blob: 827a6352419125930b0572865f0569f5a0f6df87 [file] [log] [blame]
/*
* Copyright 2019 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "src/core/SkDescriptor.h"
#include "include/core/SkTypes.h"
#include "include/private/base/SkTo.h"
#include "include/private/chromium/SkChromeRemoteGlyphCache.h"
#include "src/core/SkOpts.h"
#include "src/core/SkReadBuffer.h"
#include "src/core/SkWriteBuffer.h"
#include <string.h>
#include <new>
std::unique_ptr<SkDescriptor> SkDescriptor::Alloc(size_t length) {
SkASSERT(length >= sizeof(SkDescriptor) && SkAlign4(length) == length);
void* allocation = ::operator new(length);
return std::unique_ptr<SkDescriptor>(new (allocation) SkDescriptor{});
}
void SkDescriptor::operator delete(void* p) { ::operator delete(p); }
void* SkDescriptor::operator new(size_t) {
SK_ABORT("Descriptors are created with placement new.");
}
void SkDescriptor::flatten(SkWriteBuffer& buffer) const {
buffer.writePad32(static_cast<const void*>(this), this->fLength);
}
void* SkDescriptor::addEntry(uint32_t tag, size_t length, const void* data) {
SkASSERT(tag);
SkASSERT(SkAlign4(length) == length);
SkASSERT(this->findEntry(tag, nullptr) == nullptr);
Entry* entry = (Entry*)((char*)this + fLength);
entry->fTag = tag;
entry->fLen = SkToU32(length);
if (data) {
memcpy(entry + 1, data, length);
}
fCount += 1;
fLength = SkToU32(fLength + sizeof(Entry) + length);
return (entry + 1); // return its data
}
void SkDescriptor::computeChecksum() {
fChecksum = SkDescriptor::ComputeChecksum(this);
}
const void* SkDescriptor::findEntry(uint32_t tag, uint32_t* length) const {
const Entry* entry = (const Entry*)(this + 1);
int count = fCount;
while (--count >= 0) {
if (entry->fTag == tag) {
if (length) {
*length = entry->fLen;
}
return entry + 1;
}
entry = (const Entry*)((const char*)(entry + 1) + entry->fLen);
}
return nullptr;
}
std::unique_ptr<SkDescriptor> SkDescriptor::copy() const {
std::unique_ptr<SkDescriptor> desc = SkDescriptor::Alloc(fLength);
memcpy(desc.get(), this, fLength);
return desc;
}
bool SkDescriptor::operator==(const SkDescriptor& other) const {
// the first value we should look at is the checksum, so this loop
// should terminate early if they descriptors are different.
// NOTE: if we wrote a sentinel value at the end of each, we could
// remove the aa < stop test in the loop...
const uint32_t* aa = (const uint32_t*)this;
const uint32_t* bb = (const uint32_t*)&other;
const uint32_t* stop = (const uint32_t*)((const char*)aa + fLength);
do {
if (*aa++ != *bb++)
return false;
} while (aa < stop);
return true;
}
SkString SkDescriptor::dumpRec() const {
const SkScalerContextRec* rec = static_cast<const SkScalerContextRec*>(
this->findEntry(kRec_SkDescriptorTag, nullptr));
SkString result;
result.appendf(" Checksum: %x\n", fChecksum);
if (rec != nullptr) {
result.append(rec->dump());
}
return result;
}
uint32_t SkDescriptor::ComputeChecksum(const SkDescriptor* desc) {
const uint32_t* ptr = (const uint32_t*)desc + 1; // skip the checksum field
size_t len = desc->fLength - sizeof(uint32_t);
return SkOpts::hash(ptr, len);
}
bool SkDescriptor::isValid() const {
uint32_t count = fCount;
size_t lengthRemaining = this->fLength;
if (lengthRemaining < sizeof(SkDescriptor)) {
return false;
}
lengthRemaining -= sizeof(SkDescriptor);
size_t offset = sizeof(SkDescriptor);
while (lengthRemaining > 0 && count > 0) {
if (lengthRemaining < sizeof(Entry)) {
return false;
}
lengthRemaining -= sizeof(Entry);
const Entry* entry = (const Entry*)(reinterpret_cast<const char*>(this) + offset);
if (lengthRemaining < entry->fLen) {
return false;
}
lengthRemaining -= entry->fLen;
// rec tags are always a known size.
if (entry->fTag == kRec_SkDescriptorTag && entry->fLen != sizeof(SkScalerContextRec)) {
return false;
}
offset += sizeof(Entry) + entry->fLen;
count--;
}
return lengthRemaining == 0 && count == 0;
}
SkAutoDescriptor::SkAutoDescriptor() = default;
SkAutoDescriptor::SkAutoDescriptor(size_t size) { this->reset(size); }
SkAutoDescriptor::SkAutoDescriptor(const SkDescriptor& desc) { this->reset(desc); }
SkAutoDescriptor::SkAutoDescriptor(const SkAutoDescriptor& that) {
this->reset(*that.getDesc());
}
SkAutoDescriptor& SkAutoDescriptor::operator=(const SkAutoDescriptor& that) {
this->reset(*that.getDesc());
return *this;
}
SkAutoDescriptor::SkAutoDescriptor(SkAutoDescriptor&& that) {
if (that.fDesc == (SkDescriptor*)&that.fStorage) {
this->reset(*that.getDesc());
} else {
fDesc = that.fDesc;
that.fDesc = nullptr;
}
}
SkAutoDescriptor& SkAutoDescriptor::operator=(SkAutoDescriptor&& that) {
if (that.fDesc == (SkDescriptor*)&that.fStorage) {
this->reset(*that.getDesc());
} else {
this->free();
fDesc = that.fDesc;
that.fDesc = nullptr;
}
return *this;
}
SkAutoDescriptor::~SkAutoDescriptor() { this->free(); }
std::optional<SkAutoDescriptor> SkAutoDescriptor::MakeFromBuffer(SkReadBuffer& buffer) {
SkDescriptor descriptorHeader;
if (!buffer.readPad32(&descriptorHeader, sizeof(SkDescriptor))) { return {}; }
// Basic bounds check on header length to make sure that bodyLength calculation does not
// underflow.
if (descriptorHeader.getLength() < sizeof(SkDescriptor)) { return {}; }
uint32_t bodyLength = descriptorHeader.getLength() - sizeof(SkDescriptor);
// Make sure the fLength makes sense with respect to the incoming data.
if (bodyLength > buffer.available()) {
return {};
}
SkAutoDescriptor ad{descriptorHeader.getLength()};
memcpy(ad.fDesc, &descriptorHeader, sizeof(SkDescriptor));
if (!buffer.readPad32(SkTAddOffset<void>(ad.fDesc, sizeof(SkDescriptor)), bodyLength)) {
return {};
}
// If the fuzzer produces data but the checksum does not match, let it continue. This will boost
// fuzzing speed. We leave the actual checksum computation in for fuzzing builds to make sure
// the ComputeChecksum function is covered.
#if defined(SK_BUILD_FOR_FUZZER)
SkDescriptor::ComputeChecksum(ad.getDesc());
#else
if (SkDescriptor::ComputeChecksum(ad.getDesc()) != ad.getDesc()->fChecksum) { return {}; }
#endif
if (!ad.getDesc()->isValid()) { return {}; }
return {ad};
}
void SkAutoDescriptor::reset(size_t size) {
this->free();
if (size <= sizeof(fStorage)) {
fDesc = new (&fStorage) SkDescriptor{};
} else {
fDesc = SkDescriptor::Alloc(size).release();
}
}
void SkAutoDescriptor::reset(const SkDescriptor& desc) {
size_t size = desc.getLength();
this->reset(size);
memcpy(fDesc, &desc, size);
}
void SkAutoDescriptor::free() {
if (fDesc == (SkDescriptor*)&fStorage) {
fDesc->~SkDescriptor();
} else {
delete fDesc;
}
}