rm_/lib/fstatat.c

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2020-09-02 16:47:03 +08:00
/* Work around an fstatat bug on Solaris 9.
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Copyright (C) 2006, 2009-2022 Free Software Foundation, Inc.
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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
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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.
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. If not, see <https://www.gnu.org/licenses/>. */
/* Written by Paul Eggert and Jim Meyering. */
/* If the user's config.h happens to include <sys/stat.h>, let it include only
the system's <sys/stat.h> here, so that orig_fstatat doesn't recurse to
rpl_fstatat. */
#define __need_system_sys_stat_h
#include <config.h>
/* Get the original definition of fstatat. It might be defined as a macro. */
#include <sys/types.h>
#include <sys/stat.h>
#undef __need_system_sys_stat_h
#if HAVE_FSTATAT && HAVE_WORKING_FSTATAT_ZERO_FLAG
static int
orig_fstatat (int fd, char const *filename, struct stat *buf, int flags)
{
return fstatat (fd, filename, buf, flags);
}
#endif
#ifdef __osf__
/* Write "sys/stat.h" here, not <sys/stat.h>, otherwise OSF/1 5.1 DTK cc
eliminates this include because of the preliminary #include <sys/stat.h>
above. */
# include "sys/stat.h"
#else
# include <sys/stat.h>
#endif
#include "stat-time.h"
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#if HAVE_FSTATAT && HAVE_WORKING_FSTATAT_ZERO_FLAG
# ifndef LSTAT_FOLLOWS_SLASHED_SYMLINK
# define LSTAT_FOLLOWS_SLASHED_SYMLINK 0
# endif
static int
normal_fstatat (int fd, char const *file, struct stat *st, int flag)
{
return stat_time_normalize (orig_fstatat (fd, file, st, flag), st);
}
/* fstatat should always follow symbolic links that end in /, but on
Solaris 9 it doesn't if AT_SYMLINK_NOFOLLOW is specified.
Likewise, trailing slash on a non-directory should be an error.
These are the same problems that lstat.c and stat.c address, so
solve it in a similar way.
AIX 7.1 fstatat (AT_FDCWD, ..., 0) always fails, which is a bug.
Work around this bug if FSTATAT_AT_FDCWD_0_BROKEN is nonzero. */
int
rpl_fstatat (int fd, char const *file, struct stat *st, int flag)
{
int result = normal_fstatat (fd, file, st, flag);
size_t len;
if (LSTAT_FOLLOWS_SLASHED_SYMLINK || result != 0)
return result;
len = strlen (file);
if (flag & AT_SYMLINK_NOFOLLOW)
{
/* Fix lstat behavior. */
if (file[len - 1] != '/' || S_ISDIR (st->st_mode))
return 0;
if (!S_ISLNK (st->st_mode))
{
errno = ENOTDIR;
return -1;
}
result = normal_fstatat (fd, file, st, flag & ~AT_SYMLINK_NOFOLLOW);
}
/* Fix stat behavior. */
if (result == 0 && !S_ISDIR (st->st_mode) && file[len - 1] == '/')
{
errno = ENOTDIR;
return -1;
}
return result;
}
#else /* ! (HAVE_FSTATAT && HAVE_WORKING_FSTATAT_ZERO_FLAG) */
/* On mingw, the gnulib <sys/stat.h> defines 'stat' as a function-like
macro; but using it in AT_FUNC_F2 causes compilation failure
because the preprocessor sees a use of a macro that requires two
arguments but is only given one. Hence, we need an inline
forwarder to get past the preprocessor. */
static int
stat_func (char const *name, struct stat *st)
{
return stat (name, st);
}
/* Likewise, if there is no native 'lstat', then the gnulib
<sys/stat.h> defined it as stat, which also needs adjustment. */
# if !HAVE_LSTAT
# undef lstat
# define lstat stat_func
# endif
/* Replacement for Solaris' function by the same name.
<https://www.google.com/search?q=fstatat+site:docs.oracle.com>
First, try to simulate it via l?stat ("/proc/self/fd/FD/FILE").
Failing that, simulate it via save_cwd/fchdir/(stat|lstat)/restore_cwd.
If either the save_cwd or the restore_cwd fails (relatively unlikely),
then give a diagnostic and exit nonzero.
Otherwise, this function works just like Solaris' fstatat. */
# define AT_FUNC_NAME fstatat
# define AT_FUNC_F1 lstat
# define AT_FUNC_F2 stat_func
# define AT_FUNC_USE_F1_COND AT_SYMLINK_NOFOLLOW
# define AT_FUNC_POST_FILE_PARAM_DECLS , struct stat *st, int flag
# define AT_FUNC_POST_FILE_ARGS , st
# include "at-func.c"
# undef AT_FUNC_NAME
# undef AT_FUNC_F1
# undef AT_FUNC_F2
# undef AT_FUNC_USE_F1_COND
# undef AT_FUNC_POST_FILE_PARAM_DECLS
# undef AT_FUNC_POST_FILE_ARGS
#endif /* !HAVE_FSTATAT */