Cloning a bunch of stuff from the native_client repository at r6528

ppapi/native_client/src/shared/ppapi_proxy/plugin_resource_tracker.cc

+// Copyright (c) 2011 The Native Client Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "native_client/src/shared/ppapi_proxy/plugin_resource_tracker.h"
+
+#include <limits>
+#include <set>
+
+#include "native_client/src/include/nacl_macros.h"
+#include "native_client/src/include/portability.h"
+#include "native_client/src/shared/ppapi_proxy/plugin_globals.h"
+#include "native_client/src/shared/ppapi_proxy/plugin_resource.h"
+#include "native_client/src/shared/ppapi_proxy/untrusted/srpcgen/ppb_rpc.h"
+#include "ppapi/c/pp_resource.h"
+
+namespace ppapi_proxy {
+
+PluginResourceTracker::ResourceAndRefCounts::ResourceAndRefCounts(
+    PluginResource* r, size_t browser_count)
+    : resource(r), browser_refcount(browser_count), plugin_refcount(1) {
+}
+
+PluginResourceTracker::ResourceAndRefCounts::~ResourceAndRefCounts() {
+}
+
+scoped_refptr<PluginResource> PluginResourceTracker::GetExistingResource(
+    PP_Resource res) const {
+  ResourceMap::const_iterator result = live_resources_.find(res);
+  if (result == live_resources_.end())
+    return scoped_refptr<PluginResource>();
+  else
+    return result->second.resource;
+}
+
+PluginResourceTracker::PluginResourceTracker() {
+}
+
+void PluginResourceTracker::AddResource(PluginResource* resource,
+                                        PP_Resource id,
+                                        size_t browser_refcount) {
+  // Add the resource with plugin use-count 1.
+  live_resources_.insert(
+      std::make_pair(id, ResourceAndRefCounts(resource, browser_refcount)));
+}
+
+bool PluginResourceTracker::AddRefResource(PP_Resource res) {
+  ResourceMap::iterator i = live_resources_.find(res);
+  if (i == live_resources_.end()) {
+    return false;
+  } else {
+    // We don't protect against overflow, since a plugin as malicious as to ref
+    // once per every byte in the address space could have just as well unrefed
+    // one time too many.
+    i->second.plugin_refcount++;
+    if (i->second.browser_refcount == 0) {
+      // If we don't currently have any refcount with the browser, try to
+      // obtain one.
+      i->second.browser_refcount++;
+      ObtainBrowserResource(res);
+    }
+    return true;
+  }
+}
+
+bool PluginResourceTracker::UnrefResource(PP_Resource res) {
+  ResourceMap::iterator i = live_resources_.find(res);
+  if (i != live_resources_.end()) {
+    i->second.plugin_refcount--;
+    if (0 == i->second.plugin_refcount) {
+      size_t browser_refcount = i->second.browser_refcount;
+      live_resources_.erase(i);
+
+      // Release all browser references.
+      ReleaseBrowserResource(res, browser_refcount);
+    }
+    return true;
+  } else {
+    return false;
+  }
+}
+
+void PluginResourceTracker::ObtainBrowserResource(PP_Resource res) {
+  if (res) {
+    NaClSrpcChannel* channel = ppapi_proxy::GetMainSrpcChannel();
+    PpbCoreRpcClient::PPB_Core_AddRefResource(channel, res);
+  }
+}
+
+void PluginResourceTracker::ReleaseBrowserResource(PP_Resource res,
+                                                   size_t browser_refcount) {
+  // Release all browser references.
+  if (res && (browser_refcount > 0)) {
+    NaClSrpcChannel* channel = ppapi_proxy::GetMainSrpcChannel();
+    PpbCoreRpcClient::ReleaseResourceMultipleTimes(channel, res,
+                                                   browser_refcount);
+  }
+}
+
+}  // namespace ppapi_proxy
+