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Macro code crasher on re-run
- From: Daniel Jacobowitz <drow at mvista dot com>
- To: gdb at sources dot redhat dot com, jimb at redhat dot com
- Date: Sun, 2 Nov 2003 23:07:51 -0500
- Subject: Macro code crasher on re-run
There's a bug in default_macro_scope. I was in the middle of working on
something else when GDB crashed, so I can't fix it now, and Jim probably can
think of a better fix than I can - hence this message :) Or I'll get to it
in a few days.
Here's the problem. I've just typed "run".
82 struct macro_scope *
83 default_macro_scope (void)
84 {
85 struct symtab_and_line sal;
86 struct macro_source_file *main;
87 struct macro_scope *ms;
88
89 /* If there's a selected frame, use its PC. */
90 if (deprecated_selected_frame)
91 sal = find_pc_line (get_frame_pc (deprecated_selected_frame), 0);
So deprecated_selected_frame is NULL...
92
93 /* If the target has any registers at all, then use its PC. Why we
94 would have registers but no stack, I'm not sure. */
95 else if (target_has_registers)
96 sal = find_pc_line (read_pc (), 0);
And target_has_registers is false.
97
98 /* If all else fails, fall back to the current listing position. */
99 else
100 {
101 /* Don't call select_source_symtab here. That can raise an
102 error if symbols aren't loaded, but GDB calls the expression
103 evaluator in all sorts of contexts.
104
105 For example, commands like `set width' call the expression
106 evaluator to evaluate their numeric arguments. If the
107 current language is C, then that may call this function to
108 choose a scope for macro expansion. If you don't have any
109 symbol files loaded, then get_current_or_default would raise an
110 error. But `set width' shouldn't raise an error just because
111 it can't decide which scope to macro-expand its argument in. */
112 struct symtab_and_line cursal =
113 get_current_source_symtab_and_line ();
114
115 sal.symtab = cursal.symtab;
116 sal.line = cursal.line;
117 }
So we initialize just the symtab and line pointers.
118
119 return sal_macro_scope (sal);
120 }
39 if (! sal.symtab
40 || ! sal.symtab->macro_table)
41 return 0;
Oops, uninitialized memory read. That else case can't work; Jim, should we
just return 0 from default_macro_scope if the target isn't running, or
is there a function I don't see somewhere to find the macrotab and
initialize the rest of the symtab? Should it be "sal = cursal"?
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer