Add defensive code in pickle to preclude realloc of shared header_ memory....

base/pickle.cc

Index: base/pickle.cc
===================================================================
--- base/pickle.cc	(revision 22260)
+++ base/pickle.cc	(working copy)
@@ -65,12 +65,16 @@
 }
 
 Pickle& Pickle::operator=(const Pickle& other) {

[cpu_(ooo_6.6-7.5), 2009/08/03 16:18:57]

this operator is lacking a check against self assignment.

[jar (doing other things), 2009/08/03 20:11:22]

I'll create a CL that handles this explicitly.

-  if (header_size_ != other.header_size_ && capacity_ != kCapacityReadOnly) {
+  if (capacity_ == kCapacityReadOnly) {
+    header_ = NULL;
+    capacity_ = 0;
+  }
+  if (header_size_ != other.header_size_) {
     free(header_);
     header_ = NULL;
     header_size_ = other.header_size_;
   }
-  bool resized = Resize(other.header_size_ + other.header_->payload_size);
+  bool resized = Resize(header_size_ + other.header_->payload_size);

[cpu_(ooo_6.6-7.5), 2009/08/03 16:18:57]

I don't get the change in line 73. It seems more clear the previous version.
What about changing line 79 so the two match?

[jar (doing other things), 2009/08/03 20:11:22]

The goal was to have the argument of the memcpy (two lines from now) have
EXACTLY the same size argument as we have in the resize (which was not the case
before). 

It can be deduced from the last 4 lines that they have to be the same, but it
seemed better to use the same text in both users (resize and memcpy).

If you'd rather I use the longer one in both cases, I can do that.  I'll add it
to the CL containing more defensive code for the self-assignment.

   CHECK(resized);  // Realloc failed.
   memcpy(header_, other.header_, header_size_ + other.header_->payload_size);
   variable_buffer_offset_ = other.variable_buffer_offset_;
@@ -365,6 +369,7 @@
 bool Pickle::Resize(size_t new_capacity) {
   new_capacity = AlignInt(new_capacity, kPayloadUnit);
 
+  CHECK(capacity_ != kCapacityReadOnly);
   void* p = realloc(header_, new_capacity);
   if (!p)
     return false;