1/* Work around an fstatat bug on Solaris 9.
2
3   Copyright (C) 2006, 2009-2022 Free Software Foundation, Inc.
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 <https://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 && HAVE_WORKING_FSTATAT_ZERO_FLAG
32static int
33orig_fstatat (int fd, char const *filename, struct stat *buf, int flags)
34{
35  return fstatat (fd, filename, buf, flags);
36}
37#endif
38
39#ifdef __osf__
40/* Write "sys/stat.h" here, not <sys/stat.h>, otherwise OSF/1 5.1 DTK cc
41   eliminates this include because of the preliminary #include <sys/stat.h>
42   above.  */
43# include "sys/stat.h"
44#else
45# include <sys/stat.h>
46#endif
47
48#include "stat-time.h"
49
50#include <errno.h>
51#include <fcntl.h>
52#include <stdlib.h>
53#include <string.h>
54
55#if HAVE_FSTATAT && HAVE_WORKING_FSTATAT_ZERO_FLAG
56
57# ifndef LSTAT_FOLLOWS_SLASHED_SYMLINK
58#  define LSTAT_FOLLOWS_SLASHED_SYMLINK 0
59# endif
60
61static int
62normal_fstatat (int fd, char const *file, struct stat *st, int flag)
63{
64  return stat_time_normalize (orig_fstatat (fd, file, st, flag), st);
65}
66
67/* fstatat should always follow symbolic links that end in /, but on
68   Solaris 9 it doesn't if AT_SYMLINK_NOFOLLOW is specified.
69   Likewise, trailing slash on a non-directory should be an error.
70   These are the same problems that lstat.c and stat.c address, so
71   solve it in a similar way.
72
73   AIX 7.1 fstatat (AT_FDCWD, ..., 0) always fails, which is a bug.
74   Work around this bug if FSTATAT_AT_FDCWD_0_BROKEN is nonzero.  */
75
76int
77rpl_fstatat (int fd, char const *file, struct stat *st, int flag)
78{
79  int result = normal_fstatat (fd, file, st, flag);
80  size_t len;
81
82  if (LSTAT_FOLLOWS_SLASHED_SYMLINK || result != 0)
83    return result;
84  len = strlen (file);
85  if (flag & AT_SYMLINK_NOFOLLOW)
86    {
87      /* Fix lstat behavior.  */
88      if (file[len - 1] != '/' || S_ISDIR (st->st_mode))
89        return 0;
90      if (!S_ISLNK (st->st_mode))
91        {
92          errno = ENOTDIR;
93          return -1;
94        }
95      result = normal_fstatat (fd, file, st, flag & ~AT_SYMLINK_NOFOLLOW);
96    }
97  /* Fix stat behavior.  */
98  if (result == 0 && !S_ISDIR (st->st_mode) && file[len - 1] == '/')
99    {
100      errno = ENOTDIR;
101      return -1;
102    }
103  return result;
104}
105
106#else /* ! (HAVE_FSTATAT && HAVE_WORKING_FSTATAT_ZERO_FLAG) */
107
108/* On mingw, the gnulib <sys/stat.h> defines 'stat' as a function-like
109   macro; but using it in AT_FUNC_F2 causes compilation failure
110   because the preprocessor sees a use of a macro that requires two
111   arguments but is only given one.  Hence, we need an inline
112   forwarder to get past the preprocessor.  */
113static int
114stat_func (char const *name, struct stat *st)
115{
116  return stat (name, st);
117}
118
119/* Likewise, if there is no native 'lstat', then the gnulib
120   <sys/stat.h> defined it as stat, which also needs adjustment.  */
121# if !HAVE_LSTAT
122#  undef lstat
123#  define lstat stat_func
124# endif
125
126/* Replacement for Solaris' function by the same name.
127   <https://www.google.com/search?q=fstatat+site:docs.oracle.com>
128   First, try to simulate it via l?stat ("/proc/self/fd/FD/FILE").
129   Failing that, simulate it via save_cwd/fchdir/(stat|lstat)/restore_cwd.
130   If either the save_cwd or the restore_cwd fails (relatively unlikely),
131   then give a diagnostic and exit nonzero.
132   Otherwise, this function works just like Solaris' fstatat.  */
133
134# define AT_FUNC_NAME fstatat
135# define AT_FUNC_F1 lstat
136# define AT_FUNC_F2 stat_func
137# define AT_FUNC_USE_F1_COND AT_SYMLINK_NOFOLLOW
138# define AT_FUNC_POST_FILE_PARAM_DECLS , struct stat *st, int flag
139# define AT_FUNC_POST_FILE_ARGS        , st
140# include "at-func.c"
141# undef AT_FUNC_NAME
142# undef AT_FUNC_F1
143# undef AT_FUNC_F2
144# undef AT_FUNC_USE_F1_COND
145# undef AT_FUNC_POST_FILE_PARAM_DECLS
146# undef AT_FUNC_POST_FILE_ARGS
147
148#endif /* !HAVE_FSTATAT */
149