summaryrefslogtreecommitdiff
path: root/lib/rubygems/package/tar_writer.rb
blob: dfd635724bbc7965159cfa74cced100e125772fb (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
# -*- coding: utf-8 -*-
#--
# Copyright (C) 2004 Mauricio Julio Fernández Pradier
# See LICENSE.txt for additional licensing information.
#++

require 'digest'

##
# Allows writing of tar files

class Gem::Package::TarWriter

  class FileOverflow < StandardError; end

  ##
  # IO wrapper that allows writing a limited amount of data

  class BoundedStream

    ##
    # Maximum number of bytes that can be written

    attr_reader :limit

    ##
    # Number of bytes written

    attr_reader :written

    ##
    # Wraps +io+ and allows up to +limit+ bytes to be written

    def initialize(io, limit)
      @io = io
      @limit = limit
      @written = 0
    end

    ##
    # Writes +data+ onto the IO, raising a FileOverflow exception if the
    # number of bytes will be more than #limit

    def write(data)
      if data.bytesize + @written > @limit
        raise FileOverflow, "You tried to feed more data than fits in the file."
      end
      @io.write data
      @written += data.bytesize
      data.bytesize
    end

  end

  ##
  # IO wrapper that provides only #write

  class RestrictedStream

    ##
    # Creates a new RestrictedStream wrapping +io+

    def initialize(io)
      @io = io
    end

    ##
    # Writes +data+ onto the IO

    def write(data)
      @io.write data
    end

  end

  ##
  # Creates a new TarWriter, yielding it if a block is given

  def self.new(io)
    writer = super

    return writer unless block_given?

    begin
      yield writer
    ensure
      writer.close
    end

    nil
  end

  ##
  # Creates a new TarWriter that will write to +io+

  def initialize(io)
    @io = io
    @closed = false
  end

  ##
  # Adds file +name+ with permissions +mode+, and yields an IO for writing the
  # file to

  def add_file(name, mode) # :yields: io
    check_closed

    raise Gem::Package::NonSeekableIO unless @io.respond_to? :pos=

    name, prefix = split_name name

    init_pos = @io.pos
    @io.write "\0" * 512 # placeholder for the header

    yield RestrictedStream.new(@io) if block_given?

    size = @io.pos - init_pos - 512

    remainder = (512 - (size % 512)) % 512
    @io.write "\0" * remainder

    final_pos = @io.pos
    @io.pos = init_pos

    header = Gem::Package::TarHeader.new :name => name, :mode => mode,
                                         :size => size, :prefix => prefix,
                                         :mtime => Time.now

    @io.write header
    @io.pos = final_pos

    self
  end

  ##
  # Adds +name+ with permissions +mode+ to the tar, yielding +io+ for writing
  # the file.  The +digest_algorithm+ is written to a read-only +name+.sum
  # file following the given file contents containing the digest name and
  # hexdigest separated by a tab.
  #
  # The created digest object is returned.

  def add_file_digest name, mode, digest_algorithms # :yields: io
    digests = digest_algorithms.map do |digest_algorithm|
      digest = digest_algorithm.new
      digest_name =
        if digest.respond_to? :name then
          digest.name
        else
          /::([^:]+)$/ =~ digest_algorithm.name
          $1
        end

      [digest_name, digest]
    end

    digests = Hash[*digests.flatten]

    add_file name, mode do |io|
      Gem::Package::DigestIO.wrap io, digests do |digest_io|
        yield digest_io
      end
    end

    digests
  end

  ##
  # Adds +name+ with permissions +mode+ to the tar, yielding +io+ for writing
  # the file.  The +signer+ is used to add a digest file using its
  # digest_algorithm per add_file_digest and a cryptographic signature in
  # +name+.sig.  If the signer has no key only the checksum file is added.
  #
  # Returns the digest.

  def add_file_signed name, mode, signer
    digest_algorithms = [
      signer.digest_algorithm,
      Digest::SHA512,
    ].compact.uniq

    digests = add_file_digest name, mode, digest_algorithms do |io|
      yield io
    end

    signature_digest = digests.values.compact.find do |digest|
      digest_name =
        if digest.respond_to? :name then
          digest.name
        else
          /::([^:]+)$/ =~ digest.class.name
          $1
        end

      digest_name == signer.digest_name
    end

    if signer.key then
      signature = signer.sign signature_digest.digest

      add_file_simple "#{name}.sig", 0444, signature.length do |io|
        io.write signature
      end
    end

    digests
  end

  ##
  # Add file +name+ with permissions +mode+ +size+ bytes long.  Yields an IO
  # to write the file to.

  def add_file_simple(name, mode, size) # :yields: io
    check_closed

    name, prefix = split_name name

    header = Gem::Package::TarHeader.new(:name => name, :mode => mode,
                                         :size => size, :prefix => prefix,
                                         :mtime => Time.now).to_s

    @io.write header
    os = BoundedStream.new @io, size

    yield os if block_given?

    min_padding = size - os.written
    @io.write("\0" * min_padding)

    remainder = (512 - (size % 512)) % 512
    @io.write("\0" * remainder)

    self
  end

  ##
  # Raises IOError if the TarWriter is closed

  def check_closed
    raise IOError, "closed #{self.class}" if closed?
  end

  ##
  # Closes the TarWriter

  def close
    check_closed

    @io.write "\0" * 1024
    flush

    @closed = true
  end

  ##
  # Is the TarWriter closed?

  def closed?
    @closed
  end

  ##
  # Flushes the TarWriter's IO

  def flush
    check_closed

    @io.flush if @io.respond_to? :flush
  end

  ##
  # Creates a new directory in the tar file +name+ with +mode+

  def mkdir(name, mode)
    check_closed

    name, prefix = split_name(name)

    header = Gem::Package::TarHeader.new :name => name, :mode => mode,
                                         :typeflag => "5", :size => 0,
                                         :prefix => prefix,
                                         :mtime => Time.now

    @io.write header

    self
  end

  ##
  # Splits +name+ into a name and prefix that can fit in the TarHeader

  def split_name(name) # :nodoc:
    if name.bytesize > 256
      raise Gem::Package::TooLongFileName.new("File \"#{name}\" has a too long path (should be 256 or less)")
    end

    if name.bytesize <= 100 then
      prefix = ""
    else
      parts = name.split(/\//)
      newname = parts.pop
      nxt = ""

      loop do
        nxt = parts.pop
        break if newname.bytesize + 1 + nxt.bytesize > 100
        newname = nxt + "/" + newname
      end

      prefix = (parts + [nxt]).join "/"
      name = newname

      if name.bytesize > 100
        raise Gem::Package::TooLongFileName.new("File \"#{prefix}/#{name}\" has a too long name (should be 100 or less)")
      end

      if prefix.bytesize > 155 then
        raise Gem::Package::TooLongFileName.new("File \"#{prefix}/#{name}\" has a too long base path (should be 155 or less)")
      end
    end

    return name, prefix
  end

end