1 /* Work around an fstatat bug on Solaris 9.
2
3 Copyright (C) 2006, 2009-2023 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
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 #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
61 static int
62 normal_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
76 int
77 rpl_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. */
113 static int
114 stat_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 */