net: Change type of UploadData::elements from std::vector to ScopedVector

ipc/ipc_message_utils.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 IPC_IPC_MESSAGE_UTILS_H_
 #define IPC_IPC_MESSAGE_UTILS_H_
 
 #include <algorithm>
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/format_macros.h"
+#include "base/memory/scoped_vector.h"
 #include "base/platform_file.h"
 #include "base/string16.h"
 #include "base/stringprintf.h"
 #include "base/string_util.h"
 #include "base/tuple.h"
 #include "ipc/ipc_message_start.h"
 #include "ipc/ipc_param_traits.h"
 #include "ipc/ipc_sync_message.h"
 
 #if defined(COMPILER_GCC)
@@ skipping 601 matching lines @@
     LogParam(p.b, l);
     l->append(", ");
     LogParam(p.c, l);
     l->append(", ");
     LogParam(p.d, l);
     l->append(", ");
     LogParam(p.e, l);
   }
 };
 
+template<class P>
+struct ParamTraits<ScopedVector<P> > {
+  typedef ScopedVector<P> param_type;
+  static void Write(Message* m, const param_type& p) {
+    WriteParam(m, static_cast<int>(p.size()));
+    for (size_t i = 0; i < p.size(); i++)
+      WriteParam(m, *p[i]);
+  }
+  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
+    int size = 0;
+    if (!m->ReadLength(iter, &size))
+      return false;
+    for (int i = 0; i < size; i++) {

[jam, 2012/11/12 20:58:54]

you should do error checking just like std::vector does, i.e. the
 if (INT_MAX / sizeof(P) <= static_cast<size_t>(size))
 322       return false;	 323       return false;

[hashimoto, 2012/11/13 05:03:51]

What is still unclear for me is that do we need to replace "sizeof(P)" here with
"sizeof(P*)" or not.
Since ScopedVector<P> is virtually a std::vector<P*>, perhaps INT_MAX/sizeof(P*)
might make more sense.

INT_MAX/sizeof(P) may work better in some cases if we want to avoid consuming
memory more than INT_MAX bytes (=2GB), but it does not work for some cases
including net::UploadElement because net::UploadElement has a std::vector as its
member and sizeof(std::vector<P>) is constant (i.e. sizeof(std::vector) cannot
know how much heap does the vector consume)
It means "INT_MAX > size*sizeof(P)" cannot guarantee that the total memory
consumed by the deserialized ScopedVector<P> not exceeding INT_MAX bytes when P
holds data on heap.

Anyways, I leave INT_MAX/sizeof(P) here for now.

+      r->push_back(new P());
+      if (!ReadParam(m, iter, r->back()))
+        return false;
+    }
+    return true;
+  }
+  static void Log(const param_type& p, std::string* l) {
+    for (size_t i = 0; i < p.size(); ++i) {
+      if (i != 0)
+        l->append(" ");
+      LogParam(*p[i], l);
+    }
+  }
+};
+
 // IPC types ParamTraits -------------------------------------------------------
 
 // A ChannelHandle is basically a platform-inspecific wrapper around the
 // fact that IPC endpoints are handled specially on POSIX.  See above comments
 // on FileDescriptor for more background.
 template<>
 struct IPC_EXPORT ParamTraits<IPC::ChannelHandle> {
   typedef ChannelHandle param_type;
   static void Write(Message* m, const param_type& p);
   static bool Read(const Message* m, PickleIterator* iter, param_type* r);
@@ skipping 195 matching lines @@
   template<typename TA, typename TB, typename TC, typename TD, typename TE>
   static void WriteReplyParams(Message* reply, TA a, TB b, TC c, TD d, TE e) {
     ReplyParam p(a, b, c, d, e);
     WriteParam(reply, p);
   }
 };
 
 }  // namespace IPC
 
 #endif  // IPC_IPC_MESSAGE_UTILS_H_