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Do not block handled signals in interactive mode

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Let these signals be handled asynchronously as they are acted on
only when waiting for process state changes.

* strace.c (start_set, blocked_set): Remove.
(set_sighandler): Do not update blocked_set.
(startup_attach, init, next_event): Remove all sigprocmask calls.
This commit is contained in:
Дмитрий Левин 2018-03-22 06:23:25 +00:00
parent 2bcf86777b
commit c3393d4770
1 changed files with 7 additions and 40 deletions
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47
strace.c
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@ -165,7 +165,6 @@ unsigned os_release; /* generated from uname()'s u.release */
static void detach(struct tcb *tcp);
static void cleanup(void);
static void interrupt(int sig);
static sigset_t start_set, blocked_set;
#ifdef HAVE_SIG_ATOMIC_T
static volatile sig_atomic_t interrupted;
@ -1081,15 +1080,6 @@ startup_attach(void)
unsigned int tcbi;
struct tcb *tcp;
/*
* Block user interruptions as we would leave the traced
* process stopped (process state T) if we would terminate in
* between PTRACE_ATTACH and wait4() on SIGSTOP.
* We rely on cleanup() from this point on.
*/
if (interactive)
sigprocmask(SIG_SETMASK, &blocked_set, NULL);
if (daemonized_tracer) {
pid_t pid = fork();
if (pid < 0)
@ -1129,12 +1119,8 @@ startup_attach(void)
attach_tcb(tcp);
if (interactive) {
sigprocmask(SIG_SETMASK, &start_set, NULL);
if (interrupted)
goto ret;
sigprocmask(SIG_SETMASK, &blocked_set, NULL);
}
if (interrupted)
return;
} /* for each tcbtab[] */
if (daemonized_tracer) {
@ -1145,10 +1131,6 @@ startup_attach(void)
kill(parent_pid, SIGKILL);
strace_child = 0;
}
ret:
if (interactive)
sigprocmask(SIG_SETMASK, &start_set, NULL);
}
/* Stack-o-phobic exec helper, in the hope to work around
@ -1553,10 +1535,6 @@ get_os_release(void)
static void
set_sighandler(int signo, void (*sighandler)(int), struct sigaction *oldact)
{
/* if signal handler is a function, add the signal to blocked_set */
if (sighandler != SIG_IGN && sighandler != SIG_DFL)
sigaddset(&blocked_set, signo);
const struct sigaction sa = { .sa_handler = sighandler };
sigaction(signo, &sa, oldact);
}
@ -1779,9 +1757,6 @@ init(int argc, char *argv[])
memset(acolumn_spaces, ' ', acolumn);
acolumn_spaces[acolumn] = '\0';
sigprocmask(SIG_SETMASK, NULL, &start_set);
memcpy(&blocked_set, &start_set, sizeof(blocked_set));
set_sighandler(SIGCHLD, SIG_DFL, &params_for_tracee.child_sa);
#ifdef USE_LIBUNWIND
@ -1895,9 +1870,9 @@ init(int argc, char *argv[])
set_sighandler(SIGTSTP, SIG_IGN, NULL);
/*
* In interactive mode (if no -o OUTFILE, or -p PID is used),
* fatal signals are blocked while syscall stop is processed,
* and acted on in between, when waiting for new syscall stops.
* In non-interactive mode, signals are ignored.
* fatal signals are handled asynchronously and acted
* when waiting for process state changes.
* In non-interactive mode these signals are ignored.
*/
set_sighandler(SIGHUP, interactive ? interrupt : SIG_IGN, NULL);
set_sighandler(SIGINT, interactive ? interrupt : SIG_IGN, NULL);
@ -2225,7 +2200,6 @@ static enum trace_event
next_event(int *pstatus, siginfo_t *si)
{
int pid;
int wait_errno;
int status;
struct tcb *tcp;
struct rusage ru;
@ -2254,23 +2228,16 @@ next_event(int *pstatus, siginfo_t *si)
return TE_BREAK;
}
if (interactive)
sigprocmask(SIG_SETMASK, &start_set, NULL);
pid = wait4(-1, pstatus, __WALL, (cflag ? &ru : NULL));
wait_errno = errno;
if (interactive)
sigprocmask(SIG_SETMASK, &blocked_set, NULL);
if (pid < 0) {
if (wait_errno == EINTR)
if (errno == EINTR)
return TE_NEXT;
if (nprocs == 0 && wait_errno == ECHILD)
if (nprocs == 0 && errno == ECHILD)
return TE_BREAK;
/*
* If nprocs > 0, ECHILD is not expected,
* treat it as any other error here:
*/
errno = wait_errno;
perror_msg_and_die("wait4(__WALL)");
}