Re: [RFA] Avoid segfault in decode_line_2

[Elena Zannoni <ezannoni@redhat.com>]

Michal Ludvig writes:
 > Hi all,
 > this patch fixes a problem that I met while debugging a testsuite 
 > failure on amd64:
 > 
 >  > Running gdb-head/gdb/testsuite/gdb.c++/templates.exp ...
 >  > FAIL: gdb.c++/templates.exp: constructor breakpoint (timeout)
 > 
 > (gdb) break T5<int>::T5
 > -> Segfault in linespec.c:486 [decode_line_2()] because
 >     values.sals[i].symtab is NULL and dereferencing of
 >     values.sals[i].symtab->filename crashes.
 > 
 > After some investigation I found out that .debug_line section of the 
 > input file was broken (reported to binutils@ list).
 > However broken debug info is not an excuse for GDB to crash.
 > 
 > OK to apply to head and branch?
 > 
 > Michal Ludvig
 > -- 
 > * SuSE CR, s.r.o     * mludvig@suse.cz
 > * (+420) 296.545.373 * http://www.suse.cz
 > 2003-07-11  Michal Ludvig  <mludvig@suse.cz>
 > 
 > 	* linespec.c (decode_line_2): Avoid crash if 
 > 	find_function_start_sal() returns empty record.
 > 
 > Index: linespec.c
 > ===================================================================
 > RCS file: /cvs/src/src/gdb/linespec.c,v
 > retrieving revision 1.49
 > diff -u -p -r1.49 linespec.c
 > --- linespec.c	8 Jun 2003 18:27:13 -0000	1.49
 > +++ linespec.c	11 Jul 2003 06:59:01 -0000
 > @@ -483,11 +483,16 @@ decode_line_2 (struct symbol *sym_arr[],
 >        if (sym_arr[i] && SYMBOL_CLASS (sym_arr[i]) == LOC_BLOCK)
 >  	{
 >  	  values.sals[i] = find_function_start_sal (sym_arr[i], funfirstline);
 > -	  printf_unfiltered ("[%d] %s at %s:%d\n",
 > +	  printf_unfiltered ("[%d] %s at %s:%d ",
 >  			     (i + 2),
 >  			     SYMBOL_PRINT_NAME (sym_arr[i]),
 > -			     values.sals[i].symtab->filename,
 > +			     values.sals[i].symtab ? 
 > +			       values.sals[i].symtab->filename :
 > +			       "?FILE",
 >  			     values.sals[i].line);
 > +	  if (! values.sals[i].symtab)
 > +	    printf_unfiltered ("[No symtab? Probably a broken debug info...]" );
 > +	  printf_unfiltered ("\n");
 >  	}
 >        else
 >  	printf_unfiltered ("?HERE\n");

Yes, but, could you change this to use an if (values.sals[i].symtab)
before the printf_filtered and avoid the conditional expression? You
will end up getting rid of the if() for the No symtab?.. case as well,
since that can be folded into a single printf.

elena