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|
require "./zip/*"
require "zlib"
module Zip
VERSION = "0.1.0"
LE = IO::ByteFormat::LittleEndian
# 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.
#
@[Flags]
enum GeneralFlags
WEAK_ENCRYPTION
COMPRESSION_OPTION_1
COMPRESSION_OPTION_2
FOOTER
RESERVED_4
PATCH
STRONG_ENCRYPTION
RESERVED_7
RESERVED_8
RESERVED_9
RESERVED_10
EFS
RESERVED_12
MASKED_VALUES
RESERVED_14
RESERVED_15
end
enum CompressionMethod
NONE = 0 # Stored (no compression)
SHRUNK = 1 # Shrunk
REDUCED_1 = 2 # Reduced with compression factor 1
REDUCED_2 = 3 # Reduced with compression factor 2
REDUCED_3 = 4 # Reduced with compression factor 3
REDUCED_4 = 5 # Reduced with compression factor 4
IMPLODED = 6 # Imploded
# Tokenized = 7 # Reserved for Tokenizing compression algorithm
DEFLATE = 8 # Deflated
DEFLATE64 = 9 # Enhanced Deflating using Deflate64(tm)
TERSE_OLD = 10 # PKWARE Data Compression Library Imploding (old IBM TERSE)
# RESERVED_11 = 11 # Reserved by PKWARE
BZIP2 = 12 # BZIP2
# RESERVED_13 = 13 # Reserved by PKWARE
LZMA = 14 # LZMA (EFS)
# RESERVED_15 = 15 # Reserved by PKWARE
# RESERVED_16 = 16 # Reserved by PKWARE
# RESERVED_17 = 17 # Reserved by PKWARE
TERSE = 18 # IBM TERSE (new)
LZ77 = 19 # IBM LZ77 z Architecture (PFS)
WAVPACK = 97 # WavPack compressed data
PPMD = 98 # PPMd version I, Rev 1
end
# FIXME: should this have a better class?
class Error < Exception
end
module Util
def self.write_time(io : IO, time : Time) : UInt64
# TODO
0_u32.to_u16.to_io(io, LE)
0_u32.to_u16.to_io(io, LE)
# return number of bytes written
4_u64
end
end
# TODO
class Reader
def initialize(path : String)
end
def initialize(io : IO)
end
end
module NoneCompressor
def compress_none(src_io, dst_io)
crc = 0_u32
buf = Bytes.new(4096)
src_len = 0_u64
while ((len = src_io.read(buf)) > 0)
# TODO: crc32
dst_io.write((len < buf.size) ? Bytes.new(buf.to_unsafe, len) : buf)
src_len += len
end
# return results
{ crc, src_len, src_len }
end
end
module DeflateCompressor
def compress_deflate(src_io, dst_io)
crc = 0_u32
src_len = 0_u64
dst_len = 0_u64
# create buffer and intermediate memory io
buf = Bytes.new(4096)
mem_io = MemoryIO.new(4096)
Zlib::Deflate.new(
output: mem_io,
sync_close: false,
) do |zlib_io|
while ((len = src_io.read(buf)) > 0)
# TODO: crc32
# compress bytes to memory io
zlib_io.write((len < buf.size) ? Bytes.new(buf.to_unsafe, len) : buf)
src_len += len
# write compressed bytes to dst_io
dst_io.write(Bytes.new(mem_io.buffer, mem_io.pos))
dst_len += mem_io.pos
# clear memio
mem_io.rewind
end
end
# return results
{ crc, src_len, dst_len }
end
end
class WriterEntry
include NoneCompressor
include DeflateCompressor
# TODO version needed to extract and header flags
# (used for header and central header)
VERSION_NEEDED = 0_u32
GENERAL_FLAGS = GeneralFlags.flags(FOOTER, EFS)
def initialize(
@pos : UInt64,
@path : String,
@io : IO,
@method : CompressionMethod = CompressionMethod::DEFLATE,
@time : Time = Time.now,
@comment : String = "",
)
@crc = 0_u32
@src_len = 0_u64
@dst_len = 0_u64
end
def to_s(dst_io) : UInt64
# 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
#
# 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)
#
HEADER_MAGIC = 0x04034b50_u32
private def write_header(
io : IO,
path : String,
method : CompressionMethod,
time : Time,
) : UInt64
# get path length, in bytes
path_len = path.bytesize
# check file path
raise "empty file path" if path_len == 0
raise "file path too long" if path_len >= UInt16::MAX
raise "file path contains leading slash" if path[0] == '/'
# write magic, version needed, flags, and compression method
HEADER_MAGIC.to_io(io, LE)
VERSION_NEEDED.to_u16.to_io(io, LE)
GENERAL_FLAGS.to_u16.to_io(io, LE)
method.to_u16.to_io(io, LE)
# write time
Util.write_time(io, time)
# crc, compressed size, uncompressed size
# (these will be populated in the footer)
0_u32.to_io(io, LE)
0_u32.to_io(io, LE)
0_u32.to_io(io, LE)
path_len.to_u16.to_io(io, LE)
# write extras field length
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_u64 + path_len + extras_len
end
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 "unsupported compression method"
end
end
# 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
FOOTER_MAGIC = 0x08074b50_u32
private def write_footer(
io : IO,
crc : UInt32,
src_len : UInt64,
dst_len : UInt64,
) : UInt64
# write footer
FOOTER_MAGIC.to_io(io, LE)
crc.to_io(io, LE)
dst_len.to_io(io, LE)
src_len.to_io(io, LE)
# return number of bytes written
16_u64
end
#
# 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)
CENTRAL_MAGIC = 0x02014b50_u32
# TODO: version made by, if unspecified
CENTRAL_VERSION_MADE_BY = 0_u32
def write_central(
io : IO,
version : UInt32 = CENTRAL_VERSION_MADE_BY
) : UInt64
CENTRAL_MAGIC.to_io(io, LE)
version.to_u16.to_io(io, LE)
VERSION_NEEDED.to_u16.to_io(io, LE)
GENERAL_FLAGS.to_u16.to_io(io, LE)
@method.to_u16.to_io(io, LE)
# write time
Util.write_time(io, @time)
@crc.to_io(io, LE)
@dst_len.to_io(io, LE)
@src_len.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
extras_len = 0_u32
extras_len.to_u16.to_io(io, LE)
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_u16.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
30_u64 + path_len + extras_len
# TODO
0_u64
end
end
class Writer
def initialize(
@io : IO,
@pos : UInt64 = 0,
@comment : String = "",
@version : UInt32 = 0,
)
@entries = [] of WriterEntry
@closed = false
@src_pos = @pos
end
def closed?
@closed
end
private def assert_open
raise "already closed" if closed?
end
def bytes_written : UInt64
# return total number of bytes written
@src_pos - @pos
end
def close
assert_open
# cache cdr position
cdr_pos = @pos
@entries.each do |entry|
@pos += entry.write_central(@io)
end
# write zip footer
write_footer(cdr_pos)
# flag as closed
@closed = true
# return total number of bytes written
bytes_written
end
def add(
path : String,
io : IO,
method : CompressionMethod = CompressionMethod::DEFLATE,
time : Time = Time.now,
comment : String = "",
) : UInt64
# cache input position
src_pos = @pos
# 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
# write entry, update offset
@pos += entry.to_s(@io)
# return number of bytes written
@pos - src_pos
end
def add(
path : String,
body : String | Bytes,
method : CompressionMethod = CompressionMethod::DEFLATE,
time : Time = Time.now,
comment : String = "",
) : UInt64
add(path, MemoryIO.new(body), method, time, comment)
end
def add_file(
path : String,
file_path : String,
method : CompressionMethod = CompressionMethod::DEFLATE,
time : Time = Time.now,
comment : String = "",
) : UInt64
File.open(file_path, "rb") do |io|
add(path, io, method, time, comment)
end
end
# 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)
FOOTER_MAGIC = 0x06054b50_u32
private def write_footer(cdr_pos : UInt64)
# write magic (u32), disk num (u16), start footer disk (u16)
FOOTER_MAGIC.to_io(@io, LE)
0_u32.to_u16.to_io(@io, LE)
0_u32.to_u16.to_io(@io, LE)
# write num entries (u16) / total entries (u16)
num_entries = @entries.size
num_entries.to_u16.to_io(@io, LE)
num_entries.to_u16.to_io(@io, LE)
# write offset (u32)
(cdr_pos - @src_pos).to_u32.to_io(@io, LE)
cdr_pos.to_io(@io, LE)
# write comment length (u16) and comment
@comment.bytesize.to_u16.to_io(@io, LE)
@comment.to_s(@io)
end
end
def self.write(
io : IO,
pos : UInt64 = 0_u64,
comment : String = "",
version : UInt32 = 0_u32,
&cb : Writer -> \
) : UInt64
r = 0_u64
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
def self.write(
path : String,
pos : UInt64 = 0_u64,
comment : String = "",
version : UInt32 = 0_u32,
&cb : Writer -> \
) : UInt64
File.open(path, "wb") do |io|
write(io, pos, comment, version, &cb)
end
end
end
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