Sha256: 9c73daefa8d5a88432b6d1815bad8f1e9ce8e3e4d3865a08348753686fe50cab
Contents?: true
Size: 1.78 KB
Versions: 53
Compression:
Stored size: 1.78 KB
Contents
require 'fileutils'
class File
# Write to a file atomically. Useful for situations where you don't
# want other processes or threads to see half-written files.
#
# File.atomic_write('important.file') do |file|
# file.write('hello')
# end
#
# If your temp directory is not on the same filesystem as the file you're
# trying to write, you can provide a different temporary directory.
#
# File.atomic_write('/data/something.important', '/data/tmp') do |file|
# file.write('hello')
# end
def self.atomic_write(file_name, temp_dir = Dir.tmpdir)
require 'tempfile' unless defined?(Tempfile)
require 'fileutils' unless defined?(FileUtils)
temp_file = Tempfile.new(basename(file_name), temp_dir)
temp_file.binmode
yield temp_file
temp_file.close
if File.exist?(file_name)
# Get original file permissions
old_stat = stat(file_name)
else
# If not possible, probe which are the default permissions in the
# destination directory.
old_stat = probe_stat_in(dirname(file_name))
end
# Overwrite original file with temp file
FileUtils.mv(temp_file.path, file_name)
# Set correct permissions on new file
begin
chown(old_stat.uid, old_stat.gid, file_name)
# This operation will affect filesystem ACL's
chmod(old_stat.mode, file_name)
rescue Errno::EPERM, Errno::EACCES
# Changing file ownership failed, moving on.
end
end
# Private utility method.
def self.probe_stat_in(dir) #:nodoc:
basename = [
'.permissions_check',
Thread.current.object_id,
Process.pid,
rand(1000000)
].join('.')
file_name = join(dir, basename)
FileUtils.touch(file_name)
stat(file_name)
ensure
FileUtils.rm_f(file_name) if file_name
end
end
Version data entries
53 entries across 51 versions & 10 rubygems