root/lib/fsusage.c

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DEFINITIONS

This source file includes following definitions.
  1. statvfs_works
  2. statvfs_works
  3. get_fs_usage

     1 /* fsusage.c -- return space usage of mounted file systems
     2 
     3    Copyright (C) 1991-1992, 1996, 1998-1999, 2002-2006, 2009-2023 Free Software
     4    Foundation, Inc.
     5 
     6    This file is free software: you can redistribute it and/or modify
     7    it under the terms of the GNU Lesser General Public License as
     8    published by the Free Software Foundation, either version 3 of the
     9    License, or (at your option) any later version.
    10 
    11    This file 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 Lesser General Public License for more details.
    15 
    16    You should have received a copy of the GNU Lesser 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 }

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