Revert "Move mojo edk into mojo/edk"

mojo/edk/system/transport_data.h

-// Copyright 2014 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 MOJO_EDK_SYSTEM_TRANSPORT_DATA_H_
-#define MOJO_EDK_SYSTEM_TRANSPORT_DATA_H_
-
-#include <stdint.h>
-
-#include <vector>
-
-#include "base/macros.h"
-#include "base/memory/aligned_memory.h"
-#include "base/memory/scoped_ptr.h"
-#include "build/build_config.h"
-#include "mojo/edk/embedder/platform_handle.h"
-#include "mojo/edk/embedder/platform_handle_vector.h"
-#include "mojo/edk/system/dispatcher.h"
-#include "mojo/edk/system/system_impl_export.h"
-
-namespace mojo {
-namespace system {
-
-class Channel;
-
-// This class is used by |MessageInTransit| to represent handles (|Dispatcher|s)
-// in various stages of serialization.
-//
-// The stages are:
-//   - Before reaching |TransportData|: Turn |DispatcherTransport|s into
-//     |Dispatcher|s that are "owned" by (and attached to) a |MessageInTransit|.
-//     This invalidates the handles in the space of the sending application
-//     (and, e.g., if another thread is waiting on such a handle, it'll be
-//     notified of this invalidation).
-//   - Serialize these dispatchers into the |TransportData|: First, for each
-//     attached dispatcher, there's an entry in the |TransportData|'s "handle
-//     table", which points to a segment of (dispatcher-type-dependent) data.
-//   - During the serialization of the dispatchers, |PlatformHandle|s may be
-//     detached from the dispatchers and attached to the |TransportData|.
-//   - Before sending the |MessageInTransit|, including its main buffer and the
-//     |TransportData|'s buffer, the |Channel| sends any |PlatformHandle|s (in a
-//     platform-, and possibly sandbox-situation-, specific way) first. In doing
-//     so, it appends a "platform handle table" to the |TransportData|
-//     containing information about how to deserialize these |PlatformHandle|s.
-//   - Finally, at this point, to send the |MessageInTransit|, there only
-//     remains "inert" data: the |MessageInTransit|'s main buffer and data from
-//     the |TransportData|, consisting of the "handle table" (one entry for each
-//     attached dispatcher), dispatcher-type-specific data (one segment for each
-//     entry in the "handle table"), and the "platform handle table" (one entry
-//     for each attached |PlatformHandle|).
-//
-// To receive a message (|MessageInTransit|), the "reverse" happens:
-//   - On POSIX, receive and buffer |PlatformHandle|s (i.e., FDs), which were
-//     sent before the "inert" data.
-//   - Receive the "inert" data from the |MessageInTransit|. Examine its
-//     "platform handle table". On POSIX, match its entries with the buffered
-//     |PlatformHandle|s, which were previously received. On Windows, do what's
-//     necessary to obtain |PlatformHandle|s (e.g.: i. if the sender is fully
-//     trusted and able to duplicate handle into the receiver, then just pick
-//     out the |HANDLE| value; ii. if the receiver is fully trusted and able to
-//     duplicate handles from the receiver, do the |DuplicateHandle()|; iii.
-//     otherwise, talk to a broker to get handles). Reattach all the
-//     |PlatformHandle|s to the |MessageInTransit|.
-//   - For each entry in the "handle table", use serialized dispatcher data to
-//     reconstitute a dispatcher, taking ownership of associated
-//     |PlatformHandle|s (and detaching them). Attach these dispatchers to the
-//     |MessageInTransit|.
-//   - At this point, the |MessageInTransit| consists of its main buffer
-//     (primarily the data payload) and the attached dispatchers; the
-//     |TransportData| can be discarded.
-//   - When |MojoReadMessage()| is to give data to the application, attach the
-//     dispatchers to the (global, "core") handle table, getting handles; give
-//     the application the data payload and these handles.
-//
-// TODO(vtl): Everything above involving |PlatformHandle|s.
-class MOJO_SYSTEM_IMPL_EXPORT TransportData {
- public:
-  // The maximum size of a single serialized dispatcher. This must be a multiple
-  // of |kMessageAlignment|.
-  static const size_t kMaxSerializedDispatcherSize = 10000;
-
-  // The maximum number of platform handles to attach for a single serialized
-  // dispatcher.
-  static const size_t kMaxSerializedDispatcherPlatformHandles = 2;
-
-  // The maximum possible size of a valid transport data buffer.
-  static const size_t kMaxBufferSize;
-
-  // The maximum total number of platform handles that may be attached.
-  static const size_t kMaxPlatformHandles;
-
-  TransportData(scoped_ptr<DispatcherVector> dispatchers, Channel* channel);
-
-#if defined(OS_POSIX)
-  // This is a hacky POSIX-only constructor to directly attach only platform
-  // handles to a message, used by |RawChannelPosix| to split messages with too
-  // many platform handles into multiple messages. |Header| will be present, but
-  // be zero. (No other information will be attached, and
-  // |RawChannel::GetSerializedPlatformHandleSize()| should return zero.)
-  explicit TransportData(
-      embedder::ScopedPlatformHandleVectorPtr platform_handles);
-#endif
-
-  ~TransportData();
-
-  const void* buffer() const { return buffer_.get(); }
-  void* buffer() { return buffer_.get(); }
-  size_t buffer_size() const { return buffer_size_; }
-
-  uint32_t platform_handle_table_offset() const {
-    return header()->platform_handle_table_offset;
-  }
-
-  // Gets attached platform-specific handles; this may return null if there are
-  // none. Note that the caller may mutate the set of platform-specific handles.
-  const embedder::PlatformHandleVector* platform_handles() const {
-    return platform_handles_.get();
-  }
-  embedder::PlatformHandleVector* platform_handles() {
-    return platform_handles_.get();
-  }
-
-  // Receive-side functions:
-
-  // Checks if the given buffer (from the "wire") looks like a valid
-  // |TransportData| buffer. (Should only be called if |buffer_size| is
-  // nonzero.) Returns null if valid, and a pointer to a human-readable error
-  // message (for debug/logging purposes) on error. Note: This checks the
-  // validity of the handle table entries (i.e., does range checking), but does
-  // not check that the validity of the actual serialized dispatcher
-  // information.
-  static const char* ValidateBuffer(size_t serialized_platform_handle_size,
-                                    const void* buffer,
-                                    size_t buffer_size);
-
-  // Gets the platform handle table from a (valid) |TransportData| buffer (which
-  // should have been validated using |ValidateBuffer()| first).
-  static void GetPlatformHandleTable(const void* transport_data_buffer,
-                                     size_t* num_platform_handles,
-                                     const void** platform_handle_table);
-
-  // Deserializes dispatchers from the given (serialized) transport data buffer
-  // (typically from a |MessageInTransit::View|) and vector of platform handles.
-  // |buffer| should be non-null and |buffer_size| should be nonzero.
-  static scoped_ptr<DispatcherVector> DeserializeDispatchers(
-      const void* buffer,
-      size_t buffer_size,
-      embedder::ScopedPlatformHandleVectorPtr platform_handles,
-      Channel* channel);
-
- private:
-  // To allow us to make compile-assertions about |Header|, etc. in the .cc
-  // file.
-  struct PrivateStructForCompileAsserts;
-
-  // Header for the "secondary buffer"/"transport data". Must be a multiple of
-  // |MessageInTransit::kMessageAlignment| in size. Must be POD.
-  struct Header {
-    uint32_t num_handles;
-    // TODO(vtl): Not used yet:
-    uint32_t platform_handle_table_offset;
-    uint32_t num_platform_handles;
-    uint32_t unused;
-  };
-
-  struct HandleTableEntry {
-    int32_t type;     // From |Dispatcher::Type| (|kTypeUnknown| for "invalid").
-    uint32_t offset;  // Relative to the start of the "secondary buffer".
-    uint32_t size;    // (Not including any padding.)
-    uint32_t unused;
-  };
-
-  const Header* header() const {
-    return reinterpret_cast<const Header*>(buffer_.get());
-  }
-
-  size_t buffer_size_;
-  scoped_ptr<char, base::AlignedFreeDeleter> buffer_;  // Never null.
-
-  // Any platform-specific handles attached to this message (for inter-process
-  // transport). The vector (if any) owns the handles that it contains (and is
-  // responsible for closing them).
-  // TODO(vtl): With C++11, change it to a vector of |ScopedPlatformHandles|.
-  embedder::ScopedPlatformHandleVectorPtr platform_handles_;
-
-  DISALLOW_COPY_AND_ASSIGN(TransportData);
-};
-
-}  // namespace system
-}  // namespace mojo
-
-#endif  // MOJO_EDK_SYSTEM_TRANSPORT_DATA_H_