Rename `GPFBit3Error` to `StreamingError`.

`GPFBit3Error` doesn't really mean anything to the general user, and
it's not descriptive of the issue at hand. This error is raised when a
zip file cannot be streamed via `InputStream`, so `StreamingError` makes
more sense.

Also standardize the error message while we're about it.

README.md

@@ -185,7 +185,7 @@ There is one exception where it can not work however, and this is if the file do
 
 > If bit 3 (0x08) of the general-purpose flags field is set, then the CRC-32 and file sizes are not known when the header is written. The fields in the local header are filled with zero, and the CRC-32 and size are appended in a 12-byte structure (optionally preceded by a 4-byte signature) immediately after the compressed data.
 
-If `Zip::InputStream` finds such an entry in the zip archive it will raise an exception (`Zip::GPFBit3Error`).
+If `Zip::InputStream` finds such an entry in the zip archive it will raise an exception (`Zip::StreamingError`).
 
 `Zip::InputStream` is not designed to be used for random access in a zip file. When performing any operations on an entry that you are accessing via `Zip::InputStream.get_next_entry` then you should complete any such operations before the next call to `get_next_entry`.
 

lib/zip/errors.rb

@@ -7,7 +7,6 @@ module Zip
   class EntryNameError < Error; end
   class EntrySizeError < Error; end
   class InternalError < Error; end
-  class GPFBit3Error < Error; end
   class DecompressionError < Error; end
   class SplitArchiveError < Error; end
 
@@ -23,4 +22,19 @@ module Zip
       "Unsupported compression method: #{COMPRESSION_METHODS[@compression_method]}."
     end
   end
+
+  class StreamingError < Error
+    attr_reader :entry
+
+    def initialize(entry)
+      super()
+      @entry = entry
+    end
+
+    def message
+      "The local header of this entry ('#{@entry.name}') does not contain " \
+      'the correct metadata for `Zip::InputStream` to be able to ' \
+      'uncompress it. Please use `Zip::File` instead of `Zip::InputStream`.'
+    end
+  end
 end

lib/zip/input_stream.rb

@@ -70,12 +70,7 @@ module Zip
     # Returns nil when there are no more entries.
     def get_next_entry
       unless @current_entry.nil?
-        if @current_entry.incomplete?
-          raise GPFBit3Error,
-                'It is not possible to get complete info from the local ' \
-                'header to extract this entry (GP flags bit 3 is set). ' \
-                'Please use `Zip::File` instead of `Zip::InputStream`.'
-        end
+        raise StreamingError, @current_entry if @current_entry.incomplete?
 
         @archive_io.seek(@current_entry.next_header_offset, IO::SEEK_SET)
       end
@@ -151,10 +146,7 @@ module Zip
 
       if @current_entry.incomplete? && @current_entry.compressed_size == 0 \
         && !@complete_entry
-        raise GPFBit3Error,
-              'It is not possible to get complete info from the local ' \
-              'header to extract this entry (GP flags bit 3 is set). ' \
-              'Please use `Zip::File` instead of `Zip::InputStream`.'
+        raise StreamingError, @current_entry
       end
 
       @decrypted_io = get_decrypted_io

test/file_test.rb

@@ -46,9 +46,13 @@ class ZipFileTest < MiniTest::Test
   def test_get_input_stream_stored_with_gpflag_bit3
     ::Zip::File.open('test/data/gpbit3stored.zip') do |zf|
       zis = zf.get_input_stream('file1.txt')
-      assert_raises(::Zip::GPFBit3Error) do
+
+      error = assert_raises(::Zip::StreamingError) do
         zis.get_next_entry
       end
+      assert_match(/file1\.txt/, error.message)
+      assert_equal('file1.txt', error.entry.name)
+
       zf.get_input_stream('file2.txt')
     end
   end

test/input_stream_test.rb

@@ -69,17 +69,21 @@ class ZipInputStreamTest < MiniTest::Test
 
   def test_open_file_with_gp3bit_set
     ::Zip::InputStream.open('test/data/gpbit3stored.zip') do |zis|
-      assert_raises(::Zip::GPFBit3Error) do
+      error = assert_raises(::Zip::StreamingError) do
         zis.get_next_entry
       end
+      assert_match(/file1\.txt/, error.message)
+      assert_equal('file1.txt', error.entry.name)
     end
   end
 
   def test_open_file_with_gp3bit_set_created_by_osx_archive
     ::Zip::InputStream.open('test/data/osx-archive.zip') do |zis|
-      assert_raises(::Zip::GPFBit3Error) do
+      error = assert_raises(::Zip::StreamingError) do
         zis.get_next_entry
       end
+      assert_match(/1\.txt/, error.message)
+      assert_equal('1.txt', error.entry.name)
     end
   end