MS-Windows followup for 2013-07-07T18:00:14Z!eggert@cs.ucla.edu.

[bpt/emacs.git] / src / filelock.c

diff --git a/src/filelock.c b/src/filelock.c
index f17d318..6e939f2 100644 (file)
--- a/src/filelock.c
+++ b/src/filelock.c
@@ -47,6 +47,7 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include "systime.h"
 #ifdef WINDOWSNT
 #include <share.h>
+#include <sys/socket.h>        /* for fcntl */
 #include "w32.h"       /* for dostounix_filename */
 #endif
 
@@ -416,8 +417,13 @@ create_lock_file (char *lfname, char *lock_info_str, bool force)
       memcpy (nonce, lfname, lfdirlen);
       strcpy (nonce + lfdirlen, nonce_base);
 
-#if HAVE_MKSTEMP
-      /* Prefer mkstemp if available, as it avoids a race between
+#if HAVE_MKOSTEMP
+      /* Prefer mkostemp to mkstemp, as it avoids a window where FD is
+        temporarily open without close-on-exec.  */
+      fd = mkostemp (nonce, O_BINARY | O_CLOEXEC);
+      need_fchmod = 1;
+#elif HAVE_MKSTEMP
+      /* Prefer mkstemp to mktemp, as it avoids a race between
         mktemp and emacs_open.  */
       fd = mkstemp (nonce);
       need_fchmod = 1;
@@ -432,19 +438,17 @@ create_lock_file (char *lfname, char *lock_info_str, bool force)
        err = errno;
       else
        {
-         ptrdiff_t lock_info_len = strlen (lock_info_str);
+         ptrdiff_t lock_info_len;
+#if ! HAVE_MKOSTEMP
+         fcntl (fd, F_SETFD, FD_CLOEXEC);
+#endif
+         lock_info_len = strlen (lock_info_str);
          err = 0;
          if (emacs_write (fd, lock_info_str, lock_info_len) != lock_info_len
              || (need_fchmod && fchmod (fd, world_readable) != 0))
            err = errno;
-         else
-           while (fsync (fd) != 0)
-             if (errno != EINTR)
-               {
-                 if (errno != EINVAL)
-                   err = errno;
-                 break;
-               }
+         /* There is no need to call fsync here, as the contents of
+            the lock file need not survive system crashes.  */
          if (emacs_close (fd) != 0)
            err = errno;
          if (!err && rename_lock_file (nonce, lfname, force) != 0)