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, 50 insertions, 0 deletions

diff --git a/lib/tempname.h b/lib/tempname.h
new file mode 100644
index 00000000000..333267dfd09
--- /dev/null
+++ b/lib/tempname.h
@@ -0,0 +1,50 @@
+/* Create a temporary file or directory.
+
+   Copyright (C) 2006, 2009-2013 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* header written by Eric Blake */
+
+#ifndef GL_TEMPNAME_H
+# define GL_TEMPNAME_H
+
+# include <stdio.h>
+
+# ifdef __GT_FILE
+#  define GT_FILE     __GT_FILE
+#  define GT_DIR      __GT_DIR
+#  define GT_NOCREATE __GT_NOCREATE
+# else
+#  define GT_FILE     0
+#  define GT_DIR      1
+#  define GT_NOCREATE 2
+# endif
+
+/* Generate a temporary file name based on TMPL.  TMPL must match the
+   rules for mk[s]temp (i.e. end in "XXXXXX", possibly with a suffix).
+   The name constructed does not exist at the time of the call to
+   gen_tempname.  TMPL is overwritten with the result.
+
+   KIND may be one of:
+   GT_NOCREATE:         simply verify that the name does not exist
+                        at the time of the call.
+   GT_FILE:             create a large file using open(O_CREAT|O_EXCL)
+                        and return a read-write fd.  The file is mode 0600.
+   GT_DIR:              create a directory, which will be mode 0700.
+
+   We use a clever algorithm to get hard-to-predict names. */
+extern int gen_tempname (char *tmpl, int suffixlen, int flags, int kind);
+
+#endif /* GL_TEMPNAME_H */