lib/fsusage.c

   1 /* fsusage.c -- return space usage of mounted file systems
   2
   3    Copyright (C) 1991-1992, 1996, 1998-1999, 2002-2006, 2009-2020 Free Software
   4    Foundation, Inc.
   5
   6    This program is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  18
  19 #include <config.h>
  20
  21 #include "fsusage.h"
  22
  23 #include <limits.h>
  24 #include <sys/types.h>
  25
  26 #if STAT_STATVFS || STAT_STATVFS64 /* POSIX 1003.1-2001 (and later) with XSI */
  27 # include <sys/statvfs.h>
  28 #else
  29 /* Don't include backward-compatibility files unless they're needed.
  30    Eventually we'd like to remove all this cruft.  */
  31 # include <fcntl.h>
  32 # include <unistd.h>
  33 # include <sys/stat.h>
  34 #if HAVE_SYS_PARAM_H
  35 # include <sys/param.h>
  36 #endif
  37 #if HAVE_SYS_MOUNT_H
  38 # include <sys/mount.h>
  39 #endif
  40 #if HAVE_SYS_VFS_H
  41 # include <sys/vfs.h>
  42 #endif
  43 # if HAVE_SYS_FS_S5PARAM_H      /* Fujitsu UXP/V */
  44 #  include <sys/fs/s5param.h>
  45 # endif
  46 # if HAVE_SYS_STATFS_H
  47 #  include <sys/statfs.h>
  48 # endif
  49 #endif
  50
  51 /* Many space usage primitives use all 1 bits to denote a value that is
  52    not applicable or unknown.  Propagate this information by returning
  53    a uintmax_t value that is all 1 bits if X is all 1 bits, even if X
  54    is unsigned and narrower than uintmax_t.  */
  55 #define PROPAGATE_ALL_ONES(x) \
  56   ((sizeof (x) < sizeof (uintmax_t) \
  57     && (~ (x) == (sizeof (x) < sizeof (int) \
  58                   ? - (1 << (sizeof (x) * CHAR_BIT)) \
  59                   : 0))) \
  60    ? UINTMAX_MAX : (uintmax_t) (x))
  61
  62 /* Extract the top bit of X as an uintmax_t value.  */
  63 #define EXTRACT_TOP_BIT(x) ((x) \
  64                             & ((uintmax_t) 1 << (sizeof (x) * CHAR_BIT - 1)))
  65
  66 /* If a value is negative, many space usage primitives store it into an
  67    integer variable by assignment, even if the variable's type is unsigned.
  68    So, if a space usage variable X's top bit is set, convert X to the
  69    uintmax_t value V such that (- (uintmax_t) V) is the negative of
  70    the original value.  If X's top bit is clear, just yield X.
  71    Use PROPAGATE_TOP_BIT if the original value might be negative;
  72    otherwise, use PROPAGATE_ALL_ONES.  */
  73 #define PROPAGATE_TOP_BIT(x) ((x) | ~ (EXTRACT_TOP_BIT (x) - 1))
  74
  75 #ifdef STAT_STATVFS
  76 /* Return true if statvfs works.  This is false for statvfs on systems
  77    with GNU libc on Linux kernels before 2.6.36, which stats all
  78    preceding entries in /proc/mounts; that makes df hang if even one
  79    of the corresponding file systems is hard-mounted but not available.  */
  80 # if ! (__linux__ && (__GLIBC__ || __UCLIBC__))
  81 /* The FRSIZE fallback is not required in this case.  */
  82 #  undef STAT_STATFS2_FRSIZE
  83 static int statvfs_works (void) { return 1; }
  84 # else
  85 #  include <string.h> /* for strverscmp */
  86 #  include <sys/utsname.h>
  87 #  include <sys/statfs.h>
  88 #  define STAT_STATFS2_BSIZE 1
  89
  90 static int
  91 statvfs_works (void)
  92 {
  93   static int statvfs_works_cache = -1;
  94   struct utsname name;
  95   if (statvfs_works_cache < 0)
  96     statvfs_works_cache = (uname (&name) == 0
  97                            && 0 <= strverscmp (name.release, "2.6.36"));
  98   return statvfs_works_cache;
  99 }
 100 # endif
 101 #endif
 102
 103
 104 /* Fill in the fields of FSP with information about space usage for
 105    the file system on which FILE resides.
 106    DISK is the device on which FILE is mounted, for space-getting
 107    methods that need to know it.
 108    Return 0 if successful, -1 if not.  When returning -1, ensure that
 109    ERRNO is either a system error value, or zero if DISK is NULL
 110    on a system that requires a non-NULL value.  */
 111 int
 112 get_fs_usage (char const *file, char const *disk, struct fs_usage *fsp)
 113 {
 114 #ifdef STAT_STATVFS     /* POSIX, except pre-2.6.36 glibc/Linux */
 115
 116   if (statvfs_works ())
 117     {
 118       struct statvfs vfsd;
 119
 120       if (statvfs (file, &vfsd) < 0)
 121         return -1;
 122
 123       /* f_frsize isn't guaranteed to be supported.  */
 124       fsp->fsu_blocksize = (vfsd.f_frsize
 125                             ? PROPAGATE_ALL_ONES (vfsd.f_frsize)
 126                             : PROPAGATE_ALL_ONES (vfsd.f_bsize));
 127
 128       fsp->fsu_blocks = PROPAGATE_ALL_ONES (vfsd.f_blocks);
 129       fsp->fsu_bfree = PROPAGATE_ALL_ONES (vfsd.f_bfree);
 130       fsp->fsu_bavail = PROPAGATE_TOP_BIT (vfsd.f_bavail);
 131       fsp->fsu_bavail_top_bit_set = EXTRACT_TOP_BIT (vfsd.f_bavail) != 0;
 132       fsp->fsu_files = PROPAGATE_ALL_ONES (vfsd.f_files);
 133       fsp->fsu_ffree = PROPAGATE_ALL_ONES (vfsd.f_ffree);
 134       return 0;
 135     }
 136
 137 #endif
 138
 139 #if defined STAT_STATVFS64            /* AIX */
 140
 141   struct statvfs64 fsd;
 142
 143   if (statvfs64 (file, &fsd) < 0)
 144     return -1;
 145
 146   /* f_frsize isn't guaranteed to be supported.  */
 147   fsp->fsu_blocksize = (fsd.f_frsize
 148                         ? PROPAGATE_ALL_ONES (fsd.f_frsize)
 149                         : PROPAGATE_ALL_ONES (fsd.f_bsize));
 150
 151 #elif defined STAT_STATFS3_OSF1         /* OSF/1 */
 152
 153   struct statfs fsd;
 154
 155   if (statfs (file, &fsd, sizeof (struct statfs)) != 0)
 156     return -1;
 157
 158   fsp->fsu_blocksize = PROPAGATE_ALL_ONES (fsd.f_fsize);
 159
 160 #elif defined STAT_STATFS2_FRSIZE        /* 2.6 < glibc/Linux < 2.6.36 */
 161
 162   struct statfs fsd;
 163
 164   if (statfs (file, &fsd) < 0)
 165     return -1;
 166
 167   fsp->fsu_blocksize = PROPAGATE_ALL_ONES (fsd.f_frsize);
 168
 169 #elif defined STAT_STATFS2_BSIZE        /* glibc/Linux < 2.6, 4.3BSD, SunOS 4, \
 170                                            Mac OS X < 10.4, FreeBSD < 5.0, \
 171                                            NetBSD < 3.0, OpenBSD < 4.4 */
 172
 173   struct statfs fsd;
 174
 175   if (statfs (file, &fsd) < 0)
 176     return -1;
 177
 178   fsp->fsu_blocksize = PROPAGATE_ALL_ONES (fsd.f_bsize);
 179
 180 # ifdef STATFS_TRUNCATES_BLOCK_COUNTS
 181
 182   /* In SunOS 4.1.2, 4.1.3, and 4.1.3_U1, the block counts in the
 183      struct statfs are truncated to 2GB.  These conditions detect that
 184      truncation, presumably without botching the 4.1.1 case, in which
 185      the values are not truncated.  The correct counts are stored in
 186      undocumented spare fields.  */
 187   if (fsd.f_blocks == 0x7fffffff / fsd.f_bsize && fsd.f_spare[0] > 0)
 188     {
 189       fsd.f_blocks = fsd.f_spare[0];
 190       fsd.f_bfree = fsd.f_spare[1];
 191       fsd.f_bavail = fsd.f_spare[2];
 192     }
 193 # endif /* STATFS_TRUNCATES_BLOCK_COUNTS */
 194
 195 #elif defined STAT_STATFS2_FSIZE        /* 4.4BSD and older NetBSD */
 196
 197   struct statfs fsd;
 198
 199   if (statfs (file, &fsd) < 0)
 200     return -1;
 201
 202   fsp->fsu_blocksize = PROPAGATE_ALL_ONES (fsd.f_fsize);
 203
 204 #elif defined STAT_STATFS4              /* SVR3, old Irix */
 205
 206   struct statfs fsd;
 207
 208   if (statfs (file, &fsd, sizeof fsd, 0) < 0)
 209     return -1;
 210
 211   /* Empirically, the block counts on most SVR3 and SVR3-derived
 212      systems seem to always be in terms of 512-byte blocks,
 213      no matter what value f_bsize has.  */
 214    fsp->fsu_blocksize = 512;
 215
 216 #endif
 217
 218 #if (defined STAT_STATVFS64 || defined STAT_STATFS3_OSF1                \
 219      || defined STAT_STATFS2_FRSIZE || defined STAT_STATFS2_BSIZE       \
 220      || defined STAT_STATFS2_FSIZE || defined STAT_STATFS4)
 221
 222   fsp->fsu_blocks = PROPAGATE_ALL_ONES (fsd.f_blocks);
 223   fsp->fsu_bfree = PROPAGATE_ALL_ONES (fsd.f_bfree);
 224   fsp->fsu_bavail = PROPAGATE_TOP_BIT (fsd.f_bavail);
 225   fsp->fsu_bavail_top_bit_set = EXTRACT_TOP_BIT (fsd.f_bavail) != 0;
 226   fsp->fsu_files = PROPAGATE_ALL_ONES (fsd.f_files);
 227   fsp->fsu_ffree = PROPAGATE_ALL_ONES (fsd.f_ffree);
 228
 229 #endif
 230
 231   (void) disk;  /* avoid argument-unused warning */
 232   return 0;
 233 }