* tmpfile-safer.c: New file.

[gnulib.git] / lib / tmpfile-safer.c

diff --git a/lib/tmpfile-safer.c b/lib/tmpfile-safer.c
new file mode 100644 (file)
index 0000000..74ab959
--- /dev/null
+++ b/lib/tmpfile-safer.c
@@ -0,0 +1,76 @@
+/* Invoke tmpfile, but avoid some glitches.
+   Copyright (C) 2006 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 2, 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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* Written by Eric Blake, based on ideas from Paul Eggert.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "stdio-safer.h"
+
+#include <errno.h>
+#include <unistd.h>
+#include "unistd-safer.h"
+
+#include "binary-io.h"
+
+#ifndef STDERR_FILENO
+# define STDERR_FILENO 2
+#endif
+
+/* Like tmpfile, but do not return stdin, stdout, or stderr.
+
+   Remember that tmpfile can leave files behind if your program calls _exit,
+   so this function should not be mixed with the close_stdout module.  */
+
+FILE *
+tmpfile_safer (void)
+{
+  FILE *fp = tmpfile ();
+
+  if (fp)
+    {
+      int fd = fileno (fp);
+
+      if (0 <= fd && fd <= STDERR_FILENO)
+       {
+         int f = dup_safer (fd);
+
+         if (f < 0)
+           {
+             int e = errno;
+             fclose (fp);
+             errno = e;
+             return NULL;
+           }
+
+         /* Keep the temporary file in binary mode, on platforms
+            where that matters.  */
+         if (fclose (fp) != 0
+             || ! (fp = fdopen (f, O_BINARY ? "wb+" : "w+")))
+           {
+             int e = errno;
+             close (f);
+             errno = e;
+             return NULL;
+           }
+       }
+    }
+
+  return fp;
+}