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maint: remove fstimeprec (variable precision time stamp) support
The implementation of variable-precision time stamps relied on heuristics that made the output subtly nondeterministic, or at least hard to reproduce: http://thread.gmane.org/gmane.comp.gnu.coreutils.bugs/21531/focus=21538 So, for now at least, we're removing that feature. * bootstrap.conf (gnulib_modules): Remove fstimeprec. * gl/lib/fstimeprec.c, gl/lib/fstimeprec.h: Remove files. * gl/modules/fstimeprec, gl/modules/fstimeprec-tests: Likewise. * gl/tests/test-fstimeprec.c: Remove file.
This commit is contained in:
Jim Meyering
@@ -85,7 +85,6 @@ gnulib_modules="
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freopen
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freopen-safer
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fseeko
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fstimeprec
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fsusage
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fsync
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ftello
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@@ -1,178 +0,0 @@
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/* Determine a file system's time stamp precision.
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Copyright 2010 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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/* written by Paul Eggert */
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#include <config.h>
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#include "fstimeprec.h"
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#include "hash.h"
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#include "stat-time.h"
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#include <limits.h>
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#include <stdlib.h>
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/* A hash table that maps device numbers to precisions. */
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struct fstimeprec
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{
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/* Map device numbers to precisions. */
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struct hash_table *map;
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/* Cache of the most recently allocated and otherwise-unused storage
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for probing this table. */
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struct ent *probe;
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};
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/* A pair that maps a device number to a precision. */
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struct ent
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{
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dev_t dev;
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int prec;
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};
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/* Hash an entry. */
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static size_t
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ent_hash (void const *x, size_t table_size)
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{
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struct ent const *p = x;
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dev_t dev = p->dev;
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/* FIXME: This code is duplicated from di-set.c. */
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/* When DEV is wider than size_t, exclusive-OR the words of DEV into H.
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This avoids loss of info, without applying % to the wider type,
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which could be quite slow on some systems. */
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size_t h = dev;
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unsigned int i;
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unsigned int n_words = sizeof dev / sizeof h + (sizeof dev % sizeof h != 0);
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for (i = 1; i < n_words; i++)
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h ^= dev >> CHAR_BIT * sizeof h * i;
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return h % table_size;
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}
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/* Return true if two entries are the same. */
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static bool
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ent_compare (void const *x, void const *y)
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{
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struct ent const *a = x;
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struct ent const *b = y;
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return a->dev == b->dev;
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}
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/* Using the SET table, map a device to an entry that represents
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the file system precision. Return NULL on error. */
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static struct ent *
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map_device (struct fstimeprec *tab, dev_t dev)
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{
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/* Find space for the probe, reusing the cache if available. */
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struct ent *ent;
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struct ent *probe = tab->probe;
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if (probe)
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{
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/* If repeating a recent query, return the cached result. */
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if (probe->dev == dev)
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return probe;
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}
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else
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{
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tab->probe = probe = malloc (sizeof *probe);
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if (! probe)
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return NULL;
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probe->prec = 0;
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}
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/* Probe for the device. */
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probe->dev = dev;
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ent = hash_insert (tab->map, probe);
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if (ent == probe)
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tab->probe = NULL;
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return ent;
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}
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/* Return a newly allocated table of file system time stamp
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resolutions, or NULL if out of memory. */
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struct fstimeprec *
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fstimeprec_alloc (void)
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{
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struct fstimeprec *tab = malloc (sizeof *tab);
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if (tab)
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{
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enum { INITIAL_DEV_MAP_SIZE = 11 };
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tab->map = hash_initialize (INITIAL_DEV_MAP_SIZE, NULL,
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ent_hash, ent_compare, free);
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if (! tab->map)
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{
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free (tab);
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return NULL;
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}
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tab->probe = NULL;
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}
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return tab;
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}
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/* Free TAB. */
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void
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fstimeprec_free (struct fstimeprec *tab)
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{
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hash_free (tab->map);
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free (tab->probe);
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free (tab);
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}
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/* Using the cached information in TAB, return the estimated precision
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of time stamps for the file system containing the file whose status
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info is in ST. The returned value counts the number of decimal
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fraction digits. Return 0 on failure.
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If TAB is null, the guess is based purely on ST. */
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int
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fstimeprec (struct fstimeprec *tab, struct stat const *st)
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{
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/* Map the device number to an entry. */
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struct ent *ent = (tab ? map_device (tab, st->st_dev) : NULL);
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/* Guess the precision based on what has been seen so far. */
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int prec = (ent ? ent->prec : 0);
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/* If the current file's timestamp resolution is higher than the
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guess, increase the guess. */
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if (prec < 9)
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{
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struct timespec ats = get_stat_atime (st);
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struct timespec mts = get_stat_mtime (st);
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struct timespec cts = get_stat_ctime (st);
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struct timespec bts = get_stat_birthtime (st);
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unsigned int ans = ats.tv_nsec;
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unsigned int mns = mts.tv_nsec;
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unsigned int cns = cts.tv_nsec;
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unsigned int bns = bts.tv_nsec < 0 ? 0 : bts.tv_nsec;
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unsigned int power = 10;
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int p;
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for (p = prec + 1; p < 9; p++)
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power *= 10;
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while (ans % power | mns % power | cns % power | bns % power)
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{
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power /= 10;
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prec++;
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}
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if (ent)
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ent->prec = prec;
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}
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return prec;
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}
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@@ -1,22 +0,0 @@
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#include <sys/stat.h>
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#ifndef ATTRIBUTE_MALLOC
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# if __GNUC__ >= 3
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# define ATTRIBUTE_MALLOC __attribute__ ((__malloc__))
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# else
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# define ATTRIBUTE_MALLOC
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# endif
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#endif
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#ifndef _GL_ARG_NONNULL
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# if (__GNUC__ == 3 && __GNUC_MINOR__ >= 3) || __GNUC__ > 3
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# define _GL_ARG_NONNULL(params) __attribute__ ((__nonnull__ params))
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# else
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# define _GL_ARG_NONNULL(params)
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# endif
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#endif
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struct fstimeprec *fstimeprec_alloc (void) ATTRIBUTE_MALLOC;
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void fstimeprec_free (struct fstimeprec *) _GL_ARG_NONNULL ((1));
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int fstimeprec (struct fstimeprec *, struct stat const *)
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_GL_ARG_NONNULL ((2));
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@@ -1,24 +0,0 @@
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Description:
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estimate precision of time stamps in file systems
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Files:
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lib/fstimeprec.c
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lib/fstimeprec.h
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Depends-on:
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hash
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stat-time
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configure.ac:
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Makefile.am:
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lib_SOURCES += fstimeprec.c fstimeprec.h
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Include:
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"fstimeprec.h"
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License
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GPL
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Maintainer:
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Paul Eggert and Jim Meyering
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@@ -1,10 +0,0 @@
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Files:
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tests/test-fstimeprec.c
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Depends-on:
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configure.ac:
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Makefile.am:
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TESTS += test-fstimeprec
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check_PROGRAMS += test-fstimeprec
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@@ -1,74 +0,0 @@
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/* Test the fstimeprec module.
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Copyright (C) 2010 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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/* written by Paul Eggert */
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#include <config.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <sys/stat.h>
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#define ASSERT(expr) \
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do \
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{ \
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if (!(expr)) \
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{ \
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fprintf (stderr, "%s:%d: assertion failed\n", __FILE__, __LINE__); \
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fflush (stderr); \
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abort (); \
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} \
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} \
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while (0)
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#include "fstimeprec.h"
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static int
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fstimeprec_file (struct fstimeprec *tab, char const *file)
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{
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struct stat st;
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if (stat (file, &st) != 0)
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return 0;
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return fstimeprec (tab, &st);
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}
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int
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main (void)
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{
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struct fstimeprec *tab = fstimeprec_alloc ();
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ASSERT (tab);
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int m1 = fstimeprec_file (tab, "/");
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int m2 = fstimeprec_file (tab, ".");
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int m3 = fstimeprec_file (tab, "..");
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ASSERT (0 <= m1 && m1 <= 9);
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ASSERT (0 <= m2 && m2 <= 9);
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ASSERT (0 <= m3 && m3 <= 9);
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int n1 = fstimeprec_file (tab, "/");
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int n2 = fstimeprec_file (tab, ".");
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int n3 = fstimeprec_file (tab, "..");
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ASSERT (0 <= n1 && n1 <= 9);
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ASSERT (0 <= n2 && n2 <= 9);
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ASSERT (0 <= n3 && n3 <= 9);
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ASSERT (m1 <= n1);
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ASSERT (m2 <= n2);
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ASSERT (m3 <= n3);
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fstimeprec_free (tab);
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return 0;
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}
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