add documentation

1 files changed, 0 insertions, 1920 deletions

diff --git a/src/zip.cr b/src/zip.cr
deleted file mode 100644
index 0037d0e..0000000
--- a/src/zip.cr
+++ /dev/null
@@ -1,1920 +0,0 @@
-require "./zip/*"
-require "zlib"
-
-# :nodoc:
-#
-# TODO:
-# [x] date/time
-# [x] reader (store and deflate only)
-# [x] documentation
-# [-] extras (at least infozip)
-# [x] convert datetime to Time
-# [x] add size to Entry
-# [x] Version
-# [ ] directories
-# [ ] full tests
-# [ ] zip64
-# [ ] legacy unicode (e.g., non-bit 11) path/comment support
-# [ ] unix uids
-# [ ] bzip2/lzma support
-#
-# References:
-#   https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT
-#   http://www.onicos.com/staff/iz/formats/zip.html
-#
-# :nodoc:
-
-#
-# Library for reading and writing zip files.
-#
-# Examples:
-#
-# Reading from a zip file:
-#
-#   # create output MemoryIO
-#   mem_io = MemoryIO.new
-#
-#   # read from "foo.zip"
-#   Zip.read("foo.zip") do |zip|
-#     # read contents of "bar.txt" in "foo.zip" into mem_io
-#     zip["bar.txt"].read(mem_io)
-#   end
-#
-# Writing to a zip file:
-#
-#   # write to "foo.zip"
-#   Zip.write("foo.zip") do |zip|
-#     # create "bar.txt" with contents "hello!"
-#     zip.add("bar.txt", "hello!")
-#   end
-#
-module Zip
-  #
-  # Version of zip-crystal library.
-  #
-  VERSION = "0.1.0"
-
-  #
-  # Magic numbers for various data in Zip stream.
-  #
-  MAGIC = {
-    cdr_header:   0x02014b50_u32,
-    cdr_footer:   0x06054b50_u32,
-    file_header:  0x04034b50_u32,
-    file_footer:  0x08074b50_u32,
-  }
-
-  # :nodoc:
-  LE = IO::ByteFormat::LittleEndian
-
-  #
-  # Size of internal buffers, in bytes.
-  #
-  BUFFER_SIZE = 8192
-
-  # :nodoc:
-  # 4.4.4 general purpose bit flag: (2 bytes)
-  #
-  # Bit 0: If set, indicates that the file is encrypted.
-  #
-  # (For Method 6 - Imploding)
-  # Bit 1: If the compression method used was type 6,
-  #        Imploding, then this bit, if set, indicates
-  #        an 8K sliding dictionary was used.  If clear,
-  #        then a 4K sliding dictionary was used.
-  #
-  # Bit 2: If the compression method used was type 6,
-  #        Imploding, then this bit, if set, indicates
-  #        3 Shannon-Fano trees were used to encode the
-  #        sliding dictionary output.  If clear, then 2
-  #        Shannon-Fano trees were used.
-  #
-  # (For Methods 8 and 9 - Deflating)
-  # Bit 2  Bit 1
-  #   0      0    Normal (-en) compression option was used.
-  #   0      1    Maximum (-exx/-ex) compression option was used.
-  #   1      0    Fast (-ef) compression option was used.
-  #   1      1    Super Fast (-es) compression option was used.
-  #
-  # (For Method 14 - LZMA)
-  # Bit 1: If the compression method used was type 14,
-  #        LZMA, then this bit, if set, indicates
-  #        an end-of-stream (EOS) marker is used to
-  #        mark the end of the compressed data stream.
-  #        If clear, then an EOS marker is not present
-  #        and the compressed data size must be known
-  #        to extract.
-  #
-  # Note:  Bits 1 and 2 are undefined if the compression
-  #        method is any other.
-  #
-  # Bit 3: If this bit is set, the fields crc-32, compressed
-  #        size and uncompressed size are set to zero in the
-  #        local header.  The correct values are put in the
-  #        data descriptor immediately following the compressed
-  #        data.  (Note: PKZIP version 2.04g for DOS only
-  #        recognizes this bit for method 8 compression, newer
-  #        versions of PKZIP recognize this bit for any
-  #        compression method.)
-  #
-  # Bit 4: Reserved for use with method 8, for enhanced
-  #        deflating.
-  #
-  # Bit 5: If this bit is set, this indicates that the file is
-  #        compressed patched data.  (Note: Requires PKZIP
-  #        version 2.70 or greater)
-  #
-  # Bit 6: Strong encryption.  If this bit is set, you MUST
-  #        set the version needed to extract value to at least
-  #        50 and you MUST also set bit 0.  If AES encryption
-  #        is used, the version needed to extract value MUST
-  #        be at least 51. See the section describing the Strong
-  #        Encryption Specification for details.  Refer to the
-  #        section in this document entitled "Incorporating PKWARE
-  #        Proprietary Technology into Your Product" for more
-  #        information.
-  #
-  # Bit 7: Currently unused.
-  #
-  # Bit 8: Currently unused.
-  #
-  # Bit 9: Currently unused.
-  #
-  # Bit 10: Currently unused.
-  #
-  # Bit 11: Language encoding flag (EFS).  If this bit is set,
-  #         the filename and comment fields for this file
-  #         MUST be encoded using UTF-8. (see APPENDIX D)
-  #
-  # Bit 12: Reserved by PKWARE for enhanced compression.
-  #
-  # Bit 13: Set when encrypting the Central Directory to indicate
-  #         selected data values in the Local Header are masked to
-  #         hide their actual values.  See the section describing
-  #         the Strong Encryption Specification for details.  Refer
-  #         to the section in this document entitled "Incorporating
-  #         PKWARE Proprietary Technology into Your Product" for
-  #         more information.
-  #
-  # Bit 14: Reserved by PKWARE.
-  #
-  # Bit 15: Reserved by PKWARE.
-  # :nodoc:
-
-  #
-  # General flags.
-  #
-  # Used by local header and central directory header.
-  #
-  @[Flags]
-  enum GeneralFlags
-    # encrypted using weak encryption
-    ENCRYPTION
-
-    # compression method-specific flag
-    COMPRESSION_OPTION_1
-
-    # compression method-specific flag
-    COMPRESSION_OPTION_2
-
-    # this entry has a data descriptor footer
-    FOOTER
-
-    # reserved flag
-    RESERVED_4
-
-    # this entry is patch data
-    PATCH
-
-    # this entry uses strong encryption
-    STRONG_ENCRYPTION
-
-    # reserved flag
-    RESERVED_7
-
-    # reserved flag
-    RESERVED_8
-
-    # reserved flag
-    RESERVED_9
-
-    # reserved flag
-    RESERVED_10
-
-    # the file name and comment for this entry are UTF-8 encoded.
-    EFS
-
-    # reserved flag
-    RESERVED_12
-
-    # Some fields in the local header are masked (that is, empty).
-    MASKED_VALUES
-
-    # reserved flag
-    RESERVED_14
-
-    # reserved flag
-    RESERVED_15
-  end
-
-  #
-  # Compression methods.
-  #
-  enum CompressionMethod
-    # Stored (no compression)
-    NONE = 0
-
-    # Shrunk
-    SHRUNK = 1
-
-    # Reduced with compression factor 1
-    REDUCED_1 = 2
-
-    # Reduced with compression factor 2
-    REDUCED_2 = 3
-
-    # Reduced with compression factor 3
-    REDUCED_3 = 4
-
-    # Reduced with compression factor 4
-    REDUCED_4 = 5
-
-    # Imploded
-    IMPLODED = 6
-
-    # Reserved for Tokenizing compression algorithm
-    TOKENIZED = 7
-
-    # Deflated
-    DEFLATE = 8
-
-    # Enhanced Deflating using Deflate64(tm)
-    DEFLATE64 = 9
-
-    # PKWARE Data Compression Library Imploding (old IBM TERSE)
-    TERSE_OLD = 10
-
-    # Reserved by PKWARE
-    RESERVED_11 = 11
-
-    # BZIP2
-    BZIP2 = 12
-
-    # Reserved by PKWARE
-    RESERVED_13 = 13
-
-    # LZMA (EFS)
-    LZMA = 14
-
-    # Reserved by PKWARE
-    RESERVED_15 = 15
-
-    # Reserved by PKWARE
-    RESERVED_16 = 16
-
-    # Reserved by PKWARE
-    RESERVED_17 = 17
-
-    # IBM TERSE (new)
-    TERSE = 18
-
-    # IBM LZ77 z Architecture (PFS)
-    LZ77 = 19
-
-    # WavPack compressed data
-    WAVPACK = 97
-
-    # PPMd version I, Rev 1
-    PPMD = 98
-  end
-
-  #
-  # Wrapper class for exceptions.
-  #
-  class Error < Exception
-  end
-
-  #
-  # Helper methods for converting to and from `Time` objects.
-  #
-  module TimeHelper
-    #
-    # Convert given `Time` to a DOS-style datetime, write the result to
-    # the given IO, and return the number of bytes written.
-    #
-    private def write_time(io : IO, time : Time) : UInt32
-      year = Math.max(1980, time.year) - 1980
-
-      # convert to dos timestamp
-      ((
-        (year << 25) | (time.month << 21) | (time.day << 16) |
-        (time.hour << 11) | (time.minute << 5) | (time.second >> 1)
-      ) & UInt32::MAX).to_u32.to_io(io, LE)
-
-      # return number of bytes written
-      4_u32
-    end
-
-    #
-    # Convert given DOS datetime to a `Time` object.
-    #
-    private def from_dos_time(v : UInt32) : Time
-      Time.new(
-        year:   (v >> 25) + 1980,
-        month:  (v >> 21) & 0b0000_1111,
-        day:    (v >> 16) & 0b0001_1111,
-        hour:   (v >> 11) & 0b0001_1111,
-        minute: (v >> 5)  & 0b0011_1111,
-        second: (v << 1)  & 0b0011_1110,
-      )
-    end
-  end
-
-  #
-  # Version identifier used to identify the version needed to extract a
-  # given file and to indicate the format of the external file
-  # attributes.
-  #
-  # See section 4.4.3.2 of APPNOTE.TXT for version details.
-  #
-  class Version
-    #
-    # Version needed to extract this entry (4.4.3.2).
-    #
-    NEEDED = new(2, 0)
-
-    #
-    # Default version made by, if unspecified.
-    #
-    DEFAULT = new(0, 0)
-
-    #
-    # Create a version identifier from a major number, minor number, and
-    # optional compatability number.
-    #
-    def initialize(
-      @major  : Int32,
-      @minor  : Int32,
-      @compat : Int32 = 0
-    )
-    end
-
-    #
-    # Create a version identifier from a major number, minor number, and
-    # optional compatability number.
-    #
-    def initialize(v : UInt16)
-      @compat = v >> 8
-      @major = (v & 0xff) / 10
-      @minor = (v & 0xff) % 10
-    end
-
-    #
-    # Write version as string.
-    #
-    def to_s(io)
-      io << @major << "." << @minor
-    end
-
-    #
-    # Write version as 16-bit, little-endian integer and return number
-    # of bytes written.
-    #
-    def to_io(io)
-      (
-        ((@compat & 0xff) << 8) +
-        ((@major * 10) + (@minor % 10)) & 0xff
-      ).to_u16.to_io(io, LE)
-    end
-  end
-
-  #
-  # Helper methods for reading and writing uncompressed data.
-  #
-  module NoneCompressionHelper
-    private def compress_none(src_io, dst_io)
-      crc = 0_u32
-
-      buf = Bytes.new(BUFFER_SIZE)
-      src_len = 0_u32
-
-      while ((len = src_io.read(buf)) > 0)
-        # build output slice
-        dst_buf = (len < buf.size) ? buf[0, len] : buf
-        dst_crc = Zlib.crc32(dst_buf)
-
-        # update crc
-        crc = if crc != 0
-          Zlib.crc32_combine(crc, dst_crc, dst_buf.size)
-        else
-          Zlib.crc32(dst_buf)
-        end
-
-
-        # write to output buffer
-        dst_io.write(dst_buf)
-        src_len += len
-      end
-
-      # return results
-      { crc.to_u32, src_len, src_len }
-    end
-
-    private def decompress_none(src_io, dst_io, src_len, dst_len)
-      # TODO: verify CRC
-      IO.copy(src_io, dst_io, src_len)
-
-      # return number of bytes read
-      dst_len
-    end
-  end
-
-  #
-  # Helper methods for compressing and decompressing deflated data.
-  #
-  module DeflateCompressionHelper
-    ZALLOC_PROC = LibZ::AllocFunc.new do |data, num_items, size|
-      GC.malloc(num_items * size)
-    end
-
-    ZFREE_PROC = LibZ::FreeFunc.new do |data, addr|
-      GC.free(addr)
-    end
-
-    ZLIB_VERSION = LibZ.zlibVersion
-
-    #
-    # Read data from src_io, and write the compressed result to dst_io.
-    #
-    private def compress_deflate(src_io, dst_io)
-      crc = 0_u32
-
-      # create read and compress buffers
-      src_buf = Bytes.new(BUFFER_SIZE)
-      dst_buf = Bytes.new(BUFFER_SIZE)
-
-      # create deflate stream
-      z = LibZ::ZStream.new(
-        zalloc: ZALLOC_PROC,
-        zfree:  ZFREE_PROC,
-      )
-
-      # init stream
-      err = LibZ.deflateInit2(
-        pointerof(z),
-        LibZ::DEFAULT_COMPRESSION, # FIXME: make this configurable
-        LibZ::Z_DEFLATED,
-        -15, # raw deflate, window bits = 15
-        LibZ::DEF_MEM_LEVEL,
-        LibZ::Strategy::DEFAULT_STRATEGY,
-        ZLIB_VERSION,
-        sizeof(LibZ::ZStream)
-      )
-
-      # check for error
-      if err != LibZ::Error::OK
-        # raise zlib error
-        raise Zlib::Error.new(err, z)
-      end
-
-      # loop and compress input data
-      while ((len = src_io.read(src_buf)) > 0)
-        # build temp slice (if necessary)
-        tmp_buf = (len < src_buf.size) ? src_buf[0, len] : src_buf
-        tmp_crc = Zlib.crc32(tmp_buf)
-
-        # update crc
-        crc = if crc != 0
-          Zlib.crc32_combine(crc, tmp_crc, tmp_buf.size)
-        else
-          Zlib.crc32(tmp_buf)
-        end
-
-        # set zlib input buffer
-        z.next_in = tmp_buf.to_unsafe
-        z.avail_in = tmp_buf.size.to_u32
-
-        # write compressed data to dst io
-        write_compressed(dst_io, dst_buf, pointerof(z), false)
-      end
-
-      # set zlib input buffer to null
-      z.next_in = Pointer(UInt8).null
-      z.avail_in = 0_u32
-
-      # flush remaining data
-      write_compressed(dst_io, dst_buf, pointerof(z), true)
-
-      # free stream
-      LibZ.deflateEnd(pointerof(z))
-
-      # return results
-      { crc.to_u32, z.total_in.to_u32, z.total_out.to_u32 }
-    end
-
-    #
-    # Deflate data in ZStream and write it to given IO.
-    #
-    private def write_compressed(
-      io    : IO,
-      buf   : Bytes,
-      zp    : Pointer(LibZ::ZStream),
-      flush : Bool,
-    )
-      zf = flush ? LibZ::Flush::FINISH : LibZ::Flush::NO_FLUSH
-
-      loop do
-        # set zlib output buffer
-        zp.value.next_out = buf.to_unsafe
-        zp.value.avail_out = buf.size.to_u32
-
-        # compress data (TODO: check for error)
-        LibZ.deflate(zp, zf)
-
-        if ((len = buf.size - zp.value.avail_out) > 0)
-          # write compressed buffer to dst io
-          io.write((len < buf.size) ? buf[0, len] : buf)
-        end
-
-        # exit loop if there is no remaining space
-        break if zp.value.avail_out != 0
-      end
-    end
-
-    #
-    # Decompress src_len bytes of DEFLATEd data from src_io and write it
-    # to dst_io.
-    #
-    private def decompress_deflate(src_io, dst_io, src_len, dst_len)
-      crc = 0_u32
-
-      # create read and compress buffers
-      src_buf = Bytes.new(BUFFER_SIZE)
-      dst_buf = Bytes.new(BUFFER_SIZE)
-
-      # create deflate stream
-      z = LibZ::ZStream.new(
-        zalloc: ZALLOC_PROC,
-        zfree:  ZFREE_PROC,
-      )
-
-      # init stream
-      err = LibZ.inflateInit2(
-        pointerof(z),
-        -15, # raw deflate, window bits = 15
-        ZLIB_VERSION,
-        sizeof(LibZ::ZStream)
-      )
-
-      # check for error
-      if err != LibZ::Error::OK
-        # raise zlib error
-        raise Zlib::Error.new(err, z)
-      end
-
-      src_ofs, left = 0_u32, src_len
-      while left > 0
-        # calculate read buffer size
-        tmp_len = Math.min(BUFFER_SIZE - src_ofs, left)
-
-        # decriment remaining bytes
-        left -= tmp_len
-
-        # create read buffer (if necessary)
-        tmp_buf = (tmp_len < BUFFER_SIZE) ? src_buf[src_ofs, tmp_len] : src_buf
-
-        # read from source into buffer
-        if ((len = src_io.read(tmp_buf)) != tmp_len)
-          raise Error.new("truncated read (got #{len}, expected #{tmp_len})")
-        end
-
-        # calculate crc
-        tmp_crc = Zlib.crc32(tmp_buf)
-
-        # update crc
-        crc = if crc != 0
-          Zlib.crc32_combine(crc, tmp_crc, tmp_buf.size)
-        else
-          tmp_crc
-        end
-
-        # set zlib input buffer
-        z.next_in = src_buf.to_unsafe
-        z.avail_in = src_ofs + tmp_buf.size.to_u32
-
-        # read compressed data to dst io
-        read_compressed(dst_io, dst_buf, pointerof(z), false)
-      end
-
-      # set zlib input buffer to null
-      z.next_in = Pointer(UInt8).null
-      z.avail_in = 0_u32
-
-      # flush remaining data
-      read_compressed(dst_io, dst_buf, pointerof(z), true)
-
-      # free stream
-      LibZ.inflateEnd(pointerof(z))
-
-      # check crc
-      if false && crc != @crc
-        raise Error.new("crc mismatch (got #{crc}, expected #{@crc}")
-      end
-
-      # check input size
-      if z.total_in != src_len
-        raise Error.new("read length mismatch (got #{z.total_in}, expected #{src_len}")
-      end
-
-      # check output size
-      if z.total_out != dst_len
-        raise Error.new("write length mismatch (got #{z.total_out}, expected #{dst_len}")
-      end
-
-      # return number of bytes read
-      dst_len
-    end
-
-    #
-    # Inflate compressed data from ZStream and write it to given IO.
-    #
-    private def read_compressed(
-      io    : IO,
-      buf   : Bytes,
-      zp    : Pointer(LibZ::ZStream),
-      flush : Bool,
-    )
-      zf = flush ? LibZ::Flush::FINISH : LibZ::Flush::NO_FLUSH
-
-      r, done = 0_u32, false
-      while zp.value.avail_in > 0
-        # set zlib output buffer
-        zp.value.next_out = buf.to_unsafe
-        zp.value.avail_out = buf.size.to_u32
-
-        # inflate data, check for error
-        case err = LibZ.inflate(zp, zf)
-        when LibZ::Error::DATA_ERROR,
-             LibZ::Error::NEED_DICT,
-             LibZ::Error::MEM_ERROR
-          # pp zp.value
-          raise Zlib::Error.new(err, zp.value)
-        when LibZ::Error::OK
-          # do nothing
-        when LibZ::Error::STREAM_END
-          done = true
-        end
-
-        if ((len = buf.size - zp.value.avail_out) > 0)
-          # write uncompressed data to io
-          io.write((len < buf.size) ? Bytes.new(zp.value.next_out, len) : buf)
-        end
-      end
-
-      # return number of unread bytes
-      nil
-    end
-  end
-
-  #
-  # Internal class used to store files for `Writer` instance.
-  #
-  # You should not need to instantiate this class directly; it is called
-  # automatically by `Writer#add` and `Writer#add_file`.
-  #
-  class WriterEntry
-    include TimeHelper
-    include NoneCompressionHelper
-    include DeflateCompressionHelper
-
-    #
-    # Default flags for local and central header.
-    #
-    GENERAL_FLAGS = GeneralFlags.flags(FOOTER, EFS)
-
-    #
-    # Create a new WriterEntry instance.
-    #
-    # You should not need to call this method directly; it is called
-    # automatically by `Writer#add` and `Writer#add_file`.
-    #
-    def initialize(
-      @pos      : UInt32,
-      @path     : String,
-      @io       : IO,
-      @method   : CompressionMethod = CompressionMethod::DEFLATE,
-      @time     : Time = Time.now,
-      @comment  : String = "",
-    )
-      @crc = 0_u32
-      @src_len = 0_u32
-      @dst_len = 0_u32
-    end
-
-    #
-    # Write local file entry to IO and return the number of bytes
-    # written.
-    #
-    # You should not need to call this method directly; it is called
-    # automatically by `Writer#add` and `Writer#add_file`.
-    #
-    def to_s(dst_io) : UInt32
-      # write header
-      r = write_header(dst_io, @path, @method, @time)
-
-      # write body
-      @crc, @src_len, @dst_len = write_body(dst_io)
-      r += @dst_len
-
-      # write footer
-      r += write_footer(dst_io, @crc, @src_len, @dst_len)
-
-      # return number of bytes written
-      r
-    end
-
-    # :nodoc:
-    # local file header signature     4 bytes  (0x04034b50)
-    # version needed to extract       2 bytes
-    # general purpose bit flag        2 bytes
-    # compression method              2 bytes
-    # last mod file time              2 bytes
-    # last mod file date              2 bytes
-    # crc-32                          4 bytes
-    # compressed size                 4 bytes
-    # uncompressed size               4 bytes
-    # file name length                2 bytes
-    # extra field length              2 bytes
-    # file name (variable size)
-    # extra field (variable size)
-    # :nodoc:
-
-    #
-    # Write file header and return the number of bytes written.
-    #
-    private def write_header(
-      io      : IO,
-      path    : String,
-      method  : CompressionMethod,
-      time    : Time,
-    ) : UInt32
-      # get path length, in bytes
-      path_len = path.bytesize
-
-      # check file path
-      raise Error.new("empty file path") if path_len == 0
-      raise Error.new("file path too long") if path_len >= UInt16::MAX
-      raise Error.new("file path contains leading slash") if path[0] == '/'
-
-      # write magic (u32), version needed (u16), flags (u16), and
-      # compression method (u16)
-      MAGIC[:file_header].to_u32.to_io(io, LE)
-      Version::NEEDED.to_io(io)
-      GENERAL_FLAGS.to_u16.to_io(io, LE)
-      method.to_u16.to_io(io, LE)
-
-      # write time (u32)
-      write_time(io, time)
-
-      # crc (u32), compressed size (u32), uncompressed size (u32)
-      # (these will be populated in the footer)
-      0_u32.to_u32.to_io(io, LE)
-      0_u32.to_u32.to_io(io, LE)
-      0_u32.to_u32.to_io(io, LE)
-
-      # write file path length (u16)
-      path_len.to_u16.to_io(io, LE)
-
-      # write extras field length (u16)
-      extras_len = 0_u32
-      extras_len.to_u16.to_io(io, LE)
-
-      # write path field
-      path.to_s(io)
-
-      # write extra fields
-      # TODO: implement this
-
-      # return number of bytes written
-      30_u32 + path_len + extras_len
-    end
-
-    #
-    # Write file contents and return the number of bytes written.
-    #
-    private def write_body(dst_io : IO)
-      case @method
-      when CompressionMethod::NONE
-        compress_none(@io, dst_io)
-      when CompressionMethod::DEFLATE
-        compress_deflate(@io, dst_io)
-      else
-        raise Error.new("unsupported compression method: #{@method}")
-      end
-    end
-
-    # :nodoc:
-    #  4.3.9  Data descriptor:
-    #       MAGIC = 0x08074b50              4 bytes
-    #       crc-32                          4 bytes
-    #       compressed size                 4 bytes
-    #       uncompressed size               4 bytes
-    #
-    # 4.3.9.3 Although not originally assigned a signature, the value
-    # 0x08074b50 has commonly been adopted as a signature value
-    # :nodoc:
-
-    #
-    # Write file footer (data descriptor) and return the number of bytes
-    # written.
-    #
-    private def write_footer(
-      io      : IO,
-      crc     : UInt32,
-      src_len : UInt32,
-      dst_len : UInt32,
-    ) : UInt32
-      # write magic (u32)
-      MAGIC[:file_footer].to_u32.to_io(io, LE)
-
-      # write crc (u32), compressed size (u32), and full size (u32)
-      crc.to_u32.to_io(io, LE)
-      dst_len.to_u32.to_io(io, LE)
-      src_len.to_u32.to_io(io, LE)
-
-      # return number of bytes written
-      16_u32
-    end
-
-    # :nodoc:
-    # central file header signature   4 bytes  (0x02014b50)
-    # version made by                 2 bytes
-    # version needed to extract       2 bytes
-    # general purpose bit flag        2 bytes
-    # compression method              2 bytes
-    # last mod file time              2 bytes
-    # last mod file date              2 bytes
-    # crc-32                          4 bytes
-    # compressed size                 4 bytes
-    # uncompressed size               4 bytes
-    # file name length                2 bytes
-    # extra field length              2 bytes
-    # file comment length             2 bytes
-    # disk number start               2 bytes
-    # internal file attributes        2 bytes
-    # external file attributes        4 bytes
-    # relative offset of local header 4 bytes
-    #
-    # file name (variable size)
-    # extra field (variable size)
-    # file comment (variable size)
-    # :nodoc:
-
-    #
-    # Write central directory data for this `WriterEntry` and return the
-    # number of bytes written.
-    #
-    # You should not need to call this method directly; it is called
-    # automatically by `Writer#close`.
-    #
-    def write_central(
-      io      : IO,
-      version : Version = Version::DEFAULT,
-    ) : UInt32
-      MAGIC[:cdr_header].to_u32.to_io(io, LE)
-      version.to_io(io)
-      Version::NEEDED.to_io(io)
-      GENERAL_FLAGS.to_u16.to_io(io, LE)
-      @method.to_u16.to_io(io, LE)
-
-      # write time
-      write_time(io, @time)
-
-      @crc.to_u32.to_io(io, LE)
-      @dst_len.to_u32.to_io(io, LE)
-      @src_len.to_u32.to_io(io, LE)
-
-      # get path length and write it
-      path_len = @path.bytesize
-      path_len.to_u16.to_io(io, LE)
-
-      # write extras field length (u16)
-      extras_len = 0_u32
-      extras_len.to_u16.to_io(io, LE)
-
-      # write comment field length (u16)
-      comment_len = @comment.bytesize
-      comment_len.to_u16.to_io(io, LE)
-
-      # write disk number
-      0_u32.to_u16.to_io(io, LE)
-
-      # write file attributes (internal, external)
-      # TODO
-      0_u32.to_u16.to_io(io, LE)
-      0_u32.to_u32.to_io(io, LE)
-
-      # write local header offset
-      @pos.to_u32.to_io(io, LE)
-
-      # write path field
-      @path.to_s(io)
-
-      # write extra fields
-      # TODO: implement this
-
-      # write comment
-      @comment.to_s(io)
-
-      # return number of bytes written
-      46_u32 + path_len + extras_len + comment_len
-    end
-  end
-
-  class Writer
-    #
-    # Is this `Writer` closed?
-    #
-    getter? :closed
-
-    #
-    # Create a new `Writer` object.
-    #
-    # You shouldn't need to instantiate this class directly; use
-    # `Zip.write()` instead.
-    #
-    def initialize(
-      @io       : IO,
-      @pos      : UInt32 = 0,
-      @comment  : String = "",
-      @version  : Version = Version::DEFAULT,
-    )
-      @entries = [] of WriterEntry
-      @closed = false
-      @src_pos = @pos
-    end
-
-    private def assert_open
-      raise Error.new("already closed") if closed?
-    end
-
-    #
-    # Return the total number of bytes written so far.
-    #
-    # Example:
-    #
-    #   Zip.write("foo.zip") do |zip|
-    #     # add "bar.txt"
-    #     zip.add_file("bar.txt", "/path/to/bar.txt")
-    #
-    #     # print number of bytes written so far
-    #     puts "bytes written so far: #{zip.bytes_written}"
-    #   end
-    #
-    def bytes_written : UInt32
-      # return total number of bytes written
-      @src_pos - @pos
-    end
-
-    #
-    # Close this writer and return the total number of bytes written.
-    #
-    def close
-      assert_open
-
-      # cache cdr position
-      cdr_pos = @pos
-
-      @entries.each do |entry|
-        @pos += entry.write_central(@io, @version)
-      end
-
-      # write zip footer
-      @pos += write_footer(cdr_pos, @pos - cdr_pos)
-
-      # flag as closed
-      @closed = true
-
-      # return total number of bytes written
-      bytes_written
-    end
-
-    #
-    # Read data from `IO` *io*, write it to *path* in archive, then
-    # return the number of bytes written.
-    #
-    # Example:
-    #
-    #   # create IO from "/path/to/bar.txt"
-    #   File.open("/path/to/bar.txt, "rb") do |io|
-    #     # write to "foo.zip"
-    #     Zip.write("foo.zip") do |zip|
-    #       # add "bar.txt" with contents of given IO
-    #       zip.add("bar.txt", io)
-    #     end
-    #   end
-    #
-    def add(
-      path    : String,
-      io      : IO,
-      method  : CompressionMethod = CompressionMethod::DEFLATE,
-      time    : Time = Time.now,
-      comment : String = "",
-    ) : UInt32
-      # make sure writer is still open
-      assert_open
-
-      # create entry
-      entry = WriterEntry.new(
-        pos:      @pos,
-        path:     path,
-        io:       io,
-        method:   method,
-        time:     time,
-        comment:  comment,
-      )
-
-      # add to list of entries
-      @entries << entry
-
-      # cache offset
-      src_pos = @pos
-
-      # write entry, update offset
-      @pos += entry.to_s(@io)
-
-      # return number of bytes written
-      @pos - src_pos
-    end
-
-    #
-    # Write *data* to *path* in archive and return number of bytes
-    # written.
-    #
-    # Example:
-    #
-    #   # write to "foo.zip"
-    #   Zip.write("foo.zip") do |zip|
-    #     # add "bar.txt" with contents "hello!"
-    #     zip.add("bar.txt", "hello!")
-    #   end
-    #
-    def add(
-      path    : String,
-      data    : String | Bytes,
-      method  : CompressionMethod = CompressionMethod::DEFLATE,
-      time    : Time = Time.now,
-      comment : String = "",
-    ) : UInt32
-      add(path, MemoryIO.new(data), method, time, comment)
-    end
-
-    #
-    # Add local file *file_path* to archive as *path* and return number
-    # of bytes written.
-    #
-    # Example:
-    #
-    #   # write to "foo.zip"
-    #   Zip.write("foo.zip") do |zip|
-    #     # add local file "/path/to/bar.txt" as "bar.txt"
-    #     zip.add_file("bar.txt", "/path/to/bar.txt")
-    #   end
-    #
-    def add_file(
-      path      : String,
-      file_path : String,
-      method    : CompressionMethod = CompressionMethod::DEFLATE,
-      time      : Time = Time.now,
-      comment   : String = "",
-    ) : UInt32
-      File.open(file_path, "rb") do |io|
-        add(path, io, method, time, comment)
-      end
-    end
-
-    # :nodoc:
-    # 4.3.16  End of central directory record:
-    #
-    # * end of central dir signature    4 bytes  (0x06054b50)
-    # * number of this disk             2 bytes
-    # * number of the disk with the
-    #   start of the central directory  2 bytes
-    # * total number of entries in the
-    #   central directory on this disk  2 bytes
-    # * total number of entries in
-    #   the central directory           2 bytes
-    # * size of the central directory   4 bytes
-    # * offset of start of central
-    #   directory with respect to
-    #   the starting disk number        4 bytes
-    # * .ZIP file comment length        2 bytes
-    # * .ZIP file comment       (variable size)
-    # :nodoc:
-
-    private def write_footer(
-      cdr_pos : UInt32,
-      cdr_len : UInt32,
-    ) : UInt32
-      # write magic (u32)
-      MAGIC[:cdr_footer].to_io(@io, LE)
-
-      # write disk num (u16) and footer start disk (u16)
-      0_u32.to_u16.to_io(@io, LE)
-      0_u32.to_u16.to_io(@io, LE)
-
-      # write num entries (u16) and total entries (u16)
-      num_entries = @entries.size
-      num_entries.to_u16.to_io(@io, LE)
-      num_entries.to_u16.to_io(@io, LE)
-
-      # write cdr offset (u32) and cdr length (u32)
-      cdr_len.to_io(@io, LE)
-      cdr_pos.to_io(@io, LE)
-
-      # get comment length (u16)
-      comment_len = @comment.bytesize
-
-      # write comment length (u16) and comment
-      comment_len.to_u16.to_io(@io, LE)
-      @comment.to_s(@io)
-
-      # return number of bytes written
-      22_u32 + comment_len
-    end
-  end
-
-  #
-  # Create a `Zip::Writer` for the output IO *io* and yield it to
-  # the given block.  Returns number of bytes written.
-  #
-  # Example:
-  #
-  #   # create output IO
-  #   File.open("foo.zip", "wb") do |io|
-  #     Zip.write(io) do |zip|
-  #       # add "bar.txt" with contents "hello!"
-  #       zip.add("bar.txt", "hello!")
-  #     end
-  #   end
-  #
-  def self.write(
-    io      : IO,
-    pos     : UInt32 = 0_u32,
-    comment : String = "",
-    version : Version = Version::DEFAULT,
-    &cb     : Writer -> \
-  ) : UInt32
-    r = 0_u32
-
-    begin
-      w = Writer.new(io, pos, comment, version)
-      cb.call(w)
-    ensure
-      if w
-        w.close unless w.closed?
-        r = w.bytes_written
-      end
-    end
-
-    # return total number of bytes written
-    r
-  end
-
-  #
-  # Create a `Zip::Writer` for the output file *path* and yield it to
-  # the given block.  Returns number of bytes written.
-  #
-  # Example:
-  #
-  #   # create "foo.zip"
-  #   Zip.write("foo.zip") do |zip|
-  #     # add "bar.txt" with contents "hello!"
-  #     zip.add("bar.txt", "hello!")
-  #   end
-  #
-  def self.write(
-    path    : String,
-    pos     : UInt32 = 0_u32,
-    comment : String = "",
-    version : Version = Version::DEFAULT,
-    &cb     : Writer -> \
-  ) : UInt32
-    File.open(path, "wb") do |io|
-      write(io, pos, comment, version, &cb)
-    end
-  end
-
-  #
-  # Base class for input source for `Archive` object.
-  #
-  # You should not need to instantiate this class directly; use
-  # `Zip.read()` instead.
-  #
-  class Source
-    include IO
-
-    #
-    # Instantiate a new `Source` from the given `IO::FileDescriptor` or
-    # `MemoryIO` object.
-    #
-    # You should not need to instantiate this class directly; use
-    # `Zip.read()` instead.
-    #
-    def initialize(@io : IO::FileDescriptor | MemoryIO)
-    end
-
-    delegate read, to: @io
-    delegate write, to: @io
-    forward_missing_to @io
-  end
-
-  #
-  # Extra data associated with `Entry`.
-  #
-  # You should not need to instantiate this class directly; use
-  # `Zip::Entry#extras` or `Zip::Entry#local_extras` instead.
-  #
-  # Example:
-  #
-  #   # open "foo.zip"
-  #   Zip.read("foo.zip") do |zip|
-  #     # get extra data associated with "bar.txt"
-  #     extras = zip["bar.txt"].extras
-  #   end
-  #
-  class Extra
-    property :code, :data
-
-    def initialize(@code : UInt16, @data : Bytes)
-    end
-
-    def initialize(io)
-      @code = UInt16.from_io(io, LE).as(UInt16)
-      size = UInt16.from_io(io, LE).as(UInt16)
-      @data = Bytes.new(size)
-      io.read(@data)
-    end
-
-    delegate size, to: @data
-
-    def to_s(io) : UInt32
-      @code.to_s(io, LE)
-      @data.size.to_u16.to_s(io, LE)
-      @data.to_s(io)
-    end
-  end
-
-  #
-  # File entry in `Archive`.
-  #
-  # Use `Zip.read()` to read a Zip archive, then `#[]` to fetch a
-  # specific archive entry.
-  #
-  # Example:
-  #
-  #   # create MemoryIO
-  #   io = MemoryIO.new
-  #
-  #   # open "foo.zip"
-  #   Zip.read("foo.zip") do |zip|
-  #     # get "bar.txt" entry from "foo.zip"
-  #     e = zip["bar.txt"]
-  #
-  #     # read contents of "bar.txt" into io
-  #     e.read(io)
-  #   end
-  #
-  class Entry
-    include TimeHelper
-    include NoneCompressionHelper
-    include DeflateCompressionHelper
-
-    getter :version, :version_needed, :flags, :method, :time, :crc,
-           :compressed_size, :uncompressed_size, :path, :extras,
-           :comment, :internal_attr, :external_attr, :pos
-
-    # :nodoc:
-    # central file header signature   4 bytes  (0x02014b50)
-    # version made by                 2 bytes
-    # version needed to extract       2 bytes
-    # general purpose bit flag        2 bytes
-    # compression method              2 bytes
-    # last mod file time              2 bytes
-    # last mod file date              2 bytes
-    # crc-32                          4 bytes
-    # compressed size                 4 bytes
-    # uncompressed size               4 bytes
-    # file name length                2 bytes
-    # extra field length              2 bytes
-    # file comment length             2 bytes
-    # disk number start               2 bytes
-    # internal file attributes        2 bytes
-    # external file attributes        4 bytes
-    # relative offset of local header 4 bytes
-    #
-    # file name (variable size)
-    # extra field (variable size)
-    # file comment (variable size)
-    # :nodoc:
-
-    #
-    # Instantiate a new `Entry` object from the given IO.
-    #
-    # You should not need to call this method directly (use
-    # `Zip::Archive#[]` instead).
-    #
-    def initialize(@io : Source)
-      # allocate slice for header data
-      head_buf = Bytes.new(46)
-
-      # read entry
-      if ((head_len = io.read(head_buf)) != 46)
-        raise Error.new("couldn't read full CDR entry (#{head_len} != 46)")
-      end
-
-      # create memory io for slice
-      head_mem_io = MemoryIO.new(head_buf, false)
-
-      magic = UInt32.from_io(head_mem_io, LE)
-      if magic != MAGIC[:cdr_header]
-        raise Error.new("invalid CDR header magic")
-      end
-
-      # read versions
-      @version = UInt16.from_io(head_mem_io, LE).as(UInt16)
-      @version_needed = UInt16.from_io(head_mem_io, LE).as(UInt16)
-
-      # TODO: check versions
-
-      # read flags, method, and date
-      @flags = UInt16.from_io(head_mem_io, LE).as(UInt16)
-      @method = CompressionMethod.new(
-        UInt16.from_io(head_mem_io, LE).as(UInt16).to_i32
-      )
-
-      # TODO: convert to Time object
-      @time = from_dos_time(UInt32.from_io(head_mem_io, LE)).as(Time)
-
-      # read crc and lengths
-      @crc = UInt32.from_io(head_mem_io, LE).as(UInt32)
-      @compressed_size = UInt32.from_io(head_mem_io, LE).as(UInt32)
-      @uncompressed_size = UInt32.from_io(head_mem_io, LE).as(UInt32)
-
-      # read lengths
-      @path_len = UInt16.from_io(head_mem_io, LE).not_nil!.as(UInt16)
-      @extras_len = UInt16.from_io(head_mem_io, LE).as(UInt16)
-      @comment_len = UInt16.from_io(head_mem_io, LE).as(UInt16)
-
-      # read starting disk
-      @disk_start = UInt16.from_io(head_mem_io, LE).as(UInt16)
-
-      # read attributes and position
-      @internal_attr = UInt16.from_io(head_mem_io, LE).as(UInt16)
-      @external_attr = UInt32.from_io(head_mem_io, LE).as(UInt32)
-      @pos = UInt32.from_io(head_mem_io, LE).as(UInt32)
-
-      # close memory io
-      head_mem_io.close
-
-      # create and populate data buffer
-      # (holds path, extras, and comment data)
-      data_len = @path_len + @extras_len + @comment_len
-      data_buf = Bytes.new(data_len)
-      if io.read(data_buf) != data_len
-        raise Error.new("couldn't read entry CDR name, extras, and comment")
-      end
-
-      # create data memory io
-      data_mem_io = MemoryIO.new(data_buf)
-
-      # read path, extras, and comment from data memory io
-      @path = read_string(data_mem_io, @path_len, "name") as String
-      @extras = read_extras(data_mem_io, @extras_len) as Array(Extra)
-      @comment = read_string(data_mem_io, @comment_len, "comment") as String
-
-      # close data memory io
-      data_mem_io.close
-    end
-
-    #
-    # Return the uncompressed size of this entry in bytes.
-    #
-    # Example:
-    #
-    #   Zip.read("foo.zip") do |zip|
-    #     size = zip["bar.txt"].size
-    #     puts "bar.txt is #{size} bytes."
-    #   end
-    #
-    def size : UInt32
-      @uncompressed_size
-    end
-
-    # :nodoc:
-    # local file header signature     4 bytes  (0x04034b50)
-    # version needed to extract       2 bytes
-    # general purpose bit flag        2 bytes
-    # compression method              2 bytes
-    # last mod file time              2 bytes
-    # last mod file date              2 bytes
-    # crc-32                          4 bytes
-    # compressed size                 4 bytes
-    # uncompressed size               4 bytes
-    # file name length                2 bytes
-    # extra field length              2 bytes
-    # file name (variable size)
-    # extra field (variable size)
-    # :nodoc:
-
-    #
-    # Write contents of `Entry` into given `IO`.
-    #
-    # Raises an `Error` if the file contents could not be read or if the
-    # compression method is unsupported.
-    #
-    # Example:
-    #
-    #   # open "output-bar.txt" for writing
-    #   File.open("output-bar.txt", "wb") do |io|
-    #     # open archive "./foo.zip"
-    #     Zip.read("foo.zip") do |zip|
-    #       # write contents of "bar.txt" to "output-bar.txt"
-    #       zip["foo.txt"].read(io)
-    #     end
-    #   end
-    #
-    def read(dst_io : IO) : UInt32
-      # create buffer for local header
-      buf = Bytes.new(30)
-
-      # move to local header
-      @io.pos = @pos
-
-      # read local header into buffer
-      @io.read(buf)
-
-      # create memory io from buffer
-      mem_io = MemoryIO.new(buf, false)
-
-      # check magic header
-      magic = UInt32.from_io(mem_io, LE)
-      if magic != MAGIC[:file_header]
-        raise Error.new("invalid file header magic")
-      end
-
-      # skip local header
-      mem_io.pos = 26_u32
-
-      # read local name and extras length
-      path_len = UInt16.from_io(mem_io, LE)
-      extras_len = UInt16.from_io(mem_io, LE)
-
-      # close memory io
-      mem_io.close
-
-      # skip name and extras
-      @io.pos = @pos + 30_u32 + path_len + extras_len
-
-      case @method
-      when CompressionMethod::NONE
-        decompress_none(@io, dst_io, @compressed_size, @uncompressed_size)
-      when CompressionMethod::DEFLATE
-        decompress_deflate(@io, dst_io, @compressed_size, @uncompressed_size)
-      else
-        raise Error.new("unsupported method: #{@method}")
-      end
-
-      # return number of bytes written
-      @uncompressed_size
-    end
-
-    #
-    # Returns an array of `Extra` attributes for this `Entry`.
-    #
-    # Zip archives can (and do) have separate `Extra` attributes
-    # associated with the file entry itself, and the file's entry in the
-    # Central Directory.
-    #
-    # The `#extras` method returns the `Extra` attributes from the
-    # file's entry in the Central Directory, and this method returns the
-    # `Extra` data from the file entry itself.
-    #
-    # Example:
-    #
-    #   # open "./foo.zip"
-    #   Zip.read("./foo.zip") do |zip|
-    #     # get array of local extra attributes from "bar.txt"
-    #     extras = zip["bar.txt"].local_extras
-    #   end
-    #
-    def local_extras : Array(Extra)
-      unless @local_extras
-        # move to extras_len in local header
-        @io.pos = @pos + 26_u32
-
-        # read name and extras lengths
-        name_len = UInt16.from_io(@io, LE)
-        extras_len = UInt16.from_io(@io, LE)
-
-        # move to extras_len in local header
-        @io.pos = @pos + 30_u32 + name_len
-
-        # read local extras
-        @local_extras = read_extras(@io, extras_len) as Array(Extra)
-      end
-
-      # return results
-      @local_extras.not_nil!
-    end
-
-    #
-    # Returns an array of `Extra` attributes of length `len` from IO `io`.
-    #
-    private def read_extras(io, len : UInt16) : Array(Extra)
-      # read extras
-      r = [] of Extra
-
-      if len > 0
-        # create buffer of extras data
-        buf = Bytes.new(len)
-        if io.read(buf) != len
-          raise Error.new("couldn't read CDR entry extras")
-        end
-
-        # create memory io over buffer
-        mem_io = MemoryIO.new(buf, false)
-
-        # read extras from io
-        while mem_io.pos != mem_io.size
-          r << Extra.new(mem_io)
-        end
-
-        # close memory io
-        mem_io.close
-      end
-
-      # return results
-      r
-    end
-
-    #
-    # Read String of length bytes from IO.
-    #
-    # Note: At the moment this assumes UTF-8 encoding, but we should
-    # make this configurable via a parameter to `#read()`.
-    #
-    private def read_string(io, len : UInt16, name : String) : String
-      if len > 0
-        buf = Bytes.new(len)
-
-        if io.read(buf) != len
-          raise Error.new("couldn't read CDR entry #{name}")
-        end
-
-        # FIXME: should handle encoding here?
-        String.new(buf)
-      else
-        ""
-      end
-    end
-  end
-
-  # :nodoc:
-  # 4.3.16  End of central directory record:
-  #
-  # * end of central dir signature    4 bytes  (0x06054b50)
-  # * number of this disk             2 bytes
-  # * number of the disk with the
-  #   start of the central directory  2 bytes
-  # * total number of entries in the
-  #   central directory on this disk  2 bytes
-  # * total number of entries in
-  #   the central directory           2 bytes
-  # * size of the central directory   4 bytes
-  # * offset of start of central
-  #   directory with respect to
-  #   the starting disk number        4 bytes
-  # * .ZIP file comment length        2 bytes
-  # * .ZIP file comment       (variable size)
-  # :nodoc:
-
-  #
-  # Input archive.
-  #
-  # Use `Zip.read()` instead of instantiating this class directly.
-  #
-  class Archive
-    include Enumerable(Entry)
-    include Iterable
-
-    getter :entries, :comment
-
-    #
-    # Create new Zip::Archive from input Zip::Source.
-    #
-    # Use `Zip.read()` instead of calling this method directly.
-    #
-    def initialize(@io : Source)
-      # initialize entries
-      # find footer and end of io
-      footer_pos, end_pos = find_footer_and_eof(@io)
-
-      # skip magic
-      @io.pos = footer_pos + 4
-
-      # create slice and memory io
-      mem = Bytes.new(18)
-
-      # read footer into memory io
-      @io.pos = footer_pos + 4
-      if ((len = @io.read(mem)) < mem.size)
-        raise Error.new("couldn't read zip footer")
-      end
-
-      # create memory io for slice
-      mem_io = MemoryIO.new(mem, false)
-
-      # read disk numbers
-      @disk_num = mem_io.read_bytes(UInt16, LE).as(UInt16)
-      @cdr_disk = mem_io.read_bytes(UInt16, LE).as(UInt16)
-
-      # check disk numbers
-      if @disk_num != @cdr_disk
-        raise Error.new("multi-disk archives not supported")
-      end
-
-      # read entry counts
-      @num_disk_entries = mem_io.read_bytes(UInt16, LE).as(UInt16)
-      @num_entries = mem_io.read_bytes(UInt16, LE).not_nil!.as(UInt16)
-
-      # check entry counts
-      if @num_disk_entries != @num_entries
-        raise Error.new("multi-disk archives not supported")
-      end
-
-      # read cdr position and length
-      @cdr_len = mem_io.read_bytes(UInt32, LE).not_nil!.as(UInt32)
-      @cdr_pos = mem_io.read_bytes(UInt32, LE).not_nil!.as(UInt32)
-
-      # check cdr position
-      if @cdr_pos.not_nil! + @cdr_len.not_nil! >= end_pos
-        raise Error.new("invalid CDR offset: #{@cdr_pos}")
-      end
-
-      # read comment length and comment body
-      @comment_len = mem_io.read_bytes(UInt16, LE).not_nil!.as(UInt16)
-      @comment = if @comment_len.not_nil! > 0
-        # allocate space for comment
-        slice = Bytes.new(@comment_len.not_nil!)
-
-        # seek to comment position
-        @io.pos = footer_pos + 22
-
-        # read comment data
-        if ((len = @io.read(slice)) != @comment_len)
-          raise Error.new("archive comment read truncated")
-        end
-
-        # FIXME: shouldn't assume UTF-8 here
-        String.new(slice, "UTF-8")
-      else
-        ""
-      end
-
-      # close memory io
-      mem_io.close
-
-      # read entries
-      @entries = [] of Entry
-      read_entries(@entries, @io, @cdr_pos, @cdr_len, @num_entries)
-    end
-
-    #################################
-    # enumeration/iteration methods #
-    #################################
-
-    #
-    # Get hash of path -> Zip::Entries
-    #
-    private def paths
-      @paths ||= @entries.reduce({} of String => Entry) do |r, e|
-        r[e.path] = e
-        r
-      end.as(Hash(String, Entry))
-    end
-
-    #
-    # Get Zip::Entry by path.
-    #
-    # Example:
-    #
-    #   # get bar.txt and read it into memory io
-    #   io = MemoryIO.new
-    #   zip["bar.txt"].read(io)
-    #
-    def [](path : String) : Entry
-      paths[path]
-    end
-
-    #
-    # Return Zip::Entry from path, or nil if it doesn't exist.
-    #
-    # Example:
-    #
-    #   # read bar.txt into memory io if it exists
-    #   if e = zip["bar.txt"]?
-    #     io = MemoryIO.new
-    #     e.read(io)
-    #   end
-    #
-    def []?(path : String) : Entry?
-      paths[path]?
-    end
-
-    #
-    # Get Zip::Entry by number.
-    #
-    # Example:
-    #
-    #   # read third entry from archive into memory io
-    #   io = MemoryIO.new
-    #   zip[2].read(io)
-    #
-    def [](id : Int) : Entry
-      @entries[id]
-    end
-
-    #
-    # Get Zip::Entry by number, or nil if it doesn't exist
-    #
-    # Example:
-    #
-    #   # read third entry from archive into memory io
-    #   if e = zip[2]
-    #     io = MemoryIO.new
-    #     e.read(io)
-    #   end
-    #
-    def []?(id : Int) : Entry?
-      @entries[id]?
-    end
-
-    delegate each, to: @entries
-    delegate size, to: @entries
-
-    ###################
-    # loading methods #
-    ###################
-
-    #
-    # Read CDR entries from given `Zip::Source`.
-    #
-    private def read_entries(
-      entries     : Array(Entry),
-      io          : Source,
-      cdr_pos     : UInt32,
-      cdr_len     : UInt32,
-      num_entries : UInt16,
-    )
-      # get end position
-      end_cdr_pos = cdr_pos + cdr_len
-
-      # seek to start of entries
-      io.pos = cdr_pos
-
-      # read entries
-      num_entries.times do
-        # create new entry
-        entry = Entry.new(io)
-
-        # add to list of entries
-        entries << entry
-
-        # check position
-        if io.pos > end_cdr_pos
-          raise Error.new("read past CDR")
-        end
-      end
-    end
-
-    #
-    # Find EOF and end of CDR for archive.
-    #
-    private def find_footer_and_eof(io : Source)
-      # seek to end of file
-      io.seek(0, IO::Seek::End)
-      end_pos = io.pos
-
-      if end_pos < 22
-        raise Error.new("too small for end of central directory")
-      end
-
-      # create buffer and memory io around it
-      buf = Bytes.new(22)
-      mem_io = MemoryIO.new(buf, false)
-
-      curr_pos = end_pos - 22
-      while curr_pos >= 0
-        # seek to current position and load possible cdr into buffer
-        io.pos = curr_pos
-        io.read(buf)
-
-        # rewind memory io
-        mem_io.rewind
-
-        # read what might be the end_cdr magic
-        maybe_end_magic = UInt32.from_io(mem_io, LE)
-
-        if maybe_end_magic == MAGIC[:cdr_footer]
-          # jump to archive commment len (maybe)
-          mem_io.pos = 20
-
-          # get archive commment len (maybe)
-          maybe_comment_len = UInt16.from_io(mem_io, LE)
-
-          if curr_pos + 22 + maybe_comment_len == end_pos
-            # close memio
-            mem_io.close
-
-            # magic and comment line up: probably found end_cdr
-            return { curr_pos, end_pos }
-          end
-        end
-
-        # step back one byte
-        curr_pos -= 1
-      end
-
-      # throw error
-      raise Error.new("couldn't find end of central directory")
-    end
-  end
-
-
-  #
-  # Read Zip::Archive from seekable IO instance and pass it to the given
-  # block.
-  #
-  # Example:
-  #
-  #   # create memory io for contents of "bar.txt"
-  #   io = MemoryIO.new
-  #
-  #   # read "bar.txt" from "./foo.zip"
-  #   Zip.read(File.open("./foo.zip", "rb")) do |zip|
-  #     zip["bar.txt"].read(io)
-  #   end
-  #
-  def self.read(
-    io          : IO,
-    &cb         : Archive -> \
-  ) : Void
-    r = Archive.new(Source.new(io))
-    cb.call(r)
-  end
-
-  #
-  # Read Zip::Archive from Slice and pass it to the given block.
-  #
-  # Example:
-  #
-  #   # create memory io for contents of "bar.txt"
-  #   io = MemoryIO.new
-  #
-  #   # extract "bar.txt" from zip archive in Slice some_slice and
-  #   # save it to MemoryIO
-  #   Zip.read(some_slice) do |zip|
-  #     zip["bar.txt"].read(io)
-  #   end
-  #
-  def self.read(
-    slice : Bytes,
-    &cb   : Archive -> \
-  ) : Void
-    src = Source.new(MemoryIO.new(slice, false))
-    read(src, &cb)
-  end
-
-  #
-  # Read Zip::Archive from File and pass it to the given block.
-  #
-  # Example:
-  #
-  #   # create memory io for contents of "bar.txt"
-  #   io = MemoryIO.new
-  #
-  #   # extract "bar.txt" from "./foo.zip" and save it to MemoryIO
-  #   Zip.read("./foo.zip") do |zip|
-  #     zip["bar.txt"].read(io)
-  #   end
-  #
-  def self.read(
-    path : String,
-    &cb  : Archive -> \
-  ) : Void
-    File.open(path, "rb") do |io|
-      read(io, &cb)
-    end
-  end
-end