Add more testing for pthread_kill.

- Test using `pthread_kill` on yourself.
- Test using `pthread_kill` from a background thread to the main thread.

system/lib/libc/raise.c

diff --git a/system/lib/libc/raise.c b/system/lib/libc/raise.c
index 5e56d5c..b653bf7 100644
--- a/system/lib/libc/raise.c
+++ b/system/lib/libc/raise.c
@@ -71,10 +71,10 @@
         handler(sig);
       }
     } else if (handler != SIG_IGN) {
-        // Avoid a direct call to the handler, and instead call via JS so we can
-        // avoid strict signature checking.
-        // https://github.com/emscripten-core/posixtestsuite/issues/6
-        __call_sighandler(handler, sig);
+      // Avoid a direct call to the handler, and instead call via JS so we can
+      // avoid strict signature checking.
+      // https://github.com/emscripten-core/posixtestsuite/issues/6
+      __call_sighandler(handler, sig);
     }
   }
   return 0;

system/lib/pthread/pthread_kill.c

diff --git a/system/lib/pthread/pthread_kill.c b/system/lib/pthread/pthread_kill.c
index 86e486c..dcaaa00 100644
--- a/system/lib/pthread/pthread_kill.c
+++ b/system/lib/pthread/pthread_kill.c
@@ -11,10 +11,8 @@
 #include <emscripten_internal.h>
 
 #include "pthread_impl.h"
-#include "lock.h"
 
-void do_raise(void* arg) {
-  int sig = (intptr_t)arg;
+static void do_raise(int sig) {
   if (sig == SIGCANCEL) {
     // For `SIGCANCEL` there is no need to actually call raise to run the
     // handler function.  The calling thread (the one calling `pthread_cancel`)
@@ -31,17 +29,17 @@
     _emscripten_runtime_keepalive_clear();
     return;
   }
-  raise((intptr_t)sig);
+  raise(sig);
+}
+
+static void proxied_do_raise(void* arg) {
+  do_raise((intptr_t)arg);
 }
 
 int pthread_kill(pthread_t t, int sig) {
   if (sig < 0 || sig >= _NSIG) {
     return EINVAL;
   }
-  if (t == emscripten_main_runtime_thread_id()) {
-    if (sig == 0) return 0; // signal == 0 is a no-op.
-    return ESRCH;
-  }
   if (!t || !_emscripten_thread_is_valid(t)) {
     return ESRCH;
   }
@@ -49,6 +47,10 @@
 
   // The job of pthread_kill is basically to run the (process-wide) signal
   // handler on the target thread.
-  emscripten_proxy_async(emscripten_proxy_get_system_queue(), t, do_raise, (void*)(intptr_t)sig);
+  if (pthread_equal(pthread_self(), t)) {
+    do_raise(sig);
+  } else {
+    emscripten_proxy_async(emscripten_proxy_get_system_queue(), t, proxied_do_raise, (void*)(intptr_t)sig);
+  }
   return 0;
 }

test/pthread/test_pthread_kill.c

diff --git a/test/pthread/test_pthread_kill.c b/test/pthread/test_pthread_kill.c
index 2bc8095..cde9404 100644
--- a/test/pthread/test_pthread_kill.c
+++ b/test/pthread/test_pthread_kill.c
@@ -17,14 +17,18 @@
 
 pthread_cond_t started_cond = PTHREAD_COND_INITIALIZER;
 pthread_mutex_t started_lock = PTHREAD_MUTEX_INITIALIZER;
-_Atomic bool got_term_signal = false;
+_Atomic bool got_sigterm = false;
+_Atomic bool got_sigusr1 = false;
 
-pthread_t thr;
+pthread_t main_thread;
+pthread_t child_thread;
 
 void signal_handler(int sig, siginfo_t * info, void * arg) {
-  printf("signal: %d onthread=%d\n", sig, pthread_self() == thr);
+  printf("signal: %d onthread=%d\n", sig, pthread_self() == child_thread);
   if (sig == SIGTERM) {
-    got_term_signal = true;
+    got_sigterm = true;
+  } else if (sig == SIGUSR1) {
+    got_sigusr1 = true;
   }
 }
 
@@ -34,6 +38,7 @@
   act.sa_flags = SA_SIGINFO;
   act.sa_sigaction = signal_handler;
   sigaction(SIGTERM, &act, NULL);
+  sigaction(SIGUSR1, &act, NULL);
 }
 
 
@@ -46,17 +51,26 @@
   pthread_cond_signal(&started_cond);
   pthread_mutex_unlock(&started_lock);
   // As long as this thread is running, keep the shared variable latched to nonzero value.
-  while (!got_term_signal) {
+  while (!got_sigterm) {
     sleepms(1);
   }
-  printf("got term signal, shutting down thread\n");
-  pthread_exit(0);
+  printf("got term signal, sending signal back to main thread\n");
+  pthread_kill(main_thread, SIGUSR1);
+  return NULL;
 }
 
 int main() {
+  main_thread = pthread_self();
   setup_handler();
 
-  int s = pthread_create(&thr, NULL, thread_start, 0);
+  printf("tesing pthread_kill with pthread_self\n");
+  assert(!got_sigterm);
+  int s = pthread_kill(pthread_self(), SIGTERM);
+  assert(got_sigterm);
+  got_sigterm = false;
+  assert(s == 0);
+
+  s = pthread_create(&child_thread, NULL, thread_start, 0);
   assert(s == 0);
 
   // Wait until thread kicks in and sets the shared variable.
@@ -65,11 +79,15 @@
   pthread_mutex_unlock(&started_lock);
   printf("thread has started, sending SIGTERM\n");
 
-  s = pthread_kill(thr, SIGTERM);
+  s = pthread_kill(child_thread, SIGTERM);
   assert(s == 0);
   printf("SIGTERM sent\n");
 
-
-  pthread_join(thr, NULL);
+  pthread_join(child_thread, NULL);
+  printf("joined child_thread\n");
+  while (!got_sigusr1) {
+    sleepms(1);
+  }
+  printf("got SIGUSR1. all done.\n");
   return 0;
 }

test/pthread/test_pthread_kill.out

diff --git a/test/pthread/test_pthread_kill.out b/test/pthread/test_pthread_kill.out
index 63ee2d8..9c0d30a 100644
--- a/test/pthread/test_pthread_kill.out
+++ b/test/pthread/test_pthread_kill.out
@@ -1,4 +1,9 @@
+tesing pthread_kill with pthread_self
+signal: 15 onthread=0
 thread has started, sending SIGTERM
 SIGTERM sent
 signal: 15 onthread=1
-got term signal, shutting down thread
+got term signal, sending signal back to main thread
+joined child_thread
+signal: 10 onthread=0
+got SIGUSR1. all done.