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9fc77bc593
* 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.
26 lines
997 B
Plaintext
26 lines
997 B
Plaintext
@node stat-size
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@section stat-size
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The @code{stat-size} module provides a small number of macros
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intended for interpreting the file size information in an instance of
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@code{struct stat}.
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@c We deliberately don't document DEV_BSIZE (it looks to James
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@c Youngman as if the ST_NBLOCKSIZE macro should be used instead).
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@findex ST_NBLOCKS
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@findex ST_NBLOCKSIZE
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@cindex block size
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On POSIX systems, the @code{st_blocks} member of @code{struct stat}
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contains the number of disk blocks occupied by a file. The
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@code{ST_NBLOCKS} macro is used to estimate this quantity on systems
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which don't actually have @code{st_blocks}. Each of these blocks
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contains @code{ST_NBLOCKSIZE} bytes.
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@findex ST_BLKSIZE
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The value of @code{ST_NBLOCKSIZE} is often quite small, small enough
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that performing I/O in chunks that size would be inefficient.
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@code{ST_BLKSIZE} is the I/O block size recommended for I/O to this
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file. This is not guaranteed to give optimum performance, but it
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should be reasonably efficient.
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