formats/zip/reader_test.cc

// Copyright 2026 Google LLC
//
// 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 "formats/zip/reader.h"

#include <algorithm>
#include <cstdint>
#include <cstdlib>
#include <memory>
#include <optional>
#include <string>
#include <utility>
#include <vector>

#include "absl/status/status.h"
#include "absl/status/status_matchers.h"
#include "absl/strings/str_cat.h"
#include "absl/strings/string_view.h"
#include "formats/byte_range.h"
#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include "riegeli/base/types.h"
#include "riegeli/bytes/cfile_reader.h"
#include "riegeli/bytes/reader.h"
#include "riegeli/bytes/string_reader.h"

namespace credentio {
namespace {

using ::absl_testing::StatusIs;
using ::testing::AllOf;
using ::testing::Contains;
using ::testing::Field;
using ::testing::HasSubstr;

void write_le16(std::string& s, uint16_t val) {
  s.push_back(static_cast<char>(val & 0xff));
  s.push_back(static_cast<char>((val >> 8) & 0xff));
}

void write_le32(std::string& s, uint32_t val) {
  s.push_back(static_cast<char>(val & 0xff));
  s.push_back(static_cast<char>((val >> 8) & 0xff));
  s.push_back(static_cast<char>((val >> 16) & 0xff));
  s.push_back(static_cast<char>((val >> 24) & 0xff));
}

std::string MakeLfh(absl::string_view filename) {
  std::string lfh;
  lfh.append("PK\x03\x04", 4);
  write_le16(lfh, 10);  // version needed
  write_le16(lfh, 0);   // GP flag
  write_le16(lfh, 0);   // comp method
  write_le16(lfh, 0);   // last mod time
  write_le16(lfh, 0);   // last mod date
  write_le32(lfh, 0);   // crc32
  write_le32(lfh, 0);   // compressed size
  write_le32(lfh, 0);   // uncompressed size
  write_le16(lfh, filename.size());
  write_le16(lfh, 0);  // extra field length
  lfh.append(filename);
  return lfh;
}

std::string MakeCdEntry(absl::string_view filename,
                        uint32_t local_header_offset) {
  std::string entry;
  entry.append("PK\x01\x02", 4);
  write_le16(entry, 0);  // version made by
  write_le16(entry, 0);  // version needed
  write_le16(entry, 0);  // GP flag
  write_le16(entry, 0);  // comp method
  write_le16(entry, 0);  // last mod time
  write_le16(entry, 0);  // last mod date
  write_le32(entry, 0);  // crc32
  write_le32(entry, 0);  // compressed size
  write_le32(entry, 0);  // uncompressed size
  write_le16(entry, filename.size());
  write_le16(entry, 0);  // extra field length
  write_le16(entry, 0);  // file comment length
  write_le16(entry, 0);  // disk number start
  write_le16(entry, 0);  // internal attr
  write_le32(entry, 0);  // external attr
  write_le32(entry, local_header_offset);
  entry.append(filename);
  return entry;
}

std::string MakeEocd(uint32_t cd_size, uint32_t cd_offset,
                     uint16_t entry_count) {
  std::string eocd;
  eocd.append("PK\x05\x06", 4);
  write_le16(eocd, 0);            // disk number
  write_le16(eocd, 0);            // disk where CD starts
  write_le16(eocd, entry_count);  // CD records on this disk
  write_le16(eocd, entry_count);  // total CD records
  write_le32(eocd, cd_size);
  write_le32(eocd, cd_offset);
  write_le16(eocd, 0);  // comment length
  return eocd;
}

std::string GetTestDataPath(absl::string_view relative_path) {
  const char* test_srcdir = std::getenv("TEST_SRCDIR");
  const char* test_workspace = std::getenv("TEST_WORKSPACE");
  if (test_srcdir == nullptr || test_workspace == nullptr) {
    return std::string(relative_path);
  }
  return absl::StrCat(test_srcdir, "/", test_workspace, "/", relative_path);
}

constexpr char kEmptyZipFile[] = {
    'P',  'K',  '\5', '\6', '\0', '\0', '\0', '\0', '\0', '\0', '\0',
    '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0',
};

TEST(ZipReaderTest, FileTooSmall) {
  std::string file_contents = "PK\x03\x04\xab\xcd\xab\xcd\xab\xcd";
  riegeli::StringReader<> input(file_contents);

  EXPECT_THAT(ZipReader::Create(&input),
              StatusIs(absl::StatusCode::kInvalidArgument,
                       HasSubstr("Input is too small to be a ZIP file")));
}

TEST(ZipReaderTest, InvalidEocdSignature) {
  std::string file_contents = "PKPKPK12345678901234567890";
  riegeli::StringReader<> input(file_contents);

  EXPECT_THAT(
      ZipReader::Create(&input),
      StatusIs(absl::StatusCode::kInvalidArgument,
               HasSubstr("Invalid End of Central Directory record signature")));
}

TEST(ZipReaderTest, InvalidCentralDirectorySignature) {
  std::string file_contents = std::string(
      "PK\x01\x03"
      "PK\x05\x06"
      "\x00\x00"
      "\x00\x00"
      "\x01\x00"
      "\x01\x00"
      "\x04\x00\x00\x00"
      "\x00\x00\x00\x00"
      "\x00\x00",
      26);
  riegeli::StringReader<> input(file_contents);

  EXPECT_THAT(ZipReader::Create(&input),
              StatusIs(absl::StatusCode::kInvalidArgument,
                       HasSubstr("Central directory signature not found")));
}

TEST(ZipReaderTest, EmptyZipFile) {
  std::string empty_zip_file_contents(kEmptyZipFile, sizeof(kEmptyZipFile));
  riegeli::StringReader<> input(empty_zip_file_contents);
  auto reader_or = ZipReader::Create(&input);
  ABSL_ASSERT_OK(reader_or);
  auto reader = std::move(*reader_or);

  EXPECT_FALSE(reader->HasNext());
}

TEST(ZipReaderTest, Zip64Unsupported) {
  std::string zip = GetTestDataPath(
      "formats/zip/testing/"
      "asset_unsupported_zip64.zip");
  riegeli::CFileReader<> input(zip);
  ABSL_ASSERT_OK(input.status());

  EXPECT_THAT(ZipReader::Create(&input),
              StatusIs(absl::StatusCode::kUnimplemented,
                       HasSubstr("ZIP64 format is not supported")));
}

TEST(ZipReaderTest, DetectsDataDescriptorCorrectly) {
  // clang-format off
  constexpr char kZipWithDataDescriptor[] = {
      // Local File Header
      'P', 'K', '\x03', '\x04',
      '\x00', '\x00',                  // Version needed to extract
      '\x08', '\x00',                  // General purpose bit flag
      '\x00', '\x00',                  // Compression method
      '\x00', '\x00',                  // Last mod file time
      '\x00', '\x00',                  // Last mod file date
      '\x00', '\x00', '\x00', '\x00',  // CRC-32
      '\x00', '\x00', '\x00', '\x00',  // Compressed size
      '\x00', '\x00', '\x00', '\x00',  // Uncompressed size
      '\x01', '\x00',                  // File name length (1 byte)
      '\x00', '\x00',                  // Extra field length
      'a',                             // File name (1 byte)
      // Central Directory Record
      'P', 'K', '\x01', '\x02',
      '\x00', '\x00',                  // Version made by
      '\x00', '\x00',                  // Version needed to extract
      '\x08', '\x00',                  // General purpose bit flag (Bit 3 set)
      '\x00', '\x00',                  // Compression method
      '\x00', '\x00',                  // Last mod file time
      '\x00', '\x00',                  // Last mod file date
      '\x00', '\x00', '\x00', '\x00',  // CRC-32
      '\x00', '\x00', '\x00', '\x00',  // Compressed size
      '\x00', '\x00', '\x00', '\x00',  // Uncompressed size
      '\x01', '\x00',                  // File name length (1 byte)
      '\x00', '\x00',                  // Extra field length
      '\x00', '\x00',                  // File comment length
      '\x00', '\x00',                  // Disk number start
      '\x00', '\x00',                  // Internal file attributes
      '\x00', '\x00', '\x00', '\x00',  // External file attributes
      '\x00', '\x00', '\x00', '\x00',  // Relative offset of local header
      'a',                             // File name (1 byte)
      // End of central directory record (EOCD)
      'P', 'K', '\x05', '\x06',
      '\x00', '\x00',                  // Number of this disk
      '\x00', '\x00',                  // Disk where CD starts
      '\x01', '\x00',                  // Number of CD records on this disk
      '\x01', '\x00',                  // Total number of CD records
      '\x2f', '\x00', '\x00', '\x00',  // Size of CD (47 bytes)
      '\x1f', '\x00', '\x00', '\x00',  // Offset of start of CD (31 bytes)
      '\x00', '\x00',                  // ZIP file comment length (0 bytes)
  };
  // clang-format on
  std::string zip_contents(kZipWithDataDescriptor,
                           sizeof(kZipWithDataDescriptor));
  riegeli::StringReader<> input(zip_contents);
  auto reader_or = ZipReader::Create(&input);
  ABSL_ASSERT_OK(reader_or);
  auto reader = std::move(*reader_or);

  ASSERT_TRUE(reader->HasNext());
  auto entry_or = reader->Next();
  ABSL_ASSERT_OK(entry_or);
  auto entry = std::move(*entry_or);

  EXPECT_TRUE(entry.has_data_descriptor);
}

TEST(ZipReaderTest, ReadsZipFile) {
  std::string zip = GetTestDataPath("formats/zip/testing/asset_no_c2pa.zip");
  riegeli::CFileReader<> input(zip);
  ABSL_ASSERT_OK(input.status());
  auto reader_or = ZipReader::Create(&input);
  ABSL_ASSERT_OK(reader_or);
  auto reader = std::move(*reader_or);

  std::vector<ZipReader::FileEntry> entries;
  while (reader->HasNext()) {
    auto entry_or = reader->Next();
    ABSL_ASSERT_OK(entry_or);
    entries.push_back(std::move(*entry_or));
  }

  EXPECT_THAT(entries,
              testing::UnorderedElementsAre(
                  ZipReader::FileEntry{
                      .central_directory_header_offset = 139,
                      .local_file_header_offset = 0,
                      .file_name = "file_1.txt",
                      .file_range = ByteRange{.offset = 40, .length = 44},
                      .has_data_descriptor = false,
                      .general_purpose_bit_flag = 0,
                      .compression_method = 0,
                      .uncompressed_size = 44,
                  },
                  ZipReader::FileEntry{
                      .central_directory_header_offset = 195,
                      .local_file_header_offset = 84,
                      .file_name = "file_2.txt",
                      .file_range = ByteRange{.offset = 124, .length = 15},
                      .has_data_descriptor = false,
                      .general_purpose_bit_flag = 0,
                      .compression_method = 0,
                      .uncompressed_size = 15,
                  }));
  EXPECT_THAT(reader->Next(),
              StatusIs(absl::StatusCode::kOutOfRange,
                       HasSubstr("No more file entries to read")));
}

TEST(ZipReaderTest, ReadsPptxFile) {
  std::string pptx =
      GetTestDataPath("formats/zip/testing/no_c2pa_032_asset.pptx");
  riegeli::CFileReader<> input(pptx);
  ABSL_ASSERT_OK(input.status());
  auto reader_or = ZipReader::Create(&input);
  ABSL_ASSERT_OK(reader_or);
  auto reader = std::move(*reader_or);

  std::vector<ZipReader::FileEntry> entries;
  while (reader->HasNext()) {
    auto entry_or = reader->Next();
    ABSL_ASSERT_OK(entry_or);
    entries.push_back(std::move(*entry_or));
  }

  EXPECT_EQ(entries.size(), 46);
  // OOXML files should have a [Content_Types].xml file entry with a data
  // descriptor.
  EXPECT_THAT(
      entries,
      Contains(
          AllOf(Field(&ZipReader::FileEntry::file_name, "[Content_Types].xml"),
                Field(&ZipReader::FileEntry::has_data_descriptor, true))));
}

TEST(ZipReaderTest, CentralDirectoryOffsetEmptyZip) {
  std::string empty_zip_file_contents(kEmptyZipFile, sizeof(kEmptyZipFile));
  riegeli::StringReader<> input(empty_zip_file_contents);
  auto reader_or = ZipReader::Create(&input);
  ABSL_ASSERT_OK(reader_or);
  auto reader = std::move(*reader_or);

  EXPECT_EQ(reader->central_directory_offset(), 0);
}

TEST(ZipReaderTest, CentralDirectoryOffset) {
  std::string zip = GetTestDataPath("formats/zip/testing/asset_no_c2pa.zip");
  riegeli::CFileReader<> input(zip);
  ABSL_ASSERT_OK(input.status());
  auto reader_or = ZipReader::Create(&input);
  ABSL_ASSERT_OK(reader_or);
  auto reader = std::move(*reader_or);

  EXPECT_EQ(reader->central_directory_offset(), 139);
}

TEST(ZipReaderTest, LocalFileHeaderExtraFieldMismatchRejected) {
  std::string zip;
  // Local File Header for file_1.txt
  zip.append("PK\x03\x04", 4);
  write_le16(zip, 10);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 10);
  write_le32(zip, 10);
  std::string filename = "file_1.txt";
  write_le16(zip, filename.size());
  write_le16(zip, 8);  // LFH Extra field length = 8!
  zip.append(filename);
  zip.append("12345678");    // LFH Extra field data
  zip.append("abcdefghij");  // Actual file data (10 bytes)

  uint32_t cd_offset = zip.size();
  // Central Directory Record for file_1.txt
  zip.append("PK\x01\x02", 4);
  write_le16(zip, 10);
  write_le16(zip, 10);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 10);
  write_le32(zip, 10);
  write_le16(zip, filename.size());
  write_le16(zip, 0);  // CD Extra field length = 0! Mismatched!
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 0);
  zip.append(filename);

  uint32_t cd_size = zip.size() - cd_offset;
  // End of Central Directory (EOCD)
  zip.append("PK\x05\x06", 4);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 1);
  write_le16(zip, 1);
  write_le32(zip, cd_size);
  write_le32(zip, cd_offset);
  write_le16(zip, 0);

  riegeli::StringReader<> input(zip);
  EXPECT_THAT(
      ZipReader::Create(&input),
      StatusIs(absl::StatusCode::kInvalidArgument,
               HasSubstr("Local File Header extra field length does not match "
                         "Central Directory")));
}

TEST(ZipReaderTest, LocalFileHeaderInvalidSignatureRejected) {
  std::string zip;
  // Local File Header with corrupted signature
  zip.append("PK\x03\x05", 4);  // PK\x03\x05 instead of PK\x03\x04!
  write_le16(zip, 10);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 10);
  write_le32(zip, 10);
  std::string filename = "file_1.txt";
  write_le16(zip, filename.size());
  write_le16(zip, 0);
  zip.append(filename);
  zip.append("abcdefghij");

  uint32_t cd_offset = zip.size();
  // Central Directory Record
  zip.append("PK\x01\x02", 4);
  write_le16(zip, 10);
  write_le16(zip, 10);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 10);
  write_le32(zip, 10);
  write_le16(zip, filename.size());
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 0);  // Local Header Offset = 0
  zip.append(filename);

  uint32_t cd_size = zip.size() - cd_offset;
  // End of Central Directory (EOCD)
  zip.append("PK\x05\x06", 4);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 1);
  write_le16(zip, 1);
  write_le32(zip, cd_size);
  write_le32(zip, cd_offset);
  write_le16(zip, 0);

  riegeli::StringReader<> input(zip);
  EXPECT_THAT(ZipReader::Create(&input),
              StatusIs(absl::StatusCode::kInvalidArgument,
                       HasSubstr("Invalid local file header signature")));
}

TEST(ZipReaderTest, LocalFileHeaderSeekFailureRejected) {
  std::string zip;
  // No LFH at offset 0 (we start with CD)
  uint32_t cd_offset = zip.size();
  std::string filename = "file_1.txt";
  // Central Directory Record
  zip.append("PK\x01\x02", 4);
  write_le16(zip, 10);
  write_le16(zip, 10);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 10);
  write_le32(zip, 10);
  write_le16(zip, filename.size());
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 9999);  // Local Header Offset points to invalid offset 9999!
  zip.append(filename);

  uint32_t cd_size = zip.size() - cd_offset;
  // End of Central Directory (EOCD)
  zip.append("PK\x05\x06", 4);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 1);
  write_le16(zip, 1);
  write_le32(zip, cd_size);
  write_le32(zip, cd_offset);
  write_le16(zip, 0);

  riegeli::StringReader<> input(zip);
  EXPECT_THAT(
      ZipReader::Create(&input),
      StatusIs(absl::StatusCode::kInvalidArgument,
               HasSubstr("Failed to seek to local file header offset")));
}

TEST(ZipReaderTest, VulnerabilityZipEntryOverlapDetected) {
  auto write_le16 = [](std::string& s, uint16_t val) {
    s.push_back(static_cast<char>(val & 0xff));
    s.push_back(static_cast<char>((val >> 8) & 0xff));
  };
  auto write_le32 = [](std::string& s, uint32_t val) {
    s.push_back(static_cast<char>(val & 0xff));
    s.push_back(static_cast<char>((val >> 8) & 0xff));
    s.push_back(static_cast<char>((val >> 16) & 0xff));
    s.push_back(static_cast<char>((val >> 24) & 0xff));
  };

  std::string zip;
  std::string filename = "file_1.txt";
  // Local File Header at offset 0
  zip.append("PK\x03\x04", 4);
  write_le16(zip, 10);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 10);
  write_le32(zip, 10);
  write_le16(zip, filename.size());
  write_le16(zip, 0);
  zip.append(filename);
  zip.append("0123456789", 10);

  uint32_t cd_offset = zip.size();
  // Central Directory Record 1 pointing to offset 0
  zip.append("PK\x01\x02", 4);
  write_le16(zip, 10);
  write_le16(zip, 10);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 10);
  write_le32(zip, 10);
  write_le16(zip, filename.size());
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 0);
  zip.append(filename);

  // Central Directory Record 2 duplicates offset 0 (overlapping/duplicate)
  zip.append("PK\x01\x02", 4);
  write_le16(zip, 10);
  write_le16(zip, 10);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 10);
  write_le32(zip, 10);
  write_le16(zip, filename.size());
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 0);
  zip.append(filename);

  uint32_t cd_size = zip.size() - cd_offset;
  // End of Central Directory (EOCD)
  zip.append("PK\x05\x06", 4);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 2);
  write_le16(zip, 2);
  write_le32(zip, cd_size);
  write_le32(zip, cd_offset);
  write_le16(zip, 0);

  riegeli::StringReader<> input(zip);
  EXPECT_THAT(
      ZipReader::Create(&input),
      StatusIs(absl::StatusCode::kInvalidArgument,
               HasSubstr("Overlapping or duplicate ZIP entries detected")));
}

TEST(ZipReaderTest, CompressedSizeExceedsFileLimitsRejected) {
  auto write_le16 = [](std::string& s, uint16_t val) {
    s.push_back(static_cast<char>(val & 0xff));
    s.push_back(static_cast<char>((val >> 8) & 0xff));
  };
  auto write_le32 = [](std::string& s, uint32_t val) {
    s.push_back(static_cast<char>(val & 0xff));
    s.push_back(static_cast<char>((val >> 8) & 0xff));
    s.push_back(static_cast<char>((val >> 16) & 0xff));
    s.push_back(static_cast<char>((val >> 24) & 0xff));
  };

  std::string zip;
  // Local File Header for file_1.txt
  zip.append("PK\x03\x04", 4);
  write_le16(zip, 10);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 10);
  write_le32(zip, 10);
  std::string filename = "file_1.txt";
  write_le16(zip, filename.size());
  write_le16(zip, 0);
  zip.append(filename);
  zip.append("abcdefghij");

  uint32_t cd_offset = zip.size();
  // Central Directory Record for file_1.txt
  zip.append("PK\x01\x02", 4);
  write_le16(zip, 10);
  write_le16(zip, 10);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 0x7FFFFFFF);  // CD Compressed size exceeds file size
  write_le32(zip, 10);
  write_le16(zip, filename.size());
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 0);
  zip.append(filename);

  uint32_t cd_size = zip.size() - cd_offset;
  // End of Central Directory (EOCD)
  zip.append("PK\x05\x06", 4);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 1);
  write_le16(zip, 1);
  write_le32(zip, cd_size);
  write_le32(zip, cd_offset);
  write_le16(zip, 0);

  riegeli::StringReader<> input(zip);
  EXPECT_THAT(ZipReader::Create(&input),
              StatusIs(absl::StatusCode::kInvalidArgument,
                       HasSubstr("Compressed size exceeds file limits")));
}

class MockLargeZipReader : public riegeli::Reader {
 public:
  MockLargeZipReader(std::string lfh1, std::string lfh2, std::string cd,
                     std::string eocd, uint64_t lfh2_offset, uint64_t cd_offset,
                     uint64_t eocd_offset)
      : lfh1_(lfh1),
        lfh2_(lfh2),
        cd_(cd),
        eocd_(eocd),
        lfh2_offset_(lfh2_offset),
        cd_offset_(cd_offset),
        eocd_offset_(eocd_offset),
        size_(eocd_offset + eocd.size()) {
    set_limit_pos(0);
  }

  bool SupportsRandomAccess() override { return true; }
  bool SupportsSize() override { return true; }

 protected:
  bool PullSlow(size_t min_length, size_t recommended_length) override {
    uint64_t current_pos = pos();
    if (current_pos >= size_) return false;

    if (current_pos < lfh1_.size()) {
      set_buffer(lfh1_.data(), lfh1_.size(), current_pos);
      set_limit_pos(lfh1_.size());
      return true;
    }
    if (current_pos >= lfh2_offset_ &&
        current_pos < lfh2_offset_ + lfh2_.size()) {
      set_buffer(lfh2_.data(), lfh2_.size(), current_pos - lfh2_offset_);
      set_limit_pos(lfh2_offset_ + lfh2_.size());
      return true;
    }
    if (current_pos >= cd_offset_ && current_pos < cd_offset_ + cd_.size()) {
      set_buffer(cd_.data(), cd_.size(), current_pos - cd_offset_);
      set_limit_pos(cd_offset_ + cd_.size());
      return true;
    }
    if (current_pos >= eocd_offset_ &&
        current_pos < eocd_offset_ + eocd_.size()) {
      set_buffer(eocd_.data(), eocd_.size(), current_pos - eocd_offset_);
      set_limit_pos(eocd_offset_ + eocd_.size());
      return true;
    }

    // Gap handling
    uint64_t next_offset = size_;
    if (current_pos < lfh2_offset_) {
      next_offset = lfh2_offset_;
    } else if (current_pos < cd_offset_) {
      next_offset = cd_offset_;
    } else if (current_pos < eocd_offset_) {
      next_offset = eocd_offset_;
    }

    uint64_t remaining = next_offset - current_pos;
    size_t chunk =
        std::min(sizeof(kZeroBuffer), static_cast<size_t>(remaining));
    set_buffer(kZeroBuffer, chunk, 0);
    set_limit_pos(current_pos + chunk);
    return true;
  }

  bool SeekSlow(riegeli::Position new_pos) override {
    if (new_pos > size_) {
      set_buffer();
      set_limit_pos(size_);
      return false;
    }
    set_buffer();
    set_limit_pos(new_pos);
    return true;
  }

  std::optional<riegeli::Position> SizeImpl() override { return size_; }

 private:
  static constexpr char kZeroBuffer[1024] = {0};

  std::string lfh1_;
  std::string lfh2_;
  std::string cd_;
  std::string eocd_;
  uint64_t lfh2_offset_;
  uint64_t cd_offset_;
  uint64_t eocd_offset_;
  uint64_t size_;
};

TEST(ZipReaderTest, LargeZipFile) {
  // We want to test that ZipReader can handle file entries that start after
  // 4GB. We construct a mock ZIP file layout:
  // - LFH1 at 0 (size 40)
  // - Large file data of size 4294967063 (approx 4GB)
  // - LFH2 at 4294967103 (size 43)
  // - File 2 (manifest) data of size 100
  // - CD at 4294967250 (starts before 4GB, ends after 4GB)
  //   - CD Entry 1 (for large_file) starts at 4294967250, size 56.
  //   - CD Entry 2 (for manifest.json) starts at 4294967306 (after 4GB!),
  //   size 59.
  // - EOCD at 4294967365 (size 22)
  // Total size = 4294967387.

  std::string filename1 = "large_file";
  std::string filename2 = "manifest.json";

  std::string lfh1 = MakeLfh(filename1);
  std::string lfh2 = MakeLfh(filename2);

  uint64_t lfh2_offset = 4294967103;
  uint64_t cd_offset = 4294967250;

  std::string cd_entry1 = MakeCdEntry(filename1, 0);
  std::string cd_entry2 = MakeCdEntry(filename2, lfh2_offset);
  std::string cd = cd_entry1 + cd_entry2;

  uint64_t eocd_offset = cd_offset + cd.size();
  std::string eocd = MakeEocd(cd.size(), cd_offset, 2);

  MockLargeZipReader input(lfh1, lfh2, cd, eocd, lfh2_offset, cd_offset,
                           eocd_offset);

  auto reader_or = ZipReader::Create(&input);
  ABSL_ASSERT_OK(reader_or);
  auto reader = std::move(*reader_or);

  std::vector<ZipReader::FileEntry> entries;
  while (reader->HasNext()) {
    auto entry_or = reader->Next();
    ABSL_ASSERT_OK(entry_or);
    entries.push_back(std::move(*entry_or));
  }

  EXPECT_THAT(
      entries,
      testing::UnorderedElementsAre(
          ZipReader::FileEntry{
              .central_directory_header_offset = cd_offset,
              .local_file_header_offset = 0,
              .file_name = filename1,
              .file_range = ByteRange{.offset = 40, .length = 0},
              .has_data_descriptor = false,
          },
          ZipReader::FileEntry{
              .central_directory_header_offset = cd_offset + cd_entry1.size(),
              .local_file_header_offset = lfh2_offset,
              .file_name = filename2,
              .file_range =
                  ByteRange{.offset = lfh2_offset + 30 + filename2.size(),
                            .length = 0},
              .has_data_descriptor = false,
          }));
}

TEST(ZipReaderTest, LocalFileHeaderSizeMismatchRejected) {
  auto write_le16 = [](std::string& s, uint16_t val) {
    s.push_back(static_cast<char>(val & 0xff));
    s.push_back(static_cast<char>((val >> 8) & 0xff));
  };
  auto write_le32 = [](std::string& s, uint32_t val) {
    s.push_back(static_cast<char>(val & 0xff));
    s.push_back(static_cast<char>((val >> 8) & 0xff));
    s.push_back(static_cast<char>((val >> 16) & 0xff));
    s.push_back(static_cast<char>((val >> 24) & 0xff));
  };

  std::string zip;
  // Local File Header with compressed_size = 999
  zip.append("PK\x03\x04", 4);
  write_le16(zip, 10);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 999);  // LFH compressed size = 999!
  write_le32(zip, 10);
  std::string filename = "file_1.txt";
  write_le16(zip, filename.size());
  write_le16(zip, 0);
  zip.append(filename);
  zip.append("abcdefghij");

  uint32_t cd_offset = zip.size();
  // Central Directory Record with compressed_size = 10
  zip.append("PK\x01\x02", 4);
  write_le16(zip, 10);
  write_le16(zip, 10);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 10);  // CD compressed size = 10!
  write_le32(zip, 10);
  write_le16(zip, filename.size());
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 0);
  zip.append(filename);

  uint32_t cd_size = zip.size() - cd_offset;
  zip.append("PK\x05\x06", 4);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 1);
  write_le16(zip, 1);
  write_le32(zip, cd_size);
  write_le32(zip, cd_offset);
  write_le16(zip, 0);

  riegeli::StringReader<> input(zip);
  EXPECT_THAT(ZipReader::Create(&input),
              StatusIs(absl::StatusCode::kInvalidArgument,
                       HasSubstr("Local File Header sizes do not match Central "
                                 "Directory")));
}

TEST(ZipReaderTest, LocalFileHeaderFileNameLengthMismatchRejected) {
  auto write_le16 = [](std::string& s, uint16_t val) {
    s.push_back(static_cast<char>(val & 0xff));
    s.push_back(static_cast<char>((val >> 8) & 0xff));
  };
  auto write_le32 = [](std::string& s, uint32_t val) {
    s.push_back(static_cast<char>(val & 0xff));
    s.push_back(static_cast<char>((val >> 8) & 0xff));
    s.push_back(static_cast<char>((val >> 16) & 0xff));
    s.push_back(static_cast<char>((val >> 24) & 0xff));
  };

  std::string zip;
  zip.append("PK\x03\x04", 4);
  write_le16(zip, 10);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 10);
  write_le32(zip, 10);
  std::string filename = "file_1.txt";
  write_le16(zip, filename.size() + 5);  // LFH filename length mismatched!
  write_le16(zip, 0);
  zip.append(filename);
  zip.append("abcdefghij");

  uint32_t cd_offset = zip.size();
  zip.append("PK\x01\x02", 4);
  write_le16(zip, 10);
  write_le16(zip, 10);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 10);
  write_le32(zip, 10);
  write_le16(zip, filename.size());
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 0);
  zip.append(filename);

  uint32_t cd_size = zip.size() - cd_offset;
  zip.append("PK\x05\x06", 4);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 1);
  write_le16(zip, 1);
  write_le32(zip, cd_size);
  write_le32(zip, cd_offset);
  write_le16(zip, 0);

  riegeli::StringReader<> input(zip);
  EXPECT_THAT(
      ZipReader::Create(&input),
      StatusIs(absl::StatusCode::kInvalidArgument,
               HasSubstr("Local File Header file name length does not match "
                         "Central Directory")));
}

TEST(ZipReaderTest, LocalFileHeaderBitFlagMismatchRejected) {
  auto write_le16 = [](std::string& s, uint16_t val) {
    s.push_back(static_cast<char>(val & 0xff));
    s.push_back(static_cast<char>((val >> 8) & 0xff));
  };
  auto write_le32 = [](std::string& s, uint32_t val) {
    s.push_back(static_cast<char>(val & 0xff));
    s.push_back(static_cast<char>((val >> 8) & 0xff));
    s.push_back(static_cast<char>((val >> 16) & 0xff));
    s.push_back(static_cast<char>((val >> 24) & 0xff));
  };

  std::string zip;
  zip.append("PK\x03\x04", 4);
  write_le16(zip, 10);
  write_le16(zip, 0x0800);  // LFH has UTF-8 flag set
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 10);
  write_le32(zip, 10);
  std::string filename = "file_1.txt";
  write_le16(zip, filename.size());
  write_le16(zip, 0);
  zip.append(filename);
  zip.append("abcdefghij");

  uint32_t cd_offset = zip.size();
  zip.append("PK\x01\x02", 4);
  write_le16(zip, 10);
  write_le16(zip, 10);
  write_le16(zip, 0);  // CD bit flag is 0
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 10);
  write_le32(zip, 10);
  write_le16(zip, filename.size());
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 0);
  zip.append(filename);

  uint32_t cd_size = zip.size() - cd_offset;
  zip.append("PK\x05\x06", 4);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 1);
  write_le16(zip, 1);
  write_le32(zip, cd_size);
  write_le32(zip, cd_offset);
  write_le16(zip, 0);

  riegeli::StringReader<> input(zip);
  EXPECT_THAT(
      ZipReader::Create(&input),
      StatusIs(absl::StatusCode::kInvalidArgument,
               HasSubstr("Local File Header bit flag does not match Central "
                         "Directory")));
}

TEST(ZipReaderTest, LocalFileHeaderCompressionMethodMismatchRejected) {
  auto write_le16 = [](std::string& s, uint16_t val) {
    s.push_back(static_cast<char>(val & 0xff));
    s.push_back(static_cast<char>((val >> 8) & 0xff));
  };
  auto write_le32 = [](std::string& s, uint32_t val) {
    s.push_back(static_cast<char>(val & 0xff));
    s.push_back(static_cast<char>((val >> 8) & 0xff));
    s.push_back(static_cast<char>((val >> 16) & 0xff));
    s.push_back(static_cast<char>((val >> 24) & 0xff));
  };

  std::string zip;
  zip.append("PK\x03\x04", 4);
  write_le16(zip, 10);
  write_le16(zip, 0);
  write_le16(zip, 8);  // LFH compression method = 8
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 10);
  write_le32(zip, 10);
  std::string filename = "file_1.txt";
  write_le16(zip, filename.size());
  write_le16(zip, 0);
  zip.append(filename);
  zip.append("abcdefghij");

  uint32_t cd_offset = zip.size();
  zip.append("PK\x01\x02", 4);
  write_le16(zip, 10);
  write_le16(zip, 10);
  write_le16(zip, 0);
  write_le16(zip, 0);  // CD compression method = 0
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 10);
  write_le32(zip, 10);
  write_le16(zip, filename.size());
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 0);
  zip.append(filename);

  uint32_t cd_size = zip.size() - cd_offset;
  zip.append("PK\x05\x06", 4);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 1);
  write_le16(zip, 1);
  write_le32(zip, cd_size);
  write_le32(zip, cd_offset);
  write_le16(zip, 0);

  riegeli::StringReader<> input(zip);
  EXPECT_THAT(
      ZipReader::Create(&input),
      StatusIs(absl::StatusCode::kInvalidArgument,
               HasSubstr("Local File Header compression method does not match "
                         "Central Directory")));
}

TEST(ZipReaderTest, LocalFileHeaderTruncatedRejected) {
  auto write_le16 = [](std::string& s, uint16_t val) {
    s.push_back(static_cast<char>(val & 0xff));
    s.push_back(static_cast<char>((val >> 8) & 0xff));
  };
  auto write_le32 = [](std::string& s, uint32_t val) {
    s.push_back(static_cast<char>(val & 0xff));
    s.push_back(static_cast<char>((val >> 8) & 0xff));
    s.push_back(static_cast<char>((val >> 16) & 0xff));
    s.push_back(static_cast<char>((val >> 24) & 0xff));
  };

  std::string zip;
  uint32_t cd_offset = 0;
  std::string filename = "file_1.txt";

  // CD Record at offset 0
  zip.append("PK\x01\x02", 4);
  write_le16(zip, 10);
  write_le16(zip, 10);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);
  write_le32(zip, 10);
  write_le32(zip, 10);
  write_le16(zip, filename.size());
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le32(zip, 0);

  uint32_t lfh_offset = 46 + filename.size() + 12;  // Offset 12 inside EOCD
  write_le32(zip, lfh_offset);
  zip.append(filename);

  // EOCD Record
  zip.append("PK\x05\x06", 4);
  write_le16(zip, 0);
  write_le16(zip, 0);
  write_le16(zip, 1);
  write_le16(zip, 1);
  zip.append("PK\x03\x04", 4);  // Size of CD field serves as fake LFH signature
  write_le32(zip, cd_offset);   // Offset of CD = 0 (serves as flags = 0)
  write_le16(zip, 0);  // Comment length = 0 (serves as comp method = 0)

  riegeli::StringReader<> input(zip);
  EXPECT_THAT(
      ZipReader::Create(&input),
      StatusIs(absl::StatusCode::kInvalidArgument,
               HasSubstr("Failed to skip fields in local file header")));
}

}  // namespace
}  // namespace credentio