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// Copyright 2020 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_tokenizer/internal/decode.h"
#include <algorithm>
#include <array>
#include <cctype>
#include <cstring>
#include "pw_varint/varint.h"
namespace pw::tokenizer {
namespace {
// Functions for parsing a printf format specifier.
size_t SkipFlags(const char* str) {
size_t i = 0;
while (str[i] == '-' || str[i] == '+' || str[i] == '#' || str[i] == ' ' ||
str[i] == '0') {
i += 1;
}
return i;
}
size_t SkipAsteriskOrInteger(const char* str) {
if (str[0] == '*') {
return 1;
}
size_t i = (str[0] == '-' || str[0] == '+') ? 1 : 0;
while (std::isdigit(str[i])) {
i += 1;
}
return i;
}
std::array<char, 2> ReadLengthModifier(const char* str) {
// Check for ll or hh.
if (str[0] == str[1] && (str[0] == 'l' || str[0] == 'h')) {
return {str[0], str[1]};
}
if (std::strchr("hljztL", str[0]) != nullptr) {
return {str[0]};
}
return {};
}
// Returns the error message that is used in place of a decoded arg when an
// error occurs.
std::string ErrorMessage(ArgStatus status,
const std::string_view& spec,
const std::string_view& value) {
const char* message;
if (status.HasError(ArgStatus::kSkipped)) {
message = "SKIPPED";
} else if (status.HasError(ArgStatus::kMissing)) {
message = "MISSING";
} else if (status.HasError(ArgStatus::kDecodeError)) {
message = "ERROR";
} else {
message = "INTERNAL ERROR";
}
std::string result(PW_TOKENIZER_ARG_DECODING_ERROR_PREFIX);
result.append(spec);
result.push_back(' ');
result.append(message);
if (!value.empty()) {
result.push_back(' ');
result.push_back('(');
result.append(value);
result.push_back(')');
}
result.append(PW_TOKENIZER_ARG_DECODING_ERROR_SUFFIX);
return result;
}
} // namespace
DecodedArg::DecodedArg(ArgStatus error,
const std::string_view& spec,
size_t raw_size_bytes,
const std::string_view& value)
: value_(ErrorMessage(error, spec, value)),
spec_(spec),
raw_data_size_bytes_(raw_size_bytes),
status_(error) {}
StringSegment StringSegment::ParseFormatSpec(const char* format) {
if (format[0] != '%' || format[1] == '\0') {
return StringSegment();
}
// Parse the format specifier.
size_t i = 1;
// Skip the flags.
i += SkipFlags(&format[i]);
// Skip the field width.
i += SkipAsteriskOrInteger(&format[i]);
// Skip the precision.
if (format[i] == '.') {
i += 1;
i += SkipAsteriskOrInteger(&format[i]);
}
// Read the length modifier.
const std::array<char, 2> length = ReadLengthModifier(&format[i]);
i += (length[0] == '\0' ? 0 : 1) + (length[1] == '\0' ? 0 : 1);
// Read the conversion specifier.
const char spec = format[i];
Type type;
if (spec == 's') {
type = kString;
} else if (spec == 'c' || spec == 'd' || spec == 'i') {
type = kSignedInt;
} else if (std::strchr("oxXup", spec) != nullptr) {
// The source size matters for unsigned integers because they need to be
// masked off to their correct length, since zig-zag decode sign extends.
// TODO(hepler): 64-bit targets likely have 64-bit l, j, z, and t. Also, p
// needs to be 64-bit on these targets.
type = length[0] == 'j' || length[1] == 'l' ? kUnsigned64 : kUnsigned32;
} else if (std::strchr("fFeEaAgG", spec) != nullptr) {
type = kFloatingPoint;
} else if (spec == '%' && i == 1) {
type = kPercent;
} else {
return StringSegment();
}
return {std::string_view(format, i + 1), type, VarargSize(length, spec)};
}
StringSegment::ArgSize StringSegment::VarargSize(std::array<char, 2> length,
char spec) {
// Use pointer size for %p or any other type (for which this doesn't matter).
if (std::strchr("cdioxXu", spec) == nullptr) {
return VarargSize<void*>();
}
if (length[0] == 'l') {
return length[1] == 'l' ? VarargSize<long long>() : VarargSize<long>();
}
if (length[0] == 'j') {
return VarargSize<intmax_t>();
}
if (length[0] == 'z') {
return VarargSize<size_t>();
}
if (length[0] == 't') {
return VarargSize<ptrdiff_t>();
}
return VarargSize<int>();
}
DecodedArg StringSegment::DecodeString(
const std::span<const uint8_t>& arguments) const {
if (arguments.empty()) {
return DecodedArg(ArgStatus::kMissing, text_);
}
ArgStatus status =
(arguments[0] & 0x80u) == 0u ? ArgStatus::kOk : ArgStatus::kTruncated;
const uint_fast8_t size = arguments[0] & 0x7Fu;
if (arguments.size() - 1 < size) {
status.Update(ArgStatus::kDecodeError);
return DecodedArg(
status,
text_,
arguments.size(),
{reinterpret_cast<const char*>(&arguments[1]), arguments.size() - 1});
}
std::string value(reinterpret_cast<const char*>(&arguments[1]), size);
if (status.HasError(ArgStatus::kTruncated)) {
value.append("[...]");
}
return DecodedArg::FromValue(text_.c_str(), value.c_str(), 1 + size, status);
}
DecodedArg StringSegment::DecodeInteger(
const std::span<const uint8_t>& arguments) const {
if (arguments.empty()) {
return DecodedArg(ArgStatus::kMissing, text_);
}
int64_t value;
const size_t bytes = varint::Decode(std::as_bytes(arguments), &value);
if (bytes == 0u) {
return DecodedArg(ArgStatus::kDecodeError,
text_,
std::min(varint::kMaxVarintSizeBytes, arguments.size()));
}
// Unsigned ints need to be masked to their bit width due to sign extension.
if (type_ == kUnsigned32) {
value &= 0xFFFFFFFFu;
}
if (local_size_ == k32Bit) {
return DecodedArg::FromValue(
text_.c_str(), static_cast<uint32_t>(value), bytes);
}
return DecodedArg::FromValue(text_.c_str(), value, bytes);
}
DecodedArg StringSegment::DecodeFloatingPoint(
const std::span<const uint8_t>& arguments) const {
static_assert(sizeof(float) == 4u);
if (arguments.size() < sizeof(float)) {
return DecodedArg(ArgStatus::kMissing, text_);
}
float value;
std::memcpy(&value, arguments.data(), sizeof(value));
return DecodedArg::FromValue(text_.c_str(), value, sizeof(value));
}
DecodedArg StringSegment::Decode(
const std::span<const uint8_t>& arguments) const {
switch (type_) {
case kLiteral:
return DecodedArg(text_);
case kPercent:
return DecodedArg("%");
case kString:
return DecodeString(arguments);
case kSignedInt:
case kUnsigned32:
case kUnsigned64:
return DecodeInteger(arguments);
case kFloatingPoint:
return DecodeFloatingPoint(arguments);
}
return DecodedArg(ArgStatus::kDecodeError, text_);
}
DecodedArg StringSegment::Skip() const {
switch (type_) {
case kLiteral:
return DecodedArg(text_);
case kPercent:
return DecodedArg("%");
default:
return DecodedArg(ArgStatus::kSkipped, text_);
}
}
std::string DecodedFormatString::value() const {
std::string output;
for (const DecodedArg& arg : segments_) {
output.append(arg.ok() ? arg.value() : arg.spec());
}
return output;
}
std::string DecodedFormatString::value_with_errors() const {
std::string output;
for (const DecodedArg& arg : segments_) {
output.append(arg.value());
}
return output;
}
size_t DecodedFormatString::argument_count() const {
return std::count_if(segments_.begin(), segments_.end(), [](const auto& arg) {
return !arg.spec().empty();
});
}
size_t DecodedFormatString::decoding_errors() const {
return std::count_if(segments_.begin(), segments_.end(), [](const auto& arg) {
return !arg.ok();
});
}
FormatString::FormatString(const char* format) {
const char* text_start = format;
while (format[0] != '\0') {
if (StringSegment spec = StringSegment::ParseFormatSpec(format);
!spec.empty()) {
// Add the text segment seen so far (if any).
if (text_start < format) {
segments_.emplace_back(
std::string_view(text_start, format - text_start));
}
// Move along the index and text segment start.
format += spec.text().size();
text_start = format;
// Add the format specifier that was just found.
segments_.push_back(std::move(spec));
} else {
format += 1;
}
}
if (text_start < format) {
segments_.emplace_back(std::string_view(text_start, format - text_start));
}
}
DecodedFormatString FormatString::Format(
std::span<const uint8_t> arguments) const {
std::vector<DecodedArg> results;
bool skip = false;
for (const auto& segment : segments_) {
if (skip) {
results.push_back(segment.Skip());
} else {
results.push_back(segment.Decode(arguments));
arguments = arguments.subspan(results.back().raw_size_bytes());
// If an error occurred, skip decoding the remaining arguments.
if (!results.back().ok()) {
skip = true;
}
}
}
return DecodedFormatString(std::move(results), arguments.size());
}
} // namespace pw::tokenizer