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LibCompress: Make CanonicalCode::from_bytes() return ErrorOr<>

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No intended behavior change.
This commit is contained in:
Nico Weber 2023-04-01 19:52:38 -04:00 • committed by Andreas Kling
parent 36ca1386e8
commit 85d0637058
2 changed files with 18 additions and 29 deletions
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45
Userland/Libraries/LibCompress/Deflate.cpp
View file

@ -29,7 +29,7 @@ CanonicalCode const& CanonicalCode::fixed_literal_codes()
if (initialized) if (initialized)
return code; return code;
code = CanonicalCode::from_bytes(fixed_literal_bit_lengths).value(); code = MUST(CanonicalCode::from_bytes(fixed_literal_bit_lengths));
initialized = true; initialized = true;
return code; return code;
@ -43,13 +43,13 @@ CanonicalCode const& CanonicalCode::fixed_distance_codes()
if (initialized) if (initialized)
return code; return code;
code = CanonicalCode::from_bytes(fixed_distance_bit_lengths).value(); code = MUST(CanonicalCode::from_bytes(fixed_distance_bit_lengths));
initialized = true; initialized = true;
return code; return code;
} }
Optional<CanonicalCode> CanonicalCode::from_bytes(ReadonlyBytes bytes) ErrorOr<CanonicalCode> CanonicalCode::from_bytes(ReadonlyBytes bytes)
{ {
// FIXME: I can't quite follow the algorithm here, but it seems to work. // FIXME: I can't quite follow the algorithm here, but it seems to work.
@ -93,7 +93,7 @@ Optional<CanonicalCode> CanonicalCode::from_bytes(ReadonlyBytes bytes)
continue; continue;
if (next_code > start_bit) if (next_code > start_bit)
return {}; return Error::from_string_literal("Failed to decode code lengths");
if (code_length <= CanonicalCode::max_allowed_prefixed_code_length) { if (code_length <= CanonicalCode::max_allowed_prefixed_code_length) {
auto& prefix_code = prefix_codes[number_of_prefix_codes++]; auto& prefix_code = prefix_codes[number_of_prefix_codes++];
@ -114,9 +114,8 @@ Optional<CanonicalCode> CanonicalCode::from_bytes(ReadonlyBytes bytes)
} }
} }
if (next_code != (1 << 15)) { if (next_code != (1 << 15))
return {}; return Error::from_string_literal("Failed to decode code lengths");
}
for (auto [symbol_code, symbol_value, code_length] : prefix_codes) { for (auto [symbol_code, symbol_value, code_length] : prefix_codes) {
if (code_length == 0 || code_length > CanonicalCode::max_allowed_prefixed_code_length) if (code_length == 0 || code_length > CanonicalCode::max_allowed_prefixed_code_length)
@ -428,11 +427,7 @@ ErrorOr<void> DeflateDecompressor::decode_codes(CanonicalCode& literal_code, Opt
// Now we can extract the code that was used to encode the code lengths of the code that was used to // Now we can extract the code that was used to encode the code lengths of the code that was used to
// encode the block. // encode the block.
auto const code_length_code = TRY(CanonicalCode::from_bytes({ code_lengths_code_lengths, sizeof(code_lengths_code_lengths) }));
auto code_length_code_result = CanonicalCode::from_bytes({ code_lengths_code_lengths, sizeof(code_lengths_code_lengths) });
if (!code_length_code_result.has_value())
return Error::from_string_literal("Failed to decode code length code");
auto const code_length_code = code_length_code_result.value();
// Next we extract the code lengths of the code that was used to encode the block. // Next we extract the code lengths of the code that was used to encode the block.
@ -469,11 +464,7 @@ ErrorOr<void> DeflateDecompressor::decode_codes(CanonicalCode& literal_code, Opt
return Error::from_string_literal("Number of code lengths does not match the sum of codes"); return Error::from_string_literal("Number of code lengths does not match the sum of codes");
// Now we extract the code that was used to encode literals and lengths in the block. // Now we extract the code that was used to encode literals and lengths in the block.
literal_code = TRY(CanonicalCode::from_bytes(code_lengths.span().trim(literal_code_count)));
auto literal_code_result = CanonicalCode::from_bytes(code_lengths.span().trim(literal_code_count));
if (!literal_code_result.has_value())
return Error::from_string_literal("Failed to decode the literal code");
literal_code = literal_code_result.value();
// Now we extract the code that was used to encode distances in the block. // Now we extract the code that was used to encode distances in the block.
@ -486,10 +477,7 @@ ErrorOr<void> DeflateDecompressor::decode_codes(CanonicalCode& literal_code, Opt
return Error::from_string_literal("Length for a single distance code is longer than 1"); return Error::from_string_literal("Length for a single distance code is longer than 1");
} }
auto distance_code_result = CanonicalCode::from_bytes(code_lengths.span().slice(literal_code_count)); distance_code = TRY(CanonicalCode::from_bytes(code_lengths.span().slice(literal_code_count)));
if (!distance_code_result.has_value())
return Error::from_string_literal("Failed to decode the distance code");
distance_code = distance_code_result.value();
return {}; return {};
} }
@ -940,11 +928,10 @@ ErrorOr<void> DeflateCompressor::write_dynamic_huffman(CanonicalCode const& lite
TRY(m_output_stream->write_bits(code_lengths_bit_lengths[code_lengths_code_lengths_order[i]], 3)); TRY(m_output_stream->write_bits(code_lengths_bit_lengths[code_lengths_code_lengths_order[i]], 3));
} }
auto code_lengths_code = CanonicalCode::from_bytes(code_lengths_bit_lengths); auto code_lengths_code = MUST(CanonicalCode::from_bytes(code_lengths_bit_lengths));
VERIFY(code_lengths_code.has_value());
for (size_t i = 0; i < encoded_lengths_count; i++) { for (size_t i = 0; i < encoded_lengths_count; i++) {
auto encoded_length = encoded_lengths[i]; auto encoded_length = encoded_lengths[i];
TRY(code_lengths_code->write_symbol(*m_output_stream, encoded_length.symbol)); TRY(code_lengths_code.write_symbol(*m_output_stream, encoded_length.symbol));
if (encoded_length.symbol == deflate_special_code_length_copy) { if (encoded_length.symbol == deflate_special_code_length_copy) {
TRY(m_output_stream->write_bits<u8>(encoded_length.count - 3, 2)); TRY(m_output_stream->write_bits<u8>(encoded_length.count - 3, 2));
} else if (encoded_length.symbol == deflate_special_code_length_zeros) { } else if (encoded_length.symbol == deflate_special_code_length_zeros) {
@ -1037,10 +1024,12 @@ ErrorOr<void> DeflateCompressor::flush()
} else { } else {
// dynamic huffman codes // dynamic huffman codes
TRY(m_output_stream->write_bits(0b10u, 2)); TRY(m_output_stream->write_bits(0b10u, 2));
auto literal_code = CanonicalCode::from_bytes(dynamic_literal_bit_lengths); auto literal_code = MUST(CanonicalCode::from_bytes(dynamic_literal_bit_lengths));
VERIFY(literal_code.has_value()); auto distance_code_or_error = CanonicalCode::from_bytes(dynamic_distance_bit_lengths);
auto distance_code = CanonicalCode::from_bytes(dynamic_distance_bit_lengths); Optional<CanonicalCode> distance_code;
TRY(write_dynamic_huffman(literal_code.value(), literal_code_count, distance_code, distance_code_count, code_lengths_bit_lengths, code_lengths_count, encoded_lengths, encoded_lengths_count)); if (!distance_code_or_error.is_error())
distance_code = distance_code_or_error.release_value();
TRY(write_dynamic_huffman(literal_code, literal_code_count, distance_code, distance_code_count, code_lengths_bit_lengths, code_lengths_count, encoded_lengths, encoded_lengths_count));
} }
if (m_finished) if (m_finished)
TRY(m_output_stream->align_to_byte_boundary()); TRY(m_output_stream->align_to_byte_boundary());

2
Userland/Libraries/LibCompress/Deflate.h
View file

@ -27,7 +27,7 @@ public:
static CanonicalCode const& fixed_literal_codes(); static CanonicalCode const& fixed_literal_codes();
static CanonicalCode const& fixed_distance_codes(); static CanonicalCode const& fixed_distance_codes();
static Optional<CanonicalCode> from_bytes(ReadonlyBytes); static ErrorOr<CanonicalCode> from_bytes(ReadonlyBytes);
private: private:
static constexpr size_t max_allowed_prefixed_code_length = 8; static constexpr size_t max_allowed_prefixed_code_length = 8;