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- // Copyright (c) 2012 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #ifndef IPC_IPC_CHANNEL_READER_H_
- #define IPC_IPC_CHANNEL_READER_H_
- #include <stddef.h>
- #include <set>
- #include "base/component_export.h"
- #include "base/gtest_prod_util.h"
- #include "base/memory/raw_ptr.h"
- #include "ipc/ipc_channel.h"
- namespace IPC {
- namespace internal {
- // This class provides common pipe reading functionality for the
- // platform-specific IPC channel implementations.
- //
- // It does the common input buffer management and message dispatch, while the
- // platform-specific parts provide the pipe management through a virtual
- // interface implemented on a per-platform basis.
- //
- // Note that there is no "writer" corresponding to this because the code for
- // writing to the channel is much simpler and has very little common
- // functionality that would benefit from being factored out. If we add
- // something like that in the future, it would be more appropriate to add it
- // here (and rename appropriately) rather than writing a different class.
- class COMPONENT_EXPORT(IPC) ChannelReader {
- public:
- explicit ChannelReader(Listener* listener);
- ChannelReader(const ChannelReader&) = delete;
- ChannelReader& operator=(const ChannelReader&) = delete;
- virtual ~ChannelReader();
- void set_listener(Listener* listener) { listener_ = listener; }
- // This type is returned by ProcessIncomingMessages to indicate the effect of
- // the method.
- enum DispatchState {
- // All messages were successfully dispatched, or there were no messages to
- // dispatch.
- DISPATCH_FINISHED,
- // There was a channel error.
- DISPATCH_ERROR,
- // Dispatching messages is blocked on receiving more information from the
- // broker.
- DISPATCH_WAITING_ON_BROKER,
- };
- // Call to process messages received from the IPC connection and dispatch
- // them.
- DispatchState ProcessIncomingMessages();
- // Handles asynchronously read data.
- //
- // Optionally call this after returning READ_PENDING from ReadData to
- // indicate that buffer was filled with the given number of bytes of
- // data. See ReadData for more.
- DispatchState AsyncReadComplete(int bytes_read);
- // Returns true if the given message is internal to the IPC implementation,
- // like the "hello" message sent on channel set-up.
- bool IsInternalMessage(const Message& m);
- // Returns true if the given message is an Hello message
- // sent on channel set-up.
- bool IsHelloMessage(const Message& m);
- protected:
- enum ReadState { READ_SUCCEEDED, READ_FAILED, READ_PENDING };
- Listener* listener() const { return listener_; }
- // Subclasses should call this method in their destructor to give this class a
- // chance to clean up state that might be dependent on subclass members.
- void CleanUp();
- // Populates the given buffer with data from the pipe.
- //
- // Returns the state of the read. On READ_SUCCESS, the number of bytes
- // read will be placed into |*bytes_read| (which can be less than the
- // buffer size). On READ_FAILED, the channel will be closed.
- //
- // If the return value is READ_PENDING, it means that there was no data
- // ready for reading. The implementation is then responsible for either
- // calling AsyncReadComplete with the number of bytes read into the
- // buffer, or ProcessIncomingMessages to try the read again (depending
- // on whether the platform's async I/O is "try again" or "write
- // asynchronously into your buffer").
- virtual ReadState ReadData(char* buffer, int buffer_len, int* bytes_read) = 0;
- // Loads the required file desciptors into the given message. Returns true
- // on success. False means a fatal channel error.
- //
- // This will read from the input_fds_ and read more handles from the FD
- // pipe if necessary.
- virtual bool ShouldDispatchInputMessage(Message* msg) = 0;
- // Overridden by subclasses to get attachments that are sent alongside the IPC
- // channel.
- // Returns true on success. False means a fatal channel error.
- virtual bool GetAttachments(Message* msg) = 0;
- // Performs post-dispatch checks. Called when all input buffers are empty,
- // though there could be more data ready to be read from the OS.
- virtual bool DidEmptyInputBuffers() = 0;
- // Handles internal messages, like the hello message sent on channel startup.
- virtual void HandleInternalMessage(const Message& msg) = 0;
- // Exposed for testing purposes only.
- virtual void DispatchMessage(Message* m);
- private:
- FRIEND_TEST_ALL_PREFIXES(ChannelReaderTest, AttachmentAlreadyBrokered);
- FRIEND_TEST_ALL_PREFIXES(ChannelReaderTest, AttachmentNotYetBrokered);
- FRIEND_TEST_ALL_PREFIXES(ChannelReaderTest, ResizeOverflowBuffer);
- FRIEND_TEST_ALL_PREFIXES(ChannelReaderTest, InvalidMessageSize);
- FRIEND_TEST_ALL_PREFIXES(ChannelReaderTest, TrimBuffer);
- // Takes the data received from the IPC channel and translates it into
- // Messages. Complete messages are passed to HandleTranslatedMessage().
- // Returns |false| on unrecoverable error.
- bool TranslateInputData(const char* input_data, int input_data_len);
- // Internal messages and messages bound for the attachment broker are
- // immediately dispatched. Other messages are passed to
- // HandleExternalMessage().
- // Returns |false| on unrecoverable error.
- bool HandleTranslatedMessage(Message* translated_message);
- // Populates the message with brokered and non-brokered attachments. If
- // possible, the message is immediately dispatched. Otherwise, a deep copy of
- // the message is added to |queued_messages_|. |blocked_ids_| are updated if
- // necessary.
- bool HandleExternalMessage(Message* external_message);
- // If there was a dispatch error, informs |listener_|.
- void HandleDispatchError(const Message& message);
- // Checks that |size| is a valid message size. Has side effects if it's not.
- bool CheckMessageSize(size_t size);
- raw_ptr<Listener> listener_;
- // We read from the pipe into this buffer. Managed by DispatchInputData, do
- // not access directly outside that function.
- char input_buf_[Channel::kReadBufferSize];
- // Large messages that span multiple pipe buffers, get built-up using
- // this buffer.
- std::string input_overflow_buf_;
- // Maximum overflow buffer size, see Channel::kMaximumReadBufferSize.
- // This is not a constant because we update it to reflect the reality
- // of std::string::reserve() implementation.
- size_t max_input_buffer_size_;
- };
- } // namespace internal
- } // namespace IPC
- #endif // IPC_IPC_CHANNEL_READER_H_
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