Class: Zip::InputStream

Inherits:
Object
  • Object
show all
Includes:
Zip::IOExtras::AbstractInputStream
Defined in:
lib/zip/input_stream.rb

Overview

InputStream is the basic class for reading zip entries in a zip file. It is possible to create a InputStream object directly, passing the zip file name to the constructor, but more often than not the InputStream will be obtained from a File (perhaps using the ZipFileSystem interface) object for a particular entry in the zip archive.

A InputStream inherits IOExtras::AbstractInputStream in order to provide an IO-like interface for reading from a single zip entry. Beyond methods for mimicking an IO-object it contains the method get_next_entry for iterating through the entries of an archive. get_next_entry returns a Entry object that describes the zip entry the InputStream is currently reading from.

Example that creates a zip archive with ZipOutputStream and reads it back again with a InputStream.

require 'zip'

Zip::OutputStream.open("my.zip") do |io|

  io.put_next_entry("first_entry.txt")
  io.write "Hello world!"

  io.put_next_entry("adir/first_entry.txt")
  io.write "Hello again!"
end

Zip::InputStream.open("my.zip") do |io|

  while (entry = io.get_next_entry)
    puts "Contents of #{entry.name}: '#{io.read}'"
  end
end

java.util.zip.ZipInputStream is the original inspiration for this class.

Constant Summary collapse

CHUNK_SIZE =

:nodoc:

32_768

Instance Attribute Summary

Attributes included from Zip::IOExtras::AbstractInputStream

#lineno, #pos

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Zip::IOExtras::AbstractInputStream

#each, #eof?, #flush, #gets, #read, #readline, #readlines, #ungetc

Methods included from Zip::IOExtras::FakeIO

#kind_of?

Constructor Details

#initialize(context, offset: 0, decrypter: nil) ⇒ InputStream

Opens the indicated zip file. An exception is thrown if the specified offset in the specified filename is not a local zip entry header.

Parameters:

  • context (String||IO||StringIO) —

    file path or IO/StringIO object

  • offset (Integer) (defaults to: 0) —

    offset in the IO/StringIO



54
55
56
57
58
59
60
61
 
# File 'lib/zip/input_stream.rb', line 54

def initialize(context, offset: 0, decrypter: nil)
  super()
  @archive_io = get_io(context, offset)
  @decompressor = ::Zip::NullDecompressor
  @decrypter = decrypter
  @current_entry = nil
  @complete_entry = nil
end

Class Method Details

.open(filename_or_io, offset: 0, decrypter: nil) ⇒ Object

Same as #initialize but if a block is passed the opened stream is passed to the block and closed when the block returns.



127
128
129
130
131
132
133
134
135
136
 
# File 'lib/zip/input_stream.rb', line 127

def open(filename_or_io, offset: 0, decrypter: nil)
  zio = new(filename_or_io, offset: offset, decrypter: decrypter)
  return zio unless block_given?

  begin
    yield zio
  ensure
    zio.close if zio
  end
end

Instance Method Details

#close ⇒ Object

Close this InputStream. All further IO will raise an IOError.



64
65
66
 
# File 'lib/zip/input_stream.rb', line 64

def close
  @archive_io.close
end

#get_next_entry ⇒ Object

Returns an Entry object and positions the stream at the beginning of the entry data. It is necessary to call this method on a newly created InputStream before reading from the first entry in the archive. Returns nil when there are no more entries.



72
73
74
75
76
77
78
79
80
 
# File 'lib/zip/input_stream.rb', line 72

def get_next_entry
  unless @current_entry.nil?
    raise StreamingError, @current_entry if @current_entry.incomplete?

    @archive_io.seek(@current_entry.next_header_offset, IO::SEEK_SET)
  end

  open_entry
end

#rewind ⇒ Object

Rewinds the stream to the beginning of the current entry.



83
84
85
86
87
88
89
90
 
# File 'lib/zip/input_stream.rb', line 83

def rewind
  return if @current_entry.nil?

  @lineno = 0
  @pos    = 0
  @archive_io.seek(@current_entry.local_header_offset, IO::SEEK_SET)
  open_entry
end

#size ⇒ Object

Returns the size of the current entry, or ‘nil` if there isn’t one.



117
118
119
120
121
 
# File 'lib/zip/input_stream.rb', line 117

def size
  return if @current_entry.nil?

  @current_entry.size
end

#sysread(maxlen, out_string = nil) ⇒ Object

Modelled after IO#sysread.

Reads up to maxlen bytes from the stream; returns a string (either a new string or the given out_string). Its encoding is the unchanged encoding of out_string, if out_string is given; ASCII-8BIT, otherwise. Output contains maxlen bytes from the stream, if available; otherwise contains all available bytes, if any available; otherwise is an empty string.

This method should not be used with buffered input stream-reader methods, such as #read, #readline, #gets.



103
104
105
106
107
108
109
110
111
112
113
114
 
# File 'lib/zip/input_stream.rb', line 103

def sysread(maxlen, out_string = nil)
  return (maxlen.nil? || maxlen.zero? ? '' : nil) if eof?

  output = produce_input(maxlen)

  if out_string.nil?
    output.force_encoding(Encoding::ASCII_8BIT)
  else
    encoding = out_string.encoding
    out_string.replace(output).force_encoding(encoding)
  end
end