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read signed 32 if we want to treat it as signed

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Bug:793603
Change-Id: I040d775fcf76da095ea2a25c33408508b3466fd7
Reviewed-on: https://skia-review.googlesource.com/83280
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
This commit is contained in:
Mike Reed 2017-12-11 13:58:27 -05:00 committed by Skia Commit-Bot
parent e18b77972b
commit 73822257cb
1 changed files with 17 additions and 3 deletions
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20
src/core/SkReadBuffer.cpp
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@ -17,6 +17,20 @@
#include "SkTypeface.h"
namespace {
// If a signed int holds min_int (e.g. 0x80000000) it is undefined what happens when
// we negate it (even though we *know* we're 2's complement and we'll get the same
// value back). So we create this helper function that casts to size_t (unsigned) first,
// to avoid the complaint.
size_t sk_negate_to_size_t(int32_t value) {
#if defined(_MSC_VER)
#pragma warning(push)
#pragma warning(disable : 4146) // Thanks MSVC, we know what we're negating an unsigned
#endif
return -static_cast<size_t>(value);
#if defined(_MSC_VER)
#pragma warning(pop)
#endif
}
// This generator intentionally should always fail on all attempts to get its pixels,
// simulating a bad or empty codec stream.
@ -367,7 +381,7 @@ sk_sp<SkTypeface> SkReadBuffer::readTypeface() {
// >0 -- index
// <0 -- custom (serial procs) : negative size in bytes
int32_t index = this->readUInt();
int32_t index = this->read32();
if (index == 0) {
return nullptr;
} else if (index > 0) {
@ -376,7 +390,7 @@ sk_sp<SkTypeface> SkReadBuffer::readTypeface() {
}
return sk_ref_sp(fTFArray[index - 1]);
} else { // custom
size_t size = -index;
size_t size = sk_negate_to_size_t(index);
const void* data = this->skip(size);
if (!this->validate(data != nullptr)) {
return nullptr;
@ -415,7 +429,7 @@ SkFlattenable* SkReadBuffer::readFlattenable(SkFlattenable::Type ft) {
} else {
// Read the index. We are guaranteed that the first byte
// is zeroed, so we must shift down a byte.
uint32_t index = this->read32() >> 8;
uint32_t index = this->readUInt() >> 8;
if (!this->validate(index > 0)) {
return nullptr; // writer failed to give us the flattenable
}