _STDIO_H                /* <stdio.h> has the same definitions.  */
 123 #define SEEK_SET        0       /* Seek from beginning of file.  */
 124 #define SEEK_CUR        1       /* Seek from current position.  */
 125 #define SEEK_END        2       /* Seek from end of file.  */
 126 #endif
 127
 128 #if defined (__USE_BSD) && !defined (L_SET)
 129 /* Old BSD names for the same constants; just for compatibility.  */
 130 #define L_SET           SEEK_SET
 131 #define L_INCR          SEEK_CUR
 132 #define L_XTND          SEEK_END
 133 #endif
 134
 135
 136 /* Move FD's file position to OFFSET bytes from the
 137    beginning of the file (if WHENCE is SEEK_SET),
 138    the current position (if WHENCE is SEEK_CUR),
 139    or the end of the file (if WHENCE is SEEK_END).
 140    Return the new file position.  */
 141 extern __off_t __lseek __P ((int __fd, __off_t __offset, int __whence));
 142 extern __off_t lseek __P ((int __fd, __off_t __offset, int __whence));
 143
 144 /* Close the file descriptor FD.  */
 145 extern int __close __P ((int __fd));
 146 extern int close __P ((int __fd));
 147
 148 /* Read NBYTES into BUF from FD.  Return the
 149    number read, -1 for errors or 0 for EOF.  */
 150 extern ssize_t __read __P ((int __fd, __ptr_t __buf, size_t __nbytes));
 151 extern ssize_t read __P ((int __fd, __ptr_t __buf, size_t __nbytes));
 152
 153 /* Write N bytes of BUF to FD.  Return the number written, or -1.  */
 154 extern ssize_t __write __P ((int __fd, __const __ptr_t __buf, size_t __n));
 155 extern ssize_t write __P ((int __fd, __const __ptr_t __buf, size_t __n));
 156
 157
 158 /* Create a one-way communication channel (pipe).
 159    If successul, two file descriptors are stored in PIPEDES;
 160    bytes written on PIPEDES[1] can be read from PIPEDES[0].
 161    Returns 0 if successful, -1 if not.  */
 162 extern int __pipe __P ((int __pipedes[2]));
 163 extern int pipe __P ((int __pipedes[2]));
 164
 165 /* Schedule an alarm.  In SECONDS seconds, the process will get a SIGALRM.
 166    If SECONDS is zero, any currently scheduled alarm will be cancelled.
 167    The function returns the number of seconds remaining until the last
 168    alarm scheduled would have signaled, or zero if there wasn't one.
 169    There is no return value to indicate an error, but you can set `errno'
 170    to 0 and check its value after calling `alarm', and this might tell you.
 171    The signal may come late due to processor scheduling.  */
 172 extern unsigned int alarm __P ((unsigned int __seconds));
 173
 174 /* Make the process sleep for SECONDS seconds, or until a signal arrives
 175    and is not ignored.  The function returns the number of seconds less
 176    than SECONDS which it actually slept (thus zero if it slept the full time).
 177    If a signal handler does a `longjmp' or modifies the handling of the
 178    SIGALRM signal while inside `sleep' call, the handling of the SIGALRM
 179    signal afterwards is undefined.  There is no return value to indicate
 180    error, but if `sleep' returns SECONDS, it probably didn't work.  */
 181 extern unsigned int sleep __P ((unsigned int __seconds));
 182
 183
 184 /* Suspend the process until a signal arrives.
 185    This always returns -1 and sets `errno' to EINTR.  */
 186 extern int pause __P ((void));
 187
 188
 189 /* Change the owner and group of FILE.  */
 190 extern int __chown __P ((__const char *__file,
 191                          __uid_t __owner, __gid_t __group));
 192 extern int chown __P ((__const char *__file,
 193                        __uid_t __owner, __gid_t __group));
 194
 195 #ifdef  __USE_BSD
 196 /* Change the owner and group of the file that FD is open on.  */
 197 extern int __fchown __P ((int __fd,
 198                           __uid_t __owner, __gid_t __group));
 199 extern int fchown __P ((int __fd,
 200                         __uid_t __owner, __gid_t __group));
 201 #endif /* Use BSD.  */
 202
 203 /* Change the process's working directory to PATH.  */
 204 extern int __chdir __P ((__const char *__path));
 205 extern int chdir __P ((__const char *__path));
 206
 207 #ifdef __USE_BSD
 208 /* Change the process's working directory to the one FD is open on.  */
 209 extern int fchdir __P ((int __fd));
 210 #endif
 211
 212 /* Get the pathname of the current working directory,
 213    and put it in SIZE bytes of BUF.  Returns NULL if the
 214    directory couldn't be determined or SIZE was too small.
 215    If successful, returns BUF.  In GNU, if BUF is NULL,
 216    an array is allocated with `malloc'; the array is SIZE
 217    bytes long, unless SIZE <= 0, in which case it is as
 218    big as necessary.  */
 219 extern char *getcwd __P ((char *__buf, size_t __size));
 220
 221 #ifdef  __USE_GNU
 222 /* Return a malloc'd string containing the current directory name.
 223    If the environment variable `PWD' is set, and its value is correct,
 224    that value is used.  */
 225 extern char *get_current_dir_name __P ((void));
 226 #endif
 227
 228 #ifdef  __USE_BSD
 229 /* Put the absolute pathname of the current working directory in BUF.
 230    If successful, return BUF.  If not, put an error message in
 231    BUF and return NULL.  BUF should be at least PATH_MAX bytes long.  */
 232 extern char *getwd __P ((char *__buf));
 233 #endif
 234
 235
 236 /* Duplicate FD, returning a new file descriptor on the same file.  */
 237 extern int __dup __P ((int __fd));
 238 extern int dup __P ((int __fd));
 239
 240 /* Duplicate FD to FD2, closing FD2 and making it open on the same file.  */
 241 extern int __dup2 __P ((int __fd, int __fd2));
 242 extern int dup2 __P ((int __fd, int __fd2));
 243
 244 /* NULL-terminated array of "NAME=VALUE" environment variables.  */
 245 extern char **__environ;
 246 extern char **environ;
 247
 248
 249 /* Replace the current process, executing PATH with arguments ARGV and
 250    environment ENVP.  ARGV and ENVP are terminated by NULL pointers.  */
 251 extern int __execve __P ((__const char *__path, char *__const __argv[],
 252                           char *__const __envp[]));
 253 extern int execve __P ((__const char *__path, char *__const __argv[],
 254                         char *__const __envp[]));
 255
 256 #ifdef __USE_GNU
 257 /* Execute the file FD refers to, overlaying the running program image.
 258    ARGV and ENVP are passed to the new program, as for `execve'.  */
 259 extern int fexecve __P ((int __fd,
 260                          char *const __argv[], char *const __envp[]));
 261
 262 #endif
 263
 264
 265 /* Execute PATH with arguments ARGV and environment from `environ'.  */
 266 extern int execv __P ((__const char *__path, char *__const __argv[]));
 267
 268 /* Execute PATH with all arguments after PATH until a NULL pointer,
 269    and the argument after that for environment.  */
 270 extern int execle __P ((__const char *__path, __const char *__arg,...));
 271
 272 /* Execute PATH with all arguments after PATH until
 273    a NULL pointer and environment from `environ'.  */
 274 extern int execl __P ((__const char *__path, __const char *__arg,...));
 275
 276 /* Execute FILE, searching in the `PATH' environment variable if it contains
 277    no slashes, with arguments ARGV and environment from `environ'.  */
 278 extern int execvp __P ((__const char *__file, char *__const __argv[]));
 279
 280 /* Execute FILE, searching in the `PATH' environment variable if
 281    it contains no slashes, with all arguments after FILE until a
 282    NULL pointer and environment from `environ'.  */
 283 extern int execlp __P ((__const char *__file, ...));
 284
 285
 286 /* Terminate program execution with the low-order 8 bits of STATUS.  */
 287 extern void _exit __P ((int __status)) __attribute__ ((__noreturn__));
 288
 289
 290 /* Get the `_PC_*' symbols for the NAME argument to `pathconf' and `fpathconf';
 291    the `_SC_*' symbols for the NAME argument to `sysconf';
 292    and the `_CS_*' symbols for the NAME argument to `confstr'.  */
 293 #include <confname.h>
 294
 295 /* Get file-specific configuration information about PATH.  */
 296 extern long int __pathconf __P ((__const char *__path, int __name));
 297 extern long int pathconf __P ((__const char *__path, int __name));
 298
 299 /* Get file-specific configuration about descriptor FD.  */
 300 extern long int __fpathconf __P ((int __fd, int __name));
 301 extern long int fpathconf __P ((int __fd, int __name));
 302
 303 /* Get the value of the system variable NAME.  */
 304 extern long int __sysconf __P ((int __name));
 305 extern long int sysconf __P ((int __name));
 306
 307 #ifdef  __USE_POSIX2
 308 /* Get the value of the string-valued system variable NAME.  */
 309 extern size_t confstr __P ((int __name, char *__buf, size_t __len));
 310 #endif
 311
 312
 313 /* Get the process ID of the calling process.  */
 314 extern __pid_t __getpid __P ((void));
 315 extern __pid_t getpid __P ((void));
 316
 317 /* Get the process ID of the calling process's parent.  */
 318 extern __pid_t __getppid __P ((void));
 319 extern __pid_t getppid __P ((void));
 320
 321 /* Get the process group ID of the calling process.  */
 322 extern __pid_t getpgrp __P ((void));
 323
 324 /* Set the process group ID of the process matching PID to PGID.
 325    If PID is zero, the current process's process group ID is set.
 326    If PGID is zero, the process ID of the process is used.  */
 327 extern int setpgid __P ((__pid_t __pid, __pid_t __pgid));
 328
 329 /* Get the process group ID of process PID.  */
 330 extern __pid_t __getpgid __P ((__pid_t __pid));
 331 #ifdef __USE_GNU
 332 extern __pid_t getpgid __P ((__pid_t __pid));
 333 #endif
 334
 335 #ifdef  __USE_BSD
 336 /* Another name for `setpgid'.  */
 337 extern int setpgrp __P ((__pid_t __pid, __pid_t __pgrp));
 338 #endif /* Use BSD.  */
 339
 340 /* Create a new session with the calling process as its leader.
 341    The process group IDs of the session and the calling process
 342    are set to the process ID of the calling process, which is returned.  */
 343 extern __pid_t __setsid __P ((void));
 344 extern __pid_t setsid __P ((void));
 345
 346 /* Get the real user ID of the calling process.  */
 347 extern __uid_t __getuid __P ((void));
 348 extern __uid_t getuid __P ((void));
 349
 350 /* Get the effective user ID of the calling process.  */
 351 extern __uid_t __geteuid __P ((void));
 352 extern __uid_t geteuid __P ((void));
 353
 354 /* Get the real group ID of the calling process.  */
 355 extern __gid_t __getgid __P ((void));
 356 extern __gid_t getgid __P ((void));
 357
 358 /* Get the effective group ID of the calling process.  */
 359 extern __gid_t __getegid __P ((void));
 360 extern __gid_t getegid __P ((void));
 361
 362 /* If SIZE is zero, return the number of supplementary groups
 363    the calling process is in.  Otherwise, fill in the group IDs
 364    of its supplementary groups in LIST and return the number written.  */
 365 extern int __getgroups __P ((int __size, __gid_t __list[]));
 366 extern int getgroups __P ((int __size, __gid_t __list[]));
 367
 368 /* Set the user ID of the calling process to UID.
 369    If the calling process is the super-user, set the real
 370    and effective user IDs, and the saved set-user-ID to UID;
 371    if not, the effective user ID is set to UID.  */
 372 extern int __setuid __P ((__uid_t __uid));
 373 extern int setuid __P ((__uid_t __uid));
 374
 375 #ifdef  __USE_BSD
 376 /* Set the real user ID of the calling process to RUID,
 377    and the effective user ID of the calling process to EUID.  */
 378 extern int __setreuid __P ((__uid_t __ruid, __uid_t __euid));
 379 extern int setreuid __P ((__uid_t __ruid, __uid_t __euid));
 380
 381 /* Set the effective user ID of the calling process to UID.  */
 382 extern int seteuid __P ((__uid_t __uid));
 383 #endif /* Use BSD.  */
 384
 385 /* Set the group ID of the calling process to GID.
 386    If the calling process is the super-user, set the real
 387    and effective group IDs, and the saved set-group-ID to GID;
 388    if not, the effective group ID is set to GID.  */
 389 extern int __setgid __P ((__gid_t __gid));
 390 extern int setgid __P ((__gid_t __gid));
 391
 392 #ifdef  __USE_BSD
 393 /* Set the real group ID of the calling process to RGID,
 394    and the effective group ID of the calling process to EGID.  */
 395 extern int __setregid __P ((__gid_t __rgid, __gid_t __egid));
 396 extern int setregid __P ((__gid_t __rgid, __gid_t __egid));
 397
 398 /* Set the effective group ID of the calling process to GID.  */
 399 extern int setegid __P ((__gid_t __gid));
 400 #endif /* Use BSD.  */
 401
 402
 403 /* Clone the calling process, creating an exact copy.
 404    Return -1 for errors, 0 to the new process,
 405    and the process ID of the new process to the old process.  */
 406 extern __pid_t __fork __P ((void));
 407 extern __pid_t fork __P ((void));
 408
 409 #ifdef  __USE_BSD
 410 /* Clone the calling process, but without copying the whole address space.
 411    The the calling process is suspended until the the new process exits or is
 412    replaced by a call to `execve'.  Return -1 for errors, 0 to the new process,
 413    and the process ID of the new process to the old process.  */
 414 extern __pid_t __vfork __P ((void));
 415 extern __pid_t vfork __P ((void));
 416 #endif /* Use BSD. */
 417
 418
 419 /* Return the pathname of the terminal FD is open on, or NULL on errors.
 420    The returned storage is good only until the next call to this function.  */
 421 extern char *ttyname __P ((int __fd));
 422
 423 /* Return 1 if FD is a valid descriptor associated
 424    with a terminal, zero if not.  */
 425 extern int __isatty __P ((int __fd));
 426 extern int isatty __P ((int __fd));
 427
 428 #ifdef __USE_BSD
 429 /* Return the index into the active-logins file (utmp) for
 430    the controlling terminal.  */
 431 extern int ttyslot __P ((void));
 432 #endif
 433
 434
 435 /* Make a link to FROM named TO.  */
 436 extern int __link __P ((__const char *__from, __const char *__to));
 437 extern int link __P ((__const char *__from, __const char *__to));
 438
 439 #ifdef  __USE_BSD
 440 /* Make a symbolic link to FROM named TO.  */
 441 extern int __symlink __P ((__const char *__from, __const char *__to));
 442 extern int symlink __P ((__const char *__from, __const char *__to));
 443
 444 /* Read the contents of the symbolic link PATH into no more than
 445    LEN bytes of BUF.  The contents are not null-terminated.
 446    Returns the number of characters read, or -1 for errors.  */
 447 extern int __readlink __P ((__const char *__path, char *__buf, size_t __len));
 448 extern int readlink __P ((__const char *__path, char *__buf, size_t __len));
 449 #endif /* Use BSD.  */
 450
 451 /* Remove the link NAME.  */
 452 extern int __unlink __P ((__const char *__name));
 453 extern int unlink __P ((__const char *__name));
 454
 455 /* Remove the directory PATH.  */
 456 extern int __rmdir __P ((__const char *__path));
 457 extern int rmdir __P ((__const char *__path));
 458
 459
 460 /* Return the foreground process group ID of FD.  */
 461 extern __pid_t tcgetpgrp __P ((int __fd));
 462
 463 /* Set the foreground process group ID of FD set PGRP_ID.  */
 464 extern int tcsetpgrp __P ((int __fd, __pid_t __pgrp_id));
 465
 466
 467 /* Return the login name of the user.  */
 468 extern char *getlogin __P ((void));
 469
 470 #ifdef  __USE_BSD
 471 /* Set the login name returned by `getlogin'.  */
 472 extern int setlogin __P ((__const char *__name));
 473 #endif
 474
 475
 476 #ifdef  __USE_POSIX2
 477 /* Process the arguments in ARGV (ARGC of them, minus
 478    the program name) for options given in OPTS.
 479
 480    If `opterr' is zero, no messages are generated
 481    for invalid options; it defaults to 1.
 482    `optind' is the current index into ARGV.
 483    `optarg' is the argument corresponding to the current option.
 484    Return the option character from OPTS just read.
 485    Return -1 when there are no more options.
 486    For unrecognized options, or options missing arguments,
 487    `optopt' is set to the option letter, and '?' is returned.
 488
 489    The OPTS string is a list of characters which are recognized option
 490    letters, optionally followed by colons, specifying that that letter
 491    takes an argument, to be placed in `optarg'.
 492
 493    If a letter in OPTS is followed by two colons, its argument is optional.
 494    This behavior is specific to the GNU `getopt'.
 495
 496    The argument `--' causes premature termination of argument scanning,
 497    explicitly telling `getopt' that there are no more options.
 498
 499    If OPTS begins with `--', then non-option arguments
 500    are treated as arguments to the option '\0'.
 501    This behavior is specific to the GNU `getopt'.  */
 502 extern int getopt __P ((int __argc, char *__const * __argv,
 503                         __const char *__opts));
 504 extern int opterr;
 505 extern int optind;
 506 extern int optopt;
 507 extern char *optarg;
 508 #endif
 509
 510
 511 #ifdef  __USE_BSD
 512
 513 /* Put the name of the current host in no more than LEN bytes of NAME.
 514    The result is null-terminated if LEN is large enough for the full
 515    name and the terminator.  */
 516 extern int __gethostname __P ((char *__name, size_t __len));
 517 extern int gethostname __P ((char *__name, size_t __len));
 518
 519 /* Set the name of the current host to NAME, which is LEN bytes long.
 520    This call is restricted to the super-user.  */
 521 extern int sethostname __P ((__const char *__name, size_t __len));
 522
 523 /* Return the current machine's Internet number.  */
 524 extern long int gethostid __P ((void));
 525
 526 /* Set the current machine's Internet number to ID.
 527    This call is restricted to the super-user.  */
 528 extern int sethostid __P ((long int __id));
 529
 530
 531 /* Return the number of bytes in a page.  This is the system's page size,
 532    which is not necessarily the same as the hardware page size.  */
 533 extern size_t __getpagesize __P ((void));
 534 extern size_t getpagesize __P ((void));
 535
 536
 537 /* Return the maximum number of file descriptors
 538    the current process could possibly have.  */
 539 extern int __getdtablesize __P ((void));
 540 extern int getdtablesize __P ((void));
 541
 542
 543 /* Truncate FILE to LENGTH bytes.  */
 544 extern int truncate __P ((__const char *__file, __off_t __length));
 545
 546 /* Truncate the file FD is open on to LENGTH bytes.  */
 547 extern int ftruncate __P ((int __fd, __off_t __length));
 548
 549
 550 /* Make all changes done to FD actually appear on disk.  */
 551 extern int fsync __P ((int __fd));
 552
 553 /* Make all changes done to all files actually appear on disk.  */
 554 extern int sync __P ((void));
 555
 556
 557 /* Revoke access permissions to all processes currently communicating
 558    with the control terminal, and then send a SIGHUP signal to the process
 559    group of the control terminal.  */
 560 extern int vhangup __P ((void));
 561
 562 /* Revoke the access of all descriptors currently open on FILE.  */
 563 extern int revoke __P ((const char *__file));
 564
 565
 566 /* Turn accounting on if NAME is an existing file.  The system will then write
 567    a record for each process as it terminates, to this file.  If NAME is NULL,
 568    turn accounting off.  This call is restricted to the super-user.  */
 569 extern int acct __P ((__const char *__name));
 570
 571 /* Make PATH be the root directory (the starting point for absolute paths).
 572    This call is restricted to the super-user.  */
 573 extern int chroot __P ((__const char *__path));
 574
 575 /* Make the block special device PATH available to the system for swapping.
 576    This call is restricted to the super-user.  */
 577 extern int swapon __P ((__const char *__path));
 578
 579 /* Reboot or halt the system.  */
 580 extern int reboot __P ((int __howto));
 581
 582
 583 /* Successive calls return the shells listed in `/etc/shells'.  */
 584 extern char *getusershell __P ((void));
 585 extern void endusershell __P ((void)); /* Discard cached info.  */
 586 extern void setusershell __P ((void)); /* Rewind and re-read the file.  */
 587
 588
 589 /* Prompt with PROMPT and read a string from the terminal without echoing.
 590    Uses /dev/tty if possible; otherwise stderr and stdin.  */
 591 extern char *getpass __P ((const char *__prompt));
 592
 593 /* Put the program in the background, and dissociate from the controlling
 594    terminal.  If NOCHDIR is zero, do `chdir ("/")'.  If NOCLOSE is zero,
 595    redirects stdin, stdout, and stderr to /dev/null.  */
 596 extern int daemon __P ((int __nochdir, int __noclose));
 597
 598 #endif /* Use BSD.  */
 599
 600
 601 #ifdef __USE_MISC
 602
 603 /* Generate a unique temporary file name from TEMPLATE.
 604    The last six characters of TEMPLATE must be "XXXXXX";
 605    they are replaced with a string that makes the file name unique.
 606    Returns TEMPLATE, or a null pointer if it cannot get a unique file name.  */
 607 extern char *mktemp __P ((char *__template));
 608
 609 /* Generate a unique temporary file name from TEMPLATE.
 610    The last six characters of TEMPLATE must be "XXXXXX";
 611    they are replaced with a string that makes the filename unique.
 612    Returns a file descriptor open on the file for reading and writing,
 613    or -1 if it cannot create a uniquely-named file.  */
 614 extern int mkstemp __P ((char *__template));
 615
 616
 617 /* Invoke `system call' number SYSNO, passing it the remaining arguments.
 618    This is completely system-dependent, and not often useful.
 619
 620    In Unix, `syscall' sets `errno' for all errors and most calls return -1
 621    for errors; in many systems you cannot pass arguments or get return
 622    values for all system calls (`pipe', `fork', and `getppid' typically
 623    among them).
 624
 625    In Mach, all system calls take normal arguments and always return an
 626    error code (zero for success).  */
 627 extern int syscall __P ((int __sysno, ...));
 628
 629 #endif  /* Use misc.  */
 630
 631
 632 #if defined (__USE_MISC) && !defined (F_LOCK)
 633 /* NOTE: These declarations also appear in <fcntl.h>; be sure to keep both
 634    files consistent.  Some systems have them there and some here, and some
 635    software depends on the macros being defined without including both.  */
 636
 637 /* `lockf' is a simpler interface to the locking facilities of `fcntl'.
 638    LEN is always relative to the current file position.
 639    The CMD argument is one of the following.  */
 640
 641 #define F_ULOCK 0       /* Unlock a previously locked region.  */
 642 #define F_LOCK  1       /* Lock a region for exclusive use.  */
 643 #define F_TLOCK 2       /* Test and lock a region for exclusive use.  */
 644 #define F_TEST  3       /* Test a region for other processes locks.  */
 645
 646 extern int lockf __P ((int __fd, int __cmd, __off_t __len));
 647 #endif /* Use misc and F_LOCK not already defined.  */
 648
 649
 650 #ifdef __USE_GNU
 651
 652 /* Evaluate EXPRESSION, and repeat as long as it returns -1 with `errno'
 653    set to EINTR.  */
 654
 655 #define TEMP_FAILURE_RETRY(expression) \
 656   ({ long int __result;                                                       \
 657        do __result = (long int) (expression);                                 \
 658        while (__result == -1L && errno == EINTR);                             \
 659        __result; })
 660
 661 #endif
 662
 663 __END_DECLS
 664
 665 #endif /* unistd.h  */