[bpt/emacs.git] / lib / fstatat.c

/* Work around an fstatat bug on Solaris 9.

   Copyright (C) 2006, 2009-2014 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 3 of the License, 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.  If not, see <http://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
static int
orig_fstatat (int fd, char const *filename, struct stat *buf, int flags)
{
  return fstatat (fd, filename, buf, flags);
}
#endif

/* 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"

#include <errno.h>
#include <fcntl.h>
#include <string.h>

#if HAVE_FSTATAT && HAVE_WORKING_FSTATAT_ZERO_FLAG

# ifndef LSTAT_FOLLOWS_SLASHED_SYMLINK
#  define LSTAT_FOLLOWS_SLASHED_SYMLINK 0
# endif

/* 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 = orig_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 = orig_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.
   <http://www.google.com/search?q=fstatat+site:docs.sun.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 */
Commit	Line	Data
8654f9d7 PE	1	/* Work around an fstatat bug on Solaris 9.
8654f9d7 PE	2
ba318903	3	Copyright (C) 2006, 2009-2014 Free Software Foundation, Inc.
8654f9d7 PE	4
	5	This program is free software: you can redistribute it and/or modify
	6	it under the terms of the GNU General Public License as published by
	7	the Free Software Foundation; either version 3 of the License, or
	8	(at your option) any later version.
	9
	10	This program is distributed in the hope that it will be useful,
	11	but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	13	GNU General Public License for more details.
	14
	15	You should have received a copy of the GNU General Public License
	16	along with this program. If not, see <http://www.gnu.org/licenses/>. */
	17
	18	/* Written by Paul Eggert and Jim Meyering. */
	19
	20	/* If the user's config.h happens to include <sys/stat.h>, let it include only
	21	the system's <sys/stat.h> here, so that orig_fstatat doesn't recurse to
	22	rpl_fstatat. */
	23	#define __need_system_sys_stat_h
	24	#include <config.h>
	25
	26	/* Get the original definition of fstatat. It might be defined as a macro. */
	27	#include <sys/types.h>
	28	#include <sys/stat.h>
	29	#undef __need_system_sys_stat_h
	30
	31	#if HAVE_FSTATAT
	32	static int
	33	orig_fstatat (int fd, char const filename, struct stat buf, int flags)
	34	{
	35	return fstatat (fd, filename, buf, flags);
	36	}
	37	#endif
	38
	39	/* Write "sys/stat.h" here, not <sys/stat.h>, otherwise OSF/1 5.1 DTK cc
	40	eliminates this include because of the preliminary #include <sys/stat.h>
	41	above. */
	42	#include "sys/stat.h"
	43
	44	#include <errno.h>
	45	#include <fcntl.h>
	46	#include <string.h>
	47
	48	#if HAVE_FSTATAT && HAVE_WORKING_FSTATAT_ZERO_FLAG
	49
	50	# ifndef LSTAT_FOLLOWS_SLASHED_SYMLINK
	51	# define LSTAT_FOLLOWS_SLASHED_SYMLINK 0
	52	# endif
	53
	54	/* fstatat should always follow symbolic links that end in /, but on
	55	Solaris 9 it doesn't if AT_SYMLINK_NOFOLLOW is specified.
	56	Likewise, trailing slash on a non-directory should be an error.
	57	These are the same problems that lstat.c and stat.c address, so
	58	solve it in a similar way.
	59
	60	AIX 7.1 fstatat (AT_FDCWD, ..., 0) always fails, which is a bug.
	61	Work around this bug if FSTATAT_AT_FDCWD_0_BROKEN is nonzero. */
	62
	63	int
	64	rpl_fstatat (int fd, char const file, struct stat st, int flag)
	65	{
	66	int result = orig_fstatat (fd, file, st, flag);
	67	size_t len;
68
69	if (LSTAT_FOLLOWS_SLASHED_SYMLINK \|\| result != 0)
70	return result;
71	len = strlen (file);
72	if (flag & AT_SYMLINK_NOFOLLOW)
73	{
74	/* Fix lstat behavior. */
75	if (file[len - 1] != '/' \|\| S_ISDIR (st->st_mode))
76	return 0;
77	if (!S_ISLNK (st->st_mode))
78	{
79	errno = ENOTDIR;
80	return -1;
81	}
82	result = orig_fstatat (fd, file, st, flag & ~AT_SYMLINK_NOFOLLOW);
83	}
84	/* Fix stat behavior. */
85	if (result == 0 && !S_ISDIR (st->st_mode) && file[len - 1] == '/')
86	{
87	errno = ENOTDIR;
88	return -1;
89	}
90	return result;
91	}
92
93	#else /* ! (HAVE_FSTATAT && HAVE_WORKING_FSTATAT_ZERO_FLAG) */
94
95	/* On mingw, the gnulib <sys/stat.h> defines 'stat' as a function-like
96	macro; but using it in AT_FUNC_F2 causes compilation failure
97	because the preprocessor sees a use of a macro that requires two
98	arguments but is only given one. Hence, we need an inline
99	forwarder to get past the preprocessor. */
100	static int
101	stat_func (char const name, struct stat st)
102	{
103	return stat (name, st);
104	}
105
106	/* Likewise, if there is no native 'lstat', then the gnulib
107	<sys/stat.h> defined it as stat, which also needs adjustment. */
108	# if !HAVE_LSTAT
109	# undef lstat
110	# define lstat stat_func
111	# endif
112
113	/* Replacement for Solaris' function by the same name.
114	<http://www.google.com/search?q=fstatat+site:docs.sun.com>
115	First, try to simulate it via l?stat ("/proc/self/fd/FD/FILE").
116	Failing that, simulate it via save_cwd/fchdir/(stat\|lstat)/restore_cwd.
117	If either the save_cwd or the restore_cwd fails (relatively unlikely),
118	then give a diagnostic and exit nonzero.
119	Otherwise, this function works just like Solaris' fstatat. */
120
121	# define AT_FUNC_NAME fstatat
122	# define AT_FUNC_F1 lstat
123	# define AT_FUNC_F2 stat_func
124	# define AT_FUNC_USE_F1_COND AT_SYMLINK_NOFOLLOW
125	# define AT_FUNC_POST_FILE_PARAM_DECLS , struct stat *st, int flag
126	# define AT_FUNC_POST_FILE_ARGS , st
127	# include "at-func.c"
128	# undef AT_FUNC_NAME
129	# undef AT_FUNC_F1
130	# undef AT_FUNC_F2
131	# undef AT_FUNC_USE_F1_COND
132	# undef AT_FUNC_POST_FILE_PARAM_DECLS
133	# undef AT_FUNC_POST_FILE_ARGS
134
135	#endif /* !HAVE_FSTATAT */