root/lib/stat-size.h

/*   */

INCLUDED FROM

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

/*   */