Add short circuit case for self assignment, and add virtual destructor

Pickle is a base class of Message, which has a virtual destructor, so
it is better to have Pickle have a virtual destructor as well.

Add more defensive code in the case of self assignment.
**IF** self assignment was used, and the target was read-only,
then the existing code would have a memory fault.
I don't think this is currently possible in use cases, but
the defensize code is much better. (per suggestion from CPU
on last CL).

BUG=17027
BUG=17088
r=cpu
Review URL: http://codereview.chromium.org/159800

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@22826 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 8 insertions, 3 deletions

diff --git a/base/pickle.cc b/base/pickle.cc
index 31bf5b7..0be89c2 100644
--- a/base/pickle.cc
+++ b/base/pickle.cc
@@ -65,6 +65,10 @@ Pickle::~Pickle() {
 }
 
 Pickle& Pickle::operator=(const Pickle& other) {
+  if (this == &other) {
+    NOTREACHED();
+    return *this;
+  }
   if (capacity_ == kCapacityReadOnly) {
     header_ = NULL;
     capacity_ = 0;
@@ -74,9 +78,10 @@ Pickle& Pickle::operator=(const Pickle& other) {
     header_ = NULL;
     header_size_ = other.header_size_;
   }
-  bool resized = Resize(header_size_ + other.header_->payload_size);
+  bool resized = Resize(other.header_size_ + other.header_->payload_size);
   CHECK(resized);  // Realloc failed.
-  memcpy(header_, other.header_, header_size_ + other.header_->payload_size);
+  memcpy(header_, other.header_,
+         other.header_size_ + other.header_->payload_size);
   variable_buffer_offset_ = other.variable_buffer_offset_;
   return *this;
 }
diff --git a/base/pickle.h b/base/pickle.h
index 5b70729..9760483 100644
--- a/base/pickle.h
+++ b/base/pickle.h
@@ -31,7 +31,7 @@
 //
 class Pickle {
  public:
-  ~Pickle();
+  virtual ~Pickle();
 
   // Initialize a Pickle object using the default header size.
   Pickle();