##
# Ar reads ar(5) formatted files.
class Ar
class Error < RuntimeError; end
def initialize(path)
@path = path
end
##
# Removes +files+ from the archive.
def delete(*files)
require 'fileutils'
require 'tempfile'
Tempfile.open "#{File.basename @path}.new" do |io|
io.write "!<arch>\n"
each do |name, mtime, uid, gid, mode, data|
next if files.include? name
write_file io, name, mtime, uid, gid, mode, data
end
FileUtils.mv io.path, @path
end
self
end
##
# Yields each archive item's metadata and data.
def each
open @path, 'rb' do |io|
raise Error, "#{@path} is not an archive file" if io.gets != "!<arch>\n"
until io.eof? do
name = io.read 16
mtime = io.read(12).to_i
mtime = Time.at(mtime).utc
uid = io.read( 6).to_i
gid = io.read( 6).to_i
mode = io.read( 8).to_i(8)
size = io.read(10).to_i
io.read 2 # trailer
name = if name =~ /^#1\/(\d+)/ then
name_length = $1.to_i
size -= name_length
io.read(name_length).delete "\000"
else
name.rstrip
end
data = io.read size
io.read 1 if size % 2 == 1
yield name, mtime, uid, gid, mode, data
end
end
end
##
# Exctracts metadata and data for +file+. Returns an Array containing the
# name, last modification time, uid, gid, mode and archive item data.
def extract(file)
find do |name,|
file == name
end
end
##
# Lists the files in the archive in order.
def list
map do |name,| name end
end
##
# Adds or replaces the file +name+ in the archive. If the file already
# exists, it is moved to the end of the archive.
def replace(name, mtime, uid, gid, mode, data)
if File.exist? @path then
delete name if list.include? name
else
open @path, 'ab' do |io| io.write "!<arch>\n" end
end
open @path, 'ab' do |io|
write_file io, name, mtime.to_i, uid, gid, mode, data
end
self
end
##
# Writes the archive to +io+.
def write(io)
io.write "!<arch>\n"
each do |name, mtime, uid, gid, mode, data|
write_file io, name, mtime, uid, gid, mode, data
end
self
end
def write_file(io, name, mtime, uid, gid, mode, data) # :nodoc:
unless name.length > 16 then
padding = nil
io.write name.ljust(16)
else
padding = 4 - name.length % 4
padding = 0 if padding > 3
io.write "#1/#{name.length + padding}".ljust(16)
end
io.write mtime .to_i.to_s.ljust(12)
io.write uid .to_s .ljust( 6)
io.write gid .to_s .ljust( 6)
io.write mode .to_s(8) .ljust( 8)
size = data.length + (padding ? name.length + padding : 0)
io.write size .to_s .ljust(10)
io.write "`\n"
if name.length > 16 then
name = name.ljust name.length + padding, "\000"
io.write name
end
io.write data
io.write "\n" if data.length % 2 == 1
self
end
end
