1 /* provide a replacement openat function
2 Copyright (C) 2004-2011 Free Software Foundation, Inc.
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 3 of the License, or
7 (at your option) any later version.
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.
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
17 /* written by Jim Meyering */
19 /* If the user's config.h happens to include <fcntl.h>, let it include only
20 the system's <fcntl.h> here, so that orig_openat doesn't recurse to
22 #define __need_system_fcntl_h
25 /* Get the original definition of open. It might be defined as a macro. */
27 #include <sys/types.h>
28 #undef __need_system_fcntl_h
32 orig_openat (int fd, char const *filename, int flags, mode_t mode)
34 return openat (fd, filename, flags, mode);
38 /* Write "fcntl.h" here, not <fcntl.h>, otherwise OSF/1 5.1 DTK cc eliminates
39 this include because of the preliminary #include <fcntl.h> above. */
50 #include "dosname.h" /* solely for definition of IS_ABSOLUTE_FILE_NAME */
51 #include "openat-priv.h"
56 /* Like openat, but work around Solaris 9 bugs with trailing slash. */
58 rpl_openat (int dfd, char const *filename, int flags, ...)
67 va_start (arg, flags);
69 /* We have to use PROMOTED_MODE_T instead of mode_t, otherwise GCC 4
70 creates crashing code when 'mode_t' is smaller than 'int'. */
71 mode = va_arg (arg, PROMOTED_MODE_T);
76 # if OPEN_TRAILING_SLASH_BUG
77 /* If the filename ends in a slash and one of O_CREAT, O_WRONLY, O_RDWR
78 is specified, then fail.
79 Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>
81 "A pathname that contains at least one non-slash character and that
82 ends with one or more trailing slashes shall be resolved as if a
83 single dot character ( '.' ) were appended to the pathname."
85 "The special filename dot shall refer to the directory specified by
87 If the named file already exists as a directory, then
88 - if O_CREAT is specified, open() must fail because of the semantics
90 - if O_WRONLY or O_RDWR is specified, open() must fail because POSIX
91 <http://www.opengroup.org/susv3/functions/open.html> says that it
92 fails with errno = EISDIR in this case.
93 If the named file does not exist or does not name a directory, then
94 - if O_CREAT is specified, open() must fail since open() cannot create
96 - if O_WRONLY or O_RDWR is specified, open() must fail because the
97 file does not contain a '.' directory. */
98 if (flags & (O_CREAT | O_WRONLY | O_RDWR))
100 size_t len = strlen (filename);
101 if (len > 0 && filename[len - 1] == '/')
109 fd = orig_openat (dfd, filename, flags, mode);
111 # if OPEN_TRAILING_SLASH_BUG
112 /* If the filename ends in a slash and fd does not refer to a directory,
114 Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>
116 "A pathname that contains at least one non-slash character and that
117 ends with one or more trailing slashes shall be resolved as if a
118 single dot character ( '.' ) were appended to the pathname."
120 "The special filename dot shall refer to the directory specified by
122 If the named file without the slash is not a directory, open() must fail
126 /* We know len is positive, since open did not fail with ENOENT. */
127 size_t len = strlen (filename);
128 if (filename[len - 1] == '/')
132 if (fstat (fd, &statbuf) >= 0 && !S_ISDIR (statbuf.st_mode))
145 #else /* !HAVE_OPENAT */
147 /* Replacement for Solaris' openat function.
148 <http://www.google.com/search?q=openat+site:docs.sun.com>
149 First, try to simulate it via open ("/proc/self/fd/FD/FILE").
150 Failing that, simulate it by doing save_cwd/fchdir/open/restore_cwd.
151 If either the save_cwd or the restore_cwd fails (relatively unlikely),
152 then give a diagnostic and exit nonzero.
153 Otherwise, upon failure, set errno and return -1, as openat does.
154 Upon successful completion, return a file descriptor. */
156 openat (int fd, char const *file, int flags, ...)
163 va_start (arg, flags);
165 /* We have to use PROMOTED_MODE_T instead of mode_t, otherwise GCC 4
166 creates crashing code when 'mode_t' is smaller than 'int'. */
167 mode = va_arg (arg, PROMOTED_MODE_T);
172 return openat_permissive (fd, file, flags, mode, NULL);
175 /* Like openat (FD, FILE, FLAGS, MODE), but if CWD_ERRNO is
176 nonnull, set *CWD_ERRNO to an errno value if unable to save
177 or restore the initial working directory. This is needed only
178 the first time remove.c's remove_dir opens a command-line
181 If a previous attempt to restore the current working directory
182 failed, then we must not even try to access a `.'-relative name.
183 It is the caller's responsibility not to call this function
187 openat_permissive (int fd, char const *file, int flags, mode_t mode,
190 struct saved_cwd saved_cwd;
195 if (fd == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file))
196 return open (file, flags, mode);
199 char buf[OPENAT_BUFFER_SIZE];
200 char *proc_file = openat_proc_name (buf, fd, file);
203 int open_result = open (proc_file, flags, mode);
204 int open_errno = errno;
205 if (proc_file != buf)
207 /* If the syscall succeeds, or if it fails with an unexpected
208 errno value, then return right away. Otherwise, fall through
209 and resort to using save_cwd/restore_cwd. */
210 if (0 <= open_result || ! EXPECTED_ERRNO (open_errno))
218 save_ok = (save_cwd (&saved_cwd) == 0);
222 openat_save_fail (errno);
225 if (0 <= fd && fd == saved_cwd.desc)
227 /* If saving the working directory collides with the user's
228 requested fd, then the user's fd must have been closed to
230 free_cwd (&saved_cwd);
240 err = open (file, flags, mode);
242 if (save_ok && restore_cwd (&saved_cwd) != 0)
246 /* Don't write a message to just-created fd 2. */
248 if (err == STDERR_FILENO)
250 openat_restore_fail (saved_errno);
256 free_cwd (&saved_cwd);
261 /* Return true if our openat implementation must resort to
262 using save_cwd and restore_cwd. */
264 openat_needs_fchdir (void)
266 bool needs_fchdir = true;
267 int fd = open ("/", O_SEARCH);
271 char buf[OPENAT_BUFFER_SIZE];
272 char *proc_file = openat_proc_name (buf, fd, ".");
275 needs_fchdir = false;
276 if (proc_file != buf)
285 #endif /* !HAVE_OPENAT */