libdiskfs: add fsys_get_children

Keep track of active translators and handle fsys_get_children
requests.

* libdiskfs/Makefile (FSYSSRCS): Add fsys-get-children.c.
* libdiskfs/dead-name.c (ports_dead_name): Remove dead translators.
* libdiskfs/file-set-trans.c (diskfs_S_file_set_translator): Register
  active translators.
* libdiskfs/fsys-get-children.c: New file.

1 files changed, 99 insertions, 0 deletions

diff --git a/libdiskfs/fsys-get-children.c b/libdiskfs/fsys-get-children.c
new file mode 100644
index 00000000..69c9963e
--- /dev/null
+++ b/libdiskfs/fsys-get-children.c
@@ -0,0 +1,99 @@
+/* fsys_get_children
+
+   Copyright (C) 2013 Free Software Foundation, Inc.
+
+   Written by Justus Winter <4winter@informatik.uni-hamburg.de>
+
+   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 the GNU Hurd.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "priv.h"
+#include "fsys_S.h"
+
+#include <argz.h>
+
+/* Return any active translators bound to nodes of the receiving
+   filesystem.  CHILDREN is an argz vector containing file names
+   relative to the root of the receiving translator.  */
+error_t
+diskfs_S_fsys_get_children (fsys_t server,
+			    mach_port_t reply,
+			    mach_msg_type_name_t replyPoly,
+			    char **children,
+			    mach_msg_type_number_t *children_len)
+{
+  error_t err;
+
+  struct protid *cred = ports_lookup_port (diskfs_port_bucket,
+					   server,
+					   diskfs_protid_class);
+  if (! cred)
+    return EOPNOTSUPP;
+
+  /* check_access performs the same permission check as is normally
+     done, i.e. it checks that all but the last path components are
+     executable by the requesting user and that the last component is
+     readable.	*/
+  error_t check_access (const char *path)
+  {
+    error_t err;
+    char *elements = NULL;
+    size_t elements_len = 0;
+
+    err = argz_create_sep (path, '/', &elements, &elements_len);
+    if (err)
+      return err;
+
+    struct node *dp = diskfs_root_node;
+
+    for (char *entry = elements;
+	 entry;
+	 entry = argz_next (elements, elements_len, entry))
+      {
+	struct node *next;
+	err = diskfs_lookup (dp, entry, LOOKUP, &next, NULL, cred);
+
+	if (dp != diskfs_root_node)
+	  diskfs_nput (dp);
+
+	if (err)
+	  return err;
+
+	dp = next;
+      }
+
+    err = fshelp_access (&dp->dn_stat, S_IRUSR, cred->user);
+    diskfs_nput (dp);
+    return err;
+  }
+
+
+  char *c = NULL;
+  size_t c_len = 0;
+
+  err = fshelp_get_active_translators (&c, &c_len, check_access);
+  if (err)
+    goto errout;
+
+  err = iohelp_return_malloced_buffer (c, c_len, children, children_len);
+  if (err)
+    goto errout;
+
+  c = NULL; /* c was freed by iohelp_return_malloced_buffer. */
+
+ errout:
+  free (c);
+  return err;
+}