1 files changed, 98 insertions, 0 deletions
diff --git a/mojo/public/bindings/lib/scratch_buffer.cc b/mojo/public/bindings/lib/scratch_buffer.cc
new file mode 100644
index 0000000..abfb5fe
--- /dev/null
+++ b/mojo/public/bindings/lib/scratch_buffer.cc
@@ -0,0 +1,98 @@
+// 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.
+
+#include "mojo/public/bindings/lib/scratch_buffer.h"
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <algorithm>
+
+#include "mojo/public/bindings/lib/bindings_serialization.h"
+
+// Scrub memory in debug builds to help catch use-after-free bugs.
+#ifdef NDEBUG
+#define DEBUG_SCRUB(address, size) (void) (address), (void) (size)
+#else
+#define DEBUG_SCRUB(address, size) memset(address, 0xCD, size)
+#endif
+
+namespace mojo {
+namespace internal {
+
+ScratchBuffer::ScratchBuffer()
+    : overflow_(NULL) {
+  fixed_.next = NULL;
+  fixed_.cursor = fixed_data_;
+  fixed_.end = fixed_data_ + kMinSegmentSize;
+}
+
+ScratchBuffer::~ScratchBuffer() {
+  // Invoke destructors in reverse order to mirror allocation order.
+  std::deque<PendingDestructor>::reverse_iterator it;
+  for (it = pending_dtors_.rbegin(); it != pending_dtors_.rend(); ++it)
+    it->func(it->address);
+
+  while (overflow_) {
+    Segment* doomed = overflow_;
+    overflow_ = overflow_->next;
+    DEBUG_SCRUB(doomed, doomed->end - reinterpret_cast<char*>(doomed));
+    free(doomed);
+  }
+  DEBUG_SCRUB(fixed_data_, sizeof(fixed_data_));
+}
+
+void* ScratchBuffer::Allocate(size_t delta, Destructor func) {
+  delta = internal::Align(delta);
+
+  void* result = AllocateInSegment(&fixed_, delta);
+  if (!result) {
+    if (overflow_)
+      result = AllocateInSegment(overflow_, delta);
+
+    if (!result) {
+      AddOverflowSegment(delta);
+      result = AllocateInSegment(overflow_, delta);
+    }
+  }
+
+  if (func) {
+    PendingDestructor dtor;
+    dtor.func = func;
+    dtor.address = result;
+    pending_dtors_.push_back(dtor);
+  }
+  return result;
+}
+
+void* ScratchBuffer::AllocateInSegment(Segment* segment, size_t delta) {
+  void* result;
+  if (static_cast<size_t>(segment->end - segment->cursor) >= delta) {
+    result = segment->cursor;
+    memset(result, 0, delta);
+    segment->cursor += delta;
+  } else {
+    result = NULL;
+  }
+  return result;
+}
+
+void ScratchBuffer::AddOverflowSegment(size_t delta) {
+  if (delta < kMinSegmentSize)
+    delta = kMinSegmentSize;
+
+  // Ensure segment buffer is aligned.
+  size_t segment_size = internal::Align(sizeof(Segment)) + delta;
+
+  Segment* segment = static_cast<Segment*>(malloc(segment_size));
+  segment->next = overflow_;
+  segment->cursor = reinterpret_cast<char*>(segment + 1);
+  segment->end = segment->cursor + delta;
+
+  overflow_ = segment;
+}
+
+}  // namespace internal
+}  // namespace mojo