Fix some minor races in hosts lacking mkostemp.

Gnulib's emulation of mkostemp doesn't have races that Emacs's does.
* configure.ac (mkostemp): Remove check for this function;
gnulib does the check now.
(mkstemp): Remove check for this no-longer-used function.
* lib/mkostemp.c, lib/secure_getenv.c, lib/tempname.c, lib/tempname.h:
* m4/mkostemp.m4, m4/secure_getenv.m4, m4/tempname.m4:
New files, copied from Gnulib.
* lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
* admin/merge-gnulib (GNULIB_MODULES): Add mkostemp.
* lib-src/movemail.c (main):
* lib-src/update-game-score.c (write_scores):
Use mkostemp (which now works on all platforms, due to changes
in the portability layer) rather than mktemp (which has a race)
or mkstemp (which we no longer bother with).
* src/callproc.c (create_temp_file):
* src/filelock.c (create_lock_file):
Assume mkostemp, since it's now provided by Gnulib.

Fixes: debbugs:15015

3 files changed, 10 insertions, 29 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index c29c4c8da59..f8f2fa47089 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,10 @@
+2013-08-04  Paul Eggert  <eggert@cs.ucla.edu>
+
+        Fix some minor races in hosts lacking mkostemp (Bug#15015).
+        * callproc.c (create_temp_file):
+        * filelock.c (create_lock_file):
+        Assume mkostemp, since it's now provided by Gnulib.
+
 2013-08-04  Eli Zaretskii  <eliz@gnu.org>
 
         * w32.c (mkostemp): New function.
diff --git a/src/callproc.c b/src/callproc.c
index 450fc57f929..54bc5cd9dc0 100644
--- a/src/callproc.c
+++ b/src/callproc.c
@@ -1009,23 +1009,11 @@ create_temp_file (ptrdiff_t nargs, Lisp_Object *args)
     tempfile = SSDATA (filename_string);
 
     {
-      int fd;
-
-#ifdef HAVE_MKOSTEMP
-      fd = mkostemp (tempfile, O_CLOEXEC);
-#elif defined HAVE_MKSTEMP
-      fd = mkstemp (tempfile);
-#else
-      errno = EEXIST;
-      mktemp (tempfile);
-      fd = *tempfile ? 0 : -1;
-#endif
+      int fd = mkostemp (tempfile, O_CLOEXEC);
       if (fd < 0)
         report_file_error ("Failed to open temporary file using pattern",
                            pattern);
-#if defined HAVE_MKOSTEMP || defined HAVE_MKSTEMP
       emacs_close (fd);
-#endif
     }
 
     record_unwind_protect (delete_temp_file, filename_string);
diff --git a/src/filelock.c b/src/filelock.c
index b9c991e4baf..0f31b7d4deb 100644
--- a/src/filelock.c
+++ b/src/filelock.c
@@ -411,28 +411,14 @@ create_lock_file (char *lfname, char *lock_info_str, bool force)
       memcpy (nonce, lfname, lfdirlen);
       strcpy (nonce + lfdirlen, nonce_base);
 
-#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);
-#elif HAVE_MKSTEMP
-      /* Prefer mkstemp to mktemp, as it avoids a race between
-         mktemp and emacs_open.  */
-      fd = mkstemp (nonce);
-#else
-      mktemp (nonce);
-      fd = emacs_open (nonce, O_WRONLY | O_CREAT | O_EXCL | O_BINARY,
-                       S_IRUSR | S_IWUSR);
-#endif
-
       if (fd < 0)
         err = errno;
       else
         {
           ptrdiff_t lock_info_len;
-#if ! (HAVE_MKOSTEMP && O_CLOEXEC)
-          fcntl (fd, F_SETFD, FD_CLOEXEC);
-#endif
+          if (! O_CLOEXEC)
+            fcntl (fd, F_SETFD, FD_CLOEXEC);
           lock_info_len = strlen (lock_info_str);
           err = 0;
           /* Use 'write', not 'emacs_write', as garbage collection