summaryrefslogtreecommitdiff
path: root/lib/tempfile.rb
blob: 1b2a889b4a830bf2ae61e826f59e99fe42b0d399 (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
#
# tempfile - manipulates temporary files
#
# $Id$
#

require 'delegate'
require 'tmpdir'

# A class for managing temporary files.  This library is written to be
# thread safe.
class Tempfile < DelegateClass(File)
  MAX_TRY = 10
  @@cleanlist = []

  # Creates a temporary file of mode 0600 in the temporary directory
  # whose name is basename.pid.n and opens with mode "w+".  A Tempfile
  # object works just like a File object.
  #
  # If tmpdir is omitted, the temporary directory is determined by
  # Dir::tmpdir provided by 'tmpdir.rb'.
  # When $SAFE > 0 and the given tmpdir is tainted, it uses
  # /tmp. (Note that ENV values are tainted by default)
  def initialize(basename, tmpdir=Dir::tmpdir)
    if $SAFE > 0 and tmpdir.tainted?
      tmpdir = '/tmp'
    end

    lock = nil
    n = failure = 0
    
    begin
      Thread.critical = true

      begin
	tmpname = File.join(tmpdir, make_tmpname(basename, n))
	lock = tmpname + '.lock'
	n += 1
      end while @@cleanlist.include?(tmpname) or
	File.exist?(lock) or File.exist?(tmpname)

      Dir.mkdir(lock)
    rescue
      failure += 1
      retry if failure < MAX_TRY
      raise "cannot generate tempfile `%s'" % tmpname
    ensure
      Thread.critical = false
    end

    @data = [tmpname]
    @clean_proc = Tempfile.callback(@data)
    ObjectSpace.define_finalizer(self, @clean_proc)

    @tmpfile = File.open(tmpname, File::RDWR|File::CREAT|File::EXCL, 0600)
    @tmpname = tmpname
    @@cleanlist << @tmpname
    @data[1] = @tmpfile
    @data[2] = @@cleanlist

    super(@tmpfile)

    # Now we have all the File/IO methods defined, you must not
    # carelessly put bare puts(), etc. after this.

    Dir.rmdir(lock)
  end

  def make_tmpname(basename, n)
    sprintf('%s%d.%d', basename, $$, n)
  end
  private :make_tmpname

  # Opens or reopens the file with mode "r+".
  def open
    @tmpfile.close if @tmpfile
    @tmpfile = File.open(@tmpname, 'r+')
    @data[1] = @tmpfile
    __setobj__(@tmpfile)
  end

  def _close	# :nodoc:
    @tmpfile.close if @tmpfile
    @tmpfile = nil
    @data[1] = nil if @data
  end
  protected :_close

  #Closes the file.  If the optional flag is true, unlinks the file
  # after closing.
  #
  # If you don't explicitly unlink the temporary file, the removal
  # will be delayed until the object is finalized.
  def close(unlink_now=false)
    if unlink_now
      close!
    else
      _close
    end
  end

  # Closes and unlinks the file.
  def close!
    _close
    @clean_proc.call
    ObjectSpace.undefine_finalizer(self)
    @data = @tmpname = nil
  end

  # Unlinks the file.  On UNIX-like systems, it is often a good idea
  # to unlink a temporary file immediately after creating and opening
  # it, because it leaves other programs zero chance to access the
  # file.
  def unlink
    # keep this order for thread safeness
    begin
      File.unlink(@tmpname) if File.exist?(@tmpname)
      @@cleanlist.delete(@tmpname)
      @data = @tmpname = nil
      ObjectSpace.undefine_finalizer(self)
    rescue Errno::EACCES
      # may not be able to unlink on Windows; just ignore
    end
  end
  alias delete unlink

  # Returns the full path name of the temporary file.
  def path
    @tmpname
  end

  # Returns the size of the temporary file.  As a side effect, the IO
  # buffer is flushed before determining the size.
  def size
    if @tmpfile
      @tmpfile.flush
      @tmpfile.stat.size
    else
      0
    end
  end
  alias length size

  class << self
    def callback(data)	# :nodoc:
      pid = $$
      Proc.new {
	if pid == $$ 
	  path, tmpfile, cleanlist = *data

	  print "removing ", path, "..." if $DEBUG

	  tmpfile.close if tmpfile

	  # keep this order for thread safeness
	  File.unlink(path) if File.exist?(path)
	  cleanlist.delete(path) if cleanlist

	  print "done\n" if $DEBUG
	end
      }
    end

    # If no block is given, this is a synonym for new().
    #
    # If a block is given, it will be passed tempfile as an argument,
    # and the tempfile will automatically be closed when the block
    # terminates.  In this case, open() returns nil.
    def open(*args)
      tempfile = new(*args)

      if block_given?
	begin
	  yield(tempfile)
	ensure
	  tempfile.close
	end

	nil
      else
	tempfile
      end
    end
  end
end

if __FILE__ == $0
#  $DEBUG = true
  f = Tempfile.new("foo")
  f.print("foo\n")
  f.close
  f.open
  p f.gets # => "foo\n"
  f.close!
end