Bug #8669: outbuf can be "temporarily" locked forever in IO#read

• Status: Closed
• Assignee: Glass_saga (Masaki Matsushita)
• Target version: 2.1.0
• ruby -v: ruby 2.1.0dev (2013-07-23 trunk 42132) [x86_64-linux]
• Backport: 1.9.3: DONE, 2.0.0: DONE

[Glass_saga (Masaki Matsushita)]

Following code make outbuf "temporarily" locked forever.
It is needed to ensure rb_str_unlocktmp().

str = ""
t = Thread.new(str) do |str|
r, = IO.pipe
r.read(nil, str)
end
sleep 1
t.raise
sleep 1
str.clear #=> can't modify string; temporarily locked (RuntimeError)

I have attached two patches.
One fixes io_fread(), another does io_getpartial() and rb_io_sysread().
May I commit these changes?

[normalperson (Eric Wong)]

"Glass_saga (Masaki Matsushita)" [e-mail] wrote:

Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN

I can confirm the issue under 1.9.3-p448 and 2.0.0-p247

Following code make outbuf "temporarily" locked forever.
It is needed to ensure rb_str_unlocktmp().

Nasty bug. I might've hit this soon in new project I'm working on(!)

I have attached two patches.
One fixes io_fread(), another does io_getpartial() and rb_io_sysread().
May I commit these changes?

Untested, but looks correct. Thanks.

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Assigned
• Backport changed from 1.9.3: UNKNOWN, 2.0.0: UNKNOWN to 1.9.3: REQUIRED, 2.0.0: REQUIRED

Seems fine.

Furthermore, should we introduce a function to callback with locking
temporarily?

[Glass_saga (Masaki Matsushita)]

• File io_fread_callback.diff io_fread_callback.diff added
• File read_internal_callback.diff read_internal_callback.diff added

Furthermore, should we introduce a function to callback with locking temporarily?

I made rb_str_locktmp_ensure() to callback with locktmp.

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

This issue was solved with changeset r42212.
Masaki, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

---

• string.c: add internal API rb_str_locktmp_ensure().

• io.c (io_fread): use rb_str_locktmp_ensure().
  [ruby-core:56121] [Bug #8669]

• test/ruby/test_io.rb: add a test for above.

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 1.9.3: REQUIRED, 2.0.0: REQUIRED to 1.9.3: REQUIRED, 2.0.0: DONE

Backported to ruby_2_0_0 at r42216.

[usa (Usaku NAKAMURA)]

• Backport changed from 1.9.3: REQUIRED, 2.0.0: DONE to 1.9.3: DONE, 2.0.0: DONE

Backported to ruby_1_9_3 at r42327.