sysdeps/posix/pathconf.c

   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 #include <errno.h>
  19 #include <stddef.h>
  20 #include <unistd.h>
  21 #include <limits.h>
  22 #include <fcntl.h>
  23 #include <sys/stat.h>
  24 #include <sys/statfs.h>
  25 #include <sys/statvfs.h>
  26
  27
  28 /* Get file-specific information about PATH.  */
  29 long int
  30 __pathconf (const char *path, int name)
  31 {
  32   if (path[0] == '\0')
  33     {
  34       __set_errno (ENOENT);
  35       return -1;
  36     }
  37
  38   switch (name)
  39     {
  40     default:
  41       __set_errno (EINVAL);
  42       return -1;
  43
  44     case _PC_LINK_MAX:
  45 #ifdef  LINK_MAX
  46       return LINK_MAX;
  47 #else
  48       return -1;
  49 #endif
  50
  51     case _PC_MAX_CANON:
  52 #ifdef  MAX_CANON
  53       return MAX_CANON;
  54 #else
  55       return -1;
  56 #endif
  57
  58     case _PC_MAX_INPUT:
  59 #ifdef  MAX_INPUT
  60       return MAX_INPUT;
  61 #else
  62       return -1;
  63 #endif
  64
  65     case _PC_NAME_MAX:
  66 #ifdef  NAME_MAX
  67       {
  68         struct statvfs64 sv;
  69         int save_errno = errno;
  70
  71         if (__statvfs64 (path, &sv) < 0)
  72           {
  73             if (errno == ENOSYS)
  74               {
  75                 errno = save_errno;
  76                 return NAME_MAX;
  77               }
  78             return -1;
  79           }
  80         else
  81           {
  82             return sv.f_namemax;
  83           }
  84       }
  85 #else
  86       return -1;
  87 #endif
  88
  89     case _PC_PATH_MAX:
  90 #ifdef  PATH_MAX
  91       return PATH_MAX;
  92 #else
  93       return -1;
  94 #endif
  95
  96     case _PC_PIPE_BUF:
  97 #ifdef  PIPE_BUF
  98       return PIPE_BUF;
  99 #else
 100       return -1;
 101 #endif
 102
 103     case _PC_CHOWN_RESTRICTED:
 104 #if _POSIX_CHOWN_RESTRICTED == -1
 105 # error "Invalid value for _POSIX_CHOWN_RESTRICTED"
 106 #endif
 107       return _POSIX_CHOWN_RESTRICTED;
 108
 109     case _PC_NO_TRUNC:
 110 #if _POSIX_NO_TRUNC == -1
 111 # error "Invalid value for _POSIX_NO_TRUNC"
 112 #endif
 113       return _POSIX_NO_TRUNC;
 114
 115     case _PC_VDISABLE:
 116 #if _POSIX_VDISABLE == -1
 117 # error "Invalid value for _POSIX_VDISABLE"
 118 #endif
 119       return _POSIX_VDISABLE;
 120
 121     case _PC_SYNC_IO:
 122 #ifdef  _POSIX_SYNC_IO
 123       return _POSIX_SYNC_IO;
 124 #else
 125       return -1;
 126 #endif
 127
 128     case _PC_ASYNC_IO:
 129 #ifdef  _POSIX_ASYNC_IO
 130       {
 131         /* AIO is only allowed on regular files and block devices.  */
 132         struct __stat64_t64 st;
 133
 134         if (__stat64_time64 (path, &st) < 0
 135             || (! S_ISREG (st.st_mode) && ! S_ISBLK (st.st_mode)))
 136           return -1;
 137         else
 138           return 1;
 139       }
 140 #else
 141       return -1;
 142 #endif
 143
 144     case _PC_PRIO_IO:
 145 #ifdef  _POSIX_PRIO_IO
 146       return _POSIX_PRIO_IO;
 147 #else
 148       return -1;
 149 #endif
 150
 151     case _PC_SOCK_MAXBUF:
 152 #ifdef  SOCK_MAXBUF
 153       return SOCK_MAXBUF;
 154 #else
 155       return -1;
 156 #endif
 157
 158     case _PC_FILESIZEBITS:
 159 #ifdef FILESIZEBITS
 160       return FILESIZEBITS;
 161 #else
 162       /* We let platforms with larger file sizes overwrite this value.  */
 163       return 32;
 164 #endif
 165
 166     case _PC_REC_INCR_XFER_SIZE:
 167       /* XXX It is not entirely clear what the limit is supposed to do.
 168          What is incremented?  */
 169       return -1;
 170
 171     case _PC_REC_MAX_XFER_SIZE:
 172       /* XXX It is not entirely clear what the limit is supposed to do.
 173          In general there is no top limit of the number of bytes which
 174          case be transported at once.  */
 175       return -1;
 176
 177     case _PC_REC_MIN_XFER_SIZE:
 178       {
 179         /* XXX It is not entirely clear what the limit is supposed to do.
 180            I assume this is the block size of the filesystem.  */
 181         struct statvfs64 sv;
 182
 183         if (__statvfs64 (path, &sv) < 0)
 184           return -1;
 185         return sv.f_bsize;
 186       }
 187
 188     case _PC_REC_XFER_ALIGN:
 189       {
 190         /* XXX It is not entirely clear what the limit is supposed to do.
 191            I assume that the number should reflect the minimal block
 192            alignment.  */
 193         struct statvfs64 sv;
 194
 195         if (__statvfs64 (path, &sv) < 0)
 196           return -1;
 197         return sv.f_frsize;
 198       }
 199
 200     case _PC_ALLOC_SIZE_MIN:
 201       {
 202         /* XXX It is not entirely clear what the limit is supposed to do.
 203            I assume that the number should reflect the minimal block
 204            alignment.  */
 205         struct statvfs64 sv;
 206
 207         if (__statvfs64 (path, &sv) < 0)
 208           return -1;
 209         return sv.f_frsize;
 210       }
 211
 212     case _PC_SYMLINK_MAX:
 213       /* In general there are no limits.  If a system has one it should
 214          overwrite this case.  */
 215       return -1;
 216
 217     case _PC_2_SYMLINKS:
 218       /* Unix systems generally have symlinks.  */
 219       return 1;
 220     }
 221 }
 222
 223 #undef __pathconf
 224 weak_alias (__pathconf, pathconf)