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// Copyright 2020 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "absl/log/internal/proto.h"
#include <algorithm>
#include <cstddef>
#include <cstdint>
#include <cstring>
#include "absl/base/attributes.h"
#include "absl/base/config.h"
#include "absl/types/span.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace log_internal {
namespace {
void EncodeRawVarint(uint64_t value, size_t size, absl::Span<char> *buf) {
for (size_t s = 0; s < size; s++) {
(*buf)[s] = (value & 0x7f) | (s + 1 == size ? 0 : 0x80);
value >>= 7;
}
buf->remove_prefix(size);
}
constexpr uint64_t MakeTagType(uint64_t tag, WireType type) {
return tag << 3 | static_cast<uint64_t>(type);
}
} // namespace
bool EncodeVarint(uint64_t tag, uint64_t value, absl::Span<char> *buf) {
const uint64_t tag_type = MakeTagType(tag, WireType::kVarint);
const uint64_t tag_type_size = VarintSize(tag_type);
const uint64_t value_size = VarintSize(value);
if (tag_type_size + value_size > buf->size()) {
buf->remove_suffix(buf->size());
return false;
}
EncodeRawVarint(tag_type, tag_type_size, buf);
EncodeRawVarint(value, value_size, buf);
return true;
}
bool Encode64Bit(uint64_t tag, uint64_t value, absl::Span<char> *buf) {
const uint64_t tag_type = MakeTagType(tag, WireType::k64Bit);
const uint64_t tag_type_size = VarintSize(tag_type);
if (tag_type_size + sizeof(value) > buf->size()) {
buf->remove_suffix(buf->size());
return false;
}
EncodeRawVarint(tag_type, tag_type_size, buf);
for (size_t s = 0; s < sizeof(value); s++) {
(*buf)[s] = value & 0xff;
value >>= 8;
}
buf->remove_prefix(sizeof(value));
return true;
}
bool Encode32Bit(uint64_t tag, uint32_t value, absl::Span<char> *buf) {
const uint64_t tag_type = MakeTagType(tag, WireType::k32Bit);
const uint64_t tag_type_size = VarintSize(tag_type);
if (tag_type_size + sizeof(value) > buf->size()) {
buf->remove_suffix(buf->size());
return false;
}
EncodeRawVarint(tag_type, tag_type_size, buf);
for (size_t s = 0; s < sizeof(value); s++) {
(*buf)[s] = value & 0xff;
value >>= 8;
}
buf->remove_prefix(sizeof(value));
return true;
}
bool EncodeBytes(uint64_t tag, absl::Span<const char> value,
absl::Span<char> *buf) {
const uint64_t tag_type = MakeTagType(tag, WireType::kLengthDelimited);
const uint64_t tag_type_size = VarintSize(tag_type);
uint64_t length = value.size();
const uint64_t length_size = VarintSize(length);
if (tag_type_size + length_size + value.size() > buf->size()) {
buf->remove_suffix(buf->size());
return false;
}
EncodeRawVarint(tag_type, tag_type_size, buf);
EncodeRawVarint(length, length_size, buf);
memcpy(buf->data(), value.data(), value.size());
buf->remove_prefix(value.size());
return true;
}
bool EncodeBytesTruncate(uint64_t tag, absl::Span<const char> value,
absl::Span<char> *buf) {
const uint64_t tag_type = MakeTagType(tag, WireType::kLengthDelimited);
const uint64_t tag_type_size = VarintSize(tag_type);
uint64_t length = value.size();
const uint64_t length_size =
VarintSize(std::min<uint64_t>(length, buf->size()));
if (tag_type_size + length_size <= buf->size() &&
tag_type_size + length_size + value.size() > buf->size()) {
value.remove_suffix(tag_type_size + length_size + value.size() -
buf->size());
length = value.size();
}
if (tag_type_size + length_size + value.size() > buf->size()) {
buf->remove_suffix(buf->size());
return false;
}
EncodeRawVarint(tag_type, tag_type_size, buf);
EncodeRawVarint(length, length_size, buf);
memcpy(buf->data(), value.data(), value.size());
buf->remove_prefix(value.size());
return true;
}
ABSL_MUST_USE_RESULT absl::Span<char> EncodeMessageStart(
uint64_t tag, uint64_t max_size, absl::Span<char> *buf) {
const uint64_t tag_type = MakeTagType(tag, WireType::kLengthDelimited);
const uint64_t tag_type_size = VarintSize(tag_type);
max_size = std::min<uint64_t>(max_size, buf->size());
const uint64_t length_size = VarintSize(max_size);
if (tag_type_size + length_size > buf->size()) {
buf->remove_suffix(buf->size());
return absl::Span<char>();
}
EncodeRawVarint(tag_type, tag_type_size, buf);
const absl::Span<char> ret = buf->subspan(0, length_size);
EncodeRawVarint(0, length_size, buf);
return ret;
}
void EncodeMessageLength(absl::Span<char> msg, const absl::Span<char> *buf) {
if (!msg.data()) return;
const uint64_t length_size = msg.size();
EncodeRawVarint(buf->data() - msg.data() - length_size, length_size, &msg);
}
namespace {
uint64_t DecodeVarint(absl::Span<const char> *buf) {
uint64_t value = 0;
size_t s = 0;
while (s < buf->size()) {
value |= static_cast<uint64_t>(static_cast<unsigned char>((*buf)[s]) & 0x7f)
<< 7 * s;
if (!((*buf)[s++] & 0x80)) break;
}
buf->remove_prefix(s);
return value;
}
uint64_t Decode64Bit(absl::Span<const char> *buf) {
uint64_t value = 0;
size_t s = 0;
while (s < buf->size()) {
value |= static_cast<uint64_t>(static_cast<unsigned char>((*buf)[s]))
<< 8 * s;
if (++s == sizeof(value)) break;
}
buf->remove_prefix(s);
return value;
}
uint32_t Decode32Bit(absl::Span<const char> *buf) {
uint32_t value = 0;
size_t s = 0;
while (s < buf->size()) {
value |= static_cast<uint32_t>(static_cast<unsigned char>((*buf)[s]))
<< 8 * s;
if (++s == sizeof(value)) break;
}
buf->remove_prefix(s);
return value;
}
} // namespace
bool ProtoField::DecodeFrom(absl::Span<const char> *data) {
if (data->empty()) return false;
const uint64_t tag_type = DecodeVarint(data);
tag_ = tag_type >> 3;
type_ = static_cast<WireType>(tag_type & 0x07);
switch (type_) {
case WireType::kVarint:
value_ = DecodeVarint(data);
break;
case WireType::k64Bit:
value_ = Decode64Bit(data);
break;
case WireType::kLengthDelimited: {
value_ = DecodeVarint(data);
data_ = data->subspan(0, std::min<size_t>(value_, data->size()));
data->remove_prefix(data_.size());
break;
}
case WireType::k32Bit:
value_ = Decode32Bit(data);
break;
}
return true;
}
} // namespace log_internal
ABSL_NAMESPACE_END
} // namespace absl
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