Re: [BUG] coding.c/decode_coding_iso2022

[Kenichi Handa <handa@m17n.org>]

In article <usmo4rvqo.fsf@boost-consulting.com>, David Abrahams <dave@boost-consulting.com> writes:
> Tired of the numerous crashes I've been getting under NT, I
> recompiled emacs with all the runtime checks enabled.  I think I'll
> be posting lots of reports.

> The title function uses variable c2 uninitialized during this phase
> of the make process:

>    Loading language/devanagari (source)...

> The stack trace is:

>  	ntdll.dll!77f75a58() 	
>  	temacs.exe!failwithmessage(void * retaddr=0x011b5c7f, int crttype=0x00000001, int errnum=0x00000003, const char * msg=0x0111431e)  + 0x106	C++
>  	temacs.exe!_RTC_UninitUse(const char * varname=0x01114900)  + 0x9c	C++
>> 	temacs.exe!decode_coding_iso2022()  Line 2169 + 0x33c	C

It seems that the relevant line is this:

      c = DECODE_ISO_CHARACTER (charset, c1, c2);

But, ...
[...]
> Locals at the point of the error:
> 	c2	0xcccccccc	int
> 	c1	0x0000003b	int
> +	coding	0x0081f1e4 {type=coding_type_iso2022 eol_type=0x00000001 common_flags=0x00000007 ...}	coding_system *
> +	source	0x0158da80 ";;; devanagari.el --- Support for Devanagari -*- coding: iso-2022-7bit; no-byte-compile: t -*-
[...]
> +	destination	0x0158d2b0 ""	unsigned char *
> 	src_bytes	0x000006b7	int
> 	dst_bytes	0x00000000	int
> 	charset1	0xffffffff	int
> 	charset	0x00000000	int
> +	src	0x0158da81 ";; devanagari.el --- Support for Devanagari -*- coding: iso-2022-7bit; no-byte-compile: t -*-

[...]
> 	translation_table	0x41398000	int
> 	c	0xcccccccc	int
> 	charset0	0x00000000	int
> +	src_end	0x0158e137 ""	unsigned char *
> +	dst_end	0x0158d2b0 ""	unsigned char *
> +	dst	0x0158d2b0 ""	unsigned char *
> +	src_base	0x0158da80 ";;; devanagari.el --- Support for Devanagari -*- coding: iso-2022-7bit; no-byte-compile: t -*-

[...]
> 	safe_chars	0x1137e834	int

As the value of charset is 0, c2 is never referred in the
macro DECODE_ISO_CHARACTER except for as the last argument
to the function translate_char.  And in that function also,
as charset is zero, c2 is never referred.

So, I think this is not the reason of the crash of your emacs.

---
Ken'ichi HANDA
handa@m17n.org