[debbugs-tracker] bug#8211: closed (uninitialized variable in detect_coding_iso_2022's end-of-composition code)

[GNU bug Tracking System]

Your message dated Tue, 18 Jun 2019 17:19:03 -0700
with message-id <address@hidden>
and subject line Re: uninitialized variable in detect_coding_iso_2022's 
end-of-composition code
has caused the debbugs.gnu.org bug report #8211,
regarding uninitialized variable in detect_coding_iso_2022's end-of-composition 
code
to be marked as done.

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8211: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=8211
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> --- Begin Message ---
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> Subject: 
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> uninitialized variable in detect_coding_iso_2022's end-of-composition	code
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> Date: 
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> Wed, 09 Mar 2011 09:53:39 -0800
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> User-agent: 
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> Mozilla/5.0 (X11; U; Linux x86_64; en-US;	rv:1.9.2.13) Gecko/20101209 Fedora/3.1.7-0.35.b3pre.fc14	Thunderbird/3.1.7
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>
> I found this problem by compiling Emacs with GCC's -Wuninitialized flag.
>
> The following code in the Emacs trunk src/coding.c's
> detect_coding_iso_2022 function apparently uses an uninitialized variable:
>
>           ...
>           else if (c == '1')
>             {
>               /* End of composition.  */
>               if (composition_count < 0
>                   || composition_count > MAX_COMPOSITION_COMPONENTS)
>                 /* Invalid */
>                 break;
>               composition_count = -1;
>               found |= CATEGORY_MASK_ISO;
>             }
>           else
>             ...
>
>           /* We found a valid designation sequence for CHARSET.  */
>           rejected |= CATEGORY_MASK_ISO_8BIT;
>           if (SAFE_CHARSET_P (&coding_categories[coding_category_iso_7],
>                               id))
>             found |= CATEGORY_MASK_ISO_7;
>
> The problem is that the "else if (c == '1')" branch does not initialize
> the local variable "id", but the second "if" test uses that variable.
>
> I plan to work around the uninitialized-variable problem by initializing
> "id" to zero.  This will replace undefined behavior with defined behavior,
> so it shouldn't introduce a new bug, but it probably doesn't fix the
> bug in question, assuming there is one.  Could an expert in this
> area please review this and come up with a real fix?
>
> I'm CC'ing this to Kenichi Handa, who committed the code in question.
>
>
>
> --- End Message ---
> --- Begin Message ---
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>
>
> Subject: 
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> Re: uninitialized variable in detect_coding_iso_2022's end-of-composition code
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>
>
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> Date: 
>
> Tue, 18 Jun 2019 17:19:03 -0700
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>
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> User-agent: 
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> Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0
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>
>
>
> Kenichi Handa evidently fixed this old bug in 2011 after I filed it, so I'm 
> closing the bug report now.
>
>
>
> --- End Message ---