Traverse translator hierarchies using the fsys protocol.

Previously, we used the fs protocol to traverse the translator
hierarchies.  This, however, is conceptually flawed, because
translators are bound to nodes, and a node can have zero or more links
in the file system.  Therefore, the previous method of returning a
list of paths to the client and expecting them to be able to follow
these to reach the child translators was always unreliable.

Fix this by using the fsys protocol to traverse the hierarchy, and
returning the control ports of all children.  This is more robust, and
also conceptually cleaner, because the fsys protocol is about
translator linkage, hence this is the point to implement traversal.

Also move the get source routine over.  A per-node source really
does not fit the reality of most translators, while a per-translator
source makes sense in many cases.

* hurd/fs.defs (file_get_children): Drop routine.
(file_get_source): Likewise.
* hurd/fsys.defs (fsys_get_children): New routine.
(fsys_get_source): Likewise.
* libdiskfs/Makefile (FSYSSRCS): Remove files, add files.
* libdiskfs/file-get-children.c: Remove file.
* libdiskfs/fsys-get-children.c: New file.
* libdiskfs/file-get-source.c: Remove file.
* libdiskfs/fsys-get-source.c: New file.
* libfshelp/fshelp.h (fshelp_filter): Remove type.
(fshelp_get_active_translators): Remove filter and prefix argument,
return list of control ports.
* libfshelp/translator-list.c (fshelp_get_active_translators):
Likewise.
* libnetfs/Makefile (FSSRCS): Move 'get-source.c' too OTHERSRCS.
(FSYSSRCS): Remove files, add files.
* libnetfs/file-get-children.c: Remove file.
* libnetfs/fsys-get-children.c: New file.
* libnetfs/file-get-source.c: Remove file.
* libnetfs/fsys-get-source.c: New file.
* libtrivfs/Makefile: Move 'get-source.c' too OTHERSRCS.
(FSYSSRCS): Remove files, add files.
* libtrivfs/file-get-children.c: Remove file.
* libtrivfs/fsys-get-children.c: New file.
* libtrivfs/file-get-source.c: Remove file.
* libtrivfs/fsys-get-source.c: Add file.
* trans/Makefile (mtab): Build client stubs until the libc has caught
on.
* trans/mtab.c (target_control): New variable.
(insecure): Drop variable.
(all_translators): Likewise.
(MAX_DEPTH): New macro.
(max_depth): New variable.
(options): Remove '--insecure' and '--all-translators', add '--depth'.
(parse_opt): Adapt accordingly.
(trivsfs_append_args): Likewise.
(main): Get the control port of the target translator, then drop
privileges.
(is_filesystem_translator): Remove function.
(mtab_mark_as_seen): Simplify.  Just check if the control port is
known.
(mtab_populate): Limit depth of recursion, adapt to traversing over
the control ports, simplify.
(open_hook): Remove scary comment, it is not applicable anymore
because we no longer dir_lookup child translators.

2 files changed, 17 insertions, 36 deletions

diff --git a/libfshelp/fshelp.h b/libfshelp/fshelp.h
index 7663ba1d..e8ce9733 100644
--- a/libfshelp/fshelp.h
+++ b/libfshelp/fshelp.h
@@ -55,12 +55,6 @@ fshelp_set_active_translator (struct port_info *pi,
 error_t
 fshelp_remove_active_translator (mach_port_t active);
 
-/* This kind of function is used by fshelp_get_active_translators to
-   filter the list of translators to return.  If a filter returns an
-   error for a given PATH, the translator bound to the PATH is not
-   included in the list.  */
-typedef error_t (*fshelp_filter) (const char *path);
-
 /* Records the list of active translators below PREFIX into the argz
    vector specified by TRANSLATORS filtered by FILTER.  If PREFIX is
    NULL, entries with any prefix are considered.  If FILTER is NULL,
@@ -68,8 +62,8 @@ typedef error_t (*fshelp_filter) (const char *path);
 error_t
 fshelp_get_active_translators (char **translators,
 			       size_t *translators_len,
-			       fshelp_filter filter,
-			       const char *prefix);
+			       mach_port_t **controls,
+                               size_t *controls_count);
 
 /* Call FUN for each active translator.  If FUN returns non-zero, the
    iteration immediately stops, and returns that value.  FUN is called
diff --git a/libfshelp/translator-list.c b/libfshelp/translator-list.c
index 7077b217..92b31dd0 100644
--- a/libfshelp/translator-list.c
+++ b/libfshelp/translator-list.c
@@ -198,45 +198,32 @@ fshelp_remove_active_translator (mach_port_t active)
 error_t
 fshelp_get_active_translators (char **translators,
 			       size_t *translators_len,
-			       fshelp_filter filter,
-			       const char *prefix)
+			       mach_port_t **controls,
+                               size_t *controls_count)
 {
   error_t err = 0;
   pthread_mutex_lock (&translator_ihash_lock);
 
-  if (prefix && strlen (prefix) == 0)
-    prefix = NULL;
+  *controls = calloc (translator_ihash.nr_items, sizeof **controls);
+  if (*controls == NULL)
+    {
+      pthread_mutex_unlock (&translator_ihash_lock);
+      return ENOMEM;
+    }
+  *controls_count = 0;
 
   HURD_IHASH_ITERATE (&translator_ihash, value)
     {
       struct translator *t = value;
 
-      if (prefix != NULL
-	  && (strncmp (t->name, prefix, strlen (prefix)) != 0
-	      || t->name[strlen (prefix)] != '/'))
-	/* Skip this entry, as it is not below PREFIX.  */
+      err = mach_port_mod_refs (mach_task_self (), t->active,
+				MACH_PORT_RIGHT_SEND, +1);
+      if (err)
 	continue;
+      (*controls)[*controls_count] = t->active;
+      (*controls_count)++;
 
-      if (filter)
-	{
-	  char *dir = strdup (t->name);
-	  if (! dir)
-	    {
-	      err = ENOMEM;
-	      break;
-	    }
-
-	  err = filter (dirname (dir));
-	  free (dir);
-	  if (err)
-	    {
-	      err = 0;
-	      continue; /* Skip this entry.  */
-	    }
-	}
-
-      err = argz_add (translators, translators_len,
-		      &t->name[prefix? strlen (prefix) + 1: 0]);
+      err = argz_add (translators, translators_len, t->name);
       if (err)
 	break;
     }