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| 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. | |
| 4 | |
| 5 #include "mojo/public/bindings/lib/scratch_buffer.h" | |
| 6 | |
| 7 #include <assert.h> | |
| 8 #include <stdlib.h> | |
| 9 #include <string.h> | |
| 10 | |
| 11 #include <algorithm> | |
| 12 | |
| 13 #include "mojo/public/bindings/lib/bindings_serialization.h" | |
| 14 | |
| 15 // Scrub memory in debug builds to help catch use-after-free bugs. | |
| 16 #ifdef NDEBUG | |
| 17 #define DEBUG_SCRUB(address, size) (void) (address), (void) (size) | |
| 18 #else | |
| 19 #define DEBUG_SCRUB(address, size) memset(address, 0xCD, size) | |
| 20 #endif | |
| 21 | |
| 22 namespace mojo { | |
| 23 namespace internal { | |
| 24 | |
| 25 ScratchBuffer::ScratchBuffer() | |
| 26 : overflow_(NULL) { | |
| 27 fixed_.next = NULL; | |
| 28 fixed_.cursor = fixed_data_; | |
| 29 fixed_.end = fixed_data_ + kMinSegmentSize; | |
| 30 } | |
| 31 | |
| 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); | |
| 37 | |
| 38 while (overflow_) { | |
| 39 Segment* doomed = overflow_; | |
| 40 overflow_ = overflow_->next; | |
| 41 DEBUG_SCRUB(doomed, doomed->end - reinterpret_cast<char*>(doomed)); | |
| 42 free(doomed); | |
| 43 } | |
| 44 DEBUG_SCRUB(fixed_data_, sizeof(fixed_data_)); | |
| 45 } | |
| 46 | |
| 47 void* ScratchBuffer::Allocate(size_t delta, Destructor func) { | |
| 48 delta = internal::Align(delta); | |
| 49 | |
| 50 void* result = AllocateInSegment(&fixed_, delta); | |
| 51 if (!result) { | |
| 52 if (overflow_) | |
| 53 result = AllocateInSegment(overflow_, delta); | |
| 54 | |
| 55 if (!result) { | |
| 56 AddOverflowSegment(delta); | |
| 57 result = AllocateInSegment(overflow_, delta); | |
| 58 } | |
| 59 } | |
| 60 | |
| 61 if (func) { | |
| 62 PendingDestructor dtor; | |
| 63 dtor.func = func; | |
| 64 dtor.address = result; | |
| 65 pending_dtors_.push_back(dtor); | |
| 66 } | |
| 67 return result; | |
| 68 } | |
| 69 | |
| 70 void* ScratchBuffer::AllocateInSegment(Segment* segment, size_t delta) { | |
| 71 void* result; | |
| 72 if (static_cast<size_t>(segment->end - segment->cursor) >= delta) { | |
| 73 result = segment->cursor; | |
| 74 memset(result, 0, delta); | |
| 75 segment->cursor += delta; | |
| 76 } else { | |
| 77 result = NULL; | |
| 78 } | |
| 79 return result; | |
| 80 } | |
| 81 | |
| 82 void ScratchBuffer::AddOverflowSegment(size_t delta) { | |
| 83 if (delta < kMinSegmentSize) | |
| 84 delta = kMinSegmentSize; | |
| 85 | |
| 86 // Ensure segment buffer is aligned. | |
| 87 size_t segment_size = internal::Align(sizeof(Segment)) + delta; | |
| 88 | |
| 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; | |
| 93 | |
| 94 overflow_ = segment; | |
| 95 } | |
| 96 | |
| 97 } // namespace internal | |
| 98 } // namespace mojo | |
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