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Fix behavior of Tempfile#size/length in 1.9

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1 parent 5e67b11 commit 7f75914fdfc9028e4f9986f5a45276d2702645c6 @bjeanes bjeanes committed Oct 9, 2011
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+#
+# tempfile - manipulates temporary files
+#
+# $Id: tempfile.rb 31768 2011-05-28 23:31:24Z yugui $
+#
+
+require 'delegate'
+require 'tmpdir'
+require 'thread'
+
+# A utility class for managing temporary files. When you create a Tempfile
+# object, it will create a temporary file with a unique filename. A Tempfile
+# objects behaves just like a File object, and you can perform all the usual
+# file operations on it: reading data, writing data, changing its permissions,
+# etc. So although this class does not explicitly document all instance methods
+# supported by File, you can in fact call any File instance method on a
+# Tempfile object.
+#
+# == Synopsis
+#
+# require 'tempfile'
+#
+# file = Tempfile.new('foo')
+# file.path # => A unique filename in the OS's temp directory,
+# # e.g.: "/tmp/foo.24722.0"
+# # This filename contains 'foo' in its basename.
+# file.write("hello world")
+# file.rewind
+# file.read # => "hello world"
+# file.close
+# file.unlink # deletes the temp file
+#
+# == Good practices
+#
+# === Explicit close
+#
+# When a Tempfile object is garbage collected, or when the Ruby interpreter
+# exits, its associated temporary file is automatically deleted. This means
+# that's it's unnecessary to explicitly delete a Tempfile after use, though
+# it's good practice to do so: not explicitly deleting unused Tempfiles can
+# potentially leave behind large amounts of tempfiles on the filesystem
+# until they're garbage collected. The existance of these temp files can make
+# it harder to determine a new Tempfile filename.
+#
+# Therefore, one should always call #unlink or close in an ensure block, like
+# this:
+#
+# file = Tempfile.new('foo')
+# begin
+# ...do something with file...
+# ensure
+# file.close
+# file.unlink # deletes the temp file
+# end
+#
+# === Unlink after creation
+#
+# On POSIX systems, it's possible to unlink a file right after creating it,
+# and before closing it. This removes the filesystem entry without closing
+# the file handle, so it ensures that only the processes that already had
+# the file handle open can access the file's contents. It's strongly
+# recommended that you do this if you do not want any other processes to
+# be able to read from or write to the Tempfile, and you do not need to
+# know the Tempfile's filename either.
+#
+# For example, a practical use case for unlink-after-creation would be this:
+# you need a large byte buffer that's too large to comfortably fit in RAM,
+# e.g. when you're writing a web server and you want to buffer the client's
+# file upload data.
+#
+# Please refer to #unlink for more information and a code example.
+#
+# == Minor notes
+#
+# Tempfile's filename picking method is both thread-safe and inter-process-safe:
+# it guarantees that no other threads or processes will pick the same filename.
+#
+# Tempfile itself however may not be entirely thread-safe. If you access the
+# same Tempfile object from multiple threads then you should protect it with a
+# mutex.
+class Tempfile < DelegateClass(File)
+ MAX_TRY = 10 # :nodoc:
+ include Dir::Tmpname
+
+ # call-seq:
+ # new(basename, [tmpdir = Dir.tmpdir], [options])
+ #
+ # Creates a temporary file with permissions 0600 (= only readable and
+ # writable by the owner) and opens it with mode "w+".
+ #
+ # The +basename+ parameter is used to determine the name of the
+ # temporary file. You can either pass a String or an Array with
+ # 2 String elements. In the former form, the temporary file's base
+ # name will begin with the given string. In the latter form,
+ # the temporary file's base name will begin with the array's first
+ # element, and end with the second element. For example:
+ #
+ # file = Tempfile.new('hello')
+ # file.path # => something like: "/tmp/hello2843-8392-92849382--0"
+ #
+ # # Use the Array form to enforce an extension in the filename:
+ # file = Tempfile.new(['hello', '.jpg'])
+ # file.path # => something like: "/tmp/hello2843-8392-92849382--0.jpg"
+ #
+ # The temporary file will be placed in the directory as specified
+ # by the +tmpdir+ parameter. By default, this is +Dir.tmpdir+.
+ # When $SAFE > 0 and the given +tmpdir+ is tainted, it uses
+ # '/tmp' as the temporary directory. Please note that ENV values
+ # are tainted by default, and +Dir.tmpdir+'s return value might
+ # come from environment variables (e.g. <tt>$TMPDIR</tt>).
+ #
+ # file = Tempfile.new('hello', '/home/aisaka')
+ # file.path # => something like: "/home/aisaka/hello2843-8392-92849382--0"
+ #
+ # You can also pass an options hash. Under the hood, Tempfile creates
+ # the temporary file using +File.open+. These options will be passed to
+ # +File.open+. This is mostly useful for specifying encoding
+ # options, e.g.:
+ #
+ # Tempfile.new('hello', '/home/aisaka', :encoding => 'ascii-8bit')
+ #
+ # # You can also omit the 'tmpdir' parameter:
+ # Tempfile.new('hello', :encoding => 'ascii-8bit')
+ #
+ # === Exceptions
+ #
+ # If Tempfile.new cannot find a unique filename within a limited
+ # number of tries, then it will raise an exception.
+ def initialize(basename, *rest)
+ @data = []
+ @clean_proc = Remover.new(@data)
+ ObjectSpace.define_finalizer(self, @clean_proc)
+
+ create(basename, *rest) do |tmpname, n, opts|
+ lock = tmpname + '.lock'
+ mode = File::RDWR|File::CREAT|File::EXCL
+ perm = 0600
+ if opts
+ mode |= opts.delete(:mode) || 0
+ opts[:perm] = perm
+ perm = nil
+ else
+ opts = perm
+ end
+ self.class.mkdir(lock)
+ begin
+ @data[1] = @tmpfile = File.open(tmpname, mode, opts)
+ @data[0] = @tmpname = tmpname
+ ensure
+ self.class.rmdir(lock)
+ end
+ @mode = mode & ~(File::CREAT|File::EXCL)
+ perm or opts.freeze
+ @opts = opts
+ end
+
+ super(@tmpfile)
+ end
+
+ # Opens or reopens the file with mode "r+".
+ def open
+ @tmpfile.close if @tmpfile
+ @tmpfile = File.open(@tmpname, @mode, @opts)
+ @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 +unlink_now+ is true, then the file will be unlinked
+ # (deleted) after closing. Of course, you can choose to later call #unlink
+ # if you do not unlink it now.
+ #
+ # 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 (deletes) the file. Has the same effect as called
+ # <tt>close(true)</tt>.
+ def close!
+ _close
+ unlink
+ ObjectSpace.undefine_finalizer(self)
+ end
+
+ # Unlinks (deletes) the file from the filesystem. One should always unlink
+ # the file after using it, as is explained in the "Explicit close" good
+ # practice section in the Tempfile overview:
+ #
+ # file = Tempfile.new('foo')
+ # begin
+ # ...do something with file...
+ # ensure
+ # file.close
+ # file.unlink # deletes the temp file
+ # end
+ #
+ # === Unlink-before-close
+ #
+ # On POSIX systems it's possible to unlink a file before closing it. This
+ # practice is explained in detail in the Tempfile overview (section
+ # "Unlink after creation"); please refer there for more information.
+ #
+ # However, unlink-before-close may not be supported on non-POSIX operating
+ # systems. Microsoft Windows is the most notable case: unlinking a non-closed
+ # file will result in an error, which this method will silently ignore. If
+ # you want to practice unlink-before-close whenever possible, then you should
+ # write code like this:
+ #
+ # file = Tempfile.new('foo')
+ # file.unlink # On Windows this silently fails.
+ # begin
+ # ... do something with file ...
+ # ensure
+ # file.close! # Closes the file handle. If the file wasn't unlinked
+ # # because #unlink failed, then this method will attempt
+ # # to do so again.
+ # end
+ def unlink
+ # keep this order for thread safeness
+ return unless @tmpname
+ begin
+ if File.exist?(@tmpname)
+ File.unlink(@tmpname)
+ end
+ # remove tmpname from remover
+ @data[0] = @data[2] = nil
+ @tmpname = nil
+ 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.
+ # This will be nil if #unlink has been called.
+ 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
+ elsif @tmpname
+ File.size(@tmpname)
+ else
+ 0
+ end
+ end
+ alias length size
+
+ # :stopdoc:
+ class Remover
+ def initialize(data)
+ @pid = $$
+ @data = data
+ end
+
+ def call(*args)
+ if @pid == $$
+ path, tmpfile = *@data
+
+ STDERR.print "removing ", path, "..." if $DEBUG
+
+ tmpfile.close if tmpfile
+
+ # keep this order for thread safeness
+ if path
+ File.unlink(path) if File.exist?(path)
+ end
+
+ STDERR.print "done\n" if $DEBUG
+ end
+ end
+ end
+ # :startdoc:
+
+ class << self
+ # Creates a new Tempfile.
+ #
+ # If no block is given, this is a synonym for Tempfile.new.
+ #
+ # If a block is given, then a Tempfile object will be constructed,
+ # and the block is run with said object as argument. The Tempfile
+ # oject will be automatically closed after the block terminates.
+ # The call returns the value of the block.
+ #
+ # In any case, all arguments (+*args+) will be passed to Tempfile.new.
+ #
+ # Tempfile.open('foo', '/home/temp') do |f|
+ # ... do something with f ...
+ # end
+ #
+ # # Equivalent:
+ # f = Tempfile.open('foo', '/home/temp')
+ # begin
+ # ... do something with f ...
+ # ensure
+ # f.close
+ # end
+ def open(*args)
+ tempfile = new(*args)
+
+ if block_given?
+ begin
+ yield(tempfile)
+ ensure
+ tempfile.close
+ end
+ else
+ tempfile
+ end
+ end
+
+ def mkdir(*args)
+ Dir.mkdir(*args)
+ end
+ def rmdir(*args)
+ Dir.rmdir(*args)
+ 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
@@ -1 +0,0 @@
-fails:Tempfile#length returns the size of self even if self is closed
@@ -1 +0,0 @@
-fails:Tempfile#size returns the size of self even if self is closed

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