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New module 'stat-size'. * modules/stat-size: New module. Provides macros for accessing file size information in instances of struct stat. Depends on the fileblocks module because it calls st_blocks. * lib/stat-size.h: New file, adapted from coreutils' system.h. * doc/gnulib.texi: Include stat-size.texi. * doc/stat-size.texi: Documentation for this module. * m4/stat-size.m4: New file; defines gl_STAT_SIZE. * m4/fileblocks.m4: Mention that stat-size depends on the call to AC_STRUCT_ST_BLOCKS.
author James Youngman <jay@gnu.org>
date Sat, 11 Jun 2011 01:15:39 +0100
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14901:4b26d9ce6840 14902:16c748720b01
1 @node stat-size
2 @section stat-size
3
4 The @code{stat-size} module provides a small number of macros
5 intended for interpreting the file size information in an instance of
6 @code{struct stat}.
7
8 @c We deliberately don't document DEV_BSIZE (it looks to James
9 @c Youngman as if the ST_NBLOCKSIZE macro should be used instead).
10
11 @findex ST_NBLOCKS
12 @findex ST_NBLOCKSIZE
13 @cindex block size
14 On POSIX systems, the @code{st_blocks} member of @code{struct stat}
15 contains the number of disk blocks occupied by a file. The
16 @code{ST_NBLOCKS} macro is used to estimate this quantity on systems
17 which don't actually have @code{st_blocks}. Each of these blocks
18 contains @code{ST_NBLOCKSIZE} bytes.
19
20 @findex ST_BLKSIZE
21 The value of @code{ST_NBLOCKSIZE} is often quite small, small enough
22 that performing I/O in chunks that size would be inefficient.
23 @code{ST_BLKSIZE} is the I/O block size recommended for I/O to this
24 file. This is not guaranteed to give optimum performance, but it
25 should be reasonably efficient.