Get rid of TCB_SIGTRAPPED
On attempts to block or set SIGTRAP handler,
for example, using sigaction syscall, we generate
an additional SIGSTOP.
This change gets rid of this SIGSTOP sending/ignoring.
It appears to work just fine.
It also works if I force strace to not use PTRACE_O_TRACESYSGOOD,
which means strace stops will be marked with SIGTRAP,
not (SIGTRAP | 0x80) - I wondered maybe that's when
this hack is needed.
So, why we even have TCB_SIGTRAPPED? No one knows. It predates
version control: this code was present in the initial commit,
in 1999. No adequate comments, either.
Moreover, TCB_SIGTRAPPED is not set in sys_rt_sigaction
and sys_sigprocmask syscalls - the ones which are most usually
used to implement signal blocking, it is only set in obsolete
sys_signal, sys_sigaction, sys_sigsetmask, and in some dead
non-Linux code.
I think whatever bug it was fixing is gone long ago -
at least as long as sys_rt_sigaction is used by glibc.
Again, since glibc (and uclibc) uses sys_rt_sigaction
and sys_sigprocmask, modified code paths are not used
by most programs anyway.
* defs.h: Remove definition of TCB_SIGTRAPPED.
* signal.c (sys_sigvec): Don't set TCB_SIGTRAPPED and don't send SIGSTOP.
(sys_sigsetmask): Likewise.
(sys_sigaction): Likewise.
(sys_signal): Likewise.
* strace.c (trace): Remove code which executes if TCB_SIGTRAPPED is set.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
diff --git a/signal.c b/signal.c
index 999d149..271d6f2 100644
--- a/signal.c
+++ b/signal.c
@@ -842,24 +842,12 @@
tprints("{SIG_DFL}");
break;
case (int) SIG_IGN:
- if (tcp->u_arg[0] == SIGTRAP) {
- tcp->flags |= TCB_SIGTRAPPED;
- kill(tcp->pid, SIGSTOP);
- }
tprints("{SIG_IGN}");
break;
case (int) SIG_HOLD:
- if (tcp->u_arg[0] == SIGTRAP) {
- tcp->flags |= TCB_SIGTRAPPED;
- kill(tcp->pid, SIGSTOP);
- }
- tprints("SIG_HOLD");
+ tprints("{SIG_HOLD}");
break;
default:
- if (tcp->u_arg[0] == SIGTRAP) {
- tcp->flags |= TCB_SIGTRAPPED;
- kill(tcp->pid, SIGSTOP);
- }
tprintf("{%#lx, ", (unsigned long) sv.sv_handler);
printsigmask(&sv.sv_mask, 0);
tprints(", ");
@@ -923,14 +911,6 @@
sigset_t sigm;
long_to_sigset(tcp->u_arg[0], &sigm);
printsigmask(&sigm, 0);
-#ifndef USE_PROCFS
- if ((tcp->u_arg[0] & sigmask(SIGTRAP))) {
- /* Mark attempt to block SIGTRAP */
- tcp->flags |= TCB_SIGTRAPPED;
- /* Send unblockable signal */
- kill(tcp->pid, SIGSTOP);
- }
-#endif /* !USE_PROCFS */
}
else if (!syserror(tcp)) {
sigset_t sigm;
@@ -1005,24 +985,10 @@
tprints("{SIG_ERR, ");
else if ((long)sa.SA_HANDLER == (long)SIG_DFL)
tprints("{SIG_DFL, ");
- else if ((long)sa.SA_HANDLER == (long)SIG_IGN) {
-#ifndef USE_PROCFS
- if (tcp->u_arg[0] == SIGTRAP) {
- tcp->flags |= TCB_SIGTRAPPED;
- kill(tcp->pid, SIGSTOP);
- }
-#endif /* !USE_PROCFS */
+ else if ((long)sa.SA_HANDLER == (long)SIG_IGN)
tprints("{SIG_IGN, ");
- }
- else {
-#ifndef USE_PROCFS
- if (tcp->u_arg[0] == SIGTRAP) {
- tcp->flags |= TCB_SIGTRAPPED;
- kill(tcp->pid, SIGSTOP);
- }
-#endif /* !USE_PROCFS */
+ else
tprintf("{%#lx, ", (long) sa.SA_HANDLER);
- }
#ifndef LINUX
printsigmask(&sa.sa_mask, 0);
#else
@@ -1060,21 +1026,9 @@
tprints("SIG_DFL");
break;
case (long) SIG_IGN:
-#ifndef USE_PROCFS
- if (tcp->u_arg[0] == SIGTRAP) {
- tcp->flags |= TCB_SIGTRAPPED;
- kill(tcp->pid, SIGSTOP);
- }
-#endif /* !USE_PROCFS */
tprints("SIG_IGN");
break;
default:
-#ifndef USE_PROCFS
- if (tcp->u_arg[0] == SIGTRAP) {
- tcp->flags |= TCB_SIGTRAPPED;
- kill(tcp->pid, SIGSTOP);
- }
-#endif /* !USE_PROCFS */
tprintf("%#lx", tcp->u_arg[1]);
}
return 0;