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, 18 insertions, 20 deletions

diff --git a/lib-src/ChangeLog b/lib-src/ChangeLog
index f41c23df5d2..2cfe46f5352 100644
--- a/lib-src/ChangeLog
+++ b/lib-src/ChangeLog
@@ -1,3 +1,12 @@
+2013-08-04  Paul Eggert  <eggert@cs.ucla.edu>
+
+        Fix some minor races in hosts lacking mkostemp (Bug#15015).
+        * movemail.c (main):
+        * 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).
+
 2013-07-10  Paul Eggert  <eggert@cs.ucla.edu>
 
         Port to C89.
diff --git a/lib-src/movemail.c b/lib-src/movemail.c
index 81ac8aa187c..9434782cb17 100644
--- a/lib-src/movemail.c
+++ b/lib-src/movemail.c
@@ -304,24 +304,13 @@ main (int argc, char **argv)
 
           memcpy (tempname, inname, inname_dirlen);
           strcpy (tempname + inname_dirlen, "EXXXXXX");
-#ifdef HAVE_MKSTEMP
-          desc = mkstemp (tempname);
-#else
-          mktemp (tempname);
-          if (!*tempname)
-            desc = -1;
-          else
-            {
-              unlink (tempname);
-              desc = open (tempname, O_WRONLY | O_CREAT | O_EXCL, 0600);
-            }
-#endif
+          desc = mkostemp (tempname, 0);
           if (desc < 0)
             {
-              int mkstemp_errno = errno;
+              int mkostemp_errno = errno;
               error ("error while creating what would become the lock file",
                      0, 0);
-              errno = mkstemp_errno;
+              errno = mkostemp_errno;
               pfatal_with_name (tempname);
             }
           close (desc);
diff --git a/lib-src/update-game-score.c b/lib-src/update-game-score.c
index ec8b4317770..1699e305c8d 100644
--- a/lib-src/update-game-score.c
+++ b/lib-src/update-game-score.c
@@ -383,6 +383,7 @@ sort_scores (struct score_entry *scores, int count, int reverse)
 static int
 write_scores (const char *filename, const struct score_entry *scores, int count)
 {
+  int fd;
   FILE *f;
   int i;
   char *tempfile = malloc (strlen (filename) + strlen (".tempXXXXXX") + 1);
@@ -390,12 +391,11 @@ write_scores (const char *filename, const struct score_entry *scores, int count)
     return -1;
   strcpy (tempfile, filename);
   strcat (tempfile, ".tempXXXXXX");
-#ifdef HAVE_MKSTEMP
-  if (mkstemp (tempfile) < 0
-#else
-  if (mktemp (tempfile) != tempfile
-#endif
-      || !(f = fopen (tempfile, "w")))
+  fd = mkostemp (tempfile, 0);
+  if (fd < 0)
+    return -1;
+  f = fdopen (fd, "w");
+  if (! f)
     return -1;
   for (i = 0; i < count; i++)
     if (fprintf (f, "%ld %s %s\n", scores[i].score, scores[i].username,