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Re: Current GDB crashes when it sources Emacs's .gdbinit
- From: Tom Tromey <tromey at redhat dot com>
- To: Eli Zaretskii <eliz at gnu dot org>
- Cc: gdb-patches at sourceware dot org
- Date: Wed, 15 Apr 2009 13:43:56 -0600
- Subject: Re: Current GDB crashes when it sources Emacs's .gdbinit
- References: <83ocuxlopc.fsf@gnu.org>
- Reply-to: tromey at redhat dot com
>>>>> "Eli" == Eli Zaretskii <eliz@gnu.org> writes:
Eli> As far as I could see, it crashes when it reads this line of the
Eli> .gdbinit file supplied with Emacs:
Eli> if $tem[0] == 'w' && $tem[1] == 'i' && $tem[2] == 'n' && $tem[3] == 'd'
Sorry about that. I'm sending the appended fix throughq
regression testing.
Eli> #0 0x00002ae92925956f in obstack_free () from /lib/libc.so.6
Eli> #1 0x000000000044ce70 in do_my_cleanups (pmy_chain=0x8ee2b8,
Eli> old_chain=0xa2e3f0) at utils.c:389
[...]
Eli> (in fact, the
Eli> whole `struct obstack' pointed to by h looks garbled, at least to me):
Eli> I tried to debug this, but as I'm not very familiar with that part of
Eli> GDB (evaluate_expression, evaluate_subexp_c, and friends), I ran out
Eli> of time before I could find the villain. So I'm posting the
Eli> information here, in the hope that someone else could pick up where I
Eli> left off.
A situation where a cleanup is being called and the data is mangled
often means that some piece of code installed a cleanup referring to a
local variable and then forgot to manage the cleanup before a return.
That turned out to be the situation here. If the cleanup function is
unusual enough, a breakpoint in make_cleanup is the easy way to find
the bad call.
Tom
diff --git a/gdb/c-lang.c b/gdb/c-lang.c
index 0c9e4f8..1fd83a4 100644
--- a/gdb/c-lang.c
+++ b/gdb/c-lang.c
@@ -941,7 +941,10 @@ evaluate_subexp_c (struct type *expect_type, struct expression *exp,
*pos += 2;
if (noside == EVAL_SKIP)
- return NULL;
+ {
+ do_cleanups (cleanup);
+ return NULL;
+ }
if ((dest_type & C_CHAR) != 0)
{