lib/stat-size.h

   1 /* macros useful in interpreting size-related values in struct stat.
   2    Copyright (C) 1989, 1991-2021 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 <https://www.gnu.org/licenses/>.  */
  16 /*
  17    Macros defined by this file (s is an rvalue of type struct stat):
  18
  19    DEV_BSIZE:       The device blocksize.  But use ST_NBLOCKSIZE instead.
  20    ST_BLKSIZE(s):   Preferred (in the sense of best performance) I/O blocksize
  21                     for the file, in bytes.
  22    ST_NBLOCKS(s):   Number of blocks in the file, including indirect blocks.
  23    ST_NBLOCKSIZE:   Size of blocks used when calculating ST_NBLOCKS.
  24  */
  25 #ifndef STAT_SIZE_H
  26 #define STAT_SIZE_H
  27
  28 /* sys/param.h may define DEV_BSIZE */
  29 #if HAVE_SYS_PARAM_H
  30 # include <sys/param.h>
  31 #endif
  32
  33
  34 /* Get or fake the disk device blocksize.
  35    Usually defined by sys/param.h (if at all).  */
  36 #if !defined DEV_BSIZE && defined BSIZE
  37 # define DEV_BSIZE BSIZE
  38 #endif
  39 #if !defined DEV_BSIZE && defined BBSIZE /* SGI sys/param.h */
  40 # define DEV_BSIZE BBSIZE
  41 #endif
  42 #ifndef DEV_BSIZE
  43 # define DEV_BSIZE 4096
  44 #endif
  45
  46
  47
  48 /* Extract or fake data from a 'struct stat'.
  49    ST_BLKSIZE: Preferred I/O blocksize for the file, in bytes.
  50    ST_NBLOCKS: Number of blocks in the file, including indirect blocks.
  51    ST_NBLOCKSIZE: Size of blocks used when calculating ST_NBLOCKS.  */
  52 #ifndef HAVE_STRUCT_STAT_ST_BLOCKS
  53 # define ST_BLKSIZE(statbuf) DEV_BSIZE
  54   /* coreutils' fileblocks.c also uses BSIZE.  */
  55 # if defined _POSIX_SOURCE || !defined BSIZE
  56 #  define ST_NBLOCKS(statbuf) \
  57   ((statbuf).st_size / ST_NBLOCKSIZE + ((statbuf).st_size % ST_NBLOCKSIZE != 0))
  58 # else
  59    /* This definition calls st_blocks, which is in the fileblocks module. */
  60 #  define ST_NBLOCKS(statbuf) \
  61   (S_ISREG ((statbuf).st_mode) || S_ISDIR ((statbuf).st_mode) ? \
  62    st_blocks ((statbuf).st_size) : 0)
  63 # endif
  64 #else
  65 /* When running 'rsh hpux11-system cat any-file', cat would
  66    determine that the output stream had an st_blksize of 2147421096.
  67    Conversely st_blksize can be 2 GiB (or maybe even larger) with XFS
  68    on 64-bit hosts.  Somewhat arbitrarily, limit the "optimal" block
  69    size to SIZE_MAX / 8 + 1.  (Dividing SIZE_MAX by only 4 wouldn't
  70    suffice, since "cat" sometimes multiplies the result by 4.)  If
  71    anyone knows of a system for which this limit is too small, please
  72    report it as a bug in this code.  */
  73 # define ST_BLKSIZE(statbuf) ((0 < (statbuf).st_blksize \
  74                                && (statbuf).st_blksize <= ((size_t)-1) / 8 + 1) \
  75                               ? (statbuf).st_blksize : DEV_BSIZE)
  76 # if defined hpux || defined __hpux__ || defined __hpux
  77   /* HP-UX counts st_blocks in 1024-byte units.
  78      This loses when mixing HP-UX and BSD file systems with NFS.  */
  79 #  define ST_NBLOCKSIZE 1024
  80 # endif
  81 #endif
  82
  83 #ifndef ST_NBLOCKS
  84 # define ST_NBLOCKS(statbuf) ((statbuf).st_blocks)
  85 #endif
  86
  87 #ifndef ST_NBLOCKSIZE
  88 # ifdef S_BLKSIZE
  89 #  define ST_NBLOCKSIZE S_BLKSIZE
  90 # else
  91 #  define ST_NBLOCKSIZE 512
  92 # endif
  93 #endif
  94
  95 #endif /* STAT_SIZE_H */