sysdeps/unix/sysv/linux/pathconf.c

   1 /* Get file-specific information about a file.  Linux version.
   2    Copyright (C) 1991,1995,1996,1998-2003,2008,2010,2011 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <unistd.h>
  21 #include <errno.h>
  22
  23 #include "pathconf.h"
  24 #include "linux_fsinfo.h"
  25 #include <not-cancel.h>
  26
  27 static long int posix_pathconf (const char *file, int name);
  28
  29 /* Define this first, so it can be inlined.  */
  30 #define __pathconf static posix_pathconf
  31 #include <sysdeps/posix/pathconf.c>
  32
  33
  34 /* Get file-specific information about FILE.  */
  35 long int
  36 __pathconf (const char *file, int name)
  37 {
  38   struct statfs fsbuf;
  39   int fd;
  40   int flags;
  41
  42   switch (name)
  43     {
  44     case _PC_LINK_MAX:
  45       return __statfs_link_max (__statfs (file, &fsbuf), &fsbuf);
  46
  47     case _PC_FILESIZEBITS:
  48       return __statfs_filesize_max (__statfs (file, &fsbuf), &fsbuf);
  49
  50     case _PC_2_SYMLINKS:
  51       return __statfs_symlinks (__statfs (file, &fsbuf), &fsbuf);
  52
  53     case _PC_CHOWN_RESTRICTED:
  54       return __statfs_chown_restricted (__statfs (file, &fsbuf), &fsbuf);
  55
  56     case _PC_PIPE_BUF:
  57       flags = O_RDONLY|O_NONBLOCK|O_NOCTTY;
  58 #ifdef O_CLOEXEC
  59       flags |= O_CLOEXEC;
  60 #endif
  61       fd = open_not_cancel_2 (file, flags);
  62       if (fd >= 0)
  63         {
  64           long int r = __fcntl (fd, F_GETPIPE_SZ);
  65           close_not_cancel_no_status (fd);
  66           if (r > 0)
  67             return r;
  68         }
  69       /* FALLTHROUGH */
  70
  71     default:
  72       return posix_pathconf (file, name);
  73     }
  74 }
  75
  76
  77 /* Used like: return statfs_link_max (__statfs (name, &buf), &buf); */
  78 long int
  79 __statfs_link_max (int result, const struct statfs *fsbuf)
  80 {
  81   if (result < 0)
  82     {
  83       if (errno == ENOSYS)
  84         /* Not possible, return the default value.  */
  85         return LINUX_LINK_MAX;
  86
  87       /* Some error occured.  */
  88       return -1;
  89     }
  90
  91   switch (fsbuf->f_type)
  92     {
  93     case EXT2_SUPER_MAGIC:
  94       return EXT2_LINK_MAX;
  95
  96     case MINIX_SUPER_MAGIC:
  97     case MINIX_SUPER_MAGIC2:
  98       return MINIX_LINK_MAX;
  99
 100     case MINIX2_SUPER_MAGIC:
 101     case MINIX2_SUPER_MAGIC2:
 102       return MINIX2_LINK_MAX;
 103
 104     case XENIX_SUPER_MAGIC:
 105       return XENIX_LINK_MAX;
 106
 107     case SYSV4_SUPER_MAGIC:
 108     case SYSV2_SUPER_MAGIC:
 109       return SYSV_LINK_MAX;
 110
 111     case COH_SUPER_MAGIC:
 112       return COH_LINK_MAX;
 113
 114     case UFS_MAGIC:
 115     case UFS_CIGAM:
 116       return UFS_LINK_MAX;
 117
 118     case REISERFS_SUPER_MAGIC:
 119       return REISERFS_LINK_MAX;
 120
 121     case XFS_SUPER_MAGIC:
 122       return XFS_LINK_MAX;
 123
 124     default:
 125       return LINUX_LINK_MAX;
 126     }
 127 }
 128
 129
 130 /* Used like: return statfs_filesize_max (__statfs (name, &buf), &buf); */
 131 long int
 132 __statfs_filesize_max (int result, const struct statfs *fsbuf)
 133 {
 134   if (result < 0)
 135     {
 136       if (errno == ENOSYS)
 137         /* Not possible, return the default value.  */
 138         return 32;
 139
 140       /* Some error occured.  */
 141       return -1;
 142     }
 143
 144   switch (fsbuf->f_type)
 145     {
 146     case BTRFS_SUPER_MAGIC:
 147       return 255;
 148
 149     case EXT2_SUPER_MAGIC:
 150     case UFS_MAGIC:
 151     case UFS_CIGAM:
 152     case REISERFS_SUPER_MAGIC:
 153     case XFS_SUPER_MAGIC:
 154     case SMB_SUPER_MAGIC:
 155     case NTFS_SUPER_MAGIC:
 156     case UDF_SUPER_MAGIC:
 157     case JFS_SUPER_MAGIC:
 158     case VXFS_SUPER_MAGIC:
 159     case CGROUP_SUPER_MAGIC:
 160       return 64;
 161
 162     case MSDOS_SUPER_MAGIC:
 163     case JFFS_SUPER_MAGIC:
 164     case JFFS2_SUPER_MAGIC:
 165     case NCP_SUPER_MAGIC:
 166     case ROMFS_SUPER_MAGIC:
 167       return 32;
 168
 169     default:
 170       return 32;
 171     }
 172 }
 173
 174
 175 /* Used like: return statfs_link_max (__statfs (name, &buf), &buf); */
 176 long int
 177 __statfs_symlinks (int result, const struct statfs *fsbuf)
 178 {
 179   if (result < 0)
 180     {
 181       if (errno == ENOSYS)
 182         /* Not possible, return the default value.  */
 183         return 1;
 184
 185       /* Some error occured.  */
 186       return -1;
 187     }
 188
 189   switch (fsbuf->f_type)
 190     {
 191     case ADFS_SUPER_MAGIC:
 192     case BFS_MAGIC:
 193     case CRAMFS_MAGIC:
 194     case DEVPTS_SUPER_MAGIC:
 195     case EFS_SUPER_MAGIC:
 196     case EFS_MAGIC:
 197     case MSDOS_SUPER_MAGIC:
 198     case NTFS_SUPER_MAGIC:
 199     case QNX4_SUPER_MAGIC:
 200     case ROMFS_SUPER_MAGIC:
 201       /* No symlink support.  */
 202       return 0;
 203
 204     default:
 205       return 1;
 206     }
 207 }
 208
 209
 210 /* Used like: return __statfs_chown_restricted (__statfs (name, &buf), &buf);*/
 211 long int
 212 __statfs_chown_restricted (int result, const struct statfs *fsbuf)
 213 {
 214   if (result < 0)
 215     {
 216       if (errno == ENOSYS)
 217         /* Not possible, return the default value.  */
 218         return 1;
 219
 220       /* Some error occured.  */
 221       return -1;
 222     }
 223
 224   int fd;
 225   long int retval = 1;
 226   switch (fsbuf->f_type)
 227     {
 228     case XFS_SUPER_MAGIC:
 229       /* Read the value from /proc/sys/fs/xfs/restrict_chown.  If we cannot
 230          read it default to assume the restriction is in place.  */
 231       fd = open_not_cancel_2 ("/proc/sys/fs/xfs/restrict_chown", O_RDONLY);
 232       if (fd != -1)
 233         {
 234           char buf[2];
 235           if (TEMP_FAILURE_RETRY (read_not_cancel (fd, buf, 2)) == 2
 236               && buf[0] >= '0' && buf[0] <= '1')
 237             retval = buf[0] - '0';
 238
 239           close_not_cancel_no_status (fd);
 240         }
 241       break;
 242
 243     default:
 244       break;
 245     }
 246
 247   return retval;
 248 }