io/fcntl.h

   1 /* Copyright (C) 1991-2024 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 Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the 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    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 /*
  19  *      POSIX Standard: 6.5 File Control Operations     <fcntl.h>
  20  */
  21
  22 #ifndef _FCNTL_H
  23 #define _FCNTL_H        1
  24
  25 #include <features.h>
  26
  27 /* This must be early so <bits/fcntl.h> can define types winningly.  */
  28 __BEGIN_DECLS
  29
  30 /* Get __mode_t, __dev_t and __off_t  .*/
  31 #include <bits/types.h>
  32
  33 /* Get the definitions of O_*, F_*, FD_*: all the
  34    numbers and flag bits for `open', `fcntl', et al.  */
  35 #include <bits/fcntl.h>
  36
  37 /* Detect if open needs mode as a third argument (or for openat as a fourth
  38    argument).  */
  39 #ifdef __O_TMPFILE
  40 # define __OPEN_NEEDS_MODE(oflag) \
  41   (((oflag) & O_CREAT) != 0 || ((oflag) & __O_TMPFILE) == __O_TMPFILE)
  42 #else
  43 # define __OPEN_NEEDS_MODE(oflag) (((oflag) & O_CREAT) != 0)
  44 #endif
  45
  46 /* POSIX.1-2001 specifies that these types are defined by <fcntl.h>.
  47    Earlier POSIX standards permitted any type ending in `_t' to be defined
  48    by any POSIX header, so we don't conditionalize the definitions here.  */
  49 #ifndef __mode_t_defined
  50 typedef __mode_t mode_t;
  51 # define __mode_t_defined
  52 #endif
  53
  54 #ifndef __off_t_defined
  55 # ifndef __USE_FILE_OFFSET64
  56 typedef __off_t off_t;
  57 # else
  58 typedef __off64_t off_t;
  59 # endif
  60 # define __off_t_defined
  61 #endif
  62
  63 #if defined __USE_LARGEFILE64 && !defined __off64_t_defined
  64 typedef __off64_t off64_t;
  65 # define __off64_t_defined
  66 #endif
  67
  68 #ifndef __pid_t_defined
  69 typedef __pid_t pid_t;
  70 # define __pid_t_defined
  71 #endif
  72
  73 /* For XPG all symbols from <sys/stat.h> should also be available.  */
  74 #ifdef __USE_XOPEN2K8
  75 # include <bits/types/struct_timespec.h>
  76 #endif
  77 #if defined __USE_XOPEN || defined __USE_XOPEN2K8
  78 # include <bits/stat.h>
  79
  80 # define S_IFMT         __S_IFMT
  81 # define S_IFDIR        __S_IFDIR
  82 # define S_IFCHR        __S_IFCHR
  83 # define S_IFBLK        __S_IFBLK
  84 # define S_IFREG        __S_IFREG
  85 # ifdef __S_IFIFO
  86 #  define S_IFIFO       __S_IFIFO
  87 # endif
  88 # ifdef __S_IFLNK
  89 #  define S_IFLNK       __S_IFLNK
  90 # endif
  91 # if (defined __USE_UNIX98 || defined __USE_XOPEN2K8) && defined __S_IFSOCK
  92 #  define S_IFSOCK      __S_IFSOCK
  93 # endif
  94
  95 /* Protection bits.  */
  96
  97 # define S_ISUID        __S_ISUID       /* Set user ID on execution.  */
  98 # define S_ISGID        __S_ISGID       /* Set group ID on execution.  */
  99
 100 # if defined __USE_MISC || defined __USE_XOPEN
 101 /* Save swapped text after use (sticky bit).  This is pretty well obsolete.  */
 102 #  define S_ISVTX       __S_ISVTX
 103 # endif
 104
 105 # define S_IRUSR        __S_IREAD       /* Read by owner.  */
 106 # define S_IWUSR        __S_IWRITE      /* Write by owner.  */
 107 # define S_IXUSR        __S_IEXEC       /* Execute by owner.  */
 108 /* Read, write, and execute by owner.  */
 109 # define S_IRWXU        (__S_IREAD|__S_IWRITE|__S_IEXEC)
 110
 111 # define S_IRGRP        (S_IRUSR >> 3)  /* Read by group.  */
 112 # define S_IWGRP        (S_IWUSR >> 3)  /* Write by group.  */
 113 # define S_IXGRP        (S_IXUSR >> 3)  /* Execute by group.  */
 114 /* Read, write, and execute by group.  */
 115 # define S_IRWXG        (S_IRWXU >> 3)
 116
 117 # define S_IROTH        (S_IRGRP >> 3)  /* Read by others.  */
 118 # define S_IWOTH        (S_IWGRP >> 3)  /* Write by others.  */
 119 # define S_IXOTH        (S_IXGRP >> 3)  /* Execute by others.  */
 120 /* Read, write, and execute by others.  */
 121 # define S_IRWXO        (S_IRWXG >> 3)
 122 #endif
 123
 124 #ifdef  __USE_MISC
 125 # ifndef R_OK                   /* Verbatim from <unistd.h>.  Ugh.  */
 126 /* Values for the second argument to access.
 127    These may be OR'd together.  */
 128 #  define R_OK  4               /* Test for read permission.  */
 129 #  define W_OK  2               /* Test for write permission.  */
 130 #  define X_OK  1               /* Test for execute permission.  */
 131 #  define F_OK  0               /* Test for existence.  */
 132 # endif
 133 #endif /* Use misc.  */
 134
 135 /* XPG wants the following symbols.   <stdio.h> has the same definitions.  */
 136 #if defined __USE_XOPEN || defined __USE_XOPEN2K8
 137 # define SEEK_SET       0       /* Seek from beginning of file.  */
 138 # define SEEK_CUR       1       /* Seek from current position.  */
 139 # define SEEK_END       2       /* Seek from end of file.  */
 140 #endif  /* XPG */
 141
 142 /* The constants AT_REMOVEDIR and AT_EACCESS have the same value.  AT_EACCESS
 143    is meaningful only to faccessat, while AT_REMOVEDIR is meaningful only to
 144    unlinkat.  The two functions do completely different things and therefore,
 145    the flags can be allowed to overlap.  For example, passing AT_REMOVEDIR to
 146    faccessat would be undefined behavior and thus treating it equivalent to
 147    AT_EACCESS is valid undefined behavior.  */
 148 #ifdef __USE_ATFILE
 149 # define AT_FDCWD               -100    /* Special value used to indicate
 150                                            the *at functions should use the
 151                                            current working directory. */
 152 # define AT_SYMLINK_NOFOLLOW    0x100   /* Do not follow symbolic links.  */
 153 # define AT_REMOVEDIR           0x200   /* Remove directory instead of
 154                                            unlinking file.  */
 155 # define AT_SYMLINK_FOLLOW      0x400   /* Follow symbolic links.  */
 156 # ifdef __USE_GNU
 157 #  define AT_NO_AUTOMOUNT       0x800   /* Suppress terminal automount
 158                                            traversal.  */
 159 #  define AT_EMPTY_PATH         0x1000  /* Allow empty relative pathname.  */
 160 #  define AT_STATX_SYNC_TYPE    0x6000
 161 #  define AT_STATX_SYNC_AS_STAT 0x0000
 162 #  define AT_STATX_FORCE_SYNC   0x2000
 163 #  define AT_STATX_DONT_SYNC    0x4000
 164 #  define AT_RECURSIVE          0x8000  /* Apply to the entire subtree.  */
 165 # endif
 166 # define AT_EACCESS             0x200   /* Test access permitted for
 167                                            effective IDs, not real IDs.  */
 168 #endif
 169
 170 /* Do the file control operation described by CMD on FD.
 171    The remaining arguments are interpreted depending on CMD.
 172
 173    This function is a cancellation point and therefore not marked with
 174    __THROW.  */
 175 #ifndef __USE_TIME64_REDIRECTS
 176 # ifndef __USE_FILE_OFFSET64
 177 extern int fcntl (int __fd, int __cmd, ...);
 178 # else
 179 #  ifdef __REDIRECT
 180 extern int __REDIRECT (fcntl, (int __fd, int __cmd, ...), fcntl64);
 181 #  else
 182 #   define fcntl fcntl64
 183 #  endif
 184 # endif
 185 # ifdef __USE_LARGEFILE64
 186 extern int fcntl64 (int __fd, int __cmd, ...);
 187 # endif
 188 #else /* __USE_TIME64_REDIRECTS */
 189 # ifdef __REDIRECT
 190 extern int __REDIRECT_NTH (fcntl, (int __fd, int __request, ...),
 191                            __fcntl_time64);
 192 extern int __REDIRECT_NTH (fcntl64, (int __fd, int __request, ...),
 193                            __fcntl_time64);
 194 # else
 195 extern int __fcntl_time64 (int __fd, int __request, ...) __THROW;
 196 #  define fcntl64 __fcntl_time64
 197 #  define fcntl __fcntl_time64
 198 # endif
 199 #endif
 200
 201 /* Open FILE and return a new file descriptor for it, or -1 on error.
 202    OFLAG determines the type of access used.  If O_CREAT or O_TMPFILE is set
 203    in OFLAG, the third argument is taken as a `mode_t', the mode of the
 204    created file.
 205
 206    This function is a cancellation point and therefore not marked with
 207    __THROW.  */
 208 #ifndef __USE_FILE_OFFSET64
 209 extern int open (const char *__file, int __oflag, ...) __nonnull ((1));
 210 #else
 211 # ifdef __REDIRECT
 212 extern int __REDIRECT (open, (const char *__file, int __oflag, ...), open64)
 213      __nonnull ((1));
 214 # else
 215 #  define open open64
 216 # endif
 217 #endif
 218 #ifdef __USE_LARGEFILE64
 219 extern int open64 (const char *__file, int __oflag, ...) __nonnull ((1));
 220 #endif
 221
 222 #ifdef __USE_ATFILE
 223 /* Similar to `open' but a relative path name is interpreted relative to
 224    the directory for which FD is a descriptor.
 225
 226    NOTE: some other `openat' implementation support additional functionality
 227    through this interface, especially using the O_XATTR flag.  This is not
 228    yet supported here.
 229
 230    This function is a cancellation point and therefore not marked with
 231    __THROW.  */
 232 # ifndef __USE_FILE_OFFSET64
 233 extern int openat (int __fd, const char *__file, int __oflag, ...)
 234      __nonnull ((2));
 235 # else
 236 #  ifdef __REDIRECT
 237 extern int __REDIRECT (openat, (int __fd, const char *__file, int __oflag,
 238                                 ...), openat64) __nonnull ((2));
 239 #  else
 240 #   define openat openat64
 241 #  endif
 242 # endif
 243 # ifdef __USE_LARGEFILE64
 244 extern int openat64 (int __fd, const char *__file, int __oflag, ...)
 245      __nonnull ((2));
 246 # endif
 247 #endif
 248
 249 /* Create and open FILE, with mode MODE.  This takes an `int' MODE
 250    argument because that is what `mode_t' will be widened to.
 251
 252    This function is a cancellation point and therefore not marked with
 253    __THROW.  */
 254 #ifndef __USE_FILE_OFFSET64
 255 extern int creat (const char *__file, mode_t __mode) __nonnull ((1));
 256 #else
 257 # ifdef __REDIRECT
 258 extern int __REDIRECT (creat, (const char *__file, mode_t __mode),
 259                        creat64) __nonnull ((1));
 260 # else
 261 #  define creat creat64
 262 # endif
 263 #endif
 264 #ifdef __USE_LARGEFILE64
 265 extern int creat64 (const char *__file, mode_t __mode) __nonnull ((1));
 266 #endif
 267
 268 #if !defined F_LOCK && (defined __USE_MISC || (defined __USE_XOPEN_EXTENDED \
 269                                                && !defined __USE_POSIX))
 270 /* NOTE: These declarations also appear in <unistd.h>; be sure to keep both
 271    files consistent.  Some systems have them there and some here, and some
 272    software depends on the macros being defined without including both.  */
 273
 274 /* `lockf' is a simpler interface to the locking facilities of `fcntl'.
 275    LEN is always relative to the current file position.
 276    The CMD argument is one of the following.  */
 277
 278 # define F_ULOCK 0      /* Unlock a previously locked region.  */
 279 # define F_LOCK  1      /* Lock a region for exclusive use.  */
 280 # define F_TLOCK 2      /* Test and lock a region for exclusive use.  */
 281 # define F_TEST  3      /* Test a region for other processes locks.  */
 282
 283 # ifndef __USE_FILE_OFFSET64
 284 extern int lockf (int __fd, int __cmd, off_t __len);
 285 # else
 286 #  ifdef __REDIRECT
 287 extern int __REDIRECT (lockf, (int __fd, int __cmd, __off64_t __len), lockf64);
 288 #  else
 289 #   define lockf lockf64
 290 #  endif
 291 # endif
 292 # ifdef __USE_LARGEFILE64
 293 extern int lockf64 (int __fd, int __cmd, off64_t __len);
 294 # endif
 295 #endif
 296
 297 #ifdef __USE_XOPEN2K
 298 /* Advice the system about the expected behaviour of the application with
 299    respect to the file associated with FD.  */
 300 # ifndef __USE_FILE_OFFSET64
 301 extern int posix_fadvise (int __fd, off_t __offset, off_t __len,
 302                           int __advise) __THROW;
 303 # else
 304  # ifdef __REDIRECT_NTH
 305 extern int __REDIRECT_NTH (posix_fadvise, (int __fd, __off64_t __offset,
 306                                            __off64_t __len, int __advise),
 307                            posix_fadvise64);
 308 #  else
 309 #   define posix_fadvise posix_fadvise64
 310 #  endif
 311 # endif
 312 # ifdef __USE_LARGEFILE64
 313 extern int posix_fadvise64 (int __fd, off64_t __offset, off64_t __len,
 314                             int __advise) __THROW;
 315 # endif
 316
 317
 318 /* Reserve storage for the data of the file associated with FD.
 319
 320    This function is a possible cancellation point and therefore not
 321    marked with __THROW.  */
 322 # ifndef __USE_FILE_OFFSET64
 323 extern int posix_fallocate (int __fd, off_t __offset, off_t __len);
 324 # else
 325  # ifdef __REDIRECT
 326 extern int __REDIRECT (posix_fallocate, (int __fd, __off64_t __offset,
 327                                          __off64_t __len),
 328                        posix_fallocate64);
 329 #  else
 330 #   define posix_fallocate posix_fallocate64
 331 #  endif
 332 # endif
 333 # ifdef __USE_LARGEFILE64
 334 extern int posix_fallocate64 (int __fd, off64_t __offset, off64_t __len);
 335 # endif
 336 #endif
 337
 338
 339 /* Define some inlines helping to catch common problems.  */
 340 #if __USE_FORTIFY_LEVEL > 0 && defined __fortify_function
 341 # include <bits/fcntl2.h>
 342 #endif
 343
 344 __END_DECLS
 345
 346 #endif /* fcntl.h  */