Cloning a bunch of stuff from the native_client repository at r6528

ppapi/native_client/src/shared/ppapi_proxy/plugin_callback.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_callback.h"
+#include <string.h>
+#include "native_client/src/shared/ppapi_proxy/utility.h"
+#include "ppapi/c/pp_errors.h"
+#include "srpcgen/ppp_rpc.h"
+
+namespace ppapi_proxy {
+
+int32_t MayForceCallback(PP_CompletionCallback callback, int32_t result) {
+  if (result == PP_OK_COMPLETIONPENDING)
+    return result;
+
+  if (callback.func == NULL ||
+      (callback.flags & PP_COMPLETIONCALLBACK_FLAG_OPTIONAL) != 0)
+    return result;
+
+  PPBCoreInterface()->CallOnMainThread(0, callback, result);
+  return PP_OK_COMPLETIONPENDING;
+}
+
+// Initialize static mutex used as critical section for all callback tables.
+pthread_mutex_t CompletionCallbackTable::mutex_ = PTHREAD_MUTEX_INITIALIZER;
+
+int32_t CompletionCallbackTable::AddCallback(
+    const PP_CompletionCallback& callback,
+    void* read_buffer) {
+  CallbackTableCriticalSection guard;
+  if (callback.func == NULL) {
+    DebugPrintf("CompletionCallbackTable attempted to add NULL func!!\n");
+    return 0;
+  }
+  int32_t callback_id = next_id_;
+  ++next_id_;
+  CallbackInfo info = { callback, read_buffer };
+  table_.insert(std::pair<int32_t, CallbackInfo>(callback_id, info));
+  return callback_id;
+}
+
+int32_t CompletionCallbackTable::AddCallback(
+    const PP_CompletionCallback& callback) {
+  return AddCallback(callback, NULL);
+}
+
+PP_CompletionCallback CompletionCallbackTable::RemoveCallback(
+    int32_t callback_id, void** read_buffer) {
+  CallbackTableCriticalSection guard;
+  CallbackTable::iterator it = table_.find(callback_id);
+  DebugPrintf("CompletionCallbackTable::RemoveCallback id: %"NACL_PRId32"\n",
+      callback_id);
+  if (table_.end() != it) {
+    CallbackInfo info = it->second;
+    table_.erase(it);
+    if (read_buffer != NULL)
+      *read_buffer = info.read_buffer;
+    return info.callback;
+  }
+  *read_buffer = NULL;
+  return PP_BlockUntilComplete();
+}
+
+}  // namespace ppapi_proxy
+
+// SRPC-abstraction wrapper around a PP_CompletionCallback.
+void CompletionCallbackRpcServer::RunCompletionCallback(
+    NaClSrpcRpc* rpc,
+    NaClSrpcClosure* done,
+    // inputs
+    int32_t callback_id,
+    int32_t result,
+    // TODO(polina): use shm for read buffer
+    nacl_abi_size_t read_buffer_size, char* read_buffer) {
+  NaClSrpcClosureRunner runner(done);
+  rpc->result = NACL_SRPC_RESULT_APP_ERROR;
+
+  void* user_buffer;
+  PP_CompletionCallback callback =
+      ppapi_proxy::CompletionCallbackTable::Get()->RemoveCallback(
+          callback_id, &user_buffer);
+  if (callback.func == NULL) {
+    ppapi_proxy::DebugPrintf(
+        "CompletionCallbackRpcServer: id of %"NACL_PRId32" is NULL callback!\n",
+        callback_id);
+    return;
+  }
+
+  if (user_buffer != NULL && read_buffer_size > 0)
+    memcpy(user_buffer, read_buffer, read_buffer_size);
+  PP_RunCompletionCallback(&callback, result);
+
+  rpc->result = NACL_SRPC_RESULT_OK;
+}