/* provide a replacement openat function
- Copyright (C) 2004, 2005 Free Software Foundation, Inc.
+ Copyright (C) 2004, 2005, 2006 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
#include "openat.h"
-#include <stdlib.h>
#include <stdarg.h>
-#include <unistd.h>
-#include <errno.h>
-#include <fcntl.h>
+#include <stddef.h>
-#include "error.h"
-#include "exitfail.h"
+#include "dirname.h" /* solely for definition of IS_ABSOLUTE_FILE_NAME */
+#include "fcntl--.h"
+#include "lchown.h"
+#include "lstat.h"
+#include "openat-priv.h"
#include "save-cwd.h"
-#include "gettext.h"
-#define _(msgid) gettext (msgid)
-
/* Replacement for Solaris' openat function.
<http://www.google.com/search?q=openat+site:docs.sun.com>
- Simulate it by doing save_cwd/fchdir/open/restore_cwd.
- If either the save_cwd or the restore_cwd fails (relatively unlikely,
- and usually indicative of a problem that deserves close attention),
+ 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
-rpl_openat (int fd, char const *file, int flags, ...)
+openat (int fd, char const *file, int flags, ...)
{
- struct saved_cwd saved_cwd;
- int saved_errno;
- int new_fd;
mode_t mode = 0;
if (flags & O_CREAT)
va_list arg;
va_start (arg, flags);
- /* Assume that mode_t is passed compatibly with mode_t's type
- after argument promotion. */
- mode = va_arg (arg, mode_t);
+ /* 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);
}
- if (fd == AT_FDCWD || *file == '/')
- return open (file, flags, mode);
+ 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 (save_cwd (&saved_cwd) != 0)
- error (exit_failure, errno,
- _("openat: unable to record current working directory"));
+ if (fd == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file))
+ return open (file, flags, mode);
- if (fchdir (fd) != 0)
+ {
+ 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)
{
- saved_errno = errno;
- free_cwd (&saved_cwd);
- errno = saved_errno;
- return -1;
+ if (! cwd_errno)
+ openat_save_fail (errno);
+ *cwd_errno = errno;
}
- new_fd = open (file, flags, mode);
+ err = fchdir (fd);
saved_errno = errno;
- if (restore_cwd (&saved_cwd) != 0)
- error (exit_failure, errno,
- _("openat: unable to restore working directory"));
+ 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 new_fd;
+ 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>
- Simulate it by doing save_cwd/fchdir/opendir(".")/restore_cwd.
- If either the save_cwd or the restore_cwd fails (relatively unlikely,
- and usually indicative of a problem that deserves close attention),
+ 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. */
+ 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)
{
int saved_errno;
DIR *dir;
- if (fd == AT_FDCWD)
- return opendir (".");
-
- if (save_cwd (&saved_cwd) != 0)
- error (exit_failure, errno,
- _("fdopendir: unable to record current working directory"));
-
- if (fchdir (fd) != 0)
+ char buf[OPENAT_BUFFER_SIZE];
+ char *proc_file = openat_proc_name (buf, fd, ".");
+ if (proc_file)
{
+ dir = opendir (proc_file);
saved_errno = errno;
- free_cwd (&saved_cwd);
- errno = saved_errno;
- return NULL;
+ }
+ else
+ {
+ dir = NULL;
+ saved_errno = EOPNOTSUPP;
}
- dir = opendir (".");
- saved_errno = errno;
-
- if (restore_cwd (&saved_cwd) != 0)
- error (exit_failure, errno,
- _("fdopendir: unable to restore working directory"));
+ /* 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);
+ 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>
- Simulate it by doing save_cwd/fchdir/(stat|lstat)/restore_cwd.
- If either the save_cwd or the restore_cwd fails (relatively unlikely,
- and usually indicative of a problem that deserves close attention),
+ 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. */
-int
-fstatat (int fd, char const *file, struct stat *st, int flag)
-{
- struct saved_cwd saved_cwd;
- int saved_errno;
- int err;
-
- if (fd == AT_FDCWD)
- return (flag == AT_SYMLINK_NOFOLLOW
- ? lstat (file, st)
- : stat (file, st));
- if (save_cwd (&saved_cwd) != 0)
- error (exit_failure, errno,
- _("fstatat: unable to record current working directory"));
+#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
- if (fchdir (fd) != 0)
- {
- saved_errno = errno;
- free_cwd (&saved_cwd);
- errno = saved_errno;
- return -1;
- }
-
- err = (flag == AT_SYMLINK_NOFOLLOW
- ? lstat (file, st)
- : stat (file, st));
- saved_errno = errno;
-
- if (restore_cwd (&saved_cwd) != 0)
- error (exit_failure, errno,
- _("fstatat: unable to restore working directory"));
-
- free_cwd (&saved_cwd);
-
- errno = saved_errno;
- return err;
-}
+/* 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
projects / gnulib.git / blobdiff