libfshelp: add translator-list.c

Add functions that maintain a list of active translators.

* libfshelp/translator-list.c: New file.
* libfshelp/fshelp.h: Add function declarations.
* libfshelp/Makefile: Add translator-list.c, link against libihash.

3 files changed, 203 insertions, 2 deletions

diff --git a/libfshelp/Makefile b/libfshelp/Makefile
index 4de38372..6ba6a14f 100644
--- a/libfshelp/Makefile
+++ b/libfshelp/Makefile
@@ -20,6 +20,7 @@ makemode := library
 
 libname = libfshelp
 SRCS =	lock-acquire.c lock-init.c \
+	translator-list.c \
 	start-translator-long.c start-translator.c \
 	fetch-root.c transbox-init.c set-active.c fetch-control.c \
 	drop-transbox.c translated.c \
@@ -32,7 +33,7 @@ SRCS =	lock-acquire.c lock-init.c \
 	touch.c
 installhdrs = fshelp.h
 
-HURDLIBS = shouldbeinlibc iohelp ports
+HURDLIBS = shouldbeinlibc iohelp ports ihash
 LDLIBS += -lpthread
 OBJS = $(subst .c,.o,$(SRCS))
 
diff --git a/libfshelp/fshelp.h b/libfshelp/fshelp.h
index cf39fbc4..43fbcd78 100644
--- a/libfshelp/fshelp.h
+++ b/libfshelp/fshelp.h
@@ -1,5 +1,6 @@
 /* FS helper library definitions
-   Copyright (C) 1994,95,96,97,98,99,2000,01,02 Free Software Foundation, Inc.
+   Copyright (C) 1994,95,96,97,98,99,2000,01,02,13
+     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
@@ -32,6 +33,36 @@
 #include <maptime.h>
 
 
+/* Keeping track of active translators */
+/* These routines keep a list of active translators.  They are
+   self-contained and do not require multi threading or the ports
+   library.  */
+
+/* Record an active translator being bound to the given file name
+   NAME.  ACTIVE is the control port of the translator.  */
+error_t
+fshelp_set_active_translator (const char *name, mach_port_t active);
+
+/* Remove the active translator specified by its control port ACTIVE.
+   If there is no active translator with the given control port, this
+   does nothing.  */
+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 into the argz vector
+   specified by TRANSLATORS filtered by FILTER.  */
+error_t
+fshelp_get_active_translators (char **translators,
+			       size_t *translators_len,
+			       fshelp_filter filter);
+
+
 /* Passive translator linkage */
 /* These routines are self-contained and start passive translators,
    returning the control port.  They do not require multi threading
diff --git a/libfshelp/translator-list.c b/libfshelp/translator-list.c
new file mode 100644
index 00000000..a24d9762
--- /dev/null
+++ b/libfshelp/translator-list.c
@@ -0,0 +1,169 @@
+/* A list of active translators.
+
+   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 <argz.h>
+#include <hurd/fsys.h>
+#include <hurd/ihash.h>
+#include <mach.h>
+#include <mach/notify.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "fshelp.h"
+
+struct translator
+{
+  char *name;
+  mach_port_t active;
+};
+
+/* The list of active translators.  */
+static struct hurd_ihash translator_ihash
+  = HURD_IHASH_INITIALIZER (HURD_IHASH_NO_LOCP);
+
+/* The lock protecting the translator_ihash.  */
+static pthread_mutex_t translator_ihash_lock = PTHREAD_MUTEX_INITIALIZER;
+
+static void
+translator_ihash_cleanup (void *element, void *arg)
+{
+  /* No need to deallocate port, we only keep the name of the
+     port, not a reference.  */
+  free (element);
+}
+
+/* Record an active translator being bound to the given file name
+   NAME.  ACTIVE is the control port of the translator.  */
+error_t
+fshelp_set_active_translator (const char *name, mach_port_t active)
+{
+  error_t err = 0;
+  pthread_mutex_lock (&translator_ihash_lock);
+
+  if (! translator_ihash.cleanup)
+    hurd_ihash_set_cleanup (&translator_ihash, translator_ihash_cleanup, NULL);
+
+  struct translator *t = NULL;
+  HURD_IHASH_ITERATE (&translator_ihash, value)
+    {
+      t = value;
+      if (strcmp (name, t->name) == 0)
+	goto update; /* Entry exists.  */
+    }
+
+  t = malloc (sizeof (struct translator));
+  if (! t)
+    return ENOMEM;
+
+  t->active = MACH_PORT_NULL;
+  t->name = strdup (name);
+  if (! t->name)
+    {
+      err = errno;
+      free (t);
+      goto out;
+    }
+
+  err = hurd_ihash_add (&translator_ihash, (hurd_ihash_key_t) t, t);
+  if (err)
+    goto out;
+
+ update:
+  if (active)
+    /* No need to increment the reference count, we only keep the
+       name, not a reference.  */
+    t->active = active;
+  else
+    hurd_ihash_remove (&translator_ihash, (hurd_ihash_key_t) t);
+
+ out:
+  pthread_mutex_unlock (&translator_ihash_lock);
+  return err;
+}
+
+/* Remove the active translator specified by its control port ACTIVE.
+   If there is no active translator with the given control port, this
+   does nothing.  */
+error_t
+fshelp_remove_active_translator (mach_port_t active)
+{
+  error_t err = 0;
+  pthread_mutex_lock (&translator_ihash_lock);
+
+  struct translator *t = NULL;
+  HURD_IHASH_ITERATE (&translator_ihash, value)
+    {
+      struct translator *v = value;
+      if (active == v->active)
+	{
+	  t = v;
+	  break;
+	}
+    }
+
+  if (t)
+    hurd_ihash_remove (&translator_ihash, (hurd_ihash_key_t) t);
+
+  pthread_mutex_unlock (&translator_ihash_lock);
+  return err;
+}
+
+/* Records the list of active translators into the argz vector
+   specified by TRANSLATORS filtered by FILTER.  */
+error_t
+fshelp_get_active_translators (char **translators,
+			       size_t *translators_len,
+			       fshelp_filter filter)
+{
+  error_t err = 0;
+  pthread_mutex_lock (&translator_ihash_lock);
+
+  HURD_IHASH_ITERATE (&translator_ihash, value)
+    {
+      struct translator *t = value;
+      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);
+      if (err)
+	break;
+    }
+
+  pthread_mutex_unlock (&translator_ihash_lock);
+  return err;
+}