text: // Copyright 2015 The Bazel Authors. All rights reserved.
  //
  // 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
  //
  //    http://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.
  //
  // zip.cc -- .zip (.jar) file reading/writing routines.
  //
  
  // See README.txt for details.
  //
  // See http://www.pkware.com/documents/casestudies/APPNOTE.TXT
  // for definition of PKZIP file format.
  
  #define _FILE_OFFSET_BITS 64  // Support zip files larger than 2GB
  
  #include <errno.h>
  #include <fcntl.h>
  #include <stddef.h>
  #include <stdint.h>
  #include <stdarg.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <limits.h>
  #include <limits>
  #include <vector>
  
  #include "third_party/ijar/mapped_file.h"
  #include "third_party/ijar/platform_utils.h"
  #include "third_party/ijar/zip.h"
  #include "third_party/ijar/zlib_client.h"
  
  #define LOCAL_FILE_HEADER_SIGNATURE   0x04034b50
  #define CENTRAL_FILE_HEADER_SIGNATURE 0x02014b50
  #define DIGITAL_SIGNATURE             0x05054b50
  #define ZIP64_EOCD_SIGNATURE          0x06064b50
  #define ZIP64_EOCD_LOCATOR_SIGNATURE  0x07064b50
  #define EOCD_SIGNATURE                0x06054b50
  #define DATA_DESCRIPTOR_SIGNATURE     0x08074b50
  
  #define U2_MAX 0xffff
  #define U4_MAX 0xffffffffUL
  
  #define ZIP64_EOCD_LOCATOR_SIZE 20
  // zip64 eocd is fixed size in the absence of a zip64 extensible data sector
  #define ZIP64_EOCD_FIXED_SIZE 56
  
  // version to extract: 1.0 - default value from APPNOTE.TXT.
  // Output JAR files contain no extra ZIP features, so this is enough.
  #define ZIP_VERSION_TO_EXTRACT                10
  #define COMPRESSION_METHOD_STORED             0   // no compression
  #define COMPRESSION_METHOD_DEFLATED           8
  
  #define GENERAL_PURPOSE_BIT_FLAG_COMPRESSED (1 << 3)
  #define GENERAL_PURPOSE_BIT_FLAG_UTF8_ENCODED (1 << 11)
  #define GENERAL_PURPOSE_BIT_FLAG_COMPRESSION_SPEED ((1 << 2) | (1 << 1))
  #define GENERAL_PURPOSE_BIT_FLAG_SUPPORTED \
    (GENERAL_PURPOSE_BIT_FLAG_COMPRESSED \
    | GENERAL_PURPOSE_BIT_FLAG_UTF8_ENCODED \
    | GENERAL_PURPOSE_BIT_FLAG_COMPRESSION_SPEED)
  
  namespace devtools_ijar {
  // In the absence of ZIP64 support, zip files are limited to 4GB.
  // http://www.info-zip.org/FAQ.html#limits
  static const size_t kMaximumOutputSize = std::numeric_limits<uint32_t>::max();
  
  static const u4 kDefaultTimestamp =
      30 << 25 | 1 << 21 | 1 << 16;  // January 1, 2010 in DOS time
  
  //
  // A class representing a ZipFile for reading. Its public API is exposed
  // using the ZipExtractor abstract class.
  //
  class InputZipFile : public ZipExtractor {
   public:
    InputZipFile(ZipExtractorProcessor *processor, const char* filename);
    virtual ~InputZipFile();
  
    virtual const char* GetError() {
      if (errmsg[0] == 0) {
        return NULL;
      }
      return errmsg;
    }
  
    bool Open();
    virtual bool ProcessNext();
    virtual void Reset();
    virtual size_t GetSize() {
      return input_file_->Length();
    }
  
    virtual u8 CalculateOutputLength();
  
    virtual bool ProcessCentralDirEntry(const u1 *&p, size_t *compressed_size,
                                        size_t *uncompressed_size, char *filename,
                                        size_t filename_size, u4 *attr,
                                        u4 *offset);
  
   private:
    ZipExtractorProcessor *processor;
    const char* filename_;
    MappedInputFile *input_file_;
  
    // InputZipFile is responsible for maintaining the following
    // pointers. They are allocated by the Create() method before
    // the object is actually created using mmap.
    const u1 * zipdata_in_;   // start of input file mmap
    size_t bytes_unmapped_;         // bytes that have already been unmapped
    const u1 * central_dir_;  // central directory in input file
  
    size_t in_offset_;  // offset  the input file
  
    const u1 *p;  // input cursor
  
    const u1* central_dir_current_;  // central dir input cursor
  
    // Buffer size is initially INITIAL_BUFFER_SIZE. It doubles in size every
    // time it is found too small, until it reaches MAX_BUFFER_SIZE. If that is
    // not enough, we bail out. We only decompress class files, so they should
    // be smaller than 64K anyway, but we give a little leeway.
    // MAX_BUFFER_SIZE must be bigger than the size of the biggest file in the
    // ZIP. It is set to 2GB here because no one has audited the code for 64-bit
    // cleanliness.
    static const size_t INITIAL_BUFFER_SIZE = 256 * 1024;  // 256K
    static const size_t MAX_BUFFER_SIZE = std::numeric_limits<int32_t>::max();
    static const size_t MAX_MAPPED_REGION = 32 * 1024 * 1024;
  
    // These metadata fields are the fields of the ZIP header of the file being
    // processed.
    u2 extract_version_;
    u2 general_purpose_bit_flag_;
    u2 compression_method_;
    u4 uncompressed_size_;
    u4 compressed_size_;
    u2 file_name_length_;
    u2 extra_field_length_;
    const u1 *file_name_;
    const u1 *extra_field_;
  
    // Copy of the last filename entry - Null-terminated.
    char filename[PATH_MAX];
    // The external file attribute field
    u4 attr;
  
    // last error
    char errmsg[4*PATH_MAX];
  
    Decompressor *decompressor_;
  
    int error(const char *fmt, ...) {
      va_list ap;
      va_start(ap, fmt);
      vsnprintf(errmsg, 4*PATH_MAX, fmt, ap);
      va_end(ap);
      return -1;
    }
  
    // Check that at least n bytes remain in the input file, otherwise
    // abort with an error message.  "state" is the name of the field
    // we're about to read, for diagnostics.
    int EnsureRemaining(size_t n, const char *state) {
      size_t in_offset = p - zipdata_in_;
      size_t remaining = input_file_->Length() - in_offset;
      if (n > remaining) {
        return error("Premature end of file (at offset %zd, state=%s); "
                     "expected %zd more bytes but found %zd.\n",
                     in_offset, state, n, remaining);
      }
      return 0;
    }
  
    // Read one entry from input zip file
    int ProcessLocalFileEntry(size_t compressed_size, size_t uncompressed_size);
  
    // Uncompress a file from the archive using zlib. The pointer returned
    // is owned by InputZipFile, so it must not be freed. Advances the input
    // cursor to the first byte after the compressed data.
    u1* UncompressFile();
  
    // Skip a file
    int SkipFile(const bool compressed);
  
    // Process a file
    int ProcessFile(const bool compressed);
  };
  
  //
  // A class implementing ZipBuilder that represent an open zip file for writing.
  //
  class OutputZipFile : public ZipBuilder {
   public:
    OutputZipFile(const char *filename, size_t estimated_size)
        : output_file_(NULL),
          filename_(filename),
          estimated_size_(estimated_size),
          finished_(false) {
      errmsg[0] = 0;
    }
  
    virtual const char* GetError() {
      if (errmsg[0] == 0) {
        return NULL;
      }
      return errmsg;
    }
  
    virtual ~OutputZipFile() { Finish(); }
    virtual u1* NewFile(const char* filename, const u4 attr);
    virtual int FinishFile(size_t filelength, bool compress = false,
                           bool compute_crc = false);
    virtual int WriteEmptyFile(const char *filename);
    virtual size_t GetSize() {
      return Offset(q);
    }
    virtual int GetNumberFiles() {
      return entries_.size();
    }
    virtual int Finish();
    bool Open();
  
   private:
    struct LocalFileEntry {
      // Start of the local header (in the output buffer).
      size_t local_header_offset;
  
      // Sizes of the file entry
      size_t uncompressed_length;
      size_t compressed_length;
  
      // Compression method
      u2 compression_method;
  
      // CRC32
      u4 crc32;
  
      // external attributes field
      u4 external_attr;
  
      // Start/length of the file_name in the local header.
      u1 *file_name;
      u2 file_name_length;
  
      // Start/length of the extra_field in the local header.
      const u1 *extra_field;
      u2 extra_field_length;
    };
  
    MappedOutputFile* output_file_;
    const char* filename_;
    size_t estimated_size_;
    bool finished_;
  
    // OutputZipFile is responsible for maintaining the following
    // pointers. They are allocated by the Create() method before
    // the object is actually created using mmap.
    u1 *zipdata_out_;        // start of output file mmap
    u1 *q;  // output cursor
  
    u1 *header_ptr;  // Current pointer to "compression method" entry.
  
    // List of entries to write the central directory
    std::vector<LocalFileEntry*> entries_;
  
    // last error
    char errmsg[4*PATH_MAX];
  
    int error(const char *fmt, ...) {
      va_list ap;
      va_start(ap, fmt);
      vsnprintf(errmsg, 4*PATH_MAX, fmt, ap);
      va_end(ap);
      return -1;
    }
  
    // Write the ZIP central directory structure for each local file
    // entry in "entries".
    void WriteCentralDirectory();
  
    // Returns the offset of the pointer relative to the start of the
    // output zip file.
    size_t Offset(const u1 *const x) {
      return x - zipdata_out_;
    }
  
    // Write ZIP file header in the output. Since the compressed size is not
    // known in advance, it must be recorded later. This method returns a pointer
    // to "compressed size" in the file header that should be passed to
    // WriteFileSizeInLocalFileHeader() later.
    u1* WriteLocalFileHeader(const char *filename, const u4 attr);
  
    // Fill in the "compressed size" and "uncompressed size" fields in a local
    // file header previously written by WriteLocalFileHeader().
    size_t WriteFileSizeInLocalFileHeader(u1 *header_ptr,
                                          size_t out_length,
                                          bool compress = false,
                                          const u4 crc = 0);
  };
  
  //
  // Implementation of InputZipFile
  //
  bool InputZipFile::ProcessNext() {
    // Process the next entry in the central directory. Also make sure that the
    // content pointer is in sync.
    size_t compressed, uncompressed;
    u4 offset;
    if (!ProcessCentralDirEntry(central_dir_current_, &compressed, &uncompressed,
                                filename, PATH_MAX, &attr, &offset)) {
      return false;
    }
  
    // There might be an offset specified in the central directory that does
    // not match the file offset, if so, correct the pointer.
    if (offset != 0 && (p != (zipdata_in_ + in_offset_ + offset))) {
      p = zipdata_in_ + offset;
    }
  
    if (EnsureRemaining(4, "signature") < 0) {
      return false;
    }
    u4 signature = get_u4le(p);
    if (signature == LOCAL_FILE_HEADER_SIGNATURE) {
      if (ProcessLocalFileEntry(compressed, uncompressed) < 0) {
        return false;
      }
    } else {
      error("local file header signature for file %s not found\n", filename);
      return false;
    }
  
    return true;
  }
  
  int InputZipFile::ProcessLocalFileEntry(
      size_t compressed_size, size_t uncompressed_size) {
    if (EnsureRemaining(26, "extract_version") < 0) {
      return -1;
    }
    extract_version_ = get_u2le(p);
    general_purpose_bit_flag_ = get_u2le(p);
  
    if ((general_purpose_bit_flag_ & ~GENERAL_PURPOSE_BIT_FLAG_SUPPORTED) != 0) {
      return error("Unsupported value (0x%04x) in general purpose bit flag.\n",
                   general_purpose_bit_flag_);
    }
  
    compression_method_ = get_u2le(p);
  
    if (compression_method_ != COMPRESSION_METHOD_DEFLATED &&
        compression_method_ != COMPRESSION_METHOD_STORED) {
      return error("Unsupported compression method (%d).\n",
                   compression_method_);
    }
  
    // skip over: last_mod_file_time, last_mod_file_date, crc32
    p += 2 + 2 + 4;
    compressed_size_ = get_u4le(p);
    uncompressed_size_ = get_u4le(p);
    file_name_length_ = get_u2le(p);
    extra_field_length_ = get_u2le(p);
  
    if (EnsureRemaining(file_name_length_, "file_name") < 0) {
      return -1;
    }
    file_name_ = p;
    p += file_name_length_;
  
    if (EnsureRemaining(extra_field_length_, "extra_field") < 0) {
      return -1;
    }
    extra_field_ = p;
    p += extra_field_length_;
  
    bool is_compressed = compression_method_ == COMPRESSION_METHOD_DEFLATED;
  
    // If the zip is compressed, compressed and uncompressed size members are
    // zero in the local file header. If not, check that they are the same as the
    // lengths from the central directory, otherwise, just believe the central
    // directory
    if (compressed_size_ == 0) {
      compressed_size_ = compressed_size;
    } else {
      if (compressed_size_ != compressed_size) {
        return error("central directory and file header inconsistent\n");
      }
    }
  
    if (uncompressed_size_ == 0) {
      uncompressed_size_ = uncompressed_size;
    } else {
      if (uncompressed_size_ != uncompressed_size) {
        return error("central directory and file header inconsistent\n");
      }
    }
  
    if (processor->Accept(filename, attr)) {
      if (ProcessFile(is_compressed) < 0) {
        return -1;
      }
    } else {
      if (SkipFile(is_compressed) < 0) {
        return -1;
      }
    }
  
    if (general_purpose_bit_flag_ & GENERAL_PURPOSE_BIT_FLAG_COMPRESSED) {
      // Skip the data descriptor. Some implementations do not put the signature
      // here, so check if the next 4 bytes are a signature, and if so, skip the
      // next 12 bytes (for CRC, compressed/uncompressed size), otherwise skip
      // the next 8 bytes (because the value just read was the CRC).
      u4 signature = get_u4le(p);
      if (signature == DATA_DESCRIPTOR_SIGNATURE) {
        p += 4 * 3;
      } else {
        p += 4 * 2;
      }
    }
  
    size_t bytes_processed = p - zipdata_in_;
    if (bytes_processed > bytes_unmapped_ + MAX_MAPPED_REGION) {
      input_file_->Discard(MAX_MAPPED_REGION);
      bytes_unmapped_ += MAX_MAPPED_REGION;
    }
  
    return 0;
  }
  
  int InputZipFile::SkipFile(const bool compressed) {
    if (!compressed) {
      // In this case, compressed_size_ == uncompressed_size_ (since the file is
      // uncompressed), so we can use either.
      if (compressed_size_ != uncompressed_size_) {
        return error("compressed size != uncompressed size, although the file "
                     "is uncompressed.\n");
      }
    }
  
    if (EnsureRemaining(compressed_size_, "file_data") < 0) {
      return -1;
    }
    p += compressed_size_;
    return 0;
  }
  
  u1* InputZipFile::UncompressFile() {
    size_t in_offset = p - zipdata_in_;
    size_t remaining = input_file_->Length() - in_offset;
    DecompressedFile *decompressed_file =
        decompressor_->UncompressFile(p, remaining);
    if (decompressed_file == NULL) {
      if (decompressor_->GetError() != NULL) {
        error(decompressor_->GetError());
      }
      return NULL;
    } else {
      compressed_size_ = decompressed_file->compressed_size;
      uncompressed_size_ = decompressed_file->uncompressed_size;
      u1 *uncompressed_data = decompressed_file->uncompressed_data;
      free(decompressed_file);
      p += compressed_size_;
      return uncompressed_data;
    }
  }
  
  int InputZipFile::ProcessFile(const bool compressed) {
    const u1 *file_data;
    if (compressed) {
      file_data = UncompressFile();
      if (file_data == NULL) {
        return -1;
      }
    } else {
      // In this case, compressed_size_ == uncompressed_size_ (since the file is
      // uncompressed), so we can use either.
      if (compressed_size_ != uncompressed_size_) {
        return error("compressed size != uncompressed size, although the file "
                     "is uncompressed.\n");
      }
  
      if (EnsureRemaining(compressed_size_, "file_data") < 0) {
        return -1;
      }
      file_data = p;
      p += compressed_size_;
    }
    processor->Process(filename, attr, file_data, uncompressed_size_);
    return 0;
  }
  
  
  // Reads and returns some metadata of the next file from the central directory:
  // - compressed size
  // - uncompressed size
  // - whether the entry is a class file (to be included in the output).
  // Precondition: p points to the beginning of an entry in the central dir
  // Postcondition: p points to the beginning of the next entry in the central dir
  // Returns true if the central directory contains another file and false if not.
  // Of course, in the latter case, the size output variables are not changed.
  // Note that the central directory is always followed by another data structure
  // that has a signature, so parsing it this way is safe.
  bool InputZipFile::ProcessCentralDirEntry(const u1 *&p, size_t *compressed_size,
                                            size_t *uncompressed_size,
                                            char *filename, size_t filename_size,
                                            u4 *attr, u4 *offset) {
    u4 signature = get_u4le(p);
  
    if (signature != CENTRAL_FILE_HEADER_SIGNATURE) {
      if (signature != DIGITAL_SIGNATURE && signature != EOCD_SIGNATURE &&
          signature != ZIP64_EOCD_SIGNATURE) {
        error("invalid central file header signature: 0x%x\n", signature);
      }
      return false;
    }
  
    p += 16;  // skip to 'compressed size' field
    *compressed_size = get_u4le(p);
    *uncompressed_size = get_u4le(p);
    u2 file_name_length = get_u2le(p);
    u2 extra_field_length = get_u2le(p);
    u2 file_comment_length = get_u2le(p);
    p += 4;  // skip to external file attributes field
    *attr = get_u4le(p);
    *offset = get_u4le(p);
    {
      size_t len = (file_name_length < filename_size)
        ? file_name_length
        : (filename_size - 1);
      memcpy(reinterpret_cast<void*>(filename), p, len);
      filename[len] = 0;
    }
    p += file_name_length;
    p += extra_field_length;
    p += file_comment_length;
    return true;
  }
  
  // Gives a maximum bound on the size of the interface JAR. Basically, adds
  // the difference between the compressed and uncompressed sizes to the size
  // of the input file.
  u8 InputZipFile::CalculateOutputLength() {
    const u1* current = central_dir_;
  
    u8 compressed_size = 0;
    u8 uncompressed_size = 0;
    u8 skipped_compressed_size = 0;
    u4 attr;
    u4 offset;
    char filename[PATH_MAX];
  
    while (true) {
      size_t file_compressed, file_uncompressed;
      if (!ProcessCentralDirEntry(current,
                                  &file_compressed, &file_uncompressed,
                                  filename, PATH_MAX, &attr, &offset)) {
        break;
      }
  
      if (processor->Accept(filename, attr)) {
        compressed_size += (u8) file_compressed;
        uncompressed_size += (u8) file_uncompressed;
      } else {
        skipped_compressed_size += file_compressed;
      }
    }
  
    // The worst case is when the output is simply the input uncompressed. The
    // metadata in the zip file will stay the same, so the file will grow by the
    // difference between the compressed and uncompressed sizes.
    return (u8) input_file_->Length() - skipped_compressed_size
        + (uncompressed_size - compressed_size);
  }
  
  // An end of central directory record, sized for optional zip64 contents.
  struct EndOfCentralDirectoryRecord {
    u4 number_of_this_disk;
    u4 disk_with_central_dir;
    u8 central_dir_entries_on_this_disk;
    u8 central_dir_entries;
    u8 central_dir_size;
    u8 central_dir_offset;
  };
  
  // Checks for a zip64 end of central directory record. If a valid zip64 EOCD is
  // found, updates the original EOCD record and returns true.
  bool MaybeReadZip64CentralDirectory(const u1 *bytes, size_t /*in_length*/,
                                      const u1 *current,
                                      const u1 **end_of_central_dir,
                                      EndOfCentralDirectoryRecord *cd) {
    if (current < bytes) {
      return false;
    }
    const u1 *candidate = current;
    u4 zip64_directory_signature = get_u4le(current);
    if (zip64_directory_signature != ZIP64_EOCD_SIGNATURE) {
      return false;
    }
  
    // size of zip64 end of central directory record
    // (fixed size unless there's a zip64 extensible data sector, which
    // we don't need to read)
    get_u8le(current);
    get_u2be(current);  // version made by
    get_u2be(current);  // version needed to extract
  
    u4 number_of_this_disk = get_u4be(current);
    u4 disk_with_central_dir = get_u4le(current);
    u8 central_dir_entries_on_this_disk = get_u8le(current);
    u8 central_dir_entries = get_u8le(current);
    u8 central_dir_size = get_u8le(current);
    u8 central_dir_offset = get_u8le(current);
  
    // check for a zip64 EOCD that matches the regular EOCD
    if (number_of_this_disk != cd->number_of_this_disk &&
        cd->number_of_this_disk != U2_MAX) {
      return false;
    }
    if (disk_with_central_dir != cd->disk_with_central_dir &&
        cd->disk_with_central_dir != U2_MAX) {
      return false;
    }
    if (central_dir_entries_on_this_disk !=
            cd->central_dir_entries_on_this_disk &&
        cd->central_dir_entries_on_this_disk != U2_MAX) {
      return false;
    }
    if (central_dir_entries != cd->central_dir_entries &&
        cd->central_dir_entries != U2_MAX) {
      return false;
    }
    if (central_dir_size != cd->central_dir_size &&
        cd->central_dir_size != U4_MAX) {
      return false;
    }
    if (central_dir_offset != cd->central_dir_offset &&
        cd->central_dir_offset != U4_MAX) {
      return false;
    }
  
    *end_of_central_dir = candidate;
    cd->number_of_this_disk = number_of_this_disk;
    cd->disk_with_central_dir = disk_with_central_dir;
    cd->central_dir_entries_on_this_disk = central_dir_entries_on_this_disk;
    cd->central_dir_entries = central_dir_entries;
    cd->central_dir_size = central_dir_size;
    cd->central_dir_offset = central_dir_offset;
    return true;
  }
  
  // Starting from the end of central directory record, attempts to locate a zip64
  // end of central directory record. If found, updates the given record and
  // offset with the zip64 data. Returns false on error.
  bool FindZip64CentralDirectory(const u1 *bytes, size_t in_length,
                                 const u1 **end_of_central_dir,
                                 EndOfCentralDirectoryRecord *cd) {
    // In the absence of a zip64 extensible data sector, the zip64 EOCD is at a
    // fixed offset from the regular central directory.
    if (MaybeReadZip64CentralDirectory(
            bytes, in_length,
            *end_of_central_dir - ZIP64_EOCD_LOCATOR_SIZE - ZIP64_EOCD_FIXED_SIZE,
            end_of_central_dir, cd)) {
      return true;
    }
  
    // If we couldn't find a zip64 EOCD at a fixed offset, either it doesn't exist
    // or there was a zip64 extensible data sector, so try going through the
    // locator. This approach doesn't work if data was prepended to the archive
    // without updating the offset in the locator.
    const u1 *zip64_locator = *end_of_central_dir - ZIP64_EOCD_LOCATOR_SIZE;
    if (zip64_locator - ZIP64_EOCD_FIXED_SIZE < bytes) {
      return true;
    }
    u4 zip64_locator_signature = get_u4le(zip64_locator);
    if (zip64_locator_signature != ZIP64_EOCD_LOCATOR_SIGNATURE) {
      return true;
    }
    u4 disk_with_zip64_central_directory = get_u4le(zip64_locator);
    u8 zip64_end_of_central_dir_offset = get_u8le(zip64_locator);
    u4 zip64_total_disks = get_u4le(zip64_locator);
    if (MaybeReadZip64CentralDirectory(bytes, in_length,
                                       bytes + zip64_end_of_central_dir_offset,
                                       end_of_central_dir, cd)) {
      if (disk_with_zip64_central_directory != 0 || zip64_total_disks != 1) {
        fprintf(stderr, "multi-disk JAR files are not supported\n");
        return false;
      }
      return true;
    }
    return true;
  }
  
  // Given the data in the zip file, returns the offset of the central directory
  // and the number of files contained in it.
  bool FindZipCentralDirectory(const u1 *bytes, size_t in_length, u4 *offset,
                               const u1 **central_dir) {
    static const int MAX_COMMENT_LENGTH = 0xffff;
    static const int CENTRAL_DIR_LOCATOR_SIZE = 22;
    // Maximum distance of start of central dir locator from end of file
    static const int MAX_DELTA = MAX_COMMENT_LENGTH + CENTRAL_DIR_LOCATOR_SIZE;
    const u1* last_pos_to_check = in_length < MAX_DELTA
        ? bytes
        : bytes + (in_length - MAX_DELTA);
    const u1* current;
    bool found = false;
  
    for (current = bytes + in_length - CENTRAL_DIR_LOCATOR_SIZE;
         current >= last_pos_to_check;
         current-- ) {
      const u1* p = current;
      if (get_u4le(p) != EOCD_SIGNATURE) {
        continue;
      }
  
      p += 16;  // skip to comment length field
      u2 comment_length = get_u2le(p);
  
      // Does the comment go exactly till the end of the file?
      if (current + comment_length + CENTRAL_DIR_LOCATOR_SIZE
          != bytes + in_length) {
        continue;
      }
  
      // Hooray, we found it!
      found = true;
      break;
    }
  
    if (!found) {
      fprintf(stderr, "file is invalid or corrupted (missing end of central "
                      "directory record)\n");
      return false;
    }
  
    EndOfCentralDirectoryRecord cd;
    const u1* end_of_central_dir = current;
    get_u4le(current);  // central directory locator signature, already checked
    cd.number_of_this_disk = get_u2le(current);
    cd.disk_with_central_dir = get_u2le(current);
    cd.central_dir_entries_on_this_disk = get_u2le(current);
    cd.central_dir_entries = get_u2le(current);
    cd.central_dir_size = get_u4le(current);
    cd.central_dir_offset = get_u4le(current);
    u2 file_comment_length = get_u2le(current);
    current += file_comment_length;  // set current to the end of the central dir
  
    if (!FindZip64CentralDirectory(bytes, in_length, &end_of_central_dir, &cd)) {
      return false;
    }
  
    if (cd.number_of_this_disk != 0 || cd.disk_with_central_dir != 0 ||
        cd.central_dir_entries_on_this_disk != cd.central_dir_entries) {
      fprintf(stderr, "multi-disk JAR files are not supported\n");
      return false;
    }
  
    // Do not change output values before determining that they are OK.
    *offset = cd.central_dir_offset;
    // Central directory start can then be used to determine the actual
    // starts of the zip file (which can be different in case of a non-zip
    // header like for auto-extractable binaries).
    *central_dir = end_of_central_dir - cd.central_dir_size;
    return true;
  }
  
  void InputZipFile::Reset() {
    central_dir_current_ = central_dir_;
    bytes_unmapped_ = 0;
    p = zipdata_in_ + in_offset_;
  }
  
  int ZipExtractor::ProcessAll() {
    while (ProcessNext()) {}
    if (GetError() != NULL) {
      return -1;
    }
    return 0;
  }
  
  ZipExtractor* ZipExtractor::Create(const char* filename,
                                     ZipExtractorProcessor *processor) {
    InputZipFile* result = new InputZipFile(processor, filename);
    if (!result->Open()) {
      fprintf(stderr, "%s\n", result->GetError());
      delete result;
      return NULL;
    }
  
    return result;
  }
  
  // zipdata_in_, in_offset_, p, central_dir_current_
  
  InputZipFile::InputZipFile(ZipExtractorProcessor *processor,
                             const char* filename)
      : processor(processor), filename_(filename), input_file_(NULL),
        bytes_unmapped_(0) {
    decompressor_ = new Decompressor();
    errmsg[0] = 0;
  }
  
  bool InputZipFile::Open() {
    MappedInputFile* input_file = new MappedInputFile(filename_);
    if (!input_file->Opened()) {
      snprintf(errmsg, sizeof(errmsg), "%s", input_file->Error());
      delete input_file;
      return false;
    }
  
    void *zipdata_in = input_file->Buffer();
    u4 central_dir_offset;
    const u1 *central_dir = NULL;
  
    if (!devtools_ijar::FindZipCentralDirectory(
            static_cast<const u1*>(zipdata_in), input_file->Length(),
            &central_dir_offset, &central_dir)) {
      errno = EIO;  // we don't really have a good error number
      error("Cannot find central directory");
      delete input_file;
      return false;
    }
    const u1 *zipdata_start = static_cast<const u1*>(zipdata_in);
    in_offset_ = - static_cast<off_t>(zipdata_start
                                      + central_dir_offset
                                      - central_dir);
  
    input_file_ = input_file;
    zipdata_in_ = zipdata_start;
    central_dir_ = central_dir;
    central_dir_current_ = central_dir;
    p = zipdata_in_ + in_offset_;
    errmsg[0] = 0;
    return true;
  }
  
  InputZipFile::~InputZipFile() {
    delete decompressor_;
    if (input_file_ != NULL) {
      input_file_->Close();
      delete input_file_;
    }
  }
  
  
  //
  // Implementation of OutputZipFile
  //
  int OutputZipFile::WriteEmptyFile(const char *filename) {
    const u1* file_name = (const u1*) filename;
    size_t file_name_length = strlen(filename);
  
    LocalFileEntry *entry = new LocalFileEntry;
    entry->local_header_offset = Offset(q);
    entry->external_attr = 0;
    entry->crc32 = 0;
  
    // Output the ZIP local_file_header:
    put_u4le(q, LOCAL_FILE_HEADER_SIGNATURE);
    put_u2le(q, 10);  // extract_version
    put_u2le(q, 0);  // general_purpose_bit_flag
    put_u2le(q, 0);  // compression_method
    put_u4le(q, kDefaultTimestamp);  // last_mod_file date and time
    put_u4le(q, entry->crc32);  // crc32
    put_u4le(q, 0);  // compressed_size
    put_u4le(q, 0);  // uncompressed_size
    put_u2le(q, file_name_length);
    put_u2le(q, 0);  // extra_field_length
    put_n(q, file_name, file_name_length);
  
    entry->file_name_length = file_name_length;
    entry->extra_field_length = 0;
    entry->compressed_length = 0;
    entry->uncompressed_length = 0;
    entry->compression_method = 0;
    entry->extra_field = (const u1 *)"";
    entry->file_name = (u1*) strdup((const char *) file_name);
    entries_.push_back(entry);
  
    return 0;
  }
  
  void OutputZipFile::WriteCentralDirectory() {
    // central directory:
    const u1 *central_directory_start = q;
    for (size_t ii = 0; ii < entries_.size(); ++ii) {
      LocalFileEntry *entry = entries_[ii];
      put_u4le(q, CENTRAL_FILE_HEADER_SIGNATURE);
      put_u2le(q, 0);  // version made by
  
      put_u2le(q, ZIP_VERSION_TO_EXTRACT);  // version to extract
      put_u2le(q, 0);  // general purpose bit flag
      put_u2le(q, entry->compression_method);  // compression method:
      put_u4le(q, kDefaultTimestamp);          // last_mod_file date and time
      put_u4le(q, entry->crc32);  // crc32
      put_u4le(q, entry->compressed_length);    // compressed_size
      put_u4le(q, entry->uncompressed_length);  // uncompressed_size
      put_u2le(q, entry->file_name_length);
      put_u2le(q, entry->extra_field_length);
  
      put_u2le(q, 0);  // file comment length
      put_u2le(q, 0);  // disk number start
      put_u2le(q, 0);  // internal file attributes
      put_u4le(q, entry->external_attr);  // external file attributes
      // relative offset of local header:
      put_u4le(q, entry->local_header_offset);
  
      put_n(q, entry->file_name, entry->file_name_length);
      put_n(q, entry->extra_field, entry->extra_field_length);
    }
    u8 central_directory_size = q - central_directory_start;
  
    if (entries_.size() > U2_MAX || central_directory_size > U4_MAX ||
        Offset(central_directory_start) > U4_MAX) {
      u1 *zip64_end_of_central_directory_start = q;
  
      put_u4le(q, ZIP64_EOCD_SIGNATURE);
      // signature and size field doesn't count towards size
      put_u8le(q, ZIP64_EOCD_FIXED_SIZE - 12);
      put_u2le(q, 0);  // version made by
      put_u2le(q, 0);  // version needed to extract
      put_u4le(q, 0);  // number of this disk
      put_u4le(q, 0);  // # of the disk with the start of the central directory
      put_u8le(q, entries_.size());  // # central dir entries on this disk
      put_u8le(q, entries_.size());  // total # entries in the central directory
      put_u8le(q, central_directory_size);  // size of the central directory
      // offset of start of central directory wrt starting disk
      put_u8le(q, Offset(central_directory_start));
  
      put_u4le(q, ZIP64_EOCD_LOCATOR_SIGNATURE);
      // number of the disk with the start of the zip64 end of central directory
      put_u4le(q, 0);
      // relative offset of the zip64 end of central directory record
      put_u8le(q, Offset(zip64_end_of_central_directory_start));
      // total number of disks
      put_u4le(q, 1);
  
      put_u4le(q, EOCD_SIGNATURE);
      put_u2le(q, 0);  // number of this disk
      put_u2le(q, 0);  // # of disk with the start of the central directory
      // # central dir entries on this disk
      put_u2le(q, entries_.size() > 0xffff ? 0xffff : entries_.size());
      // total # entries in the central directory
      put_u2le(q, entries_.size() > 0xffff ? 0xffff : entries_.size());
      // size of the central directory
      put_u4le(q,
               central_directory_size > U4_MAX ? U4_MAX : central_directory_size);
      // offset of start of central
      put_u4le(q, Offset(central_directory_start) > U4_MAX
                      ? U4_MAX
                      : Offset(central_directory_start));
      put_u2le(q, 0);  // .ZIP file comment length
  
    } else {
      put_u4le(q, EOCD_SIGNATURE);
      put_u2le(q, 0);  // number of this disk
      put_u2le(q, 0);  // # of the disk with the start of the central directory
      put_u2le(q, entries_.size());  // # central dir entries on this disk
      put_u2le(q, entries_.size());  // total # entries in the central directory
      put_u4le(q, central_directory_size);  // size of the central directory
      // offset of start of central directory wrt starting disk
      put_u4le(q, Offset(central_directory_start));
      put_u2le(q, 0);  // .ZIP file comment length
    }
  }
  
  u1* OutputZipFile::WriteLocalFileHeader(const char* filename, const u4 attr) {
    off_t file_name_length_ = strlen(filename);
    LocalFileEntry *entry = new LocalFileEntry;
    entry->local_header_offset = Offset(q);
    entry->file_name_length = file_name_length_;
    entry->file_name = new u1[file_name_length_];
    entry->external_attr = attr;
    memcpy(entry->file_name, filename, file_name_length_);
    entry->extra_field_length = 0;
    entry->extra_field = (const u1 *)"";
    entry->crc32 = 0;
  
    // Output the ZIP local_file_header:
    put_u4le(q, LOCAL_FILE_HEADER_SIGNATURE);
    put_u2le(q, ZIP_VERSION_TO_EXTRACT);     // version to extract
    put_u2le(q, 0);                          // general purpose bit flag
    u1 *header_ptr = q;
    put_u2le(q, COMPRESSION_METHOD_STORED);  // compression method = placeholder
    put_u4le(q, kDefaultTimestamp);          // last_mod_file date and time
    put_u4le(q, entry->crc32);               // crc32
    put_u4le(q, 0);  // compressed_size = placeholder
    put_u4le(q, 0);  // uncompressed_size = placeholder
    put_u2le(q, entry->file_name_length);
    put_u2le(q, entry->extra_field_length);
  
    put_n(q, entry->file_name, entry->file_name_length);
    put_n(q, entry->extra_field, entry->extra_field_length);
    entries_.push_back(entry);
  
    return header_ptr;
  }
  
  size_t OutputZipFile::WriteFileSizeInLocalFileHeader(u1 *header_ptr,
                                                       size_t out_length,
                                                       bool compress,
                                                       const u4 crc) {
    size_t compressed_size = out_length;
    if (compress) {
      compressed_size = TryDeflate(q, out_length);
    }
    // compression method
    if (compressed_size < out_length) {
      put_u2le(header_ptr, COMPRESSION_METHOD_DEFLATED);
    } else {
      put_u2le(header_ptr, COMPRESSION_METHOD_STORED);
    }
    header_ptr += 4;
    put_u4le(header_ptr, crc);              // crc32
    put_u4le(header_ptr, compressed_size);  // compressed_size
    put_u4le(header_ptr, out_length);       // uncompressed_size
    return compressed_size;
  }
  
  int OutputZipFile::Finish() {
    if (finished_) {
      return 0;
    }
  
    finished_ = true;
    WriteCentralDirectory();
    if (output_file_->Close(GetSize()) < 0) {
      return error("%s", output_file_->Error());
    }
    delete output_file_;
    output_file_ = NULL;
    return 0;
  }
  
  u1* OutputZipFile::NewFile(const char* filename, const u4 attr) {
    header_ptr = WriteLocalFileHeader(filename, attr);
    return q;
  }
  
  int OutputZipFile::FinishFile(size_t filelength, bool compress,
                                bool compute_crc) {
    u4 crc = 0;
    if (compute_crc) {
      crc = ComputeCrcChecksum(q, filelength);
  
      if (filelength > 0 && crc == 0) {
        fprintf(stderr, "Error calculating CRC32 checksum.\n");
        return -1;
      }
    }
    size_t compressed_size =
        WriteFileSizeInLocalFileHeader(header_ptr, filelength, compress, crc);
  
    if (compressed_size == 0 && filelength > 0) {
      fprintf(stderr, "Error compressing files.\n");
      return -1;
    }
  
    entries_.back()->crc32 = crc;
    entries_.back()->compressed_length = compressed_size;
    entries_.back()->uncompressed_length = filelength;
    if (compressed_size < filelength) {
      entries_.back()->compression_method = COMPRESSION_METHOD_DEFLATED;
    } else {
      entries_.back()->compression_method = COMPRESSION_METHOD_STORED;
    }
    q += compressed_size;
    return 0;
  }
  
  bool OutputZipFile::Open() {
    if (estimated_size_ > kMaximumOutputSize) {
      fprintf(stderr,
              "Uncompressed input jar has size %lu, "
              "which exceeds the maximum supported output size %lu.\n"
              "Assuming that ijar will be smaller and hoping for the best.\n",
              estimated_size_, kMaximumOutputSize);
      estimated_size_ = kMaximumOutputSize;
    }
  
    MappedOutputFile* output_file = new MappedOutputFile(
        filename_, estimated_size_);
    if (!output_file->Opened()) {
      snprintf(errmsg, sizeof(errmsg), "%s", output_file->Error());
      delete output_file;
      return false;
    }
  
    output_file_ = output_file;
    q = output_file->Buffer();
    zipdata_out_ = output_file->Buffer();
    return true;
  }
  
  ZipBuilder *ZipBuilder::Create(const char *zip_file, size_t estimated_size) {
    OutputZipFile* result = new OutputZipFile(zip_file, estimated_size);
    if (!result->Open()) {
      fprintf(stderr, "%s\n", result->GetError());
      delete result;
      return NULL;
    }
  
    return result;
  }
  
  u8 ZipBuilder::EstimateSize(char const* const* files,
                              char const* const* zip_paths,
                              int nb_entries) {
    Stat file_stat;
    // Digital signature field size = 6, End of central directory = 22, Total = 28
    u8 size = 28;
    // Count the size of all the files in the input to estimate the size of the
    // output.
    for (int i = 0; i < nb_entries; i++) {
      file_stat.total_size = 0;
      if (files[i] != NULL && !stat_file(files[i], &file_stat)) {
        fprintf(stderr, "File %s does not seem to exist.", files[i]);
        return 0;
      }
      size += file_stat.total_size;
      // Add sizes of Zip meta data
      // local file header = 30 bytes
      // data descriptor = 12 bytes
      // central directory descriptor = 46 bytes
      //    Total: 88bytes
      size += 88;
      // The filename is stored twice (once in the central directory
      // and once in the local file header).
      size += strlen((zip_paths[i] != NULL) ? zip_paths[i] : files[i]) * 2;
    }
    return size;
  }
  
  }  // namespace devtools_ijar
  