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Mini Shell
Mini Shell
# frozen_string_literal: true
#--
# Copyright (C) 2004 Mauricio Julio Fernández Pradier
# See LICENSE.txt for additional licensing information.
#++
##
#--
# struct tarfile_entry_posix {
# char name[100]; # ASCII + (Z unless filled)
# char mode[8]; # 0 padded, octal, null
# char uid[8]; # ditto
# char gid[8]; # ditto
# char size[12]; # 0 padded, octal, null
# char mtime[12]; # 0 padded, octal, null
# char checksum[8]; # 0 padded, octal, null, space
# char typeflag[1]; # file: "0" dir: "5"
# char linkname[100]; # ASCII + (Z unless filled)
# char magic[6]; # "ustar\0"
# char version[2]; # "00"
# char uname[32]; # ASCIIZ
# char gname[32]; # ASCIIZ
# char devmajor[8]; # 0 padded, octal, null
# char devminor[8]; # o padded, octal, null
# char prefix[155]; # ASCII + (Z unless filled)
# };
#++
# A header for a tar file
class Gem::Package::TarHeader
##
# Fields in the tar header
FIELDS = [
:checksum,
:devmajor,
:devminor,
:gid,
:gname,
:linkname,
:magic,
:mode,
:mtime,
:name,
:prefix,
:size,
:typeflag,
:uid,
:uname,
:version,
].freeze
##
# Pack format for a tar header
PACK_FORMAT = "a100" + # name
"a8" + # mode
"a8" + # uid
"a8" + # gid
"a12" + # size
"a12" + # mtime
"a7a" + # chksum
"a" + # typeflag
"a100" + # linkname
"a6" + # magic
"a2" + # version
"a32" + # uname
"a32" + # gname
"a8" + # devmajor
"a8" + # devminor
"a155" # prefix
##
# Unpack format for a tar header
UNPACK_FORMAT = "A100" + # name
"A8" + # mode
"A8" + # uid
"A8" + # gid
"A12" + # size
"A12" + # mtime
"A8" + # checksum
"A" + # typeflag
"A100" + # linkname
"A6" + # magic
"A2" + # version
"A32" + # uname
"A32" + # gname
"A8" + # devmajor
"A8" + # devminor
"A155" # prefix
attr_reader(*FIELDS)
EMPTY_HEADER = ("\0" * 512).freeze # :nodoc:
##
# Creates a tar header from IO +stream+
def self.from(stream)
header = stream.read 512
empty = (EMPTY_HEADER == header)
fields = header.unpack UNPACK_FORMAT
new :name => fields.shift,
:mode => strict_oct(fields.shift),
:uid => oct_or_256based(fields.shift),
:gid => oct_or_256based(fields.shift),
:size => strict_oct(fields.shift),
:mtime => strict_oct(fields.shift),
:checksum => strict_oct(fields.shift),
:typeflag => fields.shift,
:linkname => fields.shift,
:magic => fields.shift,
:version => strict_oct(fields.shift),
:uname => fields.shift,
:gname => fields.shift,
:devmajor => strict_oct(fields.shift),
:devminor => strict_oct(fields.shift),
:prefix => fields.shift,
:empty => empty
end
def self.strict_oct(str)
return str.strip.oct if str.strip =~ /\A[0-7]*\z/
raise ArgumentError, "#{str.inspect} is not an octal string"
end
def self.oct_or_256based(str)
# \x80 flags a positive 256-based number
# \ff flags a negative 256-based number
# In case we have a match, parse it as a signed binary value
# in big-endian order, except that the high-order bit is ignored.
return str.unpack("N2").last if str =~ /\A[\x80\xff]/n
strict_oct(str)
end
##
# Creates a new TarHeader using +vals+
def initialize(vals)
unless vals[:name] && vals[:size] && vals[:prefix] && vals[:mode]
raise ArgumentError, ":name, :size, :prefix and :mode required"
end
vals[:uid] ||= 0
vals[:gid] ||= 0
vals[:mtime] ||= 0
vals[:checksum] ||= ""
vals[:typeflag] = "0" if vals[:typeflag].nil? || vals[:typeflag].empty?
vals[:magic] ||= "ustar"
vals[:version] ||= "00"
vals[:uname] ||= "wheel"
vals[:gname] ||= "wheel"
vals[:devmajor] ||= 0
vals[:devminor] ||= 0
FIELDS.each do |name|
instance_variable_set "@#{name}", vals[name]
end
@empty = vals[:empty]
end
##
# Is the tar entry empty?
def empty?
@empty
end
def ==(other) # :nodoc:
self.class === other &&
@checksum == other.checksum &&
@devmajor == other.devmajor &&
@devminor == other.devminor &&
@gid == other.gid &&
@gname == other.gname &&
@linkname == other.linkname &&
@magic == other.magic &&
@mode == other.mode &&
@mtime == other.mtime &&
@name == other.name &&
@prefix == other.prefix &&
@size == other.size &&
@typeflag == other.typeflag &&
@uid == other.uid &&
@uname == other.uname &&
@version == other.version
end
def to_s # :nodoc:
update_checksum
header
end
##
# Updates the TarHeader's checksum
def update_checksum
header = header " " * 8
@checksum = oct calculate_checksum(header), 6
end
private
def calculate_checksum(header)
header.unpack("C*").inject {|a, b| a + b }
end
def header(checksum = @checksum)
header = [
name,
oct(mode, 7),
oct(uid, 7),
oct(gid, 7),
oct(size, 11),
oct(mtime, 11),
checksum,
" ",
typeflag,
linkname,
magic,
oct(version, 2),
uname,
gname,
oct(devmajor, 7),
oct(devminor, 7),
prefix,
]
header = header.pack PACK_FORMAT
header << ("\0" * ((512 - header.size) % 512))
end
def oct(num, len)
"%0#{len}o" % num
end
end
Zerion Mini Shell 1.0