[PATCH 07/16] libnetfs: add fsys_get_children

[Justus Winter]

Keep track of active translators and handle fsys_get_children
requests.

* libnetfs/Makefile (FSYSSRCS): Add fsys-get-children.c.
* libnetfs/dead-name.c (ports_dead_name): Remove dead translators.
* libnetfs/file-set-translator.c (netfs_S_file_set_translator): Register
  active translators.
* libnetfs/fsys-get-children.c: New file.
---
 libnetfs/Makefile              |    2 +-
 libnetfs/dead-name.c           |    2 +
 libnetfs/file-set-translator.c |   17 +++++-
 libnetfs/fsys-get-children.c   |  112 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 131 insertions(+), 2 deletions(-)
 create mode 100644 libnetfs/fsys-get-children.c

diff --git a/libnetfs/Makefile b/libnetfs/Makefile
index a9810d2..f456740 100644
--- a/libnetfs/Makefile
+++ b/libnetfs/Makefile
@@ -44,7 +44,7 @@ IOSRCS=       io-read.c io-readable.c io-seek.c io-write.c 
io-stat.c io-async.c     \
        io-version.c
 
 FSYSSRCS= fsys-syncfs.c fsys-getroot.c fsys-get-options.c fsys-set-options.c \
-       fsys-goaway.c fsysstubs.c
+       fsys-goaway.c fsysstubs.c fsys-get-children.c
 
 IFSOCKSRCS=
 OTHERSRCS= drop-node.c init-init.c make-node.c make-peropen.c make-protid.c   \
diff --git a/libnetfs/dead-name.c b/libnetfs/dead-name.c
index ff29cfe..6f2d78d 100644
--- a/libnetfs/dead-name.c
+++ b/libnetfs/dead-name.c
@@ -41,5 +41,7 @@ ports_dead_name (void *notify, mach_port_t dead_name)
        pthread_mutex_unlock (&np->lock);
     }
 
+  fshelp_remove_active_translator (dead_name);
+
   ports_interrupt_notified_rpcs (notify, dead_name, MACH_NOTIFY_DEAD_NAME);
 }
diff --git a/libnetfs/file-set-translator.c b/libnetfs/file-set-translator.c
index b107ccd..a9883a3 100644
--- a/libnetfs/file-set-translator.c
+++ b/libnetfs/file-set-translator.c
@@ -1,5 +1,5 @@
 /*
-   Copyright (C) 1996, 1997, 1999, 2001 Free Software Foundation, Inc.
+   Copyright (C) 1996, 1997, 1999, 2001, 2013 Free Software Foundation, Inc.
    Written by Michael I. Bushnell, p/BSG.
 
    This file is part of the GNU Hurd.
@@ -175,6 +175,21 @@ netfs_S_file_set_translator (struct protid *user,
        }
     }
 
+  if (! err && user->po->path)
+    err = fshelp_set_active_translator (user->po->path, active);
+
+  if (! err && active != MACH_PORT_NULL)
+    {
+      mach_port_t old;
+      err = mach_port_request_notification (mach_task_self (), active,
+                                           MACH_NOTIFY_DEAD_NAME, 0,
+                                           user->pi.port_right,
+                                           MACH_MSG_TYPE_MAKE_SEND_ONCE,
+                                           &old);
+      if (old != MACH_PORT_NULL)
+       mach_port_deallocate (mach_task_self (), old);
+    }
+
  out:
   pthread_mutex_unlock (&np->lock);
   return err;
diff --git a/libnetfs/fsys-get-children.c b/libnetfs/fsys-get-children.c
new file mode 100644
index 0000000..fb3af91
--- /dev/null
+++ b/libnetfs/fsys-get-children.c
@@ -0,0 +1,112 @@
+/* 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 <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
+netfs_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 (netfs_port_bucket,
+                                          server,
+                                          netfs_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 = netfs_root_node;
+
+    /* Lock the root node. netfs_attempt_lookup expects the directory to
+       be locked.  */
+    pthread_mutex_lock (&dp->lock);
+
+    /* Increase the reference count, it will be decremented in the loop
+       ahead.  */
+    netfs_nref (dp);
+
+    for (char *entry = elements;
+        entry;
+        entry = argz_next (elements, elements_len, entry))
+      {
+       struct node *next;
+       err = netfs_attempt_lookup (cred->user, dp, entry, &next);
+       /* netfs_attempt_lookup has unlocked dp and returned next
+          locked, so there is no locking to do here.  */
+
+       /* Decrease reference count.  */
+       netfs_nrele (dp);
+
+       if (err)
+         goto errout;
+
+       dp = next;
+      }
+
+    err = fshelp_access (&dp->nn_stat, S_IRUSR, cred->user);
+
+  errout:
+    /* Unlock and unreference the last node.  */
+    netfs_nput (dp);
+
+    free (elements);
+    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;
+}
-- 
1.7.10.4