Bug #8342: IO.readlines ignores Encoding.default_internal if Encoding.default_external is ASCII-8BIT

• Status: Closed
• Assignee: naruse (Yui NARUSE)
• Target version: 2.1.0
• ruby -v: 1.9.3
• Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN

[leocassarani (Leo Cassarani)]

Under normal circumstances, IO.readlines will transcode from Encoding.default_external to Encoding.default_internal:

File.open('hi', 'w') { |f| f.puts "hello\n" }
Encoding.default_external = Encoding::US_ASCII
Encoding.default_internal = Encoding::UTF_8
puts IO.readlines('hi').first.encoding
#=> UTF-8

However, when Encoding.default_external is set to ASCII-8BIT, IO.readlines will always use ASCII-8BIT, regardless of what Encoding.default_internal is set to:

File.open('hi', 'w') { |f| f.puts "hello\n" }
Encoding.default_external = Encoding::ASCII_8BIT
Encoding.default_internal = Encoding::UTF_8
puts IO.readlines('hi').first.encoding
#=> ASCII-8BIT

Using IO#gets instead of IO.readlines will produce the same behaviour.

[nobu (Nobuyoshi Nakada)]

• Category set to M17N
• Status changed from Open to Assigned
• Assignee set to naruse (Yui NARUSE)
• Target version set to 2.1.0

Seems intended behavior to me.

[naruse (Yui NARUSE)]

• Status changed from Assigned to Rejected

If external encoding is ASCII-8BIT, the input content is considered as binary.
It is out of text encoding conversion and its encoding kept as ASCII-8BIT even if default_internal is set.

[leocassarani (Leo Cassarani)]

Thanks naruse. However, this seems inconsistent with the way encodings are handled for individual IO instances. For example:

io = File.open('hi', :encoding => "ascii-8bit:utf-16")
puts io.gets.encoding

=> UTF-16

This happens even if Encoding.default_external is set to ASCII-8BIT before opening the file.

[naruse (Yui NARUSE)]

• Status changed from Rejected to Assigned

leocassarani (Leo Cassarani) wrote:

Thanks naruse. However, this seems inconsistent with the way encodings are handled for individual IO instances. For example:

io = File.open('hi', :encoding => "ascii-8bit:utf-16")
puts io.gets.encoding

=> UTF-16

This happens even if Encoding.default_external is set to ASCII-8BIT before opening the file.

That side sounds buggy

[naruse (Yui NARUSE)]

• Status changed from Assigned to Closed
• % Done changed from 0 to 100

This issue was solved with changeset r40610.
Leo, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

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• io.c (rb_io_ext_int_to_encs): ignore internal encoding if external
  encoding is ASCII-8BIT. [Bug #8342]