From: nobu@...
Date: 2014-08-17T21:50:25+00:00
Subject: [ruby-core:64437] [ruby-trunk - Bug #10146] [Assigned] DateTime#jisx0301 returns corrupted string when GC.stress is set to true.

Issue #10146 has been updated by Nobuyoshi Nakada.

Description updated
Category set to ext
Status changed from Open to Assigned
Assignee set to tadayoshi funaba
Target version set to current: 2.2.0
Backport changed from 2.0.0: UNKNOWN, 2.1: UNKNOWN to 2.0.0: REQUIRED, 2.1: REQUIRED

LGTM

----------------------------------------
Bug #10146: DateTime#jisx0301 returns corrupted string when GC.stress is set to true.
https://bugs.ruby-lang.org/issues/10146#change-48389

* Author: Masamitsu Murase
* Status: Assigned
* Priority: Normal
* Assignee: tadayoshi funaba
* Category: ext
* Target version: current: 2.2.0
* ruby -v: ruby 2.2.0dev (2014-08-17) [i386-mswin32_100]
* Backport: 2.0.0: REQUIRED, 2.1: REQUIRED
----------------------------------------
`DateTime#jisx0301` returns corrupted string when `GC.stress` is set to true.

**Sample script to reproduce this issue:**

~~~ruby
# sample.rb
require("date")

GC.stress = true
p DateTime.parse('2001-02-03T04:05:06.123456789+07:00').jisx0301(9)
~~~

This script shows invalid string as follows:

~~~
> ruby sample.rb
"\x16T04:05:06.123456789+07:00"
~~~

The following string is expected:

~~~
"H13.02.03T04:05:06.123456789+07:00"
~~~


**Cause:**
This is caused by unexpected GC.
Some variables in 'ext/date/date_core.c' should be marked with `RB_GC_GUARD` to prevent GC.

For example, variable 's' in dt_lite_jisx0301 should be marked with `RB_GC_GUARD`
so that the object pointed by 's' is kept while `rb_str_append` is called.

~~~C
static VALUE
dt_lite_jisx0301(int argc, VALUE *argv, VALUE self)
{
    VALUE n, s;
/* ...snip... */
    {
	get_d1(self);
	s = jisx0301_date(m_real_local_jd(dat),
			  m_real_year(dat));
	return rb_str_append(strftimev(RSTRING_PTR(s), self, set_tmx),
			     iso8601_timediv(self, n));
    }
}
~~~

should be

~~~C
static VALUE
dt_lite_jisx0301(int argc, VALUE *argv, VALUE self)
{
    VALUE n, s, result;
/* ...snip... */
    {
	get_d1(self);
	s = jisx0301_date(m_real_local_jd(dat),
			  m_real_year(dat));
	result = rb_str_append(strftimev(RSTRING_PTR(s), self, set_tmx),
			       iso8601_timediv(self, n));
	RB_GC_GUARD(s);
	return result;
    }
}
~~~


I attached a patch, date_core.c.diff, which also includes other fixes regarding `RB_GC_GUARD` in date_core.c.
If this patch is not so appropriate, please ignore it.

Regards,
Murase


---Files--------------------------------
date_core.c.diff (1.72 KB)


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