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rtc::Buffer: Handle move self-assignment

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The object should end up in a valid state, just like after being moved
from.

Bug: webrtc:9857
Change-Id: Ia11f9b8e3191ffe749e4a0640cad946038f494a4
Reviewed-on: https://webrtc-review.googlesource.com/c/106701
Reviewed-by: Niels Moller <nisse@webrtc.org>
Commit-Queue: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25233}
This commit is contained in:
Karl Wiberg 2018-10-17 13:34:33 +02:00 committed by Commit Bot
parent d1892520ba
commit 4f3ce27ddc
2 changed files with 15 additions and 1 deletions
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5
rtc_base/buffer.h
View file

@ -152,7 +152,9 @@ class BufferT {
RTC_DCHECK(buf.IsConsistent()); RTC_DCHECK(buf.IsConsistent());
size_ = buf.size_; size_ = buf.size_;
capacity_ = buf.capacity_; capacity_ = buf.capacity_;
data_ = std::move(buf.data_); using std::swap;
swap(data_, buf.data_);
buf.data_.reset();
buf.OnMovedFrom(); buf.OnMovedFrom();
return *this; return *this;
} }
@ -399,6 +401,7 @@ class BufferT {
// Called when *this has been moved from. Conceptually it's a no-op, but we // Called when *this has been moved from. Conceptually it's a no-op, but we
// can mutate the state slightly to help subsequent sanity checks catch bugs. // can mutate the state slightly to help subsequent sanity checks catch bugs.
void OnMovedFrom() { void OnMovedFrom() {
RTC_DCHECK(!data_); // Our heap block should have been stolen.
#if RTC_DCHECK_IS_ON #if RTC_DCHECK_IS_ON
// Ensure that *this is always inconsistent, to provoke bugs. // Ensure that *this is always inconsistent, to provoke bugs.
size_ = 1; size_ = 1;

11
rtc_base/buffer_unittest.cc
View file

@ -185,6 +185,17 @@ TEST(BufferTest, TestMoveAssign) {
EXPECT_TRUE(buf1.empty()); EXPECT_TRUE(buf1.empty());
} }
TEST(BufferTest, TestMoveAssignSelf) {
// Move self-assignment isn't required to produce a meaningful state, but
// should not leave the object in an inconsistent state. (Such inconsistent
// state could be caught by the DCHECKs and/or by the leak checker.) We need
// to be sneaky when testing this; if we're doing a too-obvious
// move-assign-to-self, clang's -Wself-move triggers at compile time.
Buffer buf(kTestData, 3, 40);
Buffer* buf_ptr = &buf;
buf = std::move(*buf_ptr);
}
TEST(BufferTest, TestSwap) { TEST(BufferTest, TestSwap) {
Buffer buf1(kTestData, 3); Buffer buf1(kTestData, 3);
Buffer buf2(kTestData, 6, 40); Buffer buf2(kTestData, 6, 40);