/*

* The concurrency test target. A background thread calls the same function

* the host is about to trace, in a loop, which is what exposed the second

* v0.3.0 bug: Interceptor hooks are process-wide, not per-thread, so the

* other thread's callbacks were stopping Stalker in the middle of the call

* actually being measured. Before the fix, the first trace_call against this

* binary never returned at all. See the README field note.

*

* `check_license` here is a copy of the one in licensecheck.c, on purpose:

* the only variable under test is the second thread, so the traced function

* should be one whose correct trace is already known from that target.

*

* main() blocks forever instead of exiting, because the point is to trace a

* running process with live threads -- resume it, then trace.

*

* Build (non-PIE, so the address below is fixed and predictable):

*

* gcc -O0 -no-pie -fno-pie -fno-inline -pthread -o mt examples/mt.c

* nm mt | grep ' T check_license'

* # 0000000000401186 T check_license

*

* This one does not terminate on its own; kill it when you're done with it.

*/

#include <pthread.h>

#include <stdio.h>

#include <string.h>

#include <unistd.h>

__attribute__((noinline))

int check_license(const char *key) {

int score = 0;

if (key[0] == 'V') {

score += 1;

} else {

score -= 1;

}

if (strcmp(key, "VALID-KEY-123") == 0) {

score += 10;

} else {

score -= 10;

}

if (score >= 10) {

return 1;

}

return 0;

}

static void *worker(void *arg) {

(void)arg;

for (;;) {

check_license("BACKGROUND-KEY");

usleep(20);

}

return NULL;

}

int main(void) {

pthread_t t;

if (pthread_create(&t, NULL, worker, NULL) != 0) {

fprintf(stderr, "pthread_create failed\n");

return 1;

}

for (;;) {

pause();

}

}