X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fopenat.c;h=fd1ff911e54d29d36ccb9c4d63739afb6102e138;hb=43593319b31e6b0175b8eec4433bac744959822d;hp=f7eb39d0ec5035997692246a0b6e900e85a8062f;hpb=357e1c26576e584fbc24b72798d2f7cf70bd9867;p=gnulib.git

diff --git a/lib/openat.c b/lib/openat.c
index f7eb39d0e..fd1ff911e 100644
--- a/lib/openat.c
+++ b/lib/openat.c
@@ -1,10 +1,10 @@
 /* provide a replacement openat function
-   Copyright (C) 2004, 2005 Free Software Foundation, Inc.
+   Copyright (C) 2004-2013 Free Software Foundation, Inc.
 
-   This program is free software; you can redistribute it and/or modify
+   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 2, or (at your option)
-   any later version.
+   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
@@ -12,210 +12,275 @@
    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, write to the Free Software Foundation,
-   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 /* written by Jim Meyering */
 
-#ifdef HAVE_CONFIG_H
-# include <config.h>
+/* If the user's config.h happens to include <fcntl.h>, let it include only
+   the system's <fcntl.h> here, so that orig_openat doesn't recurse to
+   rpl_openat.  */
+#define __need_system_fcntl_h
+#include <config.h>
+
+/* Get the original definition of open.  It might be defined as a macro.  */
+#include <fcntl.h>
+#include <sys/types.h>
+#undef __need_system_fcntl_h
+
+#if HAVE_OPENAT
+static int
+orig_openat (int fd, char const *filename, int flags, mode_t mode)
+{
+  return openat (fd, filename, flags, mode);
+}
 #endif
 
+/* Write "fcntl.h" here, not <fcntl.h>, otherwise OSF/1 5.1 DTK cc eliminates
+   this include because of the preliminary #include <fcntl.h> above.  */
+#include "fcntl.h"
+
 #include "openat.h"
 
-#include <stdlib.h>
 #include <stdarg.h>
-#include <unistd.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <string.h>
+#include <sys/stat.h>
 #include <errno.h>
-#include <fcntl.h>
-
-#include "dirname.h" /* solely for definition of IS_ABSOLUTE_FILE_NAME */
-#include "save-cwd.h"
 
-#include "gettext.h"
-#define _(msgid) gettext (msgid)
+#if HAVE_OPENAT
 
-/* 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),
-   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.  */
+/* Like openat, but work around Solaris 9 bugs with trailing slash.  */
 int
-rpl_openat (int fd, char const *file, int flags, ...)
+rpl_openat (int dfd, char const *filename, int flags, ...)
 {
-  struct saved_cwd saved_cwd;
-  int saved_errno;
-  int new_fd;
-  mode_t mode = 0;
+  mode_t mode;
+  int fd;
 
+  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);
+      /* We have to use PROMOTED_MODE_T instead of mode_t, otherwise GCC 4
+         creates crashing code when 'mode_t' is smaller than 'int'.  */
+      mode = va_arg (arg, PROMOTED_MODE_T);
 
       va_end (arg);
     }
 
-  if (fd == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file))
-    return open (file, flags, mode);
-
-  if (save_cwd (&saved_cwd) != 0)
-    openat_save_fail (errno);
-
-  if (fchdir (fd) != 0)
+# if OPEN_TRAILING_SLASH_BUG
+  /* If the filename ends in a slash and one of O_CREAT, O_WRONLY, O_RDWR
+     is specified, then fail.
+     Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>
+     says that
+       "A pathname that contains at least one non-slash character and that
+        ends with one or more trailing slashes shall be resolved as if a
+        single dot character ( '.' ) were appended to the pathname."
+     and
+       "The special filename dot shall refer to the directory specified by
+        its predecessor."
+     If the named file already exists as a directory, then
+       - if O_CREAT is specified, open() must fail because of the semantics
+         of O_CREAT,
+       - if O_WRONLY or O_RDWR is specified, open() must fail because POSIX
+         <http://www.opengroup.org/susv3/functions/open.html> says that it
+         fails with errno = EISDIR in this case.
+     If the named file does not exist or does not name a directory, then
+       - if O_CREAT is specified, open() must fail since open() cannot create
+         directories,
+       - if O_WRONLY or O_RDWR is specified, open() must fail because the
+         file does not contain a '.' directory.  */
+  if (flags & (O_CREAT | O_WRONLY | O_RDWR))
     {
-      saved_errno = errno;
-      free_cwd (&saved_cwd);
-      errno = saved_errno;
-      return -1;
+      size_t len = strlen (filename);
+      if (len > 0 && filename[len - 1] == '/')
+        {
+          errno = EISDIR;
+          return -1;
+        }
     }
+# endif
+
+  fd = orig_openat (dfd, filename, flags, mode);
+
+# if OPEN_TRAILING_SLASH_BUG
+  /* If the filename ends in a slash and fd does not refer to a directory,
+     then fail.
+     Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>
+     says that
+       "A pathname that contains at least one non-slash character and that
+        ends with one or more trailing slashes shall be resolved as if a
+        single dot character ( '.' ) were appended to the pathname."
+     and
+       "The special filename dot shall refer to the directory specified by
+        its predecessor."
+     If the named file without the slash is not a directory, open() must fail
+     with ENOTDIR.  */
+  if (fd >= 0)
+    {
+      /* We know len is positive, since open did not fail with ENOENT.  */
+      size_t len = strlen (filename);
+      if (filename[len - 1] == '/')
+        {
+          struct stat statbuf;
+
+          if (fstat (fd, &statbuf) >= 0 && !S_ISDIR (statbuf.st_mode))
+            {
+              close (fd);
+              errno = ENOTDIR;
+              return -1;
+            }
+        }
+    }
+# endif
 
-  new_fd = open (file, flags, mode);
-  saved_errno = errno;
-
-  if (restore_cwd (&saved_cwd) != 0)
-    openat_restore_fail (errno);
+  return fd;
+}
 
-  free_cwd (&saved_cwd);
+#else /* !HAVE_OPENAT */
 
-  errno = saved_errno;
-  return new_fd;
-}
+# include "dosname.h" /* solely for definition of IS_ABSOLUTE_FILE_NAME */
+# include "openat-priv.h"
+# include "save-cwd.h"
 
-/* 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),
+/* 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, 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 after calling this function.  */
-DIR *
-fdopendir (int fd)
+   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, ...)
 {
-  struct saved_cwd saved_cwd;
-  int saved_errno;
-  DIR *dir;
+  mode_t mode = 0;
 
-  if (fd == AT_FDCWD)
-    return opendir (".");
+  if (flags & O_CREAT)
+    {
+      va_list arg;
+      va_start (arg, flags);
 
-  if (save_cwd (&saved_cwd) != 0)
-    openat_save_fail (errno);
+      /* We have to use PROMOTED_MODE_T instead of mode_t, otherwise GCC 4
+         creates crashing code when 'mode_t' is smaller than 'int'.  */
+      mode = va_arg (arg, PROMOTED_MODE_T);
 
-  if (fchdir (fd) != 0)
-    {
-      saved_errno = errno;
-      free_cwd (&saved_cwd);
-      close (fd);
-      errno = saved_errno;
-      return NULL;
+      va_end (arg);
     }
 
-  dir = opendir (".");
-  saved_errno = errno;
+  return openat_permissive (fd, file, flags, mode, NULL);
+}
 
-  if (restore_cwd (&saved_cwd) != 0)
-    openat_restore_fail (errno);
+/* 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.
 
-  free_cwd (&saved_cwd);
-  close (fd);
+   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.  */
 
-  errno = saved_errno;
-  return dir;
-}
-
-/* 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),
-   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)
+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)
-    return (flag == AT_SYMLINK_NOFOLLOW
-	    ? lstat (file, st)
-	    : stat (file, st));
-
-  if (save_cwd (&saved_cwd) != 0)
-    openat_save_fail (errno);
+  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;
+      if (! cwd_errno)
+        openat_save_fail (errno);
+      *cwd_errno = errno;
+    }
+  if (0 <= fd && fd == saved_cwd.desc)
+    {
+      /* If saving the working directory collides with the user's
+         requested fd, then the user's fd must have been closed to
+         begin with.  */
       free_cwd (&saved_cwd);
-      errno = saved_errno;
+      errno = EBADF;
       return -1;
     }
 
-  err = (flag == AT_SYMLINK_NOFOLLOW
-	 ? lstat (file, st)
-	 : stat (file, st));
+  err = fchdir (fd);
   saved_errno = errno;
 
-  if (restore_cwd (&saved_cwd) != 0)
-    openat_restore_fail (errno);
+  if (! err)
+    {
+      err = open (file, flags, mode);
+      saved_errno = errno;
+      if (save_ok && restore_cwd (&saved_cwd) != 0)
+        {
+          if (! cwd_errno)
+            {
+              /* Don't write a message to just-created fd 2.  */
+              saved_errno = errno;
+              if (err == STDERR_FILENO)
+                close (err);
+              openat_restore_fail (saved_errno);
+            }
+          *cwd_errno = errno;
+        }
+    }
 
   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>
-   Simulate it by doing save_cwd/fchdir/(unlink|rmdir)/restore_cwd.
-   If either the save_cwd or the restore_cwd fails (relatively unlikely,
-   and usually indicative of a problem that deserves close attention),
-   then give a diagnostic and exit nonzero.
-   Otherwise, this function works just like Solaris' unlinkat.  */
-int
-unlinkat (int fd, char const *file, int flag)
+/* Return true if our openat implementation must resort to
+   using save_cwd and restore_cwd.  */
+bool
+openat_needs_fchdir (void)
 {
-  struct saved_cwd saved_cwd;
-  int saved_errno;
-  int err;
-
-  if (fd == AT_FDCWD)
-    return (flag == AT_REMOVEDIR ? rmdir (file) : unlink (file));
-
-  if (save_cwd (&saved_cwd) != 0)
-    openat_save_fail (errno);
+  bool needs_fchdir = true;
+  int fd = open ("/", O_SEARCH);
 
-  if (fchdir (fd) != 0)
+  if (0 <= fd)
     {
-      saved_errno = errno;
-      free_cwd (&saved_cwd);
-      errno = saved_errno;
-      return -1;
+      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);
     }
 
-  err = (flag == AT_REMOVEDIR ? rmdir (file) : unlink (file));
-  saved_errno = errno;
-
-  if (restore_cwd (&saved_cwd) != 0)
-    openat_restore_fail (errno);
-
-  free_cwd (&saved_cwd);
-
-  errno = saved_errno;
-  return err;
+  return needs_fchdir;
 }
+
+#endif /* !HAVE_OPENAT */