Make platform plug-ins implement an extension point

Instead of using dlopen/dlsym manually, turn existing platform modules into implementations of the platform extension point. This is mostly mechanical work to apply the following changes to each platform plug-in: - Add a subclass of CogPlatform e.g. CogFdoPlatform. - Make callback functions private to the platform plug-ins and install them as vfuncs of the CogPlatform class. - Support automatic selection of platform plug-ins by adding a new "is_suported" static vfunc. Note than other than the "is_supported" bit, no attempt is done at changing the architecture of the platform plug-ins.
Igalia · Jun 23, 2021 · a3815bb · a3815bb
1 parent 42e2214
commit a3815bb
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Showing 15 changed files with 517 additions and 177 deletions.
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -70,6 +70,9 @@ option(USE_SOUP2 "Build with libsoup2 instead of libsoup3" ON)
 set(COG_APPID "" CACHE STRING "Default GApplication unique identifier")
 set(COG_HOME_URI "" CACHE STRING "Default home URI")
 
+set(COG_MODULEDIR "${CMAKE_INSTALL_PREFIX}/lib/cog/modules"
+    CACHE STRING "Default search path for loadable modules")
+
 if (NOT COG_APPID OR COG_APPID STREQUAL "")
     set(COG_DEFAULT_APPID com.igalia.Cog)
 else ()
@@ -157,7 +160,7 @@ set_target_properties(cogcore PROPERTIES
     VERSION ${COGCORE_VERSION}
     SOVERSION ${COGCORE_VERSION_MAJOR}
 )
-target_link_libraries(cogcore PkgConfig::WebKit PkgConfig::SOUP)
+target_link_libraries(cogcore PkgConfig::GIO PkgConfig::WebKit PkgConfig::SOUP)
 target_compile_definitions(cogcore PRIVATE G_LOG_DOMAIN=\"Cog-Core\")
 if (HAS_WALL)
     target_compile_options(cogcore PUBLIC -Wall)

diff --git a/cog.c b/cog.c
@@ -289,31 +289,23 @@ platform_setup (CogShell *shell)
 
     g_debug ("%s: Platform name: %s", __func__, s_options.platform_name);
 
-    if (!s_options.platform_name)
-        return FALSE;
-
-    g_autofree char *platform_soname =
-        g_strdup_printf ("libcogplatform-%s.so", s_options.platform_name);
-    g_clear_pointer (&s_options.platform_name, g_free);
-
-    g_debug ("%s: Platform plugin: %s", __func__, platform_soname);
-
-    g_autoptr(CogPlatform) platform = cog_platform_new ();
-    if (!cog_platform_try_load (platform, platform_soname)) {
-        g_warning ("Could not load: %s (possible cause: %s).\n",
-                   platform_soname, strerror (errno));
+    g_autoptr(GError) error = NULL;
+    CogPlatform *platform = cog_platform_new(s_options.platform_name, &error);
+    if (!platform) {
+        g_warning("Cannot create platform: %s", error->message);
         return FALSE;
     }
 
-    g_autoptr(GError) error = NULL;
-    if (!cog_platform_setup (platform, shell, "", &error)) {
+    g_clear_pointer(&s_options.platform_name, g_free);
+
+    if (!cog_platform_setup(platform, shell, "", &error)) {
         g_warning ("Platform setup failed: %s", error->message);
         return FALSE;
     }
 
     s_options.platform = g_steal_pointer (&platform);
 
-    g_debug ("%s: Platform = %p", __func__, s_options.platform);
+    g_debug("%s: Selected %s @ %p", __func__, g_type_name(G_OBJECT_TYPE(s_options.platform)), s_options.platform);
     return TRUE;
 }
 
@@ -325,7 +317,7 @@ on_shutdown (CogLauncher *launcher G_GNUC_UNUSED, void *user_data G_GNUC_UNUSED)
 
     if (s_options.platform) {
         cog_platform_teardown (s_options.platform);
-        g_clear_pointer (&s_options.platform, cog_platform_free);
+        g_clear_object(&s_options.platform);
         g_debug ("%s: Platform teardown completed.", __func__);
     }
 }
@@ -429,6 +421,14 @@ on_create_view (CogShell *shell, void *user_data G_GNUC_UNUSED)
     return g_steal_pointer (&web_view);
 }
 
+static void
+print_module_info(GIOExtension *extension, void *userdata G_GNUC_UNUSED)
+{
+    g_info("  %s - %d/%s",
+           g_io_extension_get_name(extension),
+           g_io_extension_get_priority(extension),
+           g_type_name(g_io_extension_get_type(extension)));
+}
 
 int
 main (int argc, char *argv[])
@@ -442,6 +442,11 @@ main (int argc, char *argv[])
         g_set_application_name ("Cog");
     }
 
+    cog_modules_add_directory(g_getenv("COG_MODULEDIR") ?: COG_MODULEDIR);
+
+    g_info("%s:", COG_MODULES_PLATFORM_EXTENSION_POINT);
+    cog_modules_foreach(COG_MODULES_PLATFORM, print_module_info, NULL);
+
     g_autoptr(GApplication) app = G_APPLICATION (cog_launcher_get_default ());
     g_application_add_main_option_entries (app, s_cli_options);
     cog_launcher_add_web_settings_option_entries (COG_LAUNCHER (app));

diff --git a/core/cog-config.h.in b/core/cog-config.h.in
@@ -9,6 +9,7 @@
 #ifndef COG_CONFIG_H_IN
 #define COG_CONFIG_H_IN
 
+#define COG_MODULEDIR "@COG_MODULEDIR@"
 #define COG_VERSION_MAJOR @PROJECT_VERSION_MAJOR@
 #define COG_VERSION_MINOR @PROJECT_VERSION_MINOR@
 #define COG_VERSION_PATCH @PROJECT_VERSION_PATCH@

diff --git a/core/cog-platform.c b/core/cog-platform.c
@@ -6,90 +6,101 @@
  * Distributed under terms of the MIT license.
  */
 
-#include <dlfcn.h>
 #include "cog-platform.h"
+#include "cog-modules.h"
 
+G_DEFINE_QUARK(COG_PLATFORM_ERROR, cog_platform_error)
+G_DEFINE_QUARK(COG_PLATFORM_EGL_ERROR, cog_platform_egl_error)
+G_DEFINE_QUARK(COG_PLATFORM_WPE_ERROR, cog_platform_wpe_error)
 
-G_DEFINE_QUARK (COG_PLATFORM_EGL_ERROR, cog_platform_egl_error)
-G_DEFINE_QUARK (COG_PLATFORM_WPE_ERROR, cog_platform_wpe_error)
+G_DEFINE_ABSTRACT_TYPE(CogPlatform, cog_platform, G_TYPE_OBJECT)
 
+static void
+cog_platform_constructed(GObject *object)
+{
+    CogPlatform *platform = COG_PLATFORM(object);
 
-/* @FIXME: Move this implementation to use a GIO extension point. */
-
-struct _CogPlatform {
-    void *so;
-
-    gboolean                  (*setup)             (CogPlatform *platform,
-                                                    CogShell    *shell,
-                                                    const char  *params,
-                                                    GError     **error);
+    if (cog_platform_get_default() == NULL)
+        cog_platform_set_default(platform);
+}
 
-    void                      (*teardown)          (CogPlatform *platform);
+static void
+cog_platform_finalize(GObject *object)
+{
+    CogPlatform *platform = COG_PLATFORM(object);
 
-    WebKitWebViewBackend*     (*get_view_backend)  (CogPlatform   *platform,
-                                                    WebKitWebView *related_view,
-                                                    GError       **error);
-    void                      (*init_web_view)     (CogPlatform   *platform,
-                                                    WebKitWebView *view);
-    WebKitInputMethodContext* (*create_im_context) (CogPlatform   *platform);
-};
+    if (cog_platform_get_default() == platform)
+        cog_platform_set_default(NULL);
 
-CogPlatform*
-cog_platform_new (void)
-{
-    return g_slice_new0 (CogPlatform);
+    G_OBJECT_CLASS(cog_platform_parent_class)->finalize(object);
 }
 
-void
-cog_platform_free (CogPlatform *platform)
+static gboolean
+cog_platform_is_supported(void)
 {
-    g_clear_pointer (&platform->so, dlclose);
-    g_slice_free (CogPlatform, platform);
+    return TRUE;
 }
 
-void
-cog_platform_teardown (CogPlatform *platform)
+static void
+cog_platform_class_init(CogPlatformClass *klass)
 {
-    g_return_if_fail (platform != NULL);
+    GObjectClass *object_class = G_OBJECT_CLASS(klass);
+    object_class->constructed = cog_platform_constructed;
+    object_class->finalize = cog_platform_finalize;
 
-    platform->teardown (platform);
+    klass->is_supported = cog_platform_is_supported;
 }
 
-gboolean
-cog_platform_try_load (CogPlatform *platform,
-                       const gchar *soname)
+static void
+cog_platform_init(CogPlatform *platform)
 {
-    g_return_val_if_fail (platform != NULL, FALSE);
-    g_return_val_if_fail (soname != NULL, FALSE);
-
-    g_assert (!platform->so);
-    platform->so = dlopen (soname, RTLD_LAZY);
-    if (!platform->so)
-        return FALSE;
+}
 
-    platform->setup = dlsym (platform->so, "cog_platform_plugin_setup");
-    if (!platform->setup)
-        goto err_out;
+static CogPlatform *default_platform = NULL;
 
-    platform->teardown = dlsym (platform->so, "cog_platform_plugin_teardown");
-    if (!platform->teardown)
-        goto err_out;
+void
+cog_platform_set_default(CogPlatform *platform)
+{
+    default_platform = platform;
+}
 
-    platform->get_view_backend = dlsym (platform->so,
-                                        "cog_platform_plugin_get_view_backend");
-    if (!platform->get_view_backend)
-        goto err_out;
+CogPlatform *
+cog_platform_get_default(void)
+{
+    return default_platform;
+}
 
-    platform->init_web_view = dlsym (platform->so,
-                                     "cog_platform_plugin_init_web_view");
-    platform->create_im_context = dlsym (platform->so,
-                                         "cog_platform_plugin_create_im_context");
+CogPlatform *
+cog_platform_new(const char *name, GError **error)
+{
+    GType platform_type =
+        cog_modules_get_preferred(COG_MODULES_PLATFORM, name, G_STRUCT_OFFSET(CogPlatformClass, is_supported));
+
+    if (platform_type == G_TYPE_INVALID) {
+        g_set_error_literal(error, COG_PLATFORM_ERROR, COG_PLATFORM_ERROR_NO_MODULE,
+                            "Could not find an usable platform module");
+        return NULL;
+    }
+
+    g_autoptr(CogPlatform) self = g_object_new(platform_type, NULL);
+    if (G_IS_INITABLE(self)) {
+        if (!g_initable_init(G_INITABLE(self),
+                             NULL, /* cancellable */
+                             error))
+            return NULL;
+    }
+
+    return g_steal_pointer(&self);
+}
 
-    return TRUE;
+void
+cog_platform_teardown(CogPlatform *platform)
+{
+    g_return_if_fail(COG_IS_PLATFORM(platform));
 
- err_out:
-    g_clear_pointer (&platform->so, dlclose);
-    return FALSE;
+    CogPlatformClass *klass = COG_PLATFORM_GET_CLASS(platform);
+    if (klass->teardown)
+        klass->teardown(platform);
 }
 
 gboolean
@@ -98,39 +109,42 @@ cog_platform_setup (CogPlatform *platform,
                     const char  *params,
                     GError     **error)
 {
-    g_return_val_if_fail (platform != NULL, FALSE);
+    g_return_val_if_fail(COG_IS_PLATFORM(platform), FALSE);
     g_return_val_if_fail (COG_IS_SHELL (shell), FALSE);
 
-    return platform->setup (platform, shell, params, error);
+    return COG_PLATFORM_GET_CLASS(platform)->setup(platform, shell, params, error);
 }
 
 WebKitWebViewBackend*
 cog_platform_get_view_backend (CogPlatform   *platform,
                                WebKitWebView *related_view,
                                GError       **error)
 {
-    g_return_val_if_fail (platform != NULL, NULL);
+    g_return_val_if_fail(COG_IS_PLATFORM(platform), NULL);
 
-    return platform->get_view_backend (platform, related_view, error);
+    CogPlatformClass *klass = COG_PLATFORM_GET_CLASS(platform);
+    return klass->get_view_backend(platform, related_view, error);
 }
 
 void
 cog_platform_init_web_view (CogPlatform   *platform,
                             WebKitWebView *view)
 {
-    g_return_if_fail (platform != NULL);
+    g_return_if_fail(COG_IS_PLATFORM(platform));
 
-    if (platform->init_web_view)
-        platform->init_web_view (platform, view);
+    CogPlatformClass *klass = COG_PLATFORM_GET_CLASS(platform);
+    if (klass->init_web_view)
+        klass->init_web_view(platform, view);
 }
 
-WebKitInputMethodContext*
-cog_platform_create_im_context (CogPlatform *platform)
+WebKitInputMethodContext *
+cog_platform_create_im_context(CogPlatform *platform)
 {
-    g_return_val_if_fail (platform != NULL, NULL);
+    g_return_val_if_fail(COG_IS_PLATFORM(platform), NULL);
 
-    if (platform->create_im_context)
-        return platform->create_im_context (platform);
+    CogPlatformClass *klass = COG_PLATFORM_GET_CLASS(platform);
+    if (klass->create_im_context)
+        return klass->create_im_context(platform);
 
     return NULL;
 }
diff --git a/core/cog-platform.h b/core/cog-platform.h
@@ -13,37 +13,51 @@
 # error "Do not include this header directly, use <cog.h> instead"
 #endif
 
-#include <glib.h>
 #include "cog-shell.h"
+#include <glib-object.h>
 
 G_BEGIN_DECLS
 
+#define COG_PLATFORM_ERROR (cog_platform_error_quark())
+
+typedef enum {
+    COG_PLATFORM_ERROR_NO_MODULE,
+} CogPlatformError;
+
 #define COG_PLATFORM_EGL_ERROR  (cog_platform_egl_error_quark ())
 GQuark cog_platform_egl_error_quark (void);
 
 #define COG_PLATFORM_WPE_ERROR  (cog_platform_wpe_error_quark ())
 GQuark cog_platform_wpe_error_quark (void);
 
+typedef struct _WebKitInputMethodContext WebKitInputMethodContext;
+typedef struct _WebKitWebViewBackend WebKitWebViewBackend;
 
 typedef enum {
     COG_PLATFORM_WPE_ERROR_INIT,
 } CogPlatformWpeError;
 
+#define COG_TYPE_PLATFORM (cog_platform_get_type())
 
-/* @FIXME: Eventually move this interface to GObject. */
-typedef struct _CogPlatform CogPlatform;
-typedef struct _WebKitInputMethodContext WebKitInputMethodContext;
+G_DECLARE_DERIVABLE_TYPE(CogPlatform, cog_platform, COG, PLATFORM, GObject)
 
-CogPlatform              *cog_platform_new               (void);
-void                      cog_platform_free              (CogPlatform   *platform);
+struct _CogPlatformClass {
+    GObjectClass parent_class;
 
-gboolean                  cog_platform_try_load          (CogPlatform   *platform,
-                                                          const gchar   *soname);
+    /*< public >*/
+    gboolean (*is_supported)(void);
+    gboolean (*setup)(CogPlatform *, CogShell *shell, const char *params, GError **);
+    void (*teardown)(CogPlatform *);
+    WebKitWebViewBackend *(*get_view_backend)(CogPlatform *, WebKitWebView *related_view, GError **);
+    void (*init_web_view)(CogPlatform *, WebKitWebView *);
+    WebKitInputMethodContext *(*create_im_context)(CogPlatform *);
+};
 
-gboolean                  cog_platform_setup             (CogPlatform   *platform,
-                                                          CogShell      *shell,
-                                                          const char    *params,
-                                                          GError       **error);
+void cog_platform_set_default(CogPlatform *);
+CogPlatform *cog_platform_get_default(void);
+CogPlatform *cog_platform_new(const char *name, GError **);
+
+gboolean cog_platform_setup(CogPlatform *platform, CogShell *shell, const char *params, GError **error);
 
 void                      cog_platform_teardown          (CogPlatform   *platform);
 
@@ -56,8 +70,6 @@ void                      cog_platform_init_web_view     (CogPlatform   *platfor
 
 WebKitInputMethodContext *cog_platform_create_im_context (CogPlatform   *platform);
 
-G_DEFINE_AUTOPTR_CLEANUP_FUNC (CogPlatform, cog_platform_free)
-
 G_END_DECLS
 
 #endif /* !COG_PLATFORM_H */