Merge r172920 - [GTK] Older versions of WebKit should use the plugins…

… cache in read only mode

https://bugs.webkit.org/show_bug.cgi?id=136215

Reviewed by Philippe Normand.

Now that WebKitGTK+ 2.4 and 2.5 are parallel installable, since
they use different versions of the plugins cache, apps using 2.4
might override the plugins cache file. We should prevent this from
happening by making older versions use the plugin cache, but not
downgrade it.

* UIProcess/Plugins/gtk/PluginInfoCache.cpp:
(WebKit::PluginInfoCache::PluginInfoCache):
(WebKit::PluginInfoCache::updatePluginInfo):
* UIProcess/Plugins/gtk/PluginInfoCache.h:

Source/WebKit2/ChangeLog

@@ -1,3 +1,21 @@
+2014-08-25  Carlos Garcia Campos  <cgarcia@igalia.com>
+
+        [GTK] Older versions of WebKit should use the plugins cache in read only mode
+        https://bugs.webkit.org/show_bug.cgi?id=136215
+
+        Reviewed by Philippe Normand.
+
+        Now that WebKitGTK+ 2.4 and 2.5 are parallel installable, since
+        they use different versions of the plugins cache, apps using 2.4
+        might override the plugins cache file. We should prevent this from
+        happening by making older versions use the plugin cache, but not
+        downgrade it.
+
+        * UIProcess/Plugins/gtk/PluginInfoCache.cpp:
+        (WebKit::PluginInfoCache::PluginInfoCache):
+        (WebKit::PluginInfoCache::updatePluginInfo):
+        * UIProcess/Plugins/gtk/PluginInfoCache.h:
+
 2014-08-12  Carlos Garcia Campos  <cgarcia@igalia.com>
 
         [GTK] The plugins metadata cache doesn't work if the user cache directory doesn't exist

Source/WebKit2/UIProcess/Plugins/gtk/PluginInfoCache.cpp

@@ -46,6 +46,7 @@ PluginInfoCache& PluginInfoCache::shared()
 PluginInfoCache::PluginInfoCache()
     : m_cacheFile(g_key_file_new())
     , m_saveToFileIdleId(0)
+    , m_readOnlyMode(false)
 {
     GOwnPtr<char> cacheDirectory(g_build_filename(g_get_user_cache_dir(), "webkitgtk", nullptr));
     if (WebCore::makeAllDirectories(cacheDirectory.get())) {
@@ -55,11 +56,16 @@ PluginInfoCache::PluginInfoCache()
 
     if (g_key_file_has_group(m_cacheFile.get(), "schema")) {
         unsigned schemaVersion = static_cast<unsigned>(g_key_file_get_integer(m_cacheFile.get(), "schema", "version", nullptr));
-        if (schemaVersion == gSchemaVersion)
+        if (schemaVersion < gSchemaVersion) {
+            // Cache file using an old schema, create a new empty file.
+            m_cacheFile.set(g_key_file_new());
+        } else if (schemaVersion > gSchemaVersion) {
+            // Cache file using a newer schema, use the cache in read only mode.
+            m_readOnlyMode = true;
+        } else {
+            // Same schema version, we don't need to update it.
             return;
-
-        // Cache file using an old schema, create a new empty file.
-        m_cacheFile.set(g_key_file_new());
+        }
     }
 
     g_key_file_set_integer(m_cacheFile.get(), "schema", "version", static_cast<unsigned>(gSchemaVersion));
@@ -134,7 +140,7 @@ void PluginInfoCache::updatePluginInfo(const String& pluginPath, const PluginMod
     String mimeDescription = NetscapePluginModule::buildMIMEDescription(plugin.info.mimes);
     g_key_file_set_string(m_cacheFile.get(), pluginGroup.data(), "mime-description", mimeDescription.utf8().data());
 
-    if (m_cachePath) {
+    if (m_cachePath && !m_readOnlyMode) {
         // Save the cache file in an idle to make sure it happens in the main thread and
         // it's done only once when this is called multiple times in a very short time.
         std::lock_guard<std::mutex> lock(m_mutex);

Source/WebKit2/UIProcess/Plugins/gtk/PluginInfoCache.h

@@ -54,6 +54,7 @@ class PluginInfoCache {
     GOwnPtr<GKeyFile> m_cacheFile;
     GOwnPtr<char> m_cachePath;
     unsigned m_saveToFileIdleId;
+    bool m_readOnlyMode;
     std::mutex m_mutex;
 };