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

1 files changed, 3 insertions, 14 deletions

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);