mirror of
https://https.git.savannah.gnu.org/git/gnulib.git
synced 2026-09-01 02:34:55 +00:00
Paul Eggert
0632e11574
longer worry about uses that don't define HAVE_CONFIG_H. * acl.c, alloca.c, argmatch.c, atexit.c, backupfile.c: * basename.c, c-stack.c, c-strtod.c, calloc.c, canon-host.c: * canonicalize.c, chdir-long.c, chdir-safer.c, chown.c: * cloexec.c, close-stream.c, closeout.c, creat-safer.c: * cycle-check.c, diacrit.c, dirchownmod.c, dirfd.c, dirname.c: * dup-safer.c, dup2.c, error.c, euidaccess.c, exclude.c: * exitfail.c, fchmodat.c, fchown-stub.c, fd-safer.c: * file-type.c, fileblocks.c, filemode.c, filenamecat.c: * fnmatch.c, fopen-safer.c, fprintftime.c, free.c, fsusage.c: * ftruncate.c, fts-cycle.c, fts.c, full-write.c, gai_strerror.c: * getcwd.c, getdate.y, getdomainname.c, getgroups.c: * gethostname.c, gethrxtime.c, getloadavg.c, getlogin_r.c: * getndelim2.c, getnline.c, getopt.c, getopt1.c, getpass.c: * gettime.c, gettimeofday.c, getugroups.c, getusershell.c: * glob.c, group-member.c, hard-locale.c, hash-pjw.c, hash.c: * human.c, idcache.c, inet_ntop.c, inet_pton.c, inttostr.c: * isdir.c, lchown.c, linebuffer.c, long-options.c, lstat.c: * malloc.c, md5.c, memcasecmp.c, memchr.c, memcmp.c, memcoll.c: * memcpy.c, memmove.c, memrchr.c, mkancesdirs.c, mkdir-p.c: * mkdir.c, mkdirat.c, mkstemp-safer.c, mkstemp.c, modechange.c: * mountlist.c, nanosleep.c, obstack.c, open-safer.c: * openat-die.c, openat.c, pagealign_alloc.c, physmem.c: * pipe-safer.c, posixtm.c, posixver.c, putenv.c, quote.c: * quotearg.c, raise.c, readtokens.c, readtokens0.c, readutmp.c: * realloc.c, regex.c, rename.c, rmdir.c, rpmatch.c, safe-read.c: * same.c, save-cwd.c, savedir.c, setenv.c, settime.c, sha1.c: * sig2str.c, snprintf.c, strdup.c, strerror.c, strftime.c: * stripslash.c, strndup.c, strnlen.c, strpbrk.c, strtod.c: * strtoimax.c, strtol.c, strverscmp.c, tempname.c, time_r.c: * timegm.c, tmpfile-safer.c, unlinkdir.c, userspec.c, utime.c: * utimecmp.c, utimens.c, version-etc-fsf.c, version-etc.c: * xalloc-die.c, xgetcwd.c, xgethostname.c, xmalloc.c: * xmemcoll.c, xnanosleep.c, xreadlink.c, xstrtod.c: * xstrtoimax.c, xstrtol.c, xstrtoumax.c, yesno.c: Likewise.
88 lines
2.7 KiB
C
88 lines
2.7 KiB
C
/* help detect directory cycles efficiently
|
|
|
|
Copyright (C) 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
|
|
|
|
This program is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 2, or (at your option)
|
|
any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program; see the file COPYING.
|
|
If not, write to the Free Software Foundation,
|
|
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
|
|
|
|
/* Written by Jim Meyering */
|
|
|
|
#include <config.h>
|
|
|
|
#include <sys/types.h>
|
|
#include <sys/stat.h>
|
|
#include <stdio.h>
|
|
#include <assert.h>
|
|
#include <stdlib.h>
|
|
|
|
#include <stdbool.h>
|
|
|
|
#include "cycle-check.h"
|
|
|
|
#define CC_MAGIC 9827862
|
|
|
|
/* Return true if I is a power of 2, or is zero. */
|
|
|
|
static inline bool
|
|
is_zero_or_power_of_two (uintmax_t i)
|
|
{
|
|
return (i & (i - 1)) == 0;
|
|
}
|
|
|
|
void
|
|
cycle_check_init (struct cycle_check_state *state)
|
|
{
|
|
state->chdir_counter = 0;
|
|
state->magic = CC_MAGIC;
|
|
}
|
|
|
|
/* In traversing a directory hierarchy, call this function once for each
|
|
descending chdir call, with SB corresponding to the chdir operand.
|
|
If SB corresponds to a directory that has already been seen,
|
|
return true to indicate that there is a directory cycle.
|
|
Note that this is done `lazily', which means that some of
|
|
the directories in the cycle may be processed twice before
|
|
the cycle is detected. */
|
|
|
|
bool
|
|
cycle_check (struct cycle_check_state *state, struct stat const *sb)
|
|
{
|
|
assert (state->magic == CC_MAGIC);
|
|
|
|
/* If the current directory ever happens to be the same
|
|
as the one we last recorded for the cycle detection,
|
|
then it's obviously part of a cycle. */
|
|
if (state->chdir_counter && SAME_INODE (*sb, state->dev_ino))
|
|
return true;
|
|
|
|
/* If the number of `descending' chdir calls is a power of two,
|
|
record the dev/ino of the current directory. */
|
|
if (is_zero_or_power_of_two (++(state->chdir_counter)))
|
|
{
|
|
/* On all architectures that we know about, if the counter
|
|
overflows then there is a directory cycle here somewhere,
|
|
even if we haven't detected it yet. Typically this happens
|
|
only after the counter is incremented 2**64 times, so it's a
|
|
fairly theoretical point. */
|
|
if (state->chdir_counter == 0)
|
|
return true;
|
|
|
|
state->dev_ino.st_dev = sb->st_dev;
|
|
state->dev_ino.st_ino = sb->st_ino;
|
|
}
|
|
|
|
return false;
|
|
}
|