[dconf] engine: add support for 'file-db'

[Ryan Lortie <desrt src gnome org>]

commit 690821a22313982497f41b25940fa58a1c33e91b
Author: Ryan Lortie <desrt desrt ca>
Date:   Sun Dec 1 21:56:25 2013 -0500

    engine: add support for 'file-db'
    
    This is a new database type that is simply an absolute path to a gvdb
    anywhere on the filesystem.  Change notification is not supported.
    
    This is intended to be used by things like gdm that wish to install
    databases (somewhere in /usr) as part of the software.

 engine/Makefile.am                   |    1 +
 engine/dconf-engine-profile.c        |   14 +++---
 engine/dconf-engine-source-file.c    |   79 ++++++++++++++++++++++++++++++++++
 engine/dconf-engine-source-private.h |    1 +
 engine/dconf-engine-source.c         |    4 ++
 5 files changed, 92 insertions(+), 7 deletions(-)
---
diff --git a/engine/Makefile.am b/engine/Makefile.am
index 5266f27..0f200d5 100644
--- a/engine/Makefile.am
+++ b/engine/Makefile.am
@@ -8,6 +8,7 @@ libdconf_engine_a_SOURCES = \
        dconf-engine-profile.c          \
        dconf-engine-source-private.h   \
        dconf-engine-source.h           \
+       dconf-engine-source-file.c      \
        dconf-engine-source-user.c      \
        dconf-engine-source-service.c   \
        dconf-engine-source-system.c    \
diff --git a/engine/dconf-engine-profile.c b/engine/dconf-engine-profile.c
index 6f2208d..1fbafc3 100644
--- a/engine/dconf-engine-profile.c
+++ b/engine/dconf-engine-profile.c
@@ -69,14 +69,14 @@
  * Once a profile file is opened, each line is treated as a possible
  * source.  Comments and empty lines are ignored.
  *
- * All valid source specification lines need to start with 'user-db:' or
- * 'system-db:'.  If a line doesn't start with one of these then it gets
- * ignored.  If all the lines in the file get ignored then the result is
- * effectively the null profile.
+ * All valid source specification lines need to start with 'user-db:',
+ * 'system-db:', 'service-db:' or 'file-db:'.  If a line doesn't start
+ * with one of these then it gets ignored.  If all the lines in the file
+ * get ignored then the result is effectively the null profile.
  *
- * If the first source is a "user-db:" then the resulting profile will
- * be writable.  No profile starting with a "system-db:" source can ever
- * be writable.
+ * If the first source is a "user-db:" or "service-db:" then the
+ * resulting profile will be writable.  No profile starting with a
+ * "system-db:" or "file-db:" source can ever be writable.
  *
  * Note: even if the source fails to initialise (due to a missing file,
  * for example) it will remain in the source list.  This could have a
diff --git a/engine/dconf-engine-source-file.c b/engine/dconf-engine-source-file.c
new file mode 100644
index 0000000..6c24f9c
--- /dev/null
+++ b/engine/dconf-engine-source-file.c
@@ -0,0 +1,79 @@
+/*
+ * Copyright © 2010 Codethink Limited
+ * Copyright © 2012 Canonical Limited
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the licence, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Author: Ryan Lortie <desrt desrt ca>
+ */
+
+#include "config.h"
+
+#include "dconf-engine-source-private.h"
+
+#include <sys/mman.h>
+#include <fcntl.h>
+#include <errno.h>
+
+static void
+dconf_engine_source_file_init (DConfEngineSource *source)
+{
+  source->bus_type = G_BUS_TYPE_NONE;
+  source->bus_name = NULL;
+  source->object_path = NULL;
+}
+
+static gboolean
+dconf_engine_source_file_needs_reopen (DConfEngineSource *source)
+{
+  return !source->values;
+}
+
+static GvdbTable *
+dconf_engine_source_file_reopen (DConfEngineSource *source)
+{
+  GError *error = NULL;
+  GvdbTable *table;
+
+  table = gvdb_table_new (source->name, FALSE, &error);
+
+  if (table == NULL)
+    {
+      if (!source->did_warn)
+        {
+          g_warning ("unable to open file '%s': %s; expect degraded performance", source->name, 
error->message);
+          source->did_warn = TRUE;
+        }
+
+      g_error_free (error);
+    }
+
+  return table;
+}
+
+static void
+dconf_engine_source_file_finalize (DConfEngineSource *source)
+{
+}
+
+G_GNUC_INTERNAL
+const DConfEngineSourceVTable dconf_engine_source_file_vtable = {
+  .instance_size    = sizeof (DConfEngineSource),
+  .init             = dconf_engine_source_file_init,
+  .finalize         = dconf_engine_source_file_finalize,
+  .needs_reopen     = dconf_engine_source_file_needs_reopen,
+  .reopen           = dconf_engine_source_file_reopen
+};
diff --git a/engine/dconf-engine-source-private.h b/engine/dconf-engine-source-private.h
index e0b943d..d209d28 100644
--- a/engine/dconf-engine-source-private.h
+++ b/engine/dconf-engine-source-private.h
@@ -25,6 +25,7 @@
 
 #include "dconf-engine-source.h"
 
+G_GNUC_INTERNAL extern const DConfEngineSourceVTable dconf_engine_source_file_vtable;
 G_GNUC_INTERNAL extern const DConfEngineSourceVTable dconf_engine_source_user_vtable;
 G_GNUC_INTERNAL extern const DConfEngineSourceVTable dconf_engine_source_service_vtable;
 G_GNUC_INTERNAL extern const DConfEngineSourceVTable dconf_engine_source_system_vtable;
diff --git a/engine/dconf-engine-source.c b/engine/dconf-engine-source.c
index 9a34a01..e6701f4 100644
--- a/engine/dconf-engine-source.c
+++ b/engine/dconf-engine-source.c
@@ -106,6 +106,10 @@ dconf_engine_source_new (const gchar *description)
   else if ((colon == description + 9) && memcmp (description, "system-db", 9) == 0)
     vtable = &dconf_engine_source_system_vtable;
 
+  /* ...or "file-db" */
+  else if ((colon == description + 7) && memcmp (description, "file-db", 7) == 0)
+    vtable = &dconf_engine_source_file_vtable;
+
   /* If it's not any of those, we have failed. */
   else
     return NULL;