Mojo: (Theoretically) implement the read side of platform handle passing.

mojo/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_SYSTEM_TRANSPORT_DATA_H_
 #define MOJO_SYSTEM_TRANSPORT_DATA_H_
 
 #include <stdint.h>
 
 #include <vector>
@@ skipping 61 matching lines @@
 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);
   ~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 std::vector<embedder::PlatformHandle>* platform_handles() const {
     return platform_handles_.get();
   }
   std::vector<embedder::PlatformHandle>* 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(const void* buffer, size_t buffer_size);
+  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|). |buffer| should be non-null
   // and |buffer_size| should be nonzero.
   static scoped_ptr<DispatcherVector> DeserializeDispatchersFromBuffer(
       const void* buffer,
       size_t buffer_size,
       Channel* channel);
 
  private:
@@ skipping 11 matching lines @@
     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;
   };
 
-  // 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;
-
   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|.
   scoped_ptr<std::vector<embedder::PlatformHandle> > platform_handles_;
 
   DISALLOW_COPY_AND_ASSIGN(TransportData);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_SYSTEM_TRANSPORT_DATA_H_