1 /* provide a replacement openat function
2 Copyright (C) 2004, 2005 Free Software Foundation, Inc.
3
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2, or (at your option)
7 any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software Foundation,
16 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
17
18 /* written by Jim Meyering */
19
20 #ifdef HAVE_CONFIG_H
21 # include <config.h>
22 #endif
23
24 #include "openat.h"
25
26 #include <stdlib.h>
27 #include <stdarg.h>
28 #include <unistd.h>
29 #include <errno.h>
30 #include <fcntl.h>
31
32 #include "error.h"
33 #include "exitfail.h"
34 #include "save-cwd.h"
35
36 #include "gettext.h"
37 #define _(msgid) gettext (msgid)
38
39 /* Replacement for Solaris' openat function.
40 <http://www.google.com/search?q=openat+site:docs.sun.com>
41 Simulate it by doing save_cwd/fchdir/open/restore_cwd.
42 If either the save_cwd or the restore_cwd fails (relatively unlikely,
43 and usually indicative of a problem that deserves close attention),
44 then give a diagnostic and exit nonzero.
45 Otherwise, upon failure, set errno and return -1, as openat does.
46 Upon successful completion, return a file descriptor. */
47 int
rpl_openat(int fd,char const * file,int flags,...)48 rpl_openat (int fd, char const *file, int flags, ...)
49 {
50 struct saved_cwd saved_cwd;
51 int saved_errno;
52 int new_fd;
53 mode_t mode = 0;
54
55 if (flags & O_CREAT)
56 {
57 va_list arg;
58 va_start (arg, flags);
59
60 /* Assume that mode_t is passed compatibly with mode_t's type
61 after argument promotion. */
62 mode = va_arg (arg, mode_t);
63
64 va_end (arg);
65 }
66
67 if (fd == AT_FDCWD || *file == '/')
68 return open (file, flags, mode);
69
70 if (save_cwd (&saved_cwd) != 0)
71 error (exit_failure, errno,
72 _("openat: unable to record current working directory"));
73
74 if (fchdir (fd) != 0)
75 {
76 saved_errno = errno;
77 free_cwd (&saved_cwd);
78 errno = saved_errno;
79 return -1;
80 }
81
82 new_fd = open (file, flags, mode);
83 saved_errno = errno;
84
85 if (restore_cwd (&saved_cwd) != 0)
86 error (exit_failure, errno,
87 _("openat: unable to restore working directory"));
88
89 free_cwd (&saved_cwd);
90
91 errno = saved_errno;
92 return new_fd;
93 }
94
95 /* Replacement for Solaris' function by the same name.
96 <http://www.google.com/search?q=fdopendir+site:docs.sun.com>
97 Simulate it by doing save_cwd/fchdir/opendir(".")/restore_cwd.
98 If either the save_cwd or the restore_cwd fails (relatively unlikely,
99 and usually indicative of a problem that deserves close attention),
100 then give a diagnostic and exit nonzero.
101 Otherwise, this function works just like Solaris' fdopendir. */
102 DIR *
fdopendir(int fd)103 fdopendir (int fd)
104 {
105 struct saved_cwd saved_cwd;
106 int saved_errno;
107 DIR *dir;
108
109 if (fd == AT_FDCWD)
110 return opendir (".");
111
112 if (save_cwd (&saved_cwd) != 0)
113 error (exit_failure, errno,
114 _("fdopendir: unable to record current working directory"));
115
116 if (fchdir (fd) != 0)
117 {
118 saved_errno = errno;
119 free_cwd (&saved_cwd);
120 errno = saved_errno;
121 return NULL;
122 }
123
124 dir = opendir (".");
125 saved_errno = errno;
126
127 if (restore_cwd (&saved_cwd) != 0)
128 error (exit_failure, errno,
129 _("fdopendir: unable to restore working directory"));
130
131 free_cwd (&saved_cwd);
132
133 errno = saved_errno;
134 return dir;
135 }
136
137 /* Replacement for Solaris' function by the same name.
138 <http://www.google.com/search?q=fstatat+site:docs.sun.com>
139 Simulate it by doing save_cwd/fchdir/(stat|lstat)/restore_cwd.
140 If either the save_cwd or the restore_cwd fails (relatively unlikely,
141 and usually indicative of a problem that deserves close attention),
142 then give a diagnostic and exit nonzero.
143 Otherwise, this function works just like Solaris' fstatat. */
144 int
fstatat(int fd,char const * file,struct stat * st,int flag)145 fstatat (int fd, char const *file, struct stat *st, int flag)
146 {
147 struct saved_cwd saved_cwd;
148 int saved_errno;
149 int err;
150
151 if (fd == AT_FDCWD)
152 return (flag == AT_SYMLINK_NOFOLLOW
153 ? lstat (file, st)
154 : stat (file, st));
155
156 if (save_cwd (&saved_cwd) != 0)
157 error (exit_failure, errno,
158 _("fstatat: unable to record current working directory"));
159
160 if (fchdir (fd) != 0)
161 {
162 saved_errno = errno;
163 free_cwd (&saved_cwd);
164 errno = saved_errno;
165 return -1;
166 }
167
168 err = (flag == AT_SYMLINK_NOFOLLOW
169 ? lstat (file, st)
170 : stat (file, st));
171 saved_errno = errno;
172
173 if (restore_cwd (&saved_cwd) != 0)
174 error (exit_failure, errno,
175 _("fstatat: unable to restore working directory"));
176
177 free_cwd (&saved_cwd);
178
179 errno = saved_errno;
180 return err;
181 }
182