Re: crash: memcpy, XChangeProperty, XSetTextProperty, XSetWMIconName, x_set_name_internal

[Reiner Steib]

On Mon, Dec 05 2005, Eli Zaretskii wrote:

>> From: Reiner Steib <address@hidden>
>> Date: Mon, 05 Dec 2005 14:35:08 +0100
>> Cc: address@hidden
 
>> On Sun, Dec 04 2005, Richard M. Stallman wrote:
[...]
>> > Can you please examine the arguments that were passed to
>> > XSetWMIconName?  Are they all valid data?
[...]
> In what frame out of the 6 (#0 to #5) listed in the C backtrace did
> you issue these print commands?  

I didn't issue any frame command, so it was frame #0, I think:

(gdb) frame
#0  0x0000002a97462fe2 in memcpy () from /lib64/tls/libc.so.6

> You need to issue them in the frame #5, the one that calls
> XSetWMIconName; the GDB command to get there from the place where
> the program stops due to the fatal signal is "frame 5" or "up 5".

(gdb) frame 5
#5  0x00000000004c874e in x_set_name_internal (f=0x3563680, name=Variable 
"name" is not available.
)
    at [...]/emacs/src/xfns.c:1657
1657            XSetWMIconName (FRAME_X_DISPLAY (f), FRAME_OUTER_WINDOW (f), 
&icon);
(gdb) p f
$1 = 0x3563680
(gdb) p icon
$2 = {
  value = 0x71ab178 <Address 0x71ab178 out of bounds>, 
  encoding = 31, 
  format = 8, 
  nitems = 9
}
(gdb) p &icon
$3 = (XTextProperty *) 0x7fbfffc570

> The backtrace seems to indicate that some of the arguments were
> optimized away by GCC and not saved anywhere where GDB can find them.
> So perhaps you will need to examine some other variables whose values
> can give evidence about the arguments.  Alternatively (assuming you
> can reproduce the crash), modify xfns.c to introduce temporary global
> variables, declared `volatile' to avoid optimizations, and put the
> argument values into them just before XSetWMIconName is called.  Then
> you can examine those temporary variables in GDB (after getting to the
> correct frame as explained above).

I can't reproduce the crash upto now.  But I'll keep your suggestions
in mind.

Bye, Reiner.
-- 
       ,,,
      (o o)
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