IPC::Message -> base::Pickle

base/pickle.h

 // 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 BASE_PICKLE_H_
 #define BASE_PICKLE_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <string>
 
 #include "base/base_export.h"
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/logging.h"
+#include "base/memory/ref_counted.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_piece.h"
 
 namespace base {
 
 class Pickle;
 
 // PickleIterator reads data from a Pickle. The Pickle object must remain valid
 // while the PickleIterator object is in use.
 class BASE_EXPORT PickleIterator {
@@ skipping 89 matching lines @@
 // what value types to read and in what order to read them as the Pickle does
 // not keep track of the type of data written to it.
 //
 // The Pickle's data has a header which contains the size of the Pickle's
 // payload.  It can optionally support additional space in the header.  That
 // space is controlled by the header_size parameter passed to the Pickle
 // constructor.
 //
 class BASE_EXPORT Pickle {
  public:
+  // A base attachment type for a Pickle subclass to implement if it supports
+  // reading and writing attachments.
+  class BASE_EXPORT Attachment : public RefCountedThreadSafe<Attachment> {
+   public:
+    Attachment();
+
+   protected:
+    friend class RefCountedThreadSafe<Attachment>;
+    virtual ~Attachment();
+
+    DISALLOW_COPY_AND_ASSIGN(Attachment);
+  };
+
   // Initialize a Pickle object using the default header size.
   Pickle();
 
   // Initialize a Pickle object with the specified header size in bytes, which
   // must be greater-than-or-equal-to sizeof(Pickle::Header).  The header size
   // will be rounded up to ensure that the header size is 32bit-aligned.
   explicit Pickle(int header_size);
 
   // Initializes a Pickle from a const block of data.  The data is not copied;
   // instead the data is merely referenced by this Pickle.  Only const methods
@@ skipping 63 matching lines @@
   bool WriteString(const StringPiece& value);
   bool WriteString16(const StringPiece16& value);
   // "Data" is a blob with a length. When you read it out you will be given the
   // length. See also WriteBytes.
   bool WriteData(const char* data, int length);
   // "Bytes" is a blob with no length. The caller must specify the length both
   // when reading and writing. It is normally used to serialize PoD types of a
   // known size. See also WriteData.
   bool WriteBytes(const void* data, int length);
 
+  // WriteAttachment appends |attachment| to the pickle. It returns
+  // false iff the set is full.
+  //
+  // NOTE: It is NOT OK to call this or ReadAttachment() on a simple

[Tom Sepez, 2016/02/02 19:25:55]

It feels wrong to design a virtual API that requires knowing the concrete type
of the underlying class to avoid a NOTREACHED().  I'd be happier if we returned
false in that case and that false means the set is full or the pickle doesn't
support attachments.

+  // base::Pickle. These must be implemented and called only on subclasses that
+  // support attachments.
+  virtual bool WriteAttachment(scoped_refptr<Attachment> attachment);
+
+  // ReadAttachment parses an attachment given the parsing state |iter| and
+  // writes it to |*attachment|. It returns true on success.
+  //
+  // NOTE: It is NOT OK to call this or WriteAttachment() on a simple
+  // base::Pickle. These must be implemented and called only subclasses that
+  // support attachments.
+  virtual bool ReadAttachment(base::PickleIterator* iter,
+                              scoped_refptr<Attachment>* attachment) const;
+
   // Reserves space for upcoming writes when multiple writes will be made and
   // their sizes are computed in advance. It can be significantly faster to call
   // Reserve() before calling WriteFoo() multiple times.
   void Reserve(size_t additional_capacity);
 
   // Payload follows after allocation of Header (header size is customizable).
   struct Header {
     uint32_t payload_size;  // Specifies the size of the payload.
   };
 
@@ skipping 97 matching lines @@
   FRIEND_TEST_ALL_PREFIXES(PickleTest, PeekNext);
   FRIEND_TEST_ALL_PREFIXES(PickleTest, PeekNextOverflow);
   FRIEND_TEST_ALL_PREFIXES(PickleTest, FindNext);
   FRIEND_TEST_ALL_PREFIXES(PickleTest, FindNextWithIncompleteHeader);
   FRIEND_TEST_ALL_PREFIXES(PickleTest, FindNextOverflow);
 };
 
 }  // namespace base
 
 #endif  // BASE_PICKLE_H_