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# frozen_string_literal: true
#
# tempfile - manipulates temporary files
#
# $Id$
#
require 'delegate'
require 'tmpdir'
# 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 it's unnecessary to explicitly delete a Tempfile after use, though
# it's a good practice to do so: not explicitly deleting unused Tempfiles can
# potentially leave behind a large number of temp files on the filesystem
# until they're garbage collected. The existence 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
#
# Tempfile.create { ... } exists for this purpose and is more convenient to use.
# Note that Tempfile.create returns a File instance instead of a Tempfile, which
# also avoids the overhead and complications of delegation.
#
# Tempfile.open('foo') do |file|
# # ...do something with 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)
# Creates a temporary file with permissions 0600 (= only readable and
# writable by the owner) and opens it with mode "w+".
#
# It is recommended to use Tempfile.create { ... } instead when possible,
# because that method avoids the cost of delegation and does not rely on a
# finalizer to close and unlink the file, which is unreliable.
#
# 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+.
#
# 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')
#
# Note: +mode+ keyword argument, as accepted by Tempfile, can only be
# numeric, combination of the modes defined in File::Constants.
#
# === Exceptions
#
# If Tempfile.new cannot find a unique filename within a limited
# number of tries, then it will raise an exception.
def initialize(basename="", tmpdir=nil, mode: 0, **options)
warn "Tempfile.new doesn't call the given block.", uplevel: 1 if block_given?
@unlinked = false
@mode = mode|File::RDWR|File::CREAT|File::EXCL
::Dir::Tmpname.create(basename, tmpdir, **options) do |tmpname, n, opts|
opts[:perm] = 0600
@tmpfile = File.open(tmpname, @mode, **opts)
@opts = opts.freeze
end
ObjectSpace.define_finalizer(self, Remover.new(@tmpfile))
super(@tmpfile)
end
# Opens or reopens the file with mode "r+".
def open
_close
mode = @mode & ~(File::CREAT|File::EXCL)
@tmpfile = File.open(@tmpfile.path, mode, **@opts)
__setobj__(@tmpfile)
end
def _close # :nodoc:
@tmpfile.close
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)
_close
unlink if unlink_now
end
# Closes and unlinks (deletes) the file. Has the same effect as called
# <tt>close(true)</tt>.
def close!
close(true)
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
return if @unlinked
begin
File.unlink(@tmpfile.path)
rescue Errno::ENOENT
rescue Errno::EACCES
# may not be able to unlink on Windows; just ignore
return
end
ObjectSpace.undefine_finalizer(self)
@unlinked = true
end
alias delete unlink
# Returns the full path name of the temporary file.
# This will be nil if #unlink has been called.
def path
@unlinked ? nil : @tmpfile.path
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.closed?
@tmpfile.size # File#size calls rb_io_flush_raw()
else
File.size(@tmpfile.path)
end
end
alias length size
# :stopdoc:
def inspect
if @tmpfile.closed?
"#<#{self.class}:#{path} (closed)>"
else
"#<#{self.class}:#{path}>"
end
end
class Remover # :nodoc:
def initialize(tmpfile)
@pid = Process.pid
@tmpfile = tmpfile
end
def call(*args)
return if @pid != Process.pid
$stderr.puts "removing #{@tmpfile.path}..." if $DEBUG
@tmpfile.close
begin
File.unlink(@tmpfile.path)
rescue Errno::ENOENT
end
$stderr.puts "done" if $DEBUG
end
end
class << self
# :startdoc:
# Creates a new Tempfile.
#
# This method is not recommended and exists mostly for backward compatibility.
# Please use Tempfile.create instead, which avoids the cost of delegation,
# does not rely on a finalizer, and also unlinks the file when given a block.
#
# Tempfile.open is still appropriate if you need the Tempfile to be unlinked
# by a finalizer and you cannot explicitly know where in the program the
# Tempfile can be unlinked safely.
#
# 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 the Tempfile object as argument. The Tempfile
# object will be automatically closed after the block terminates.
# However, the file will *not* be unlinked and needs to be manually unlinked
# with Tempfile#close! or Tempfile#unlink. The finalizer will try to unlink
# but should not be relied upon as it can keep the file on the disk much
# longer than intended. For instance, on CRuby, finalizers can be delayed
# due to conservative stack scanning and references left in unused memory.
#
# The call returns the value of the block.
#
# In any case, all arguments (<code>*args</code>) 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, **kw)
tempfile = new(*args, **kw)
if block_given?
begin
yield(tempfile)
ensure
tempfile.close
end
else
tempfile
end
end
end
end
# Creates a temporary file as a usual File object (not a Tempfile).
# It does not use finalizer and delegation, which makes it more efficient and reliable.
#
# If no block is given, this is similar to Tempfile.new except
# creating File instead of Tempfile. In that case, the created file is
# not removed automatically. You should use File.unlink to remove it.
#
# If a block is given, then a File object will be constructed,
# and the block is invoked with the object as the argument.
# The File object will be automatically closed and
# the temporary file is removed after the block terminates,
# releasing all resources that the block created.
# The call returns the value of the block.
#
# In any case, all arguments (+basename+, +tmpdir+, +mode+, and
# <code>**options</code>) will be treated the same as for Tempfile.new.
#
# Tempfile.create('foo', '/home/temp') do |f|
# # ... do something with f ...
# end
#
def Tempfile.create(basename="", tmpdir=nil, mode: 0, **options)
tmpfile = nil
Dir::Tmpname.create(basename, tmpdir, **options) do |tmpname, n, opts|
mode |= File::RDWR|File::CREAT|File::EXCL
opts[:perm] = 0600
tmpfile = File.open(tmpname, mode, **opts)
end
if block_given?
begin
yield tmpfile
ensure
unless tmpfile.closed?
if File.identical?(tmpfile, tmpfile.path)
unlinked = File.unlink tmpfile.path rescue nil
end
tmpfile.close
end
unless unlinked
begin
File.unlink tmpfile.path
rescue Errno::ENOENT
end
end
end
else
tmpfile
end
end