common: Add mkdir_p.

* common/mkdir_p.c: New file.
* common/mkdir_p.h: New file.
* common/Makefile.am (common_sources): Add mkdir_p.c and mkdir_p.h.

--
Signed-off-by: Neal H. Walfield <neal@g10code.com>.

common/mkdir_p.h

@@ -0,0 +1,42 @@
+/* mkdir_p.h - Create a directory and any missing parents.
+ * Copyright (C) 2015 g10 Code GmbH
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG 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.
+ *
+ * GnuPG 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/>.
+ */
+
+#ifndef MKDIR_P_H
+#define MKDIR_P_H
+
+#include "types.h"
+
+/* Create a directory as well as any missing parents.
+
+   The arguments must be NULL termianted.  If DIRECTORY_COMPONENTS...
+   consists of two elements, "foo/bar" and "xyzzy", this function will
+   first try to create the directory "foo/bar" and then the directory
+   "foo/bar/xyzzy".  On success returns 0, otherwise an error code is
+   returned.  */
+int mkdir_p (char *directory_component, ...) GPGRT_ATTR_SENTINEL(0);
+
+/* Like mkdir_p, but DIRECTORY_COMPONENTS is a NULL terminated
+   array, e.g.:
+
+     char **dirs = { "foo", "bar", NULL };
+     amkdir_p (dirs);
+ */
+int amkdir_p (char **directory_components);
+
+#endif