clean up and factor out the 'shm' code

Remove the shm code from the engine and the service and put it in a
separate convenience library in shm/.

Remove the vestigial shmdir weirdness from the service (since shmdir is
now always relative to XDG_RUNTIME_DIR and has been for some time).

The purpose of this is so that dconf-engine can be properly unit-tested.
dconf-engine now has five points of contact with the world (excluding
the users of the engine themselves):

  - the DCONF_PROFILE environment variable

  - fopen() of profile files

  - shm

  - gvdb

  - dbus

The environment variable is quite easily controlled.  fopen() is
intercepted in the engine testcase with a interpose of the libc symbol.

With this commit now each of dbus, gvdb and shm are implemented in
separate utility modules that can be mocked from the testcases.

6 files changed, 8 insertions, 71 deletions

diff --git a/service/Makefile.am b/service/Makefile.am
index eed852a..96ad94e 100644
--- a/service/Makefile.am
+++ b/service/Makefile.am
@@ -1,12 +1,12 @@
 include $(top_srcdir)/Makefile.gtester
 
-AM_CFLAGS = $(gio_CFLAGS) -I$(top_srcdir)/gvdb -I$(top_srcdir)/common -Wall -Wmissing-prototypes -Wwrite-strings
+AM_CFLAGS = $(gio_CFLAGS) -I$(top_srcdir)/gvdb -I$(top_srcdir)/common -I$(top_srcdir)/shm -Wall -Wmissing-prototypes -Wwrite-strings
 
 libexec_PROGRAMS = dconf-service
 
 dbusservice_DATA = ca.desrt.dconf.service
 
-dconf_service_LDADD = $(gio_LIBS) ../common/libdconf-common.a
+dconf_service_LDADD = $(gio_LIBS) ../common/libdconf-common.a ../shm/libdconf-shm.a
 dconf_service_SOURCES = \
 	../gvdb/gvdb-builder.c		\
 	../gvdb/gvdb-reader.c		\
diff --git a/service/dconf-interfaces.c b/service/dconf-interfaces.c
index e824aca..45c6593 100644
--- a/service/dconf-interfaces.c
+++ b/service/dconf-interfaces.c
@@ -67,10 +67,6 @@ static const GDBusMethodInfo blame_method = {
   (GDBusArgInfo **) blame_out
 };
 
-static const GDBusPropertyInfo shmdir_property = {
-  -1, (gchar *) "ShmDirectory", (gchar *) "s", G_DBUS_PROPERTY_INFO_FLAGS_READABLE
-};
-
 static const GDBusMethodInfo *writer_methods[] = {
   &change_method, &write_method, &writemany_method, NULL
 };
@@ -83,10 +79,6 @@ static const GDBusMethodInfo *writer_info_methods[] = {
   &blame_method, NULL
 };
 
-static const GDBusPropertyInfo *writer_info_properties[] = {
-  &shmdir_property, NULL
-};
-
 const GDBusInterfaceInfo ca_desrt_dconf_Writer = {
   -1, (gchar *) "ca.desrt.dconf.Writer",
   (GDBusMethodInfo **) writer_methods,
@@ -98,5 +90,5 @@ const GDBusInterfaceInfo ca_desrt_dconf_WriterInfo = {
   -1, (gchar *) "ca.desrt.dconf.WriterInfo",
   (GDBusMethodInfo **) writer_info_methods,
   (GDBusSignalInfo **) NULL,
-  (GDBusPropertyInfo **) writer_info_properties
+  (GDBusPropertyInfo **) NULL
 };
diff --git a/service/dconf-state.c b/service/dconf-state.c
index a30054c..79e9753 100644
--- a/service/dconf-state.c
+++ b/service/dconf-state.c
@@ -1,7 +1,5 @@
 #include "dconf-state.h"
 
-#include "dconf-shmdir.h"
-
 #include <string.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -51,19 +49,6 @@ dconf_state_init_session (DConfState *state)
         g_error ("Can not create directory '%s': %s",
                  state->db_dir, g_strerror (errno));
     }
-
-  state->shm_dir = dconf_shmdir_from_environment ();
-
-  if (state->shm_dir == NULL)
-    {
-      const gchar *tmpdir = g_get_tmp_dir ();
-      gchar *shmdir;
-
-      shmdir = g_build_filename (tmpdir, "dconf.XXXXXX", NULL);
-
-      if ((state->shm_dir = mkdtemp (shmdir)) == NULL)
-        g_error ("Can not create reasonable shm directory");
-    }
 }
 
 static gboolean
diff --git a/service/dconf-state.h b/service/dconf-state.h
index 6a2ac58..f68ac3e 100644
--- a/service/dconf-state.h
+++ b/service/dconf-state.h
@@ -11,7 +11,6 @@ typedef struct
   GMainLoop *main_loop;
   guint64 serial;
   gchar *db_dir;
-  gchar *shm_dir;
   gchar *id;
 } DConfState;
 
diff --git a/service/dconf-writer.c b/service/dconf-writer.c
index 4218977..6c44c40 100644
--- a/service/dconf-writer.c
+++ b/service/dconf-writer.c
@@ -23,6 +23,7 @@
 
 #include "dconf-rebuilder.h"
 #include "dconf-state.h"
+#include "dconf-shm.h"
 
 #include <stdlib.h>
 #include <unistd.h>
@@ -35,7 +36,6 @@ struct OPAQUE_TYPE__DConfWriter
   DConfState *state;
   gchar *name;
   gchar *path;
-  gchar *shm;
 };
 
 /* Each element must only contain the ASCII characters "[A-Z][a-z][0-9]_"
@@ -77,26 +77,6 @@ dconf_writer_list_existing (void)
   return (gchar **) g_ptr_array_free (array, FALSE);
 }
 
-static void
-dconf_writer_touch_shm (DConfWriter *writer)
-{
-  gchar one = 1;
-  gint fd;
-
-  fd = open (writer->shm, O_WRONLY);
-
-  if (fd >= 0)
-    {
-      write (fd, &one, sizeof one);
-      close (fd);
-
-      unlink (writer->shm);
-    }
-
-  else if (errno != ENOENT)
-    unlink (writer->shm);
-}
-
 gboolean
 dconf_writer_write (DConfWriter  *writer,
                     const gchar  *name,
@@ -106,7 +86,7 @@ dconf_writer_write (DConfWriter  *writer,
   if (!dconf_rebuilder_rebuild (writer->path, "", &name, &value, 1, error))
     return FALSE;
 
-  dconf_writer_touch_shm (writer);
+  dconf_shm_flag (writer->name);
 
   return TRUE;
 }
@@ -123,7 +103,7 @@ dconf_writer_write_many (DConfWriter          *writer,
                                 values, n_items, error))
     return FALSE;
 
-  dconf_writer_touch_shm (writer);
+  dconf_shm_flag (writer->name);
 
   return TRUE;
 }
@@ -146,7 +126,7 @@ dconf_writer_change (DConfWriter     *writer,
   if (!dconf_rebuilder_rebuild (writer->path, prefix, keys, values, n_items, error))
     return FALSE;
 
-  dconf_writer_touch_shm (writer);
+  dconf_shm_flag (writer->name);
 
   return TRUE;
 }
@@ -172,7 +152,6 @@ dconf_writer_new (DConfState  *state,
   writer = g_slice_new (DConfWriter);
   writer->state = state;
   writer->path = g_build_filename (state->db_dir, name, NULL);
-  writer->shm = g_build_filename (state->shm_dir, name, NULL);
   writer->name = g_strdup (name);
 
   return writer;
diff --git a/service/service.c b/service/service.c
index 13dcc88..19eadb2 100644
--- a/service/service.c
+++ b/service/service.c
@@ -447,24 +447,6 @@ writer_info_method (GDBusConnection       *connection,
     g_assert_not_reached ();
 }
 
-static GVariant *
-writer_info_get_property (GDBusConnection  *connection,
-                          const gchar      *sender,
-                          const gchar      *object_path,
-                          const gchar      *interface_name,
-                          const gchar      *property_name,
-                          GError          **error,
-                          gpointer          user_data)
-{
-  DConfState *state = user_data;
-
-  /* debugging... */
-  if G_UNLIKELY (state->blame_mode)
-    gather_blame_info (state, connection, sender, object_path, "GetProperty", NULL);
-
-  return g_variant_new_string (state->shm_dir);
-}
-
 static const GDBusInterfaceVTable *
 subtree_dispatch (GDBusConnection *connection,
                   const gchar     *sender,
@@ -506,7 +488,7 @@ subtree_dispatch (GDBusConnection *connection,
   else if (strcmp (interface_name, "ca.desrt.dconf.WriterInfo") == 0)
     {
       static const GDBusInterfaceVTable vtable = {
-        writer_info_method, writer_info_get_property, NULL
+        writer_info_method, NULL
       };
 
       *out_user_data = state;