fix frozen string literal error

lib/zip/extra_field/ntfs.rb

@@ -51,7 +51,7 @@ def pack_for_c_dir
       # reserved 0 and tag 1
       s = [0, 1].pack('Vv')
 
-      tag1 = ''.force_encoding(Encoding::BINARY)
+      tag1 = (+'').force_encoding(Encoding::BINARY)
       if @mtime
         tag1 << [to_ntfs_time(@mtime)].pack('Q<')
         if @atime

lib/zip/extra_field/zip64.rb

@@ -59,7 +59,7 @@ def pack_for_local
 
     def pack_for_c_dir
       # central directory entries contain only fields that didn't fit in the main entry part
-      packed = ''.force_encoding('BINARY')
+      packed = (+'').force_encoding('BINARY')
       packed << [@original_size].pack('Q<') if @original_size
       packed << [@compressed_size].pack('Q<') if @compressed_size
       packed << [@relative_header_offset].pack('Q<') if @relative_header_offset

lib/zip/file.rb

@@ -133,7 +133,7 @@ def open(file_name, create = false, options = {})
 
       # Same as #open. But outputs data to a buffer instead of a file
       def add_buffer
-        io = ::StringIO.new('')
+        io = ::StringIO.new(+'')
         zf = ::Zip::File.new(io, true, true)
         yield zf
         zf.write_buffer(io)

lib/zip/filesystem.rb

@@ -239,7 +239,7 @@ def directory?(filename)
       end
 
       def open(filename, mode = 'r', permissions = 0o644, &block)
-        mode.delete!('b') # ignore b option
+        mode = mode.tr('b', '') # ignore b option
         case mode
         when 'r'
           @mapped_zip.get_input_stream(filename, &block)
@@ -619,7 +619,7 @@ def each
       end
 
       def expand_path(path)
-        expanded = path.start_with?('/') ? path : ::File.join(@pwd, path)
+        expanded = ::File.expand_path(path, @pwd)
         expanded.gsub!(/\/\.(\/|$)/, '')
         expanded.gsub!(/[^\/]+\/\.\.(\/|$)/, '')
         expanded.empty? ? '/' : expanded

lib/zip/inflater.rb

@@ -7,7 +7,7 @@ def initialize(*args)
       @zlib_inflater = ::Zlib::Inflate.new(-Zlib::MAX_WBITS)
     end
 
-    def read(length = nil, outbuf = '')
+    def read(length = nil, outbuf = +'')
       return (length.nil? || length.zero? ? '' : nil) if eof
 
       while length.nil? || (@buffer.bytesize < length)

lib/zip/ioextras.rb

@@ -6,14 +6,14 @@ module IOExtras #:nodoc:
 
     class << self
       def copy_stream(ostream, istream)
-        ostream.write(istream.read(CHUNK_SIZE, '')) until istream.eof?
+        ostream.write(istream.read(CHUNK_SIZE, +'')) until istream.eof?
       end
 
       def copy_stream_n(ostream, istream, nbytes)
         toread = nbytes
         while toread > 0 && !istream.eof?
           tr = toread > CHUNK_SIZE ? CHUNK_SIZE : toread
-          ostream.write(istream.read(tr, ''))
+          ostream.write(istream.read(tr, +''))
           toread -= tr
         end
       end

lib/zip/ioextras/abstract_input_stream.rb

@@ -11,13 +11,13 @@ def initialize
         super
         @lineno        = 0
         @pos           = 0
-        @output_buffer = ''
+        @output_buffer = +''
       end
 
       attr_accessor :lineno
       attr_reader :pos
 
-      def read(number_of_bytes = nil, buf = '')
+      def read(number_of_bytes = nil, buf = +'')
         tbuf = if @output_buffer.bytesize > 0
                  if number_of_bytes && number_of_bytes <= @output_buffer.bytesize
                    @output_buffer.slice!(0, number_of_bytes)
@@ -93,7 +93,7 @@ def ungetc(byte)
 
       def flush
         ret_val        = @output_buffer
-        @output_buffer = ''
+        @output_buffer = +''
         ret_val
       end
 

lib/zip/pass_thru_decompressor.rb

@@ -5,7 +5,7 @@ def initialize(*args)
       @read_so_far = 0
     end
 
-    def read(length = nil, outbuf = '')
+    def read(length = nil, outbuf = +'')
       return (length.nil? || length.zero? ? '' : nil) if eof
 
       if length.nil? || (@read_so_far + length) > decompressed_size

test/encryption_test.rb

@@ -18,7 +18,7 @@ def test_encrypt
 
     password = 'swordfish'
 
-    encrypted_zip = Zip::OutputStream.write_buffer(::StringIO.new(''), Zip::TraditionalEncrypter.new(password)) do |out|
+    encrypted_zip = Zip::OutputStream.write_buffer(::StringIO.new(+''), Zip::TraditionalEncrypter.new(password)) do |out|
       out.put_next_entry(test_filename)
       out.write content
     end

test/extra_field_test.rb

@@ -28,7 +28,7 @@ def test_bad_header_id
   end
 
   def test_ntfs
-    str = "\x0A\x00 \x00\x00\x00\x00\x00\x01\x00\x18\x00\xC0\x81\x17\xE8B\xCE\xCF\x01\xC0\x81\x17\xE8B\xCE\xCF\x01\xC0\x81\x17\xE8B\xCE\xCF\x01"
+    str = +"\x0A\x00 \x00\x00\x00\x00\x00\x01\x00\x18\x00\xC0\x81\x17\xE8B\xCE\xCF\x01\xC0\x81\x17\xE8B\xCE\xCF\x01\xC0\x81\x17\xE8B\xCE\xCF\x01"
     extra = ::Zip::ExtraField.new(str)
     assert(extra.member?('NTFS'))
     t = ::Zip::DOSTime.at(1_410_496_497.405178)

test/file_test.rb

@@ -536,7 +536,7 @@ def test_write_buffer
     zf = ::Zip::File.new(TEST_ZIP.zip_name)
     old_name = zf.entries.first
     zf.rename(old_name, new_name)
-    io = ::StringIO.new('')
+    io = ::StringIO.new(+'')
     buffer = zf.write_buffer(io)
     File.open(TEST_ZIP.zip_name, 'wb') { |f| f.write buffer.string }
     zf_read = ::Zip::File.new(TEST_ZIP.zip_name)

test/input_stream_test.rb

@@ -134,7 +134,7 @@ def test_rewind
       assert_equal(TestZipFile::TEST_ZIP2.entry_names[0], e.name)
 
       # Do a little reading
-      buf = ''
+      buf = +''
       buf << zis.read(100)
       assert_equal(100, zis.pos)
       buf << (zis.gets || '')
@@ -143,7 +143,7 @@ def test_rewind
 
       zis.rewind
 
-      buf2 = ''
+      buf2 = +''
       buf2 << zis.read(100)
       buf2 << (zis.gets || '')
       buf2 << (zis.gets || '')

test/ioextras/abstract_output_stream_test.rb

@@ -8,7 +8,7 @@ class TestOutputStream
     attr_accessor :buffer
 
     def initialize
-      @buffer = ''
+      @buffer = +''
     end
 
     def <<(data)
@@ -58,12 +58,12 @@ def test_print
     assert_equal("hello world. You ok out there?\nI sure hope so!\n", @output_stream.buffer)
 
     $, = 'X'
-    @output_stream.buffer = ''
+    @output_stream.buffer = +''
     @output_stream.print('monkey', 'duck', 'zebra')
     assert_equal("monkeyXduckXzebra\n", @output_stream.buffer)
 
     $\ = nil
-    @output_stream.buffer = ''
+    @output_stream.buffer = +''
     @output_stream.print(20)
     assert_equal('20', @output_stream.buffer)
   end
@@ -87,19 +87,19 @@ def test_puts
     @output_stream.puts('hello', 'world')
     assert_equal("\nhello\nworld\n", @output_stream.buffer)
 
-    @output_stream.buffer = ''
+    @output_stream.buffer = +''
     @output_stream.puts("hello\n", "world\n")
     assert_equal("hello\nworld\n", @output_stream.buffer)
 
-    @output_stream.buffer = ''
+    @output_stream.buffer = +''
     @output_stream.puts(%W[hello\n world\n])
     assert_equal("hello\nworld\n", @output_stream.buffer)
 
-    @output_stream.buffer = ''
+    @output_stream.buffer = +''
     @output_stream.puts(%W[hello\n world\n], 'bingo')
     assert_equal("hello\nworld\nbingo\n", @output_stream.buffer)
 
-    @output_stream.buffer = ''
+    @output_stream.buffer = +''
     @output_stream.puts(16, 20, 50, 'hello')
     assert_equal("16\n20\n50\nhello\n", @output_stream.buffer)
   end

test/output_stream_test.rb

@@ -23,7 +23,7 @@ def test_open
   end
 
   def test_write_buffer
-    io = ::StringIO.new('')
+    io = ::StringIO.new(+'')
     buffer = ::Zip::OutputStream.write_buffer(io) do |zos|
       zos.comment = TEST_ZIP.comment
       write_test_zip(zos)
@@ -33,7 +33,7 @@ def test_write_buffer
   end
 
   def test_write_buffer_binmode
-    io = ::StringIO.new('')
+    io = ::StringIO.new(+'')
     buffer = ::Zip::OutputStream.write_buffer(io) do |zos|
       zos.comment = TEST_ZIP.comment
       write_test_zip(zos)

test/test_helper.rb

@@ -146,7 +146,7 @@ class TestOutputStream
     attr_accessor :buffer
 
     def initialize
-      @buffer = ''
+      @buffer = +''
     end
 
     def <<(data)