Add support for Flash Player Component updates on Linux

chrome/common/chrome_content_client.cc

Index: chrome/common/chrome_content_client.cc
diff --git a/chrome/common/chrome_content_client.cc b/chrome/common/chrome_content_client.cc
index 57a0b4fb552457cea54628742084625a63c94616..26b979f9f92d9bafebb91c90ef342953a1796900 100644
--- a/chrome/common/chrome_content_client.cc
+++ b/chrome/common/chrome_content_client.cc
@@ -4,6 +4,8 @@
 
 #include "chrome/common/chrome_content_client.h"
 
+#include <fcntl.h>
+
 #include "base/command_line.h"
 #include "base/debug/crash_logging.h"
 #include "base/files/file_util.h"
@@ -21,6 +23,7 @@
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/chrome_version_info.h"
+#include "chrome/common/component_flash_hint_file.h"
 #include "chrome/common/crash_keys.h"
 #include "chrome/common/pepper_flash.h"
 #include "chrome/common/secure_origin_whitelist.h"
@@ -31,6 +34,7 @@
 #include "content/public/common/content_switches.h"
 #include "content/public/common/url_constants.h"
 #include "content/public/common/user_agent.h"
+#include "crypto/sha2.h"
 #include "extensions/common/constants.h"
 #include "gpu/config/gpu_info.h"
 #include "net/http/http_util.h"
@@ -281,6 +285,43 @@ void AddPepperFlashFromCommandLine(
       CreatePepperFlashInfo(base::FilePath(flash_path), flash_version));
 }
 
+#if defined(OS_LINUX)
+bool IsUserDataDirAvailable() {
+  base::FilePath user_data_dir;
+  if (!PathService::Get(chrome::DIR_USER_DATA, &user_data_dir))
+    return false;
+  return base::PathExists(user_data_dir);
+}
+#endif  // defined(OS_LINUX)
+
+// This method is used on Linux only because of architectural differences in how
+// it loads the component updated flash plugin, and not because the other
+// platforms do not support component updated flash. On other platforms, the
+// component updater sends an IPC message to all threads, at undefined points in
+// time, with the URL of the component updated flash. Because the linux zygote
+// thread has no access to the file system after it warms up, it must preload
+// the component updated flash.
+#if defined(OS_LINUX)
+bool GetComponentUpdatedPepperFlash(content::PepperPluginInfo* plugin) {
+#if defined(FLAPPER_AVAILABLE)
+  base::FilePath flash_path;
+  std::string version;
+  if (chrome::ComponentFlashHintFile::DoesHintFileExist()) {
+    bool verified =
+        chrome::ComponentFlashHintFile::VerifyAndReturnFlashLocation(
+            &flash_path, &version);
+    if (verified) {
+      *plugin = CreatePepperFlashInfo(flash_path, version);
+      return true;

[rickyz (no longer on Chrome), 2015/07/31 00:13:56]

Is there any handling for when DIR_USER_DATA is on a filesystem mounted noexec?
Luckily, we're unsandboxed here, so we can test for this by attempting to mmap a
page PROT_READ | PROT_EXEC.

[Greg K, 2015/08/04 00:21:17]

Done.

+    }
+  }
+  return false;
+#else
+  return false;
+#endif  // defined(FLAPPER_AVAILABLE)
+}
+#endif  // defined(OS_LINUX)
+
 bool GetBundledPepperFlash(content::PepperPluginInfo* plugin) {
 #if defined(FLAPPER_AVAILABLE)
   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
@@ -465,11 +506,41 @@ void ChromeContentClient::AddPepperPlugins(
   ComputeBuiltInPlugins(plugins);
   AddPepperFlashFromCommandLine(plugins);
 
-  content::PepperPluginInfo plugin;
-  if (GetBundledPepperFlash(&plugin))
-    plugins->push_back(plugin);
-  if (GetSystemPepperFlash(&plugin))
-    plugins->push_back(plugin);
+#if defined(OS_LINUX)
+  // Depending on the sandbox configurtion, the user data directory
+  // is not always available. If it is not available, do not try and load and
+  // flash plugin. It may incorrectly try to load the system flash plugin in
+  // this case.
+  if (!IsUserDataDirAvailable()) {
+    return;
+  }
+#endif
+
+  std::vector<content::PepperPluginInfo*> flash_versions;
+
+#if defined(OS_LINUX)
+  content::PepperPluginInfo component_flash;
+  if (GetComponentUpdatedPepperFlash(&component_flash))
+    flash_versions.push_back(&component_flash);
+#endif
+
+  content::PepperPluginInfo bundled_flash;
+  if (GetBundledPepperFlash(&bundled_flash))
+    flash_versions.push_back(&bundled_flash);
+
+  content::PepperPluginInfo system_flash;
+  if (GetSystemPepperFlash(&system_flash))
+    flash_versions.push_back(&system_flash);
+
+  // Now sort the list and add the most recent flash plugin to the plugins list.
+  std::sort(flash_versions.begin(), flash_versions.end(),
+            [](content::PepperPluginInfo* x, content::PepperPluginInfo* y) {
+              Version version_x(x->version);
+              DCHECK(version_x.IsValid());
+              return version_x.IsOlderThan(y->version);
+            });
+  // Use the last element in the list, which will be the most recent flash.
+  plugins->push_back(*flash_versions.back());
 #endif
 }