module: Support for loading of modules

A module is a shared library existing in, or a subdirectory of, the
module directory. The directory is by default
${libdir}/pinos-$(MAJORMINOR)/modules, but can be specified with
--with-module-dir=PATH when running configure. It is also possible to
override the module directory runtime with the environment variable
PINOS_MODULE_DIR, which is a list of directories separated with ":".

configure.ac

@@ -90,6 +90,14 @@ USE_NLS=no
 AC_SUBST(USE_NLS)
 fi
 
+AC_ARG_WITH([module-dir],
+  AS_HELP_STRING([--with-module-dir=PATH],
+    [Directory where modules are located (default is ${libdir}/pinos/modules]),
+  [moduledir=$withval],
+  [moduledir="${libdir}/pinos-${PINOS_MAJORMINOR}/modules"])
+AC_SUBST(moduledir)
+AX_DEFINE_DIR(MODULEDIR, moduledir, [Directory where modules are located])
+
 #### Compiler flags ####
 
 AX_APPEND_COMPILE_FLAGS(
@@ -193,6 +201,11 @@ PKG_CHECK_MODULES(GIOUNIX, gio-unix-2.0 >= 2.32, dummy=yes,
 GLIB_CFLAGS="$GLIB_CFLAGS $GIOUNIX_CFLAGS"
 GLIB_LIBS="$GLIB_LIBS $GIOUNIX_LIBS"
 
+PKG_CHECK_MODULES(GMODULE, gmodule-no-export-2.0 >= 2.32, dummy=yes,
+                    AC_MSG_ERROR(GModule >= 2.32 is required))
+GLIB_CFLAGS="$GLIB_CFLAGS $GMODULE_CFLAGS"
+GLIB_LIBS="$GLIB_LIBS $GMODULE_LIBS"
+
 AC_MSG_CHECKING([for glib-mkenums script])
 GLIB_MKENUMS=`$PKG_CONFIG --variable=glib_mkenums glib-2.0`
 AS_IF([test "x$GLIB_MKENUMS" = "x"],
@@ -263,6 +276,7 @@ Configuration
 	Version                    : ${VERSION}
 	Source code location       : ${srcdir}
 	Prefix                     : ${prefix}
+	Moduledir                  : ${moduledir}
 	Compiler                   : ${CC}
 
 pinos configured. Type 'make' to build.

pinos/Makefile.am

@@ -204,6 +204,7 @@ libpinoscore_@PINOS_MAJORMINOR@_la_SOURCES = \
 		server/client-node.c server/client-node.h \
 		server/daemon.c server/daemon.h \
 		server/link.c server/link.h \
+		server/module.c server/module.h \
 		server/node.c server/node.h \
 		server/port.c server/port.h \
 		server/node-factory.c server/node-factory.h \
@@ -253,12 +254,14 @@ noinst_HEADERS = gst/gstburstcache.h gst/gstpinossrc.h \
 
 CLEANFILES += daemon/pinos.desktop
 DISTCLEANFILES =
+INSTALL_DIRS = $(moduledir)
 
-install-exec-hook:
+install-directories-hook:
-	rm -f $(DESTDIR)$(modlibexecdir)/*.la
+	$(MKDIR_P) $(addprefix $(DESTDIR),$(INSTALL_DIRS))
 
-uninstall-hook:
+INSTALL_EXEC_HOOKS = install-directories-hook
-	rm -f $(DESTDIR)$(modlibexecdir)/*.so
+
+install-exec-hook: $(INSTALL_EXEC_HOOKS)
 
 # Automatically generate linker version script. We use the same one for all public .sos
 update-map-file:
@@ -271,4 +274,4 @@ update-map-file:
 
 update-all: update-map-file
 
-.PHONY: update-all update-map-file coverage
+.PHONY: update-all update-map-file coverage $(INSTALL_EXEC_HOOKS)

pinos/daemon/main.c

@@ -18,10 +18,12 @@
  */
 
 #include <gio/gio.h>
+#include <glib.h>
 #include <gst/gst.h>
 
 #include <client/pinos.h>
 #include <server/daemon.h>
+#include <server/module.h>
 #include <modules/gst/gst-manager.h>
 #include <modules/gst/gst-node-factory.h>
 #include <spa/include/spa/memory.h>

pinos/server/module.c

@@ -0,0 +1,293 @@
+/* Pinos
+ * Copyright (C) 2016 Axis Communications <dev-gstreamer@axis.com>
+ * @author Linus Svensson <linus.svensson@axis.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, 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
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <glib.h>
+#include <gmodule.h>
+
+#include "pinos/server/module.h"
+
+#define PINOS_SYMBOL_MODULE_INIT "pinos__module_init"
+
+#define PINOS_MODULE_GET_PRIVATE(module)   \
+  (G_TYPE_INSTANCE_GET_PRIVATE ((module), PINOS_TYPE_MODULE, PinosModulePrivate))
+
+struct _PinosModulePrivate
+{
+  GModule *module;
+};
+
+G_DEFINE_TYPE (PinosModule, pinos_module, G_TYPE_OBJECT);
+
+enum
+{
+  PROP_0,
+  PROP_DAEMON,
+  PROP_NAME,
+};
+
+static void
+pinos_module_finalize (GObject * object)
+{
+  PinosModule *module = PINOS_MODULE (object);
+  PinosModulePrivate *priv = module->priv;
+
+  g_clear_object (&module->daemon);
+  g_free (module->name);
+  g_module_close (priv->module);
+
+  G_OBJECT_CLASS (pinos_module_parent_class)->finalize (object);
+}
+
+static void
+pinos_module_set_property (GObject      *object,
+                           guint         prop_id,
+                           const GValue *value,
+                           GParamSpec   *pspec)
+{
+  PinosModule *module = PINOS_MODULE (object);
+
+  switch (prop_id) {
+    case PROP_DAEMON:
+      module->daemon = g_value_dup_object (value);
+      break;
+    case PROP_NAME:
+      module->name = g_value_dup_string (value);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+}
+
+static void
+pinos_module_get_property (GObject    *object,
+                           guint       prop_id,
+                           GValue     *value,
+                           GParamSpec *pspec)
+{
+  PinosModule *module = PINOS_MODULE (object);
+
+  switch (prop_id) {
+    case PROP_DAEMON:
+      g_value_set_object (value, module->daemon);
+      break;
+    case PROP_NAME:
+      g_value_set_string (value, module->name);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+}
+
+static void
+pinos_module_class_init (PinosModuleClass * klass)
+{
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+
+  g_type_class_add_private (klass, sizeof (PinosModulePrivate));
+
+  gobject_class->finalize = pinos_module_finalize;
+  gobject_class->set_property = pinos_module_set_property;
+  gobject_class->get_property = pinos_module_get_property;
+
+  g_object_class_install_property (gobject_class,
+                                   PROP_DAEMON,
+                                   g_param_spec_object ("daemon",
+                                                        "Daemon",
+                                                        "A Pinos Daemon",
+                                                        PINOS_TYPE_DAEMON,
+                                                        G_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY |
+                                                        G_PARAM_STATIC_STRINGS));
+
+  g_object_class_install_property (gobject_class,
+                                   PROP_NAME,
+                                   g_param_spec_string ("name",
+                                                        "Name",
+                                                        "The name of the plugin",
+                                                        NULL,
+                                                        G_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY |
+                                                        G_PARAM_STATIC_STRINGS));
+}
+
+static void
+pinos_module_init (PinosModule * module)
+{
+  PinosModulePrivate *priv = PINOS_MODULE_GET_PRIVATE (module);
+  module->priv = priv;
+}
+
+GQuark
+pinos_module_error_quark (void)
+{
+  static GQuark quark = 0;
+
+  if (quark == 0) {
+    quark = g_quark_from_static_string ("pinos_module_error");
+  }
+
+  return quark;
+}
+
+static PinosModule *
+pinos_module_new (const gchar * name, PinosDaemon * daemon)
+{
+  return g_object_new (PINOS_TYPE_MODULE, "name", name, "daemon", daemon, NULL);
+}
+
+static gchar *
+find_module (const gchar * path, const gchar *name)
+{
+  gchar *filename;
+  GDir *dir;
+  const gchar *entry;
+  GError *err = NULL;
+
+  filename = g_strconcat (path, G_DIR_SEPARATOR_S, name, ".", G_MODULE_SUFFIX, NULL);
+
+  if (g_file_test (filename, G_FILE_TEST_IS_REGULAR)) {
+    /* found a regular file with name */
+    return filename;
+  }
+
+  g_clear_pointer (&filename, g_free);
+
+  /* now recurse down in subdirectories and look for it there */
+
+  dir = g_dir_open (path, 0, &err);
+  if (dir == NULL) {
+    g_warning ("could not open %s: %s", path, err->message);
+    g_error_free (err);
+    return NULL;
+  }
+
+  while ((entry = g_dir_read_name (dir))) {
+    gchar *newpath;
+
+    newpath = g_build_filename (path, entry, NULL);
+    if (g_file_test (newpath, G_FILE_TEST_IS_DIR)) {
+      filename = find_module (newpath, name);
+    }
+
+    if (filename != NULL)
+      break;
+  }
+
+  g_dir_close (dir);
+
+  return filename;
+}
+
+/**
+ * pinos_module_load:
+ * @daemon: a #PinosDaemon
+ * @name: name of the module to load
+ * @err: Return location for a #GError, or %NULL
+ *
+ * Load module with @name.
+ *
+ * Returns: A #PinosModule if the module could be loaded, or %NULL on failure.
+ */
+PinosModule *
+pinos_module_load (PinosDaemon * daemon, const gchar * name, GError ** err)
+{
+  PinosModule *module;
+  PinosModulePrivate *priv;
+  GModule *gmodule;
+  gchar *filename = NULL;
+  const gchar *module_dir;
+  PinosModuleInitFunc init_func;
+
+  g_return_val_if_fail (name != NULL && name[0] != '\0', NULL);
+  g_return_val_if_fail (PINOS_IS_DAEMON (daemon), NULL);
+
+  if (!g_module_supported ()) {
+    g_set_error (err, PINOS_MODULE_ERROR, PINOS_MODULE_ERROR_LOADING,
+        "Dynamic module loading not supported");
+    return NULL;
+  }
+
+  module_dir = g_getenv ("PINOS_MODULE_DIR");
+  if (module_dir != NULL) {
+    gchar **l;
+    gint i;
+
+    g_debug ("PINOS_MODULE_DIR set to: %s", module_dir);
+
+    l = g_strsplit (module_dir, G_SEARCHPATH_SEPARATOR_S, 0);
+    for (i = 0; l[i] != NULL; i++) {
+      filename = find_module (l[i], name);
+      if (filename != NULL)
+        break;
+    }
+    g_strfreev (l);
+  } else {
+    g_debug ("moduledir set to: %s", MODULEDIR);
+
+    filename = find_module (MODULEDIR, name);
+  }
+
+  if (filename == NULL) {
+    g_set_error (err, PINOS_MODULE_ERROR, PINOS_MODULE_ERROR_NOT_FOUND,
+        "No module \"%s\" was found", name);
+    return NULL;
+  }
+
+  g_debug ("trying to load module: %s (%s)", name, filename);
+
+  gmodule = g_module_open (filename, G_MODULE_BIND_LOCAL);
+  if (gmodule == NULL) {
+    g_set_error (err, PINOS_MODULE_ERROR, PINOS_MODULE_ERROR_LOADING,
+        "Failed to open module: %s", g_module_error ());
+    return NULL;
+  }
+
+  if (!g_module_symbol (gmodule, PINOS_SYMBOL_MODULE_INIT,
+          (gpointer *) &init_func)) {
+    g_set_error (err, PINOS_MODULE_ERROR, PINOS_MODULE_ERROR_LOADING,
+        "\"%s\" is not a pinos module", name);
+    g_module_close (gmodule);
+    return NULL;
+  }
+
+  module = pinos_module_new (name, daemon);
+  priv = module->priv;
+  priv->module = gmodule;
+
+  /* don't unload this module again */
+  g_module_make_resident (gmodule);
+
+  if (!init_func (module)) {
+    g_set_error (err, PINOS_MODULE_ERROR, PINOS_MODULE_ERROR_INIT,
+        "\"%s\" failed to initialize", name);
+    g_object_unref (module);
+    return NULL;
+  }
+
+  g_debug ("loaded module: %s", module->name);
+
+  return module;
+}

pinos/server/module.h

@@ -0,0 +1,100 @@
+/* Pinos
+ * Copyright (C) 2016 Axis Communications <dev-gstreamer@axis.com>
+ * @author Linus Svensson <linus.svensson@axis.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, 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
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef __PINOS_MODULE_H__
+#define __PINOS_MODULE_H__
+
+#include <glib-object.h>
+
+G_BEGIN_DECLS
+
+#include <pinos/server/daemon.h>
+
+#define PINOS_TYPE_MODULE                  (pinos_module_get_type ())
+#define PINOS_IS_MODULE(obj)               (G_TYPE_CHECK_INSTANCE_TYPE ((obj), PINOS_TYPE_MODULE))
+#define PINOS_IS_MODULE_CLASS(klass)       (G_TYPE_CHECK_CLASS_TYPE ((klass), PINOS_TYPE_MODULE))
+#define PINOS_MODULE_GET_CLASS(obj)        (G_TYPE_INSTANCE_GET_CLASS ((obj), PINOS_TYPE_MODULE, PinosModuleClass))
+#define PINOS_MODULE(obj)                  (G_TYPE_CHECK_INSTANCE_CAST ((obj), PINOS_TYPE_MODULE, PinosModule))
+#define PINOS_MODULE_CLASS(klass)          (G_TYPE_CHECK_CLASS_CAST ((klass), PINOS_TYPE_MODULE, PinosModuleClass))
+#define PINOS_MODULE_CAST(obj)             ((PinosModule*)(obj))
+#define PINOS_MODULE_CLASS_CAST(klass)     ((PinosModuleClass*)(klass))
+
+typedef struct _PinosModule PinosModule;
+typedef struct _PinosModuleClass PinosModuleClass;
+typedef struct _PinosModulePrivate PinosModulePrivate;
+
+struct _PinosModule {
+  GObject object;
+
+  gchar *name;
+  PinosDaemon *daemon;
+
+  PinosModulePrivate *priv;
+};
+
+struct _PinosModuleClass {
+  GObjectClass parent_class;
+};
+
+GQuark pinos_module_error_quark (void);
+/**
+ * PINOS_MODULE_ERROR:
+ *
+ * Pinos module error.
+ */
+#define PINOS_MODULE_ERROR pinos_module_error_quark ()
+
+/**
+ * PinosModuleError:
+ * @PINOS_MODULE_ERROR_GENERIC: Generic module error.
+ * @PINOS_MODULE_ERROR_NOT_FOUND: Module could not be found.
+ * @PINOS_MODULE_ERROR_LOADING: Module could not be loaded.
+ * @PINOS_MODULE_ERROR_INIT: The module failed to initialize.
+ *
+ * Error codes for Pinos modules.
+ */
+typedef enum
+{
+  PINOS_MODULE_ERROR_GENERIC,
+  PINOS_MODULE_ERROR_NOT_FOUND,
+  PINOS_MODULE_ERROR_LOADING,
+  PINOS_MODULE_ERROR_INIT,
+} PinosModuleError;
+
+/**
+ * PinosModuleInitFunc:
+ * @module: A #PinosModule
+ *
+ * A module should provide an init function with this signature. This function
+ * will be called when a module is loaded.
+ *
+ * Returns: %TRUE on success, %FALSE otherwise
+ */
+typedef gboolean (*PinosModuleInitFunc) (PinosModule *module);
+
+GType             pinos_module_get_type          (void);
+
+PinosModule *     pinos_module_load              (PinosDaemon *daemon,
+                                                  const gchar *name,
+                                                  GError **err);
+
+G_END_DECLS
+
+#endif /* __PINOS_MODULE_H__ */

pkgconfig/libpinos.pc.in

@@ -2,7 +2,7 @@ prefix=@prefix@
 exec_prefix=@exec_prefix@
 libdir=@libdir@
 includedir=@includedir@/
-modlibexecdir=@modlibexecdir@
+moduledir=@moduledir@
 
 Name: libpinos
 Description: Pinos Client Interface