3 files changed, 51 insertions, 15 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index c64416a6454..a1dc1c2adab 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,14 @@
+2012-12-14  Eli Zaretskii  <eliz@gnu.org>
+
+        * w32.c (stat_worker): If w32_stat_get_owner_group is zero, do not
+        try to get accurate owner and group information from NT file
+        security APIs.  This is to make most callers of 'stat' and
+        'lstat', which don't need that information, much faster.
+
+        * dired.c (Ffile_attributes) [WINDOWSNT]: Set
+        w32_stat_get_owner_group to a non-zero value, to request accurate
+        owner and group information from 'lstat'.
+
 2012-12-13  Paul Eggert  <eggert@cs.ucla.edu>
 
         * fileio.c (Finsert_file_contents): Don't put tail into head area,
diff --git a/src/dired.c b/src/dired.c
index bdb71c46364..85af906c1da 100644
--- a/src/dired.c
+++ b/src/dired.c
@@ -895,6 +895,7 @@ so last access time will always be midnight of that day.  */)
   Lisp_Object dirname;
   struct stat sdir;
 #endif /* BSD4_2 */
+  int lstat_result;
 
   /* An array to hold the mode string generated by filemodestring,
      including its terminating space and null byte.  */
@@ -922,7 +923,21 @@ so last access time will always be midnight of that day.  */)
   encoded = ENCODE_FILE (filename);
   UNGCPRO;
 
-  if (lstat (SSDATA (encoded), &s) < 0)
+#ifdef WINDOWSNT
+  /* We usually don't request accurate owner and group info, because
+     it can be very expensive on Windows to get that, and most callers
+     of 'lstat' don't need that.  But here we do want that information
+     to be accurate.  */
+  w32_stat_get_owner_group = 1;
+#endif
+
+  lstat_result = lstat (SSDATA (encoded), &s);
+
+#ifdef WINDOWSNT
+  w32_stat_get_owner_group = 0;
+#endif
+
+  if (lstat_result < 0)
     return Qnil;
 
   values[0] = (S_ISLNK (s.st_mode) ? Ffile_symlink_p (filename)
diff --git a/src/w32.c b/src/w32.c
index e163a3a1ee3..7eaa38716f9 100644
--- a/src/w32.c
+++ b/src/w32.c
@@ -3537,6 +3537,10 @@ is_slow_fs (const char *name)
   return !(devtype == DRIVE_FIXED || devtype == DRIVE_RAMDISK);
 }
 
+/* If this is non-zero, the caller wants accurate information about
+   file's owner and group, which could be expensive to get.  */
+int w32_stat_get_owner_group;
+
 /* MSVC stat function can't cope with UNC names and has other bugs, so
    replace it with our own.  This also allows us to calculate consistent
    inode values and owner/group without hacks in the main Emacs code. */
@@ -3708,6 +3712,7 @@ stat_worker (const char * path, struct stat * buf, int follow_symlinks)
       /* We produce the fallback owner and group data, based on the
          current user that runs Emacs, in the following cases:
 
+          . caller didn't request owner and group info
           . this is Windows 9X
           . getting security by handle failed, and we need to produce
             information for the target of a symlink (this is better
@@ -3716,23 +3721,25 @@ stat_worker (const char * path, struct stat * buf, int follow_symlinks)
 
          If getting security by handle fails, and we don't need to
          resolve symlinks, we try getting security by name.  */
-      if (is_windows_9x () != TRUE)
-        psd = get_file_security_desc_by_handle (fh);
-      if (psd)
-        {
-          get_file_owner_and_group (psd, name, buf);
-          LocalFree (psd);
-        }
-      else if (is_windows_9x () == TRUE)
+      if (!w32_stat_get_owner_group || is_windows_9x () == TRUE)
         get_file_owner_and_group (NULL, name, buf);
-      else if (!(is_a_symlink && follow_symlinks))
+      else
         {
-          psd = get_file_security_desc_by_name (name);
-          get_file_owner_and_group (psd, name, buf);
-          xfree (psd);
+          psd = get_file_security_desc_by_handle (fh);
+          if (psd)
+            {
+              get_file_owner_and_group (psd, name, buf);
+              LocalFree (psd);
+            }
+          else if (!(is_a_symlink && follow_symlinks))
+            {
+              psd = get_file_security_desc_by_name (name);
+              get_file_owner_and_group (psd, name, buf);
+              xfree (psd);
+            }
+          else
+            get_file_owner_and_group (NULL, name, buf);
         }
-      else
-        get_file_owner_and_group (NULL, name, buf);
       CloseHandle (fh);
     }
   else
@@ -6849,6 +6856,9 @@ globals_of_w32 (void)
 
   /* "None" is the default group name on standalone workstations.  */
   strcpy (dflt_group_name, "None");
+
+  /* Reset, in case it has some value inherited from dump time.  */
+  w32_stat_get_owner_group = 0;
 }
 
 /* For make-serial-process  */