diff options
Diffstat (limited to 'lib/rubygems/package/tar_header.rb')
| -rw-r--r-- | lib/rubygems/package/tar_header.rb | 277 |
1 files changed, 277 insertions, 0 deletions
diff --git a/lib/rubygems/package/tar_header.rb b/lib/rubygems/package/tar_header.rb new file mode 100644 index 0000000000..dd20d65080 --- /dev/null +++ b/lib/rubygems/package/tar_header.rb @@ -0,0 +1,277 @@ +# frozen_string_literal: true + +# rubocop:disable Style/AsciiComments + +# Copyright (C) 2004 Mauricio Julio Fernández Pradier +# See LICENSE.txt for additional licensing information. + +# rubocop:enable Style/AsciiComments + +## +#-- +# 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").freeze # 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").freeze # prefix + + attr_reader(*FIELDS) + + EMPTY_HEADER = ("\0" * 512).b.freeze # :nodoc: + + ## + # Creates a tar header from IO +stream+ + + def self.from(stream) + header = stream.read 512 + return EMPTY if header == EMPTY_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: false + end + + def self.strict_oct(str) + str.strip! + return str.oct if /\A[0-7]*\z/.match?(str) + + 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.unpack1("@4N") if /\A[\x80\xff]/n.match?(str) + 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 + + @checksum = vals[:checksum] || "" + @devmajor = vals[:devmajor] || 0 + @devminor = vals[:devminor] || 0 + @gid = vals[:gid] || 0 + @gname = vals[:gname] || "wheel" + @linkname = vals[:linkname] + @magic = vals[:magic] || "ustar" + @mode = vals[:mode] + @mtime = vals[:mtime] || 0 + @name = vals[:name] + @prefix = vals[:prefix] + @size = vals[:size] + @typeflag = vals[:typeflag] + @typeflag = "0" if @typeflag.nil? || @typeflag.empty? + @uid = vals[:uid] || 0 + @uname = vals[:uname] || "wheel" + @version = vals[:version] || "00" + + @empty = vals[:empty] + end + + EMPTY = new({ # :nodoc: + checksum: 0, + gname: "", + linkname: "", + magic: "", + mode: 0, + name: "", + prefix: "", + size: 0, + uname: "", + version: 0, + + empty: true, + }).freeze + private_constant :EMPTY + + ## + # 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 + + ## + # Header's full name, including prefix + + def full_name + if prefix != "" + File.join prefix, name + else + name + end + end + + private + + def calculate_checksum(header) + header.sum(0) + 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.ljust 512, "\0" + end + + def oct(num, len) + format("%0#{len}o", num) + end +end |