Class: OPA::ZipIO::Reader

Inherits:
Object
  • Object
show all
Defined in:
lib/opa/zip_io.rb

Overview

Reads entries from a ZIP archive.

Defined Under Namespace

Classes: ParsedEntry

Class Method Summary collapse

Class Method Details

.read(data) ⇒ Object 



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# File 'lib/opa/zip_io.rb', line 104

def self.read(data)
  data = data.b
  entries = {}

  # Find end of central directory record
  eocd_pos = data.rindex([0x06054b50].pack("V"))
  raise "Invalid ZIP: no EOCD record" unless eocd_pos

  cd_size = data[eocd_pos + 12, 4].unpack1("V")
  cd_offset = data[eocd_pos + 16, 4].unpack1("V")
  entry_count = data[eocd_pos + 10, 2].unpack1("v")

  # Parse central directory to get entry metadata
  pos = cd_offset
  entry_count.times do
    sig = data[pos, 4].unpack1("V")
    raise "Invalid CD entry signature" unless sig == 0x02014b50

    compression = data[pos + 10, 2].unpack1("v")
    crc32 = data[pos + 16, 4].unpack1("V")
    comp_size = data[pos + 20, 4].unpack1("V")
    uncomp_size = data[pos + 24, 4].unpack1("V")
    name_len = data[pos + 28, 2].unpack1("v")
    extra_len = data[pos + 30, 2].unpack1("v")
    comment_len = data[pos + 32, 2].unpack1("v")
    local_offset = data[pos + 42, 4].unpack1("V")
    name = data[pos + 46, name_len].force_encoding("UTF-8")

    # Read from local file header to get actual data
    local_name_len = data[local_offset + 26, 2].unpack1("v")
    local_extra_len = data[local_offset + 28, 2].unpack1("v")
    data_start = local_offset + 30 + local_name_len + local_extra_len
    raw = data[data_start, comp_size]

    content = case compression
              when 0 then raw
              when 8 then Zlib::Inflate.new(-Zlib::MAX_WBITS).inflate(raw)
              else raise "Unsupported compression method: #{compression}"
              end

    entries[name] = content.force_encoding("UTF-8")

    pos += 46 + name_len + extra_len + comment_len
  end

  entries
end