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// Copyright 2021 The Pigweed 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 "pw_protobuf/encoder.h"
#include <algorithm>
#include <cstddef>
#include <cstring>
#include <optional>
#include "pw_assert/check.h"
#include "pw_bytes/span.h"
#include "pw_protobuf/internal/codegen.h"
#include "pw_protobuf/serialized_size.h"
#include "pw_protobuf/stream_decoder.h"
#include "pw_protobuf/wire_format.h"
#include "pw_span/span.h"
#include "pw_status/status.h"
#include "pw_status/try.h"
#include "pw_stream/memory_stream.h"
#include "pw_stream/stream.h"
#include "pw_varint/varint.h"
namespace pw::protobuf {
StreamEncoder StreamEncoder::GetNestedEncoder(uint32_t field_number,
bool write_when_empty) {
PW_CHECK(!nested_encoder_open());
PW_CHECK(ValidFieldNumber(field_number));
nested_field_number_ = field_number;
// Pass the unused space of the scratch buffer to the nested encoder to use
// as their scratch buffer.
size_t key_size =
varint::EncodedSize(FieldKey(field_number, WireType::kDelimited));
size_t reserved_size = key_size + config::kMaxVarintSize;
size_t max_size = std::min(memory_writer_.ConservativeWriteLimit(),
writer_.ConservativeWriteLimit());
// Account for reserved bytes.
max_size = max_size > reserved_size ? max_size - reserved_size : 0;
// Cap based on max varint size.
max_size = std::min(varint::MaxValueInBytes(config::kMaxVarintSize),
static_cast<uint64_t>(max_size));
ByteSpan nested_buffer;
if (max_size > 0) {
nested_buffer = ByteSpan(
memory_writer_.data() + reserved_size + memory_writer_.bytes_written(),
max_size);
} else {
nested_buffer = ByteSpan();
}
return StreamEncoder(*this, nested_buffer, write_when_empty);
}
void StreamEncoder::CloseEncoder() {
// If this was an invalidated StreamEncoder which cannot be used, permit the
// object to be cleanly destructed by doing nothing.
if (nested_field_number_ == kFirstReservedNumber) {
return;
}
PW_CHECK(
!nested_encoder_open(),
"Tried to destruct a proto encoder with an active submessage encoder");
if (parent_ != nullptr) {
parent_->CloseNestedMessage(*this);
}
}
void StreamEncoder::CloseNestedMessage(StreamEncoder& nested) {
PW_DCHECK_PTR_EQ(nested.parent_,
this,
"CloseNestedMessage() called on the wrong Encoder parent");
// Make the nested encoder look like it has an open child to block writes for
// the remainder of the object's life.
nested.nested_field_number_ = kFirstReservedNumber;
nested.parent_ = nullptr;
// Temporarily cache the field number of the child so we can re-enable
// writing to this encoder.
uint32_t temp_field_number = nested_field_number_;
nested_field_number_ = 0;
// TODO(amontanez): If a submessage fails, we could optionally discard
// it and continue happily. For now, we'll always invalidate the entire
// encoder if a single submessage fails.
status_.Update(nested.status_);
if (!status_.ok()) {
return;
}
if (varint::EncodedSize(nested.memory_writer_.bytes_written()) >
config::kMaxVarintSize) {
status_ = Status::OutOfRange();
return;
}
if (!nested.memory_writer_.bytes_written() && !nested.write_when_empty_) {
return;
}
status_ = WriteLengthDelimitedField(temp_field_number,
nested.memory_writer_.WrittenData());
}
Status StreamEncoder::WriteVarintField(uint32_t field_number, uint64_t value) {
PW_TRY(UpdateStatusForWrite(
field_number, WireType::kVarint, varint::EncodedSize(value)));
WriteVarint(FieldKey(field_number, WireType::kVarint))
.IgnoreError(); // TODO(b/242598609): Handle Status properly
return WriteVarint(value);
}
Status StreamEncoder::WriteLengthDelimitedField(uint32_t field_number,
ConstByteSpan data) {
PW_TRY(UpdateStatusForWrite(field_number, WireType::kDelimited, data.size()));
status_.Update(WriteLengthDelimitedKeyAndLengthPrefix(
field_number, data.size(), writer_));
PW_TRY(status_);
if (Status status = writer_.Write(data); !status.ok()) {
status_ = status;
}
return status_;
}
Status StreamEncoder::WriteLengthDelimitedFieldFromStream(
uint32_t field_number,
stream::Reader& bytes_reader,
size_t num_bytes,
ByteSpan stream_pipe_buffer) {
PW_CHECK_UINT_GT(
stream_pipe_buffer.size(), 0, "Transfer buffer cannot be 0 size");
PW_TRY(UpdateStatusForWrite(field_number, WireType::kDelimited, num_bytes));
status_.Update(
WriteLengthDelimitedKeyAndLengthPrefix(field_number, num_bytes, writer_));
PW_TRY(status_);
// Stream data from `bytes_reader` to `writer_`.
// TODO(pwbug/468): move the following logic to pw_stream/copy.h at a later
// time.
for (size_t bytes_written = 0; bytes_written < num_bytes;) {
const size_t chunk_size_bytes =
std::min(num_bytes - bytes_written, stream_pipe_buffer.size_bytes());
const Result<ByteSpan> read_result =
bytes_reader.Read(stream_pipe_buffer.data(), chunk_size_bytes);
status_.Update(read_result.status());
PW_TRY(status_);
status_.Update(writer_.Write(read_result.value()));
PW_TRY(status_);
bytes_written += read_result.value().size();
}
return OkStatus();
}
Status StreamEncoder::WriteFixed(uint32_t field_number, ConstByteSpan data) {
WireType type =
data.size() == sizeof(uint32_t) ? WireType::kFixed32 : WireType::kFixed64;
PW_TRY(UpdateStatusForWrite(field_number, type, data.size()));
WriteVarint(FieldKey(field_number, type))
.IgnoreError(); // TODO(b/242598609): Handle Status properly
if (Status status = writer_.Write(data); !status.ok()) {
status_ = status;
}
return status_;
}
Status StreamEncoder::WritePackedFixed(uint32_t field_number,
span<const std::byte> values,
size_t elem_size) {
if (values.empty()) {
return status_;
}
PW_CHECK_NOTNULL(values.data());
PW_DCHECK(elem_size == sizeof(uint32_t) || elem_size == sizeof(uint64_t));
PW_TRY(UpdateStatusForWrite(
field_number, WireType::kDelimited, values.size_bytes()));
WriteVarint(FieldKey(field_number, WireType::kDelimited))
.IgnoreError(); // TODO(b/242598609): Handle Status properly
WriteVarint(values.size_bytes())
.IgnoreError(); // TODO(b/242598609): Handle Status properly
for (auto val_start = values.begin(); val_start != values.end();
val_start += elem_size) {
// Allocates 8 bytes so both 4-byte and 8-byte types can be encoded as
// little-endian for serialization.
std::array<std::byte, sizeof(uint64_t)> data;
if (endian::native == endian::little) {
std::copy(val_start, val_start + elem_size, std::begin(data));
} else {
std::reverse_copy(val_start, val_start + elem_size, std::begin(data));
}
status_.Update(writer_.Write(span(data).first(elem_size)));
PW_TRY(status_);
}
return status_;
}
Status StreamEncoder::UpdateStatusForWrite(uint32_t field_number,
WireType type,
size_t data_size) {
PW_CHECK(!nested_encoder_open());
PW_TRY(status_);
if (!ValidFieldNumber(field_number)) {
return status_ = Status::InvalidArgument();
}
const Result<size_t> field_size = SizeOfField(field_number, type, data_size);
status_.Update(field_size.status());
PW_TRY(status_);
if (field_size.value() > writer_.ConservativeWriteLimit()) {
status_ = Status::ResourceExhausted();
}
return status_;
}
Status StreamEncoder::Write(span<const std::byte> message,
span<const MessageField> table) {
PW_CHECK(!nested_encoder_open());
PW_TRY(status_);
for (const auto& field : table) {
// Calculate the span of bytes corresponding to the structure field to
// read from.
const auto values =
message.subspan(field.field_offset(), field.field_size());
PW_CHECK(values.begin() >= message.begin() &&
values.end() <= message.end());
// If the field is using callbacks, interpret the input field accordingly
// and allow the caller to provide custom handling.
if (field.use_callback()) {
const Callback<StreamEncoder, StreamDecoder>* callback =
reinterpret_cast<const Callback<StreamEncoder, StreamDecoder>*>(
values.data());
PW_TRY(callback->Encode(*this));
continue;
}
switch (field.wire_type()) {
case WireType::kFixed64:
case WireType::kFixed32: {
// Fixed fields call WriteFixed() for singular case and
// WritePackedFixed() for repeated fields.
PW_CHECK(field.elem_size() == (field.wire_type() == WireType::kFixed32
? sizeof(uint32_t)
: sizeof(uint64_t)),
"Mismatched message field type and size");
if (field.is_fixed_size()) {
PW_CHECK(field.is_repeated(), "Non-repeated fixed size field");
if (static_cast<size_t>(
std::count(values.begin(), values.end(), std::byte{0})) <
values.size()) {
PW_TRY(WritePackedFixed(
field.field_number(), values, field.elem_size()));
}
} else if (field.is_repeated()) {
// The struct member for this field is a vector of a type
// corresponding to the field element size. Cast to the correct
// vector type so we're not performing type aliasing (except for
// unsigned vs signed which is explicitly allowed).
if (field.elem_size() == sizeof(uint64_t)) {
const auto* vector =
reinterpret_cast<const pw::Vector<const uint64_t>*>(
values.data());
if (!vector->empty()) {
PW_TRY(WritePackedFixed(
field.field_number(),
as_bytes(span(vector->data(), vector->size())),
field.elem_size()));
}
} else if (field.elem_size() == sizeof(uint32_t)) {
const auto* vector =
reinterpret_cast<const pw::Vector<const uint32_t>*>(
values.data());
if (!vector->empty()) {
PW_TRY(WritePackedFixed(
field.field_number(),
as_bytes(span(vector->data(), vector->size())),
field.elem_size()));
}
}
} else if (field.is_optional()) {
// The struct member for this field is a std::optional of a type
// corresponding to the field element size. Cast to the correct
// optional type so we're not performing type aliasing (except for
// unsigned vs signed which is explicitly allowed), and write from
// a temporary.
if (field.elem_size() == sizeof(uint64_t)) {
const auto* optional =
reinterpret_cast<const std::optional<uint64_t>*>(values.data());
if (optional->has_value()) {
uint64_t value = optional->value();
PW_TRY(
WriteFixed(field.field_number(), as_bytes(span(&value, 1))));
}
} else if (field.elem_size() == sizeof(uint32_t)) {
const auto* optional =
reinterpret_cast<const std::optional<uint32_t>*>(values.data());
if (optional->has_value()) {
uint32_t value = optional->value();
PW_TRY(
WriteFixed(field.field_number(), as_bytes(span(&value, 1))));
}
}
} else {
PW_CHECK(values.size() == field.elem_size(),
"Mismatched message field type and size");
if (static_cast<size_t>(
std::count(values.begin(), values.end(), std::byte{0})) <
values.size()) {
PW_TRY(WriteFixed(field.field_number(), values));
}
}
break;
}
case WireType::kVarint: {
// Varint fields call WriteVarintField() for singular case and
// WritePackedVarints() for repeated fields.
PW_CHECK(field.elem_size() == sizeof(uint64_t) ||
field.elem_size() == sizeof(uint32_t) ||
field.elem_size() == sizeof(bool),
"Mismatched message field type and size");
if (field.is_fixed_size()) {
// The struct member for this field is an array of type corresponding
// to the field element size. Cast to a span of the correct type over
// the array so we're not performing type aliasing (except for
// unsigned vs signed which is explicitly allowed).
PW_CHECK(field.is_repeated(), "Non-repeated fixed size field");
if (static_cast<size_t>(
std::count(values.begin(), values.end(), std::byte{0})) ==
values.size()) {
continue;
}
if (field.elem_size() == sizeof(uint64_t)) {
PW_TRY(WritePackedVarints(
field.field_number(),
span(reinterpret_cast<const uint64_t*>(values.data()),
values.size() / field.elem_size()),
field.varint_type()));
} else if (field.elem_size() == sizeof(uint32_t)) {
PW_TRY(WritePackedVarints(
field.field_number(),
span(reinterpret_cast<const uint32_t*>(values.data()),
values.size() / field.elem_size()),
field.varint_type()));
} else if (field.elem_size() == sizeof(bool)) {
static_assert(sizeof(bool) == sizeof(uint8_t),
"bool must be same size as uint8_t");
PW_TRY(WritePackedVarints(
field.field_number(),
span(reinterpret_cast<const uint8_t*>(values.data()),
values.size() / field.elem_size()),
field.varint_type()));
}
} else if (field.is_repeated()) {
// The struct member for this field is a vector of a type
// corresponding to the field element size. Cast to the correct
// vector type so we're not performing type aliasing (except for
// unsigned vs signed which is explicitly allowed).
if (field.elem_size() == sizeof(uint64_t)) {
const auto* vector =
reinterpret_cast<const pw::Vector<const uint64_t>*>(
values.data());
if (!vector->empty()) {
PW_TRY(WritePackedVarints(field.field_number(),
span(vector->data(), vector->size()),
field.varint_type()));
}
} else if (field.elem_size() == sizeof(uint32_t)) {
const auto* vector =
reinterpret_cast<const pw::Vector<const uint32_t>*>(
values.data());
if (!vector->empty()) {
PW_TRY(WritePackedVarints(field.field_number(),
span(vector->data(), vector->size()),
field.varint_type()));
}
} else if (field.elem_size() == sizeof(bool)) {
static_assert(sizeof(bool) == sizeof(uint8_t),
"bool must be same size as uint8_t");
const auto* vector =
reinterpret_cast<const pw::Vector<const uint8_t>*>(
values.data());
if (!vector->empty()) {
PW_TRY(WritePackedVarints(field.field_number(),
span(vector->data(), vector->size()),
field.varint_type()));
}
}
} else if (field.is_optional()) {
// The struct member for this field is a std::optional of a type
// corresponding to the field element size. Cast to the correct
// optional type so we're not performing type aliasing (except for
// unsigned vs signed which is explicitly allowed), and write from
// a temporary.
uint64_t value = 0;
if (field.elem_size() == sizeof(uint64_t)) {
if (field.varint_type() == VarintType::kUnsigned) {
const auto* optional =
reinterpret_cast<const std::optional<uint64_t>*>(
values.data());
if (!optional->has_value()) {
continue;
}
value = optional->value();
} else {
const auto* optional =
reinterpret_cast<const std::optional<int64_t>*>(
values.data());
if (!optional->has_value()) {
continue;
}
value = field.varint_type() == VarintType::kZigZag
? varint::ZigZagEncode(optional->value())
: optional->value();
}
} else if (field.elem_size() == sizeof(uint32_t)) {
if (field.varint_type() == VarintType::kUnsigned) {
const auto* optional =
reinterpret_cast<const std::optional<uint32_t>*>(
values.data());
if (!optional->has_value()) {
continue;
}
value = optional->value();
} else {
const auto* optional =
reinterpret_cast<const std::optional<int32_t>*>(
values.data());
if (!optional->has_value()) {
continue;
}
value = field.varint_type() == VarintType::kZigZag
? varint::ZigZagEncode(optional->value())
: optional->value();
}
} else if (field.elem_size() == sizeof(bool)) {
const auto* optional =
reinterpret_cast<const std::optional<bool>*>(values.data());
if (!optional->has_value()) {
continue;
}
value = optional->value();
}
PW_TRY(WriteVarintField(field.field_number(), value));
} else {
// The struct member for this field is a scalar of a type
// corresponding to the field element size. Cast to the correct
// type to retrieve the value before passing to WriteVarintField()
// so we're not performing type aliasing (except for unsigned vs
// signed which is explicitly allowed).
PW_CHECK(values.size() == field.elem_size(),
"Mismatched message field type and size");
uint64_t value = 0;
if (field.elem_size() == sizeof(uint64_t)) {
if (field.varint_type() == VarintType::kZigZag) {
value = varint::ZigZagEncode(
*reinterpret_cast<const int64_t*>(values.data()));
} else if (field.varint_type() == VarintType::kNormal) {
value = *reinterpret_cast<const int64_t*>(values.data());
} else {
value = *reinterpret_cast<const uint64_t*>(values.data());
}
if (!value) {
continue;
}
} else if (field.elem_size() == sizeof(uint32_t)) {
if (field.varint_type() == VarintType::kZigZag) {
value = varint::ZigZagEncode(
*reinterpret_cast<const int32_t*>(values.data()));
} else if (field.varint_type() == VarintType::kNormal) {
value = *reinterpret_cast<const int32_t*>(values.data());
} else {
value = *reinterpret_cast<const uint32_t*>(values.data());
}
if (!value) {
continue;
}
} else if (field.elem_size() == sizeof(bool)) {
value = *reinterpret_cast<const bool*>(values.data());
if (!value) {
continue;
}
}
PW_TRY(WriteVarintField(field.field_number(), value));
}
break;
}
case WireType::kDelimited: {
// Delimited fields are always a singular case because of the
// inability to cast to a generic vector with an element of a certain
// size (we always need a type).
PW_CHECK(!field.is_repeated(),
"Repeated delimited messages always require a callback");
if (field.nested_message_fields()) {
// Nested Message. Struct member is an embedded struct for the
// nested field. Obtain a nested encoder and recursively call Write()
// using the fields table pointer from this field.
auto nested_encoder = GetNestedEncoder(field.field_number(),
/*write_when_empty=*/false);
PW_TRY(nested_encoder.Write(values, *field.nested_message_fields()));
} else if (field.is_fixed_size()) {
// Fixed-length bytes field. Struct member is a std::array<std::byte>.
// Call WriteLengthDelimitedField() to output it to the stream.
PW_CHECK(field.elem_size() == sizeof(std::byte),
"Mismatched message field type and size");
if (static_cast<size_t>(
std::count(values.begin(), values.end(), std::byte{0})) <
values.size()) {
PW_TRY(WriteLengthDelimitedField(field.field_number(), values));
}
} else {
// bytes or string field with a maximum size. Struct member is a
// pw::Vector<std::byte>. Use the contents as a span and call
// WriteLengthDelimitedField() to output it to the stream.
PW_CHECK(field.elem_size() == sizeof(std::byte),
"Mismatched message field type and size");
const auto* vector =
reinterpret_cast<const pw::Vector<const std::byte>*>(
values.data());
if (!vector->empty()) {
PW_TRY(WriteLengthDelimitedField(
field.field_number(), span(vector->data(), vector->size())));
}
}
break;
}
}
}
return status_;
}
} // namespace pw::protobuf