1 files changed, 51 insertions, 0 deletions
diff --git a/lib/write-any-file.c b/lib/write-any-file.c
new file mode 100644
index 0000000..73a435c
--- /dev/null
+++ b/lib/write-any-file.c
@@ -0,0 +1,51 @@
+/* Determine whether we can write any file.
+
+   Copyright (C) 2007, 2009-2016 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/>.  */
+
+/* Written by Paul Eggert.  */
+
+#include <config.h>
+
+#include "write-any-file.h"
+#include "priv-set.h"
+#include "root-uid.h"
+
+#include <unistd.h>
+
+/* Return true if we know that we can write any file, including
+   writing directories.  */
+
+bool
+can_write_any_file (void)
+{
+  static bool initialized;
+  static bool can_write;
+
+  if (! initialized)
+    {
+      bool can = false;
+#if defined PRIV_FILE_DAC_WRITE
+      can = (priv_set_ismember (PRIV_FILE_DAC_WRITE) == 1);
+#else
+      /* In traditional Unix, only root can unlink directories.  */
+      can = (geteuid () == ROOT_UID);
+#endif
+      can_write = can;
+      initialized = true;
+    }
+
+  return can_write;
+}