lib/stat-size.h

   1 /* macros useful in interpreting size-related values in struct stat.
   2    Copyright (C) 1989, 1991-2016 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program 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
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  16
  17 /* *INDENT-OFF* */
  18 /*
  19    Macros defined by this file (s is an rvalue of type struct stat):
  20
  21    DEV_BSIZE:       The device blocksize.  But use ST_NBLOCKSIZE instead.
  22    ST_BLKSIZE(s):   Preferred (in the sense of best performance) I/O blocksize
  23                     for the file, in bytes.
  24    ST_NBLOCKS(s):   Number of blocks in the file, including indirect blocks.
  25    ST_NBLOCKSIZE:   Size of blocks used when calculating ST_NBLOCKS.
  26  */
  27 /* *INDENT-ON* */
  28
  29 #ifndef STAT_SIZE_H
  30 #define STAT_SIZE_H
  31
  32 /* sys/param.h may define DEV_BSIZE */
  33 #if HAVE_SYS_PARAM_H
  34 #include <sys/param.h>
  35 #endif
  36
  37
  38 /* Get or fake the disk device blocksize.
  39    Usually defined by sys/param.h (if at all).  */
  40 #if !defined DEV_BSIZE && defined BSIZE
  41 #define DEV_BSIZE BSIZE
  42 #endif
  43 #if !defined DEV_BSIZE && defined BBSIZE        /* SGI sys/param.h */
  44 #define DEV_BSIZE BBSIZE
  45 #endif
  46 #ifndef DEV_BSIZE
  47 #define DEV_BSIZE 4096
  48 #endif
  49
  50
  51
  52 /* Extract or fake data from a 'struct stat'.
  53    ST_BLKSIZE: Preferred I/O blocksize for the file, in bytes.
  54    ST_NBLOCKS: Number of blocks in the file, including indirect blocks.
  55    ST_NBLOCKSIZE: Size of blocks used when calculating ST_NBLOCKS.  */
  56 #ifndef HAVE_STRUCT_STAT_ST_BLOCKS
  57 #define ST_BLKSIZE(statbuf) DEV_BSIZE
  58   /* coreutils' fileblocks.c also uses BSIZE.  */
  59 #if defined _POSIX_SOURCE || !defined BSIZE
  60 #define ST_NBLOCKS(statbuf) \
  61   ((statbuf).st_size / ST_NBLOCKSIZE + ((statbuf).st_size % ST_NBLOCKSIZE != 0))
  62 #else
  63    /* This definition calls st_blocks, which is in the fileblocks module. */
  64 #define ST_NBLOCKS(statbuf) \
  65   (S_ISREG ((statbuf).st_mode) || S_ISDIR ((statbuf).st_mode) ? \
  66    st_blocks ((statbuf).st_size) : 0)
  67 #endif
  68 #else
  69 /* Some systems, like Sequents, return st_blksize of 0 on pipes.
  70    Also, when running 'rsh hpux11-system cat any-file', cat would
  71    determine that the output stream had an st_blksize of 2147421096.
  72    Conversely st_blksize can be 2 GiB (or maybe even larger) with XFS
  73    on 64-bit hosts.  Somewhat arbitrarily, limit the "optimal" block
  74    size to SIZE_MAX / 8 + 1.  (Dividing SIZE_MAX by only 4 wouldn't
  75    suffice, since "cat" sometimes multiplies the result by 4.)  If
  76    anyone knows of a system for which this limit is too small, please
  77    report it as a bug in this code.  */
  78 #define ST_BLKSIZE(statbuf) ((0 < (statbuf).st_blksize \
  79                                && (size_t) ((statbuf).st_blksize) <= ((size_t)-1) / 8 + 1) \
  80                               ? (size_t) ((statbuf).st_blksize) : DEV_BSIZE)
  81 #if defined hpux || defined __hpux__ || defined __hpux
  82   /* HP-UX counts st_blocks in 1024-byte units.
  83      This loses when mixing HP-UX and BSD file systems with NFS.  */
  84 #define ST_NBLOCKSIZE 1024
  85 #else /* !hpux */
  86 #if defined _AIX && defined _I386
  87     /* AIX PS/2 counts st_blocks in 4K units.  */
  88 #define ST_NBLOCKSIZE (4 * 1024)
  89 #else
  90 #if defined _CRAY
  91 #define ST_NBLOCKS(statbuf) \
  92   (S_ISREG ((statbuf).st_mode) || S_ISDIR ((statbuf).st_mode) \
  93    ? (statbuf).st_blocks * ST_BLKSIZE (statbuf) / ST_NBLOCKSIZE : 0)
  94 #endif
  95 #endif
  96 #endif
  97 #endif
  98
  99 #ifndef ST_NBLOCKS
 100 #define ST_NBLOCKS(statbuf) ((statbuf).st_blocks)
 101 #endif
 102
 103 #ifndef ST_NBLOCKSIZE
 104 #ifdef S_BLKSIZE
 105 #define ST_NBLOCKSIZE S_BLKSIZE
 106 #else
 107 #define ST_NBLOCKSIZE 512
 108 #endif
 109 #endif
 110
 111 #endif /* STAT_SIZE_H */