GDB (not) handling SIGINT...?

[Paul Smith]

On Thu, 2018-11-15 at 16:24 +0000, Pedro Alves wrote:
> If you're OK with hacking GDB, s/SIGINT/SIGSTOP/g in child_pass_ctrlc
> should work reasonably OK, even though not perfect.

I got around to trying this and it did work... except for one thing:
when I wanted to continue I had to continue once for each thread in my
program :-/.  Actually it stopped thread 1 twice, once at first then
again...

This is GDB 8.2 on x86_64 GNU/Linux (Linux 4.15, GNU libc 2.27)

Somewhat confusing.


$ gdb -p 7351
  ...
Attaching to process 7351
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
0x00007f17b0b0826c in sigtimedwait () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) c
Continuing.
^C
Thread 1 "foo" received signal SIGSTOP, Stopped (signal).
0x00007f17b0b0826c in sigtimedwait () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) c
Continuing.

Thread 11 "foo" received signal SIGSTOP, Stopped (signal).
[Switching to Thread 0x7f17a91fe700 (LWP 7369)]
0x00007f17b0ec69f3 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
(gdb)
Continuing.

Thread 6 "foo" received signal SIGSTOP, Stopped (signal).
[Switching to Thread 0x7f17acfff700 (LWP 7361)]
0x00007f17b0ec6f85 in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
(gdb)
Continuing.

Thread 3 "foo" received signal SIGSTOP, Stopped (signal).
[Switching to Thread 0x7f17af7ff700 (LWP 7356)]
0x00007f17b0be9bb7 in epoll_wait () from /lib/x86_64-linux-gnu/libc.so.6
(gdb)
Continuing.

Thread 9 "foo" received signal SIGSTOP, Stopped (signal).
[Switching to Thread 0x7f17aa5ff700 (LWP 7367)]
0x00007f17b0ec69f3 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
(gdb)
Continuing.

Thread 4 "foo" received signal SIGSTOP, Stopped (signal).
[Switching to Thread 0x7f17ae7ff700 (LWP 7357)]
0x00007f17b0ec69f3 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
(gdb)
Continuing.

Thread 7 "foo" received signal SIGSTOP, Stopped (signal).
[Switching to Thread 0x7f17ac7fe700 (LWP 7362)]
0x00007f17b0ec6f85 in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
(gdb)
Continuing.

Thread 1 "foo" received signal SIGSTOP, Stopped (signal).
[Switching to Thread 0x7f17b3ccb8c0 (LWP 7351)]
0x00007f17b0b0826c in sigtimedwait () from /lib/x86_64-linux-gnu/libc.so.6
(gdb)
Continuing.

Thread 12 "foo" received signal SIGSTOP, Stopped (signal).
[Switching to Thread 0x7f17a3fff700 (LWP 7370)]
0x00007f17b0ec6f85 in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
(gdb)
Continuing.

Thread 2 "foo" received signal SIGSTOP, Stopped (signal).
[Switching to Thread 0x7f17b03ed700 (LWP 7355)]
0x00007f17b0ec6f85 in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
(gdb)
Continuing.

Thread 10 "foo" received signal SIGSTOP, Stopped (signal).
[Switching to Thread 0x7f17a99ff700 (LWP 7368)]
0x00007f17b0eca82e in recv () from /lib/x86_64-linux-gnu/libpthread.so.0
(gdb)
Continuing.

Thread 8 "foo" received signal SIGSTOP, Stopped (signal).
[Switching to Thread 0x7f17ab3ff700 (LWP 7363)]
0x00007f17b0ec69f3 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
(gdb)
Continuing.

Thread 5 "foo" received signal SIGSTOP, Stopped (signal).
[Switching to Thread 0x7f17adbff700 (LWP 7359)]
0x00007f17b0eca82e in recv () from /lib/x86_64-linux-gnu/libpthread.so.0
(gdb)
Continuing.

  ... finally here the program is really running again ...