diff options
Diffstat (limited to 'lib/rubygems/package/tar_reader')
| -rw-r--r-- | lib/rubygems/package/tar_reader/entry.rb | 244 |
1 files changed, 244 insertions, 0 deletions
diff --git a/lib/rubygems/package/tar_reader/entry.rb b/lib/rubygems/package/tar_reader/entry.rb new file mode 100644 index 0000000000..f837e86fd6 --- /dev/null +++ b/lib/rubygems/package/tar_reader/entry.rb @@ -0,0 +1,244 @@ +# 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 + +## +# Class for reading entries out of a tar file + +class Gem::Package::TarReader::Entry + ## + # Creates a new tar entry for +header+ that will be read from +io+ + # If a block is given, the entry is yielded and then closed. + + def self.open(header, io, &block) + entry = new header, io + return entry unless block_given? + begin + yield entry + ensure + entry.close + end + end + + ## + # Header for this tar entry + + attr_reader :header + + ## + # Creates a new tar entry for +header+ that will be read from +io+ + + def initialize(header, io) + @closed = false + @header = header + @io = io + @orig_pos = @io.pos + @end_pos = @orig_pos + @header.size + @read = 0 + end + + def check_closed # :nodoc: + raise IOError, "closed #{self.class}" if closed? + end + + ## + # Number of bytes read out of the tar entry + + def bytes_read + @read + end + + ## + # Closes the tar entry + + def close + return if closed? + # Seek to the end of the entry if it wasn't fully read + seek(0, IO::SEEK_END) + # discard trailing zeros + skip = (512 - (@header.size % 512)) % 512 + @io.read(skip) + @closed = true + nil + end + + ## + # Is the tar entry closed? + + def closed? + @closed + end + + ## + # Are we at the end of the tar entry? + + def eof? + check_closed + + @read >= @header.size + end + + ## + # Full name of the tar entry + + def full_name + @header.full_name.force_encoding(Encoding::UTF_8) + rescue ArgumentError => e + raise unless e.message == "string contains null byte" + raise Gem::Package::TarInvalidError, + "tar is corrupt, name contains null byte" + end + + ## + # Read one byte from the tar entry + + def getc + return nil if eof? + + ret = @io.getc + @read += 1 if ret + + ret + end + + ## + # Is this tar entry a directory? + + def directory? + @header.typeflag == "5" + end + + ## + # Is this tar entry a file? + + def file? + @header.typeflag == "0" + end + + ## + # Is this tar entry a symlink? + + def symlink? + @header.typeflag == "2" + end + + ## + # The position in the tar entry + + def pos + check_closed + + bytes_read + end + + ## + # Seek to the position in the tar entry + + def pos=(new_pos) + seek(new_pos, IO::SEEK_SET) + end + + def size + @header.size + end + + alias_method :length, :size + + ## + # Reads +maxlen+ bytes from the tar file entry, or the rest of the entry if nil + + def read(maxlen = nil) + if eof? + return maxlen.to_i.zero? ? "" : nil + end + + max_read = [maxlen, @header.size - @read].compact.min + + ret = @io.read max_read + if ret.nil? + return maxlen ? nil : "" # IO.read returns nil on EOF with len argument + end + @read += ret.size + + ret + end + + def readpartial(maxlen, outbuf = "".b) + if eof? && maxlen > 0 + raise EOFError, "end of file reached" + end + + max_read = [maxlen, @header.size - @read].min + + @io.readpartial(max_read, outbuf) + @read += outbuf.size + + outbuf + end + + ## + # Seeks to +offset+ bytes into the tar file entry + # +whence+ can be IO::SEEK_SET, IO::SEEK_CUR, or IO::SEEK_END + + def seek(offset, whence = IO::SEEK_SET) + check_closed + + new_pos = + case whence + when IO::SEEK_SET then @orig_pos + offset + when IO::SEEK_CUR then @io.pos + offset + when IO::SEEK_END then @end_pos + offset + else + raise ArgumentError, "invalid whence" + end + + if new_pos < @orig_pos + new_pos = @orig_pos + elsif new_pos > @end_pos + new_pos = @end_pos + end + + pending = new_pos - @io.pos + + return 0 if pending == 0 + + if @io.respond_to?(:seek) + begin + # avoid reading if the @io supports seeking + @io.seek new_pos, IO::SEEK_SET + pending = 0 + rescue Errno::EINVAL + end + end + + # if seeking isn't supported or failed + # negative seek requires that we rewind and read + if pending < 0 + @io.rewind + pending = new_pos + end + + while pending > 0 do + size_read = @io.read([pending, 4096].min)&.size + raise(EOFError, "end of file reached") if size_read.nil? + pending -= size_read + end + + @read = @io.pos - @orig_pos + + 0 + end + + ## + # Rewinds to the beginning of the tar file entry + + def rewind + check_closed + seek(0, IO::SEEK_SET) + end +end |