diff options
Diffstat (limited to 'third_party/jpeg-xl/lib/jxl/toc.cc')
| -rw-r--r-- | third_party/jpeg-xl/lib/jxl/toc.cc | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/third_party/jpeg-xl/lib/jxl/toc.cc b/third_party/jpeg-xl/lib/jxl/toc.cc new file mode 100644 index 0000000000..fd7740c144 --- /dev/null +++ b/third_party/jpeg-xl/lib/jxl/toc.cc @@ -0,0 +1,105 @@ +// Copyright (c) the JPEG XL Project Authors. All rights reserved. +// +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +#include "lib/jxl/toc.h" + +#include <stdint.h> + +#include "lib/jxl/coeff_order.h" +#include "lib/jxl/coeff_order_fwd.h" +#include "lib/jxl/common.h" +#include "lib/jxl/fields.h" + +namespace jxl { +size_t MaxBits(const size_t num_sizes) { + const size_t entry_bits = U32Coder::MaxEncodedBits(kTocDist) * num_sizes; + // permutation bit (not its tokens!), padding, entries, padding. + return 1 + kBitsPerByte + entry_bits + kBitsPerByte; +} + +Status ReadToc(size_t toc_entries, BitReader* JXL_RESTRICT reader, + std::vector<uint32_t>* JXL_RESTRICT sizes, + std::vector<coeff_order_t>* JXL_RESTRICT permutation) { + if (toc_entries > 65536) { + // Prevent out of memory if invalid JXL codestream causes a bogus amount + // of toc_entries such as 2720436919446 to be computed. + // TODO(lode): verify whether 65536 is a reasonable upper bound + return JXL_FAILURE("too many toc entries"); + } + + sizes->clear(); + sizes->resize(toc_entries); + if (reader->TotalBitsConsumed() >= reader->TotalBytes() * kBitsPerByte) { + return JXL_STATUS(StatusCode::kNotEnoughBytes, "Not enough bytes for TOC"); + } + const auto check_bit_budget = [&](size_t num_entries) -> Status { + // U32Coder reads 2 bits to recognize variant and kTocDist cheapest variant + // is Bits(10), this way at least 12 bits are required per toc-entry. + size_t minimal_bit_cost = num_entries * (2 + 10); + size_t bit_budget = reader->TotalBytes() * 8; + size_t expenses = reader->TotalBitsConsumed(); + if ((expenses <= bit_budget) && + (minimal_bit_cost <= bit_budget - expenses)) { + return true; + } + return JXL_STATUS(StatusCode::kNotEnoughBytes, "Not enough bytes for TOC"); + }; + + JXL_DASSERT(toc_entries > 0); + if (reader->ReadFixedBits<1>() == 1) { + JXL_RETURN_IF_ERROR(check_bit_budget(toc_entries)); + permutation->resize(toc_entries); + JXL_RETURN_IF_ERROR(DecodePermutation(/*skip=*/0, toc_entries, + permutation->data(), reader)); + } + JXL_RETURN_IF_ERROR(reader->JumpToByteBoundary()); + JXL_RETURN_IF_ERROR(check_bit_budget(toc_entries)); + for (size_t i = 0; i < toc_entries; ++i) { + (*sizes)[i] = U32Coder::Read(kTocDist, reader); + } + JXL_RETURN_IF_ERROR(reader->JumpToByteBoundary()); + JXL_RETURN_IF_ERROR(check_bit_budget(0)); + return true; +} + +Status ReadGroupOffsets(size_t toc_entries, BitReader* JXL_RESTRICT reader, + std::vector<uint64_t>* JXL_RESTRICT offsets, + std::vector<uint32_t>* JXL_RESTRICT sizes, + uint64_t* total_size) { + std::vector<coeff_order_t> permutation; + JXL_RETURN_IF_ERROR(ReadToc(toc_entries, reader, sizes, &permutation)); + + offsets->clear(); + offsets->resize(toc_entries); + + // Prefix sum starting with 0 and ending with the offset of the last group + uint64_t offset = 0; + for (size_t i = 0; i < toc_entries; ++i) { + if (offset + (*sizes)[i] < offset) { + return JXL_FAILURE("group offset overflow"); + } + (*offsets)[i] = offset; + offset += (*sizes)[i]; + } + if (total_size) { + *total_size = offset; + } + + if (!permutation.empty()) { + std::vector<uint64_t> permuted_offsets; + std::vector<uint32_t> permuted_sizes; + permuted_offsets.reserve(toc_entries); + permuted_sizes.reserve(toc_entries); + for (coeff_order_t index : permutation) { + permuted_offsets.push_back((*offsets)[index]); + permuted_sizes.push_back((*sizes)[index]); + } + std::swap(*offsets, permuted_offsets); + std::swap(*sizes, permuted_sizes); + } + + return true; +} +} // namespace jxl |