Bug #7231: StringIO inconsistently raises IOError or RuntimeError if the string is frozen

• Status: Closed
• Assignee: nobu (Nobuyoshi Nakada)
• Target version: 2.0.0
• ruby -v: ruby 1.9.3p286 (2012-10-12 revision 37165) [x86_64-darwin10.8.0]

[brixen (Brian Shirai)]

StringIO#ungetc, #ungetbyte raise RuntimeError if the data string is frozen. StringIO#write raises IOError.

Why?

1.9.3p286 :001 > require 'stringio'
=> true
1.9.3p286 :002 > s = StringIO.new x = "abc"
=> #StringIO:0x00000101020038
1.9.3p286 :003 > x.freeze
=> "abc"
1.9.3p286 :004 > s.ungetbyte 0x42
RuntimeError: can't modify frozen String
from (irb):4:in ungetbyte' from (irb):4 from /Users/brian/.rvm/rubies/ruby-1.9.3-p286/bin/irb:16:in '
1.9.3p286 :005 > s.ungetc "w"
RuntimeError: can't modify frozen String
from (irb):5:in ungetc' from (irb):5 from /Users/brian/.rvm/rubies/ruby-1.9.3-p286/bin/irb:16:in '
1.9.3p286 :006 > s.write "d"
IOError: not modifiable string
from (irb):6:in write' from (irb):6 from /Users/brian/.rvm/rubies/ruby-1.9.3-p286/bin/irb:16:in '

Thanks,
Brian

[mame (Yusuke Endoh)]

Indeed. I think that it should raise IOError constantly. Any opinion?
Anyone could create a patch, please?

--
Yusuke Endoh [e-mail]

[usa (Usaku NAKAMURA)]

• Category set to ext
• Status changed from Open to Assigned
• Assignee set to nobu (Nobuyoshi Nakada)
• Target version set to 2.0.0

[Glass_saga (Masaki Matsushita)]

• File patch.diff patch.diff added

How about the patch?

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

This issue was solved with changeset r38628.
Brian, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

---

• ext/stringio/stringio.c (strio_ungetc): raise IOError instead of RuntimeError
  if the string is frozen.
  [Bug #7231] [ruby-core:48530]

• ext/stringio/stringio.c (strio_ungetbyte): ditto.

• test/stringio/test_stringio.rb: a test for above.