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// RUN: %clangxx_tsan %s -o %t && %run %t 2>&1 | FileCheck %s
// UNSUPPORTED: darwin
#include <errno.h>
#include <limits.h>
#include <pthread.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/select.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
// This attempts to exercise a race condition where both a thread and its signal
// handler allocate the SigCtx. If the race is allowed, it leads to a leak and
// the first signal being dropped.
// Spawn threads in a loop and send it SIGUSR1 concurrently with the thread
// doing a bogus kill() call. The signal handler writes to a self-pipe which the
// thread detects and then exits. A dropped signal results in a timeout.
int pipes[2];
static void handler(int sig) { write(pipes[1], "x", 1); }
static int do_select() {
struct timeval tvs {
0, 1000
};
fd_set fds;
FD_ZERO(&fds);
FD_SET(pipes[0], &fds);
return select(pipes[0] + 1, &fds, 0, 0, &tvs);
}
static void *thr(void *p) {
// This kill() is expected to fail; it exists only to trigger a call to SigCtx
// outside of the signal handler.
kill(INT_MIN, 0);
int success = 0;
for (int i = 0; i < 1024; i++) {
if (do_select() > 0) {
success = 1;
break;
}
}
if (success) {
char c;
read(pipes[0], &c, 1);
} else {
fprintf(stderr, "Failed to receive signal\n");
exit(1);
}
return p;
}
int main() {
if (pipe(pipes)) {
perror("pipe");
exit(1);
}
struct sigaction act = {};
act.sa_handler = &handler;
if (sigaction(SIGUSR1, &act, 0)) {
perror("sigaction");
exit(1);
}
for (int i = 0; i < (1 << 10); i++) {
pthread_t th{};
if (pthread_create(&th, 0, thr, 0)) {
perror("pthread_create");
exit(1);
}
pthread_kill(th, SIGUSR1);
pthread_join(th, 0);
}
fprintf(stderr, "DONE\n");
return 0;
}
// CHECK-NOT: WARNING: ThreadSanitizer:
// CHECK: DONE
// CHECK-NOT: WARNING: ThreadSanitizer:
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