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0f443d1b70
With a test like this:
1 #include <dlfcn.h>
2 int
3 main ()
4 {
5 dlsym (RTLD_DEFAULT, "FOO");
6 return 0;
7 }
and then "start" followed by "until 6", GDB currently incorrectly
stops inside the runtime loader, instead of line 6. Vis:
...
Temporary breakpoint 1, main () at until.c:5
4 {
(gdb) until 6
0x00007ffff7f0a90d in __GI__dl_catch_exception (exception=exception@entry=0x7fffffffdb00, operate=<optimized out>, args=0x7ffff7f0a90d <__GI__dl_catch_exception+109>) at dl-error-skeleton.c:206
206 dl-error-skeleton.c: No such file or directory.
(gdb)
The problem is related to longjmp handling -- dlsym internally
longjmps on error. The testcase can be reduced to this:
1 #include <setjmp.h>
2 void func () {
3 jmp_buf buf;
4 if (setjmp (buf) == 0)
5 longjmp (buf, 1);
6 }
7
8 int main () {
9 func ();
10 return 0; /* until to here */
11 }
and then with "start" followed by "until 10", GDB currently
incorrectly stops at line 4 (returning from setjmp), instead of line
10.
The problem is that the BPSTAT_WHAT_CLEAR_LONGJMP_RESUME code in
infrun.c fails to find the initiating frame, and so infrun thinks that
the longjmp jumped somewhere outer to "until"'s originating frame.
Here:
case BPSTAT_WHAT_CLEAR_LONGJMP_RESUME:
{
struct frame_info *init_frame;
/* There are several cases to consider.
1. The initiating frame no longer exists. In this case we
must stop, because the exception or longjmp has gone too
far.
...
init_frame = frame_find_by_id (ecs->event_thread->initiating_frame);
if (init_frame) // this is NULL!
{
...
}
/* For Cases 1 and 2, remove the step-resume breakpoint, if it
exists. */
delete_step_resume_breakpoint (ecs->event_thread);
end_stepping_range (ecs); // case 1., so we stop.
}
The initiating frame is set by until_break_command ->
set_longjmp_breakpoint. The initiating frame is supposed to be the
frame that is selected when the command was issued, but
until_break_command instead passes the frame id of the _caller_ frame
by mistake. When the "until LINE" command is issued from main, the
caller frame is the caller of main. When later infrun tries to find
that frame by id, it fails to find it, because frame_find_by_id
doesn't unwind past main.
The bug is that we passed the caller frame's id to
set_longjmp_breakpoint. We should have passed the selected frame's id
instead.
Change-Id: Iaae1af7cdddf296b7c5af82c3b5b7d9b66755b1c
35 lines
914 B
C
35 lines
914 B
C
/* This testcase is part of GDB, the GNU debugger.
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Copyright 2022 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include <setjmp.h>
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void
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func (void)
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{
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jmp_buf buf;
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if (setjmp (buf) == 0)
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longjmp (buf, 1);
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}
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int
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main ()
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{
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func ();
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return 0; /* until to here */
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}
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