+++ /dev/null
-/* provide a replacement openat function
- Copyright (C) 2004, 2005, 2006, 2007, 2008 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 Jim Meyering */
-
-#include <config.h>
-
-#include "openat.h"
-
-#include <stdarg.h>
-#include <stddef.h>
-#include <sys/stat.h>
-
-#include "dirname.h" /* solely for definition of IS_ABSOLUTE_FILE_NAME */
-#include "fcntl--.h"
-#include "openat-priv.h"
-#include "save-cwd.h"
-
-/* Replacement for Solaris' openat function.
- <http://www.google.com/search?q=openat+site:docs.sun.com>
- First, try to simulate it via open ("/proc/self/fd/FD/FILE").
- Failing that, simulate it by doing save_cwd/fchdir/open/restore_cwd.
- If either the save_cwd or the restore_cwd fails (relatively unlikely),
- then give a diagnostic and exit nonzero.
- Otherwise, upon failure, set errno and return -1, as openat does.
- Upon successful completion, return a file descriptor. */
-int
-openat (int fd, char const *file, int flags, ...)
-{
- mode_t mode = 0;
-
- if (flags & O_CREAT)
- {
- va_list arg;
- va_start (arg, flags);
-
- /* If mode_t is narrower than int, use the promoted type (int),
- not mode_t. Use sizeof to guess whether mode_t is narrower;
- we don't know of any practical counterexamples. */
- mode = (sizeof (mode_t) < sizeof (int)
- ? va_arg (arg, int)
- : va_arg (arg, mode_t));
-
- va_end (arg);
- }
-
- return openat_permissive (fd, file, flags, mode, NULL);
-}
-
-/* Like openat (FD, FILE, FLAGS, MODE), but if CWD_ERRNO is
- nonnull, set *CWD_ERRNO to an errno value if unable to save
- or restore the initial working directory. This is needed only
- the first time remove.c's remove_dir opens a command-line
- directory argument.
-
- If a previous attempt to restore the current working directory
- failed, then we must not even try to access a `.'-relative name.
- It is the caller's responsibility not to call this function
- in that case. */
-
-int
-openat_permissive (int fd, char const *file, int flags, mode_t mode,
- int *cwd_errno)
-{
- struct saved_cwd saved_cwd;
- int saved_errno;
- int err;
- bool save_ok;
-
- if (fd == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file))
- return open (file, flags, mode);
-
- {
- char buf[OPENAT_BUFFER_SIZE];
- char *proc_file = openat_proc_name (buf, fd, file);
- if (proc_file)
- {
- int open_result = open (proc_file, flags, mode);
- int open_errno = errno;
- if (proc_file != buf)
- free (proc_file);
- /* If the syscall succeeds, or if it fails with an unexpected
- errno value, then return right away. Otherwise, fall through
- and resort to using save_cwd/restore_cwd. */
- if (0 <= open_result || ! EXPECTED_ERRNO (open_errno))
- {
- errno = open_errno;
- return open_result;
- }
- }
- }
-
- save_ok = (save_cwd (&saved_cwd) == 0);
- if (! save_ok)
- {
- if (! cwd_errno)
- openat_save_fail (errno);
- *cwd_errno = errno;
- }
-
- err = fchdir (fd);
- saved_errno = errno;
-
- if (! err)
- {
- err = open (file, flags, mode);
- saved_errno = errno;
- if (save_ok && restore_cwd (&saved_cwd) != 0)
- {
- if (! cwd_errno)
- openat_restore_fail (errno);
- *cwd_errno = errno;
- }
- }
-
- free_cwd (&saved_cwd);
- errno = saved_errno;
- return err;
-}
-
-/* Return true if our openat implementation must resort to
- using save_cwd and restore_cwd. */
-bool
-openat_needs_fchdir (void)
-{
- bool needs_fchdir = true;
- int fd = open ("/", O_RDONLY);
-
- if (0 <= fd)
- {
- char buf[OPENAT_BUFFER_SIZE];
- char *proc_file = openat_proc_name (buf, fd, ".");
- if (proc_file)
- {
- needs_fchdir = false;
- if (proc_file != buf)
- free (proc_file);
- }
- close (fd);
- }
-
- return needs_fchdir;
-}
-
-#if !HAVE_FDOPENDIR
-
-/* Replacement for Solaris' function by the same name.
- <http://www.google.com/search?q=fdopendir+site:docs.sun.com>
- First, try to simulate it via opendir ("/proc/self/fd/FD"). Failing
- that, simulate it by doing save_cwd/fchdir/opendir(".")/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' fdopendir.
-
- W A R N I N G:
- Unlike the other fd-related functions here, this one
- effectively consumes its FD parameter. The caller should not
- close or otherwise manipulate FD if this function returns successfully. */
-DIR *
-fdopendir (int fd)
-{
- struct saved_cwd saved_cwd;
- int saved_errno;
- DIR *dir;
-
- char buf[OPENAT_BUFFER_SIZE];
- char *proc_file = openat_proc_name (buf, fd, ".");
- if (proc_file)
- {
- dir = opendir (proc_file);
- saved_errno = errno;
- }
- else
- {
- dir = NULL;
- saved_errno = EOPNOTSUPP;
- }
-
- /* If the syscall fails with an expected errno value, resort to
- save_cwd/restore_cwd. */
- if (! dir && EXPECTED_ERRNO (saved_errno))
- {
- if (save_cwd (&saved_cwd) != 0)
- openat_save_fail (errno);
-
- if (fchdir (fd) != 0)
- {
- dir = NULL;
- saved_errno = errno;
- }
- else
- {
- dir = opendir (".");
- saved_errno = errno;
-
- if (restore_cwd (&saved_cwd) != 0)
- openat_restore_fail (errno);
- }
-
- free_cwd (&saved_cwd);
- }
-
- if (dir)
- close (fd);
- if (proc_file != buf)
- free (proc_file);
- errno = saved_errno;
- return dir;
-}
-
-#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
-#define AT_FUNC_USE_F1_COND flag == 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
-
-/* Replacement for Solaris' function by the same name.
- <http://www.google.com/search?q=unlinkat+site:docs.sun.com>
- First, try to simulate it via (unlink|rmdir) ("/proc/self/fd/FD/FILE").
- Failing that, simulate it via save_cwd/fchdir/(unlink|rmdir)/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' unlinkat. */
-
-#define AT_FUNC_NAME unlinkat
-#define AT_FUNC_F1 rmdir
-#define AT_FUNC_F2 unlink
-#define AT_FUNC_USE_F1_COND flag == AT_REMOVEDIR
-#define AT_FUNC_POST_FILE_PARAM_DECLS , int flag
-#define AT_FUNC_POST_FILE_ARGS /* empty */
-#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
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