1 // Copyright 2014 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 #include "mojo/public/bindings/lib/scratch_buffer.h"
13 #include "mojo/public/bindings/lib/bindings_serialization.h"
15 // Scrub memory in debug builds to help catch use-after-free bugs.
17 #define DEBUG_SCRUB(address, size) (void) (address), (void) (size)
19 #define DEBUG_SCRUB(address, size) memset(address, 0xCD, size)
25 ScratchBuffer::ScratchBuffer()
28 fixed_.cursor = fixed_data_;
29 fixed_.end = fixed_data_ + kMinSegmentSize;
32 ScratchBuffer::~ScratchBuffer() {
33 // Invoke destructors in reverse order to mirror allocation order.
34 std::deque<PendingDestructor>::reverse_iterator it;
35 for (it = pending_dtors_.rbegin(); it != pending_dtors_.rend(); ++it)
36 it->func(it->address);
39 Segment* doomed = overflow_;
40 overflow_ = overflow_->next;
41 DEBUG_SCRUB(doomed, doomed->end - reinterpret_cast<char*>(doomed));
44 DEBUG_SCRUB(fixed_data_, sizeof(fixed_data_));
47 void* ScratchBuffer::Allocate(size_t delta, Destructor func) {
48 delta = internal::Align(delta);
50 void* result = AllocateInSegment(&fixed_, delta);
53 result = AllocateInSegment(overflow_, delta);
56 AddOverflowSegment(delta);
57 result = AllocateInSegment(overflow_, delta);
62 PendingDestructor dtor;
64 dtor.address = result;
65 pending_dtors_.push_back(dtor);
70 void* ScratchBuffer::AllocateInSegment(Segment* segment, size_t delta) {
72 if (static_cast<size_t>(segment->end - segment->cursor) >= delta) {
73 result = segment->cursor;
74 memset(result, 0, delta);
75 segment->cursor += delta;
82 void ScratchBuffer::AddOverflowSegment(size_t delta) {
83 if (delta < kMinSegmentSize)
84 delta = kMinSegmentSize;
86 // Ensure segment buffer is aligned.
87 size_t segment_size = internal::Align(sizeof(Segment)) + delta;
89 Segment* segment = static_cast<Segment*>(malloc(segment_size));
90 segment->next = overflow_;
91 segment->cursor = reinterpret_cast<char*>(segment + 1);
92 segment->end = segment->cursor + delta;
97 } // namespace internal