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 /* Library is conformant to X/Open version 4.  */
  59 #define _XOPEN_VERSION  4
  60
  61
  62 /* Get values of POSIX options:
  63
  64    If these symbols are defined, the corresponding features are
  65    always available.  If not, they may be available sometimes.
  66    The current values can be obtained with `sysconf'.
  67
  68    _POSIX_JOB_CONTROL           Job control is supported.
  69    _POSIX_SAVED_IDS             Processes have a saved set-user-ID
  70                                 and a saved set-group-ID.
  71    _POSIX_REALTIME_SIGNALS      Real-time, queued signals are supported.
  72    _POSIX_PRIORITY_SCHEDULING   Priority scheduling is supported.
  73    _POSIX_TIMERS                POSIX.4 clocks and timers are supported.
  74    _POSIX_ASYNCHRONOUS_IO       Asynchronous I/O is supported.
  75    _POSIX_PRIORITIZED_IO        Prioritized asynchronous I/O is supported.
  76    _POSIX_SYNCHRONIZED_IO       Synchronizing file data is supported.
  77    _POSIX_FSYNC                 The fsync function is present.
  78    _POSIX_MAPPED_FILES          Mapping of files to memory is supported.
  79    _POSIX_MEMLOCK               Locking of all memory is supported.
  80    _POSIX_MEMLOCK_RANGE         Locking of ranges of memory is supported.
  81    _POSIX_MEMORY_PROTECTION     Setting of memory protections is supported.
  82    _POSIX_MESSAGE_PASSING       POSIX.4 message queues are supported.
  83    _POSIX_SEMAPHORES            POSIX.4 counting semaphores are supported.
  84    _POSIX_SHARED_MEMORY_OBJECTS POSIX.4 shared memory objects are supported.
  85    _POSIX_PII                   Protocol-independent interfaces are supported.
  86    _POSIX_PII_XTI               XTI protocol-indep. interfaces are supported.
  87    _POSIX_PII_SOCKET            Socket protocol-indep. interfaces are supported.
  88    _POSIX_PII_INTERNET          Internet family of protocols supported.
  89    _POSIX_PII_INTERNET_STREAM   Connection-mode Internet protocol supported.
  90    _POSIX_PII_INTERNET_DGRAM    Connectionless Internet protocol supported.
  91    _POSIX_PII_OSI               ISO/OSI family of protocols supported.
  92    _POSIX_PII_OSI_COTS          Connection-mode ISO/OSI service supported.
  93    _POSIX_PII_OSI_CLTS          Connectionless ISO/OSI service supported.
  94    _POSIX_POLL                  Implementation supports `poll' function.
  95    _POSIX_SELECT                Implementation supports `select' and `pselect'.
  96
  97    If any of these symbols is defined as -1, the corresponding option is not
  98    true for any file.  If any is defined as other than -1, the corresponding
  99    option is true for all files.  If a symbol is not defined at all, the value
 100    for a specific file can be obtained from `pathconf' and `fpathconf'.
 101
 102    _POSIX_CHOWN_RESTRICTED      Only the super user can use `chown' to change
 103                                 the owner of a file.  `chown' can only be used
 104                                 to change the group ID of a file to a group of
 105                                 which the calling process is a member.
 106    _POSIX_NO_TRUNC              Pathname components longer than
 107                                 NAME_MAX generate an error.
 108    _POSIX_VDISABLE              If defined, if the value of an element of the
 109                                 `c_cc' member of `struct termios' is
 110                                 _POSIX_VDISABLE, no character will have the
 111                                 effect associated with that element.
 112    _POSIX_SYNC_IO               Synchronous I/O may be performed.
 113    _POSIX_ASYNC_IO              Asynchronous I/O may be performed.
 114    _POSIX_PRIO_IO               Prioritized Asynchronous I/O may be performed.
 115    */
 116
 117 #include <posix_opt.h>
 118
 119
 120 /* Standard file descriptors.  */
 121 #define STDIN_FILENO    0       /* Standard input.  */
 122 #define STDOUT_FILENO   1       /* Standard output.  */
 123 #define STDERR_FILENO   2       /* Standard error output.  */
 124
 125
 126 /* All functions that are not declared anywhere else.  */
 127
 128 #include <gnu/types.h>
 129
 130 #ifndef ssize_t
 131 typedef __ssize_t ssize_t;
 132 #define ssize_t ssize_t
 133 #endif
 134
 135 #define __need_size_t
 136 #define __need_NULL
 137 #include <stddef.h>
 138
 139
 140 /* Values for the second argument to access.
 141    These may be OR'd together.  */
 142 #define R_OK    4               /* Test for read permission.  */
 143 #define W_OK    2               /* Test for write permission.  */
 144 #define X_OK    1               /* Test for execute permission.  */
 145 #define F_OK    0               /* Test for existence.  */
 146
 147 /* Test for access to NAME using the real UID and real GID.  */
 148 extern int __access __P ((__const char *__name, int __type));
 149 extern int access __P ((__const char *__name, int __type));
 150
 151 #ifdef __USE_GNU
 152 /* Test for access to NAME using the effective UID and GID
 153    (as normal file operations use).  */
 154 extern int euidaccess __P ((__const char *__name, int __type));
 155 #endif
 156
 157
 158 /* Values for the WHENCE argument to lseek.  */
 159 #ifndef _STDIO_H                /* <stdio.h> has the same definitions.  */
 160 #define SEEK_SET        0       /* Seek from beginning of file.  */
 161 #define SEEK_CUR        1       /* Seek from current position.  */
 162 #define SEEK_END        2       /* Seek from end of file.  */
 163 #endif
 164
 165 #if defined (__USE_BSD) && !defined (L_SET)
 166 /* Old BSD names for the same constants; just for compatibility.  */
 167 #define L_SET           SEEK_SET
 168 #define L_INCR          SEEK_CUR
 169 #define L_XTND          SEEK_END
 170 #endif
 171
 172
 173 /* Move FD's file position to OFFSET bytes from the
 174    beginning of the file (if WHENCE is SEEK_SET),
 175    the current position (if WHENCE is SEEK_CUR),
 176    or the end of the file (if WHENCE is SEEK_END).
 177    Return the new file position.  */
 178 extern __off_t __lseek __P ((int __fd, __off_t __offset, int __whence));
 179 extern __off_t lseek __P ((int __fd, __off_t __offset, int __whence));
 180
 181 /* Close the file descriptor FD.  */
 182 extern int __close __P ((int __fd));
 183 extern int close __P ((int __fd));
 184
 185 /* Read NBYTES into BUF from FD.  Return the
 186    number read, -1 for errors or 0 for EOF.  */
 187 extern ssize_t __read __P ((int __fd, __ptr_t __buf, size_t __nbytes));
 188 extern ssize_t read __P ((int __fd, __ptr_t __buf, size_t __nbytes));
 189
 190 /* Write N bytes of BUF to FD.  Return the number written, or -1.  */
 191 extern ssize_t __write __P ((int __fd, __const __ptr_t __buf, size_t __n));
 192 extern ssize_t write __P ((int __fd, __const __ptr_t __buf, size_t __n));
 193
 194
 195 /* Create a one-way communication channel (pipe).
 196    If successul, two file descriptors are stored in PIPEDES;
 197    bytes written on PIPEDES[1] can be read from PIPEDES[0].
 198    Returns 0 if successful, -1 if not.  */
 199 extern int __pipe __P ((int __pipedes[2]));
 200 extern int pipe __P ((int __pipedes[2]));
 201
 202 /* Schedule an alarm.  In SECONDS seconds, the process will get a SIGALRM.
 203    If SECONDS is zero, any currently scheduled alarm will be cancelled.
 204    The function returns the number of seconds remaining until the last
 205    alarm scheduled would have signaled, or zero if there wasn't one.
 206    There is no return value to indicate an error, but you can set `errno'
 207    to 0 and check its value after calling `alarm', and this might tell you.
 208    The signal may come late due to processor scheduling.  */
 209 extern unsigned int alarm __P ((unsigned int __seconds));
 210
 211 /* Make the process sleep for SECONDS seconds, or until a signal arrives
 212    and is not ignored.  The function returns the number of seconds less
 213    than SECONDS which it actually slept (thus zero if it slept the full time).
 214    If a signal handler does a `longjmp' or modifies the handling of the
 215    SIGALRM signal while inside `sleep' call, the handling of the SIGALRM
 216    signal afterwards is undefined.  There is no return value to indicate
 217    error, but if `sleep' returns SECONDS, it probably didn't work.  */
 218 extern unsigned int sleep __P ((unsigned int __seconds));
 219
 220 #ifdef __USE_BSD
 221 /* Sleep USECONDS microseconds, or until a signal arrives that is not blocked
 222    or ignored.  Return value is not necessarily useful.  */
 223 extern unsigned int usleep __P ((unsigned int __useconds));
 224 #endif
 225
 226
 227 /* Suspend the process until a signal arrives.
 228    This always returns -1 and sets `errno' to EINTR.  */
 229 extern int pause __P ((void));
 230
 231
 232 /* Change the owner and group of FILE.  */
 233 extern int __chown __P ((__const char *__file,
 234                          __uid_t __owner, __gid_t __group));
 235 extern int chown __P ((__const char *__file,
 236                        __uid_t __owner, __gid_t __group));
 237
 238 #ifdef  __USE_BSD
 239 /* Change the owner and group of the file that FD is open on.  */
 240 extern int __fchown __P ((int __fd,
 241                           __uid_t __owner, __gid_t __group));
 242 extern int fchown __P ((int __fd,
 243                         __uid_t __owner, __gid_t __group));
 244 #endif /* Use BSD.  */
 245
 246 /* Change the process's working directory to PATH.  */
 247 extern int __chdir __P ((__const char *__path));
 248 extern int chdir __P ((__const char *__path));
 249
 250 #ifdef __USE_BSD
 251 /* Change the process's working directory to the one FD is open on.  */
 252 extern int fchdir __P ((int __fd));
 253 #endif
 254
 255 /* Get the pathname of the current working directory,
 256    and put it in SIZE bytes of BUF.  Returns NULL if the
 257    directory couldn't be determined or SIZE was too small.
 258    If successful, returns BUF.  In GNU, if BUF is NULL,
 259    an array is allocated with `malloc'; the array is SIZE
 260    bytes long, unless SIZE <= 0, in which case it is as
 261    big as necessary.  */
 262 extern char *__getcwd __P ((char *__buf, size_t __size));
 263 extern char *getcwd __P ((char *__buf, size_t __size));
 264
 265 #ifdef  __USE_GNU
 266 /* Return a malloc'd string containing the current directory name.
 267    If the environment variable `PWD' is set, and its value is correct,
 268    that value is used.  */
 269 extern char *get_current_dir_name __P ((void));
 270
 271 /* Get the canonical absolute name of the named directory, and put it in SIZE
 272    bytes of BUF.  Returns NULL if the directory couldn't be determined or
 273    SIZE was too small.  If successful, returns BUF.  In GNU, if BUF is
 274    NULL, an array is allocated with `malloc'; the array is SIZE bytes long,
 275    unless SIZE <= 0, in which case it is as big as necessary.  */
 276
 277 char *__canonicalize_directory_name_internal __P ((__const char *__thisdir,
 278                                                    char *__buf,
 279                                                    size_t __size));
 280 #endif
 281
 282 #ifdef  __USE_BSD
 283 /* Put the absolute pathname of the current working directory in BUF.
 284    If successful, return BUF.  If not, put an error message in
 285    BUF and return NULL.  BUF should be at least PATH_MAX bytes long.  */
 286 extern char *getwd __P ((char *__buf));
 287 #endif
 288
 289
 290 /* Duplicate FD, returning a new file descriptor on the same file.  */
 291 extern int __dup __P ((int __fd));
 292 extern int dup __P ((int __fd));
 293
 294 /* Duplicate FD to FD2, closing FD2 and making it open on the same file.  */
 295 extern int __dup2 __P ((int __fd, int __fd2));
 296 extern int dup2 __P ((int __fd, int __fd2));
 297
 298 /* NULL-terminated array of "NAME=VALUE" environment variables.  */
 299 extern char **__environ;
 300 extern char **environ;
 301
 302
 303 /* Replace the current process, executing PATH with arguments ARGV and
 304    environment ENVP.  ARGV and ENVP are terminated by NULL pointers.  */
 305 extern int __execve __P ((__const char *__path, char *__const __argv[],
 306                           char *__const __envp[]));
 307 extern int execve __P ((__const char *__path, char *__const __argv[],
 308                         char *__const __envp[]));
 309
 310 #ifdef __USE_GNU
 311 /* Execute the file FD refers to, overlaying the running program image.
 312    ARGV and ENVP are passed to the new program, as for `execve'.  */
 313 extern int fexecve __P ((int __fd,
 314                          char *__const __argv[], char *__const __envp[]));
 315
 316 #endif
 317
 318
 319 /* Execute PATH with arguments ARGV and environment from `environ'.  */
 320 extern int execv __P ((__const char *__path, char *__const __argv[]));
 321
 322 /* Execute PATH with all arguments after PATH until a NULL pointer,
 323    and the argument after that for environment.  */
 324 extern int execle __P ((__const char *__path, __const char *__arg, ...));
 325
 326 /* Execute PATH with all arguments after PATH until
 327    a NULL pointer and environment from `environ'.  */
 328 extern int execl __P ((__const char *__path, __const char *__arg, ...));
 329
 330 /* Execute FILE, searching in the `PATH' environment variable if it contains
 331    no slashes, with arguments ARGV and environment from `environ'.  */
 332 extern int execvp __P ((__const char *__file, char *__const __argv[]));
 333
 334 /* Execute FILE, searching in the `PATH' environment variable if
 335    it contains no slashes, with all arguments after FILE until a
 336    NULL pointer and environment from `environ'.  */
 337 extern int execlp __P ((__const char *__file, ...));
 338
 339
 340 #ifdef __USE_MISC
 341 /* Add INC to priority of the current process.  */
 342 extern int nice __P ((int __inc));
 343 #endif
 344
 345
 346 /* Terminate program execution with the low-order 8 bits of STATUS.  */
 347 extern void _exit __P ((int __status)) __attribute__ ((__noreturn__));
 348
 349
 350 /* Get the `_PC_*' symbols for the NAME argument to `pathconf' and `fpathconf';
 351    the `_SC_*' symbols for the NAME argument to `sysconf';
 352    and the `_CS_*' symbols for the NAME argument to `confstr'.  */
 353 #include <confname.h>
 354
 355 /* Get file-specific configuration information about PATH.  */
 356 extern long int __pathconf __P ((__const char *__path, int __name));
 357 extern long int pathconf __P ((__const char *__path, int __name));
 358
 359 /* Get file-specific configuration about descriptor FD.  */
 360 extern long int __fpathconf __P ((int __fd, int __name));
 361 extern long int fpathconf __P ((int __fd, int __name));
 362
 363 /* Get the value of the system variable NAME.  */
 364 extern long int __sysconf __P ((int __name));
 365 extern long int sysconf __P ((int __name));
 366
 367 #ifdef  __USE_POSIX2
 368 /* Get the value of the string-valued system variable NAME.  */
 369 extern size_t confstr __P ((int __name, char *__buf, size_t __len));
 370 #endif
 371
 372
 373 /* Get the process ID of the calling process.  */
 374 extern __pid_t __getpid __P ((void));
 375 extern __pid_t getpid __P ((void));
 376
 377 /* Get the process ID of the calling process's parent.  */
 378 extern __pid_t __getppid __P ((void));
 379 extern __pid_t getppid __P ((void));
 380
 381 /* Get the process group ID of the calling process.  */
 382 extern __pid_t getpgrp __P ((void));
 383
 384 /* Set the process group ID of the process matching PID to PGID.
 385    If PID is zero, the current process's process group ID is set.
 386    If PGID is zero, the process ID of the process is used.  */
 387 extern int setpgid __P ((__pid_t __pid, __pid_t __pgid));
 388
 389 /* Get the process group ID of process PID.  */
 390 extern __pid_t __getpgid __P ((__pid_t __pid));
 391 #ifdef __USE_GNU
 392 extern __pid_t getpgid __P ((__pid_t __pid));
 393 #endif
 394
 395 #if defined (__USE_SVID) || defined (__USE_BSD)
 396 /* Both System V and BSD have `setpgrp' functions, but with different
 397    calling conventions.  The BSD function is the same as POSIX.1 `setpgid'
 398    (above).  The System V function takes no arguments and puts the calling
 399    process in its on group like `setpgid (0, 0)'.
 400
 401    New programs should always use `setpgid' instead.
 402
 403    The default in GNU is to provide the System V function.  The BSD
 404    function is available under -D_BSD_SOURCE with -lbsd-compat.  */
 405
 406 #ifndef __FAVOR_BSD
 407
 408 /* Set the process group ID of the calling process to its own PID.
 409    This is exactly the same as `setpgid (0, 0)'.  */
 410 extern int setpgrp __P ((void));
 411
 412 #else
 413
 414 /* Another name for `setpgid' (above).  */
 415 extern int setpgrp __P ((__pid_t __pid, __pid_t __pgrp));
 416
 417 #endif  /* Favor BSD.  */
 418 #endif  /* Use SVID or BSD.  */
 419
 420 /* Create a new session with the calling process as its leader.
 421    The process group IDs of the session and the calling process
 422    are set to the process ID of the calling process, which is returned.  */
 423 extern __pid_t __setsid __P ((void));
 424 extern __pid_t setsid __P ((void));
 425
 426 #ifdef __USE_GNU
 427 /* Return the session ID of the given process.  */
 428 extern __pid_t getsid __P ((__pid_t __pid));
 429 #endif
 430
 431 /* Get the real user ID of the calling process.  */
 432 extern __uid_t __getuid __P ((void));
 433 extern __uid_t getuid __P ((void));
 434
 435 /* Get the effective user ID of the calling process.  */
 436 extern __uid_t __geteuid __P ((void));
 437 extern __uid_t geteuid __P ((void));
 438
 439 /* Get the real group ID of the calling process.  */
 440 extern __gid_t __getgid __P ((void));
 441 extern __gid_t getgid __P ((void));
 442
 443 /* Get the effective group ID of the calling process.  */
 444 extern __gid_t __getegid __P ((void));
 445 extern __gid_t getegid __P ((void));
 446
 447 /* If SIZE is zero, return the number of supplementary groups
 448    the calling process is in.  Otherwise, fill in the group IDs
 449    of its supplementary groups in LIST and return the number written.  */
 450 extern int __getgroups __P ((int __size, __gid_t __list[]));
 451 extern int getgroups __P ((int __size, __gid_t __list[]));
 452
 453 #ifdef  __USE_GNU
 454 /* Return nonzero iff the calling process is in group GID.  */
 455 extern int __group_member __P ((__gid_t __gid));
 456 extern int group_member __P ((__gid_t __gid));
 457 #endif
 458
 459 /* Set the user ID of the calling process to UID.
 460    If the calling process is the super-user, set the real
 461    and effective user IDs, and the saved set-user-ID to UID;
 462    if not, the effective user ID is set to UID.  */
 463 extern int __setuid __P ((__uid_t __uid));
 464 extern int setuid __P ((__uid_t __uid));
 465
 466 #ifdef  __USE_BSD
 467 /* Set the real user ID of the calling process to RUID,
 468    and the effective user ID of the calling process to EUID.  */
 469 extern int __setreuid __P ((__uid_t __ruid, __uid_t __euid));
 470 extern int setreuid __P ((__uid_t __ruid, __uid_t __euid));
 471
 472 /* Set the effective user ID of the calling process to UID.  */
 473 extern int seteuid __P ((__uid_t __uid));
 474 #endif /* Use BSD.  */
 475
 476 /* Set the group ID of the calling process to GID.
 477    If the calling process is the super-user, set the real
 478    and effective group IDs, and the saved set-group-ID to GID;
 479    if not, the effective group ID is set to GID.  */
 480 extern int __setgid __P ((__gid_t __gid));
 481 extern int setgid __P ((__gid_t __gid));
 482
 483 #ifdef  __USE_BSD
 484 /* Set the real group ID of the calling process to RGID,
 485    and the effective group ID of the calling process to EGID.  */
 486 extern int __setregid __P ((__gid_t __rgid, __gid_t __egid));
 487 extern int setregid __P ((__gid_t __rgid, __gid_t __egid));
 488
 489 /* Set the effective group ID of the calling process to GID.  */
 490 extern int setegid __P ((__gid_t __gid));
 491 #endif /* Use BSD.  */
 492
 493
 494 /* Clone the calling process, creating an exact copy.
 495    Return -1 for errors, 0 to the new process,
 496    and the process ID of the new process to the old process.  */
 497 extern __pid_t __fork __P ((void));
 498 extern __pid_t fork __P ((void));
 499
 500 #ifdef  __USE_BSD
 501 /* Clone the calling process, but without copying the whole address space.
 502    The the calling process is suspended until the the new process exits or is
 503    replaced by a call to `execve'.  Return -1 for errors, 0 to the new process,
 504    and the process ID of the new process to the old process.  */
 505 extern __pid_t __vfork __P ((void));
 506 extern __pid_t vfork __P ((void));
 507 #endif /* Use BSD. */
 508
 509
 510 /* Return the pathname of the terminal FD is open on, or NULL on errors.
 511    The returned storage is good only until the next call to this function.  */
 512 extern char *ttyname __P ((int __fd));
 513 #ifdef __USE_REENTRANT
 514 /* Store at most BUFLEN characters of the pathname of the terminal FD is
 515    open on in BUF.  Return 0 on success, -1 otherwise.  */
 516 extern int __ttyname_r __P ((int __fd, char *__buf, int __buflen));
 517 extern int ttyname_r __P ((int __fd, char *__buf, int __buflen));
 518 #endif
 519
 520 /* Return 1 if FD is a valid descriptor associated
 521    with a terminal, zero if not.  */
 522 extern int __isatty __P ((int __fd));
 523 extern int isatty __P ((int __fd));
 524
 525 #ifdef __USE_BSD
 526 /* Return the index into the active-logins file (utmp) for
 527    the controlling terminal.  */
 528 extern int ttyslot __P ((void));
 529 #endif
 530
 531
 532 /* Make a link to FROM named TO.  */
 533 extern int __link __P ((__const char *__from, __const char *__to));
 534 extern int link __P ((__const char *__from, __const char *__to));
 535
 536 #ifdef  __USE_BSD
 537 /* Make a symbolic link to FROM named TO.  */
 538 extern int __symlink __P ((__const char *__from, __const char *__to));
 539 extern int symlink __P ((__const char *__from, __const char *__to));
 540
 541 /* Read the contents of the symbolic link PATH into no more than
 542    LEN bytes of BUF.  The contents are not null-terminated.
 543    Returns the number of characters read, or -1 for errors.  */
 544 extern int __readlink __P ((__const char *__path, char *__buf, size_t __len));
 545 extern int readlink __P ((__const char *__path, char *__buf, size_t __len));
 546 #endif /* Use BSD.  */
 547
 548 /* Remove the link NAME.  */
 549 extern int __unlink __P ((__const char *__name));
 550 extern int unlink __P ((__const char *__name));
 551
 552 /* Remove the directory PATH.  */
 553 extern int __rmdir __P ((__const char *__path));
 554 extern int rmdir __P ((__const char *__path));
 555
 556
 557 /* Return the foreground process group ID of FD.  */
 558 extern __pid_t tcgetpgrp __P ((int __fd));
 559
 560 /* Set the foreground process group ID of FD set PGRP_ID.  */
 561 extern int tcsetpgrp __P ((int __fd, __pid_t __pgrp_id));
 562
 563
 564 /* Return the login name of the user.  */
 565 extern char *getlogin __P ((void));
 566 #ifdef __USE_REENTRANT
 567 /* Return at most NAME_LEN characters of the login name of the user in NAME.
 568    If it cannot be determined or some other error occured, return the error
 569    code.  Otherwise return 0.  */
 570 extern int getlogin_r __P ((char *__name, size_t __name_len));
 571 #endif
 572
 573 #ifdef  __USE_BSD
 574 /* Set the login name returned by `getlogin'.  */
 575 extern int setlogin __P ((__const char *__name));
 576 #endif
 577
 578
 579 #ifdef  __USE_POSIX2
 580 /* Process the arguments in ARGV (ARGC of them, minus
 581    the program name) for options given in OPTS.
 582
 583    If `opterr' is zero, no messages are generated
 584    for invalid options; it defaults to 1.
 585    `optind' is the current index into ARGV.
 586    `optarg' is the argument corresponding to the current option.
 587    Return the option character from OPTS just read.
 588    Return -1 when there are no more options.
 589    For unrecognized options, or options missing arguments,
 590    `optopt' is set to the option letter, and '?' is returned.
 591
 592    The OPTS string is a list of characters which are recognized option
 593    letters, optionally followed by colons, specifying that that letter
 594    takes an argument, to be placed in `optarg'.
 595
 596    If a letter in OPTS is followed by two colons, its argument is optional.
 597    This behavior is specific to the GNU `getopt'.
 598
 599    The argument `--' causes premature termination of argument scanning,
 600    explicitly telling `getopt' that there are no more options.
 601
 602    If OPTS begins with `--', then non-option arguments
 603    are treated as arguments to the option '\0'.
 604    This behavior is specific to the GNU `getopt'.  */
 605 extern int getopt __P ((int __argc, char *__const * __argv,
 606                         __const char *__opts));
 607 extern int opterr;
 608 extern int optind;
 609 extern int optopt;
 610 extern char *optarg;
 611 #endif
 612
 613
 614 #ifdef  __USE_BSD
 615
 616 /* Put the name of the current host in no more than LEN bytes of NAME.
 617    The result is null-terminated if LEN is large enough for the full
 618    name and the terminator.  */
 619 extern int __gethostname __P ((char *__name, size_t __len));
 620 extern int gethostname __P ((char *__name, size_t __len));
 621
 622 /* Set the name of the current host to NAME, which is LEN bytes long.
 623    This call is restricted to the super-user.  */
 624 extern int sethostname __P ((__const char *__name, size_t __len));
 625
 626 /* Return the current machine's Internet number.  */
 627 extern long int gethostid __P ((void));
 628
 629 /* Set the current machine's Internet number to ID.
 630    This call is restricted to the super-user.  */
 631 extern int sethostid __P ((long int __id));
 632
 633
 634 /* Get and set the NIS (aka YP) domain name, if any.
 635    Called just like `gethostname' and `sethostname'.
 636    The NIS domain name is usually the empty string when not using NIS.  */
 637 extern int getdomainname __P ((char *__name, size_t __len));
 638 extern int setdomainname __P ((__const char *__name, size_t __len));
 639
 640
 641 /* Return the number of bytes in a page.  This is the system's page size,
 642    which is not necessarily the same as the hardware page size.  */
 643 extern size_t __getpagesize __P ((void));
 644 extern size_t getpagesize __P ((void));
 645
 646
 647 /* Return the maximum number of file descriptors
 648    the current process could possibly have.  */
 649 extern int __getdtablesize __P ((void));
 650 extern int getdtablesize __P ((void));
 651
 652
 653 /* Truncate FILE to LENGTH bytes.  */
 654 extern int truncate __P ((__const char *__file, __off_t __length));
 655
 656 /* Truncate the file FD is open on to LENGTH bytes.  */
 657 extern int ftruncate __P ((int __fd, __off_t __length));
 658
 659
 660 /* Make all changes done to FD actually appear on disk.  */
 661 extern int fsync __P ((int __fd));
 662
 663 /* Make all changes done to all files actually appear on disk.  */
 664 extern int sync __P ((void));
 665
 666
 667 /* Revoke access permissions to all processes currently communicating
 668    with the control terminal, and then send a SIGHUP signal to the process
 669    group of the control terminal.  */
 670 extern int vhangup __P ((void));
 671
 672 /* Revoke the access of all descriptors currently open on FILE.  */
 673 extern int revoke __P ((__const char *__file));
 674
 675
 676 /* Enable statistical profiling, writing samples of the PC into at most
 677    SIZE bytes of SAMPLE_BUFFER; every processor clock tick while profiling
 678    is enabled, the system examines the user PC and increments
 679    SAMPLE_BUFFER[((PC - OFFSET) / 2) * SCALE / 65536].  If SCALE is zero,
 680    disable profiling.  Returns zero on success, -1 on error.  */
 681 extern int profil __P ((unsigned short int *__sample_buffer, size_t __size,
 682                         size_t __offset, unsigned int __scale));
 683
 684
 685 /* Turn accounting on if NAME is an existing file.  The system will then write
 686    a record for each process as it terminates, to this file.  If NAME is NULL,
 687    turn accounting off.  This call is restricted to the super-user.  */
 688 extern int acct __P ((__const char *__name));
 689
 690 /* Make PATH be the root directory (the starting point for absolute paths).
 691    This call is restricted to the super-user.  */
 692 extern int chroot __P ((__const char *__path));
 693
 694
 695 /* Successive calls return the shells listed in `/etc/shells'.  */
 696 extern char *getusershell __P ((void));
 697 extern void endusershell __P ((void)); /* Discard cached info.  */
 698 extern void setusershell __P ((void)); /* Rewind and re-read the file.  */
 699
 700
 701 /* Prompt with PROMPT and read a string from the terminal without echoing.
 702    Uses /dev/tty if possible; otherwise stderr and stdin.  */
 703 extern char *getpass __P ((__const char *__prompt));
 704
 705 /* Put the program in the background, and dissociate from the controlling
 706    terminal.  If NOCHDIR is zero, do `chdir ("/")'.  If NOCLOSE is zero,
 707    redirects stdin, stdout, and stderr to /dev/null.  */
 708 extern int daemon __P ((int __nochdir, int __noclose));
 709
 710 #endif /* Use BSD.  */
 711
 712
 713 #ifdef __USE_MISC
 714
 715 /* Generate a unique temporary file name from TEMPLATE.
 716    The last six characters of TEMPLATE must be "XXXXXX";
 717    they are replaced with a string that makes the file name unique.
 718    Returns TEMPLATE, or a null pointer if it cannot get a unique file name.  */
 719 extern char *mktemp __P ((char *__template));
 720
 721 /* Generate a unique temporary file name from TEMPLATE.
 722    The last six characters of TEMPLATE must be "XXXXXX";
 723    they are replaced with a string that makes the filename unique.
 724    Returns a file descriptor open on the file for reading and writing,
 725    or -1 if it cannot create a uniquely-named file.  */
 726 extern int mkstemp __P ((char *__template));
 727
 728
 729 /* Set the end of accessible data space (aka "the break") to ADDR.
 730    Returns zero on success and -1 for errors (with errno set).  */
 731 extern int __brk __P ((__ptr_t __addr));
 732 extern int brk __P ((__ptr_t __addr));
 733
 734 #define __need_ptrdiff_t
 735 #include <stddef.h>
 736
 737 /* Increase or decrease the end of accessible data space by DELTA bytes.
 738    If successful, returns the address the previous end of data space
 739    (i.e. the beginning of the new space, if DELTA > 0);
 740    returns (void *) -1 for errors (with errno set).  */
 741 extern __ptr_t __sbrk __P ((ptrdiff_t __delta));
 742 extern __ptr_t sbrk __P ((ptrdiff_t __delta));
 743
 744
 745 /* Invoke `system call' number SYSNO, passing it the remaining arguments.
 746    This is completely system-dependent, and not often useful.
 747
 748    In Unix, `syscall' sets `errno' for all errors and most calls return -1
 749    for errors; in many systems you cannot pass arguments or get return
 750    values for all system calls (`pipe', `fork', and `getppid' typically
 751    among them).
 752
 753    In Mach, all system calls take normal arguments and always return an
 754    error code (zero for success).  */
 755 extern long int syscall __P ((long int __sysno, ...));
 756
 757 #endif  /* Use misc.  */
 758
 759
 760 #if defined (__USE_MISC) && !defined (F_LOCK)
 761 /* NOTE: These declarations also appear in <fcntl.h>; be sure to keep both
 762    files consistent.  Some systems have them there and some here, and some
 763    software depends on the macros being defined without including both.  */
 764
 765 /* `lockf' is a simpler interface to the locking facilities of `fcntl'.
 766    LEN is always relative to the current file position.
 767    The CMD argument is one of the following.  */
 768
 769 #define F_ULOCK 0       /* Unlock a previously locked region.  */
 770 #define F_LOCK  1       /* Lock a region for exclusive use.  */
 771 #define F_TLOCK 2       /* Test and lock a region for exclusive use.  */
 772 #define F_TEST  3       /* Test a region for other processes locks.  */
 773
 774 extern int lockf __P ((int __fd, int __cmd, __off_t __len));
 775 #endif /* Use misc and F_LOCK not already defined.  */
 776
 777
 778 #ifdef __USE_GNU
 779
 780 /* Evaluate EXPRESSION, and repeat as long as it returns -1 with `errno'
 781    set to EINTR.  */
 782
 783 #define TEMP_FAILURE_RETRY(expression) \
 784   (__extension__                                                              \
 785     ({ long int __result;                                                     \
 786        do __result = (long int) (expression);                                 \
 787        while (__result == -1L && errno == EINTR);                             \
 788        __result; }))                                                          \
 789
 790
 791 /* This variable is set nonzero at startup if the process's effective IDs
 792    differ from its real IDs, or it is otherwise indicated that extra
 793    security should be used.  When this is set the dynamic linker ignores
 794    the various environment variables that normally affect it.  */
 795
 796 extern int __libc_enable_secure;
 797
 798 #endif
 799
 800 #ifdef __USE_POSIX
 801 /* Synchronize at least the data part of a file with the underlying
 802    media.  */
 803 extern int fdatasync __P ((int __fildes));
 804 #endif /* Use POSIX */
 805
 806 __END_DECLS
 807
 808 #endif /* unistd.h  */