2001-06-21 Neal H Walfield <neal@cs.uml.edu>

	* fshelp.h (fshelp_iscontroller): Declare new function.
	* perms-iscontroller.c: New file.
	* Makefile (SRCS): Add it.

1 files changed, 38 insertions, 0 deletions

diff --git a/libfshelp/perms-iscontroller.c b/libfshelp/perms-iscontroller.c
new file mode 100644
index 00000000..456da2a2
--- /dev/null
+++ b/libfshelp/perms-iscontroller.c
@@ -0,0 +1,38 @@
+/* see whether a user should be considered a controller of the filesystem
+   Copyright (C) 2001 Free Software Foundation, Inc.
+   Written by Neal H Walfield <neal@cs.uml.edu>.
+
+   This file is part of the GNU Hurd.
+
+   The GNU Hurd 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.
+
+   The GNU Hurd 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., 59 Temple Place - Suite 330, Boston, MA  02111, USA. */
+
+#include <unistd.h>
+#include "fshelp.h"
+
+/* Check to see whether USER should be considered a controller of the
+   filesystem.  Which is to say, check to see if we should give USER the
+   control port.  ST is the stat of the root node.  USER is the user
+   asking for a send right to the control port.  */
+error_t
+fshelp_iscontroller (struct stat *st, struct iouser *user)
+{
+  /* Permitted if USER has the superuser uid, the owner uid or if the
+     USER has authority over the process's effective id.  */
+  if (idvec_contains (user->uids, st->st_uid)
+      || idvec_contains (user->uids, st->st_uid)
+      || idvec_contains (user->uids, geteuid ()))
+    return 0;
+  return EPERM;
+}