Fix pthread init and null for C++

tests/pthread/init.cpp

@@ -0,0 +1,52 @@
+// this file is both C and CPP to check NULL and thread_local on C++ environment
+
+#include <stdio.h>
+#include <pthread.h>
+#include <stddef.h>
+#include <assert.h>
+#include <threads.h>
+
+static pthread_cond_t   global_cond   = PTHREAD_COND_INITIALIZER;
+static pthread_mutex_t  global_mutex  = PTHREAD_MUTEX_INITIALIZER;
+static pthread_rwlock_t global_rwlock = PTHREAD_RWLOCK_INITIALIZER;
+// TODO: POSIX mandates *_INITIALIZER as const initializer but not PTHREAD_ONCE_INIT
+//       But glibc and other platform support it. Ours cannot in C due to union type
+#ifdef __cplusplus
+static pthread_once_t   global_once   = PTHREAD_ONCE_INIT;
+#else
+static pthread_once_t   global_once   = {0};
+#endif
+
+static void once_callback(void) {
+    printf("once\n");
+}
+
+static thread_local int tls_counter = 100; 
+
+void* thread_func(void* args) {
+    (void)args;
+    assert(tls_counter == 100);
+    tls_counter = 200;
+    assert(tls_counter == 200);
+    return NULL;
+}
+
+int main(void) {
+    assert(pthread_mutex_lock(&global_mutex) == 0);
+    assert(pthread_mutex_unlock(&global_mutex) == 0);
+    assert(pthread_rwlock_wrlock(&global_rwlock) == 0);
+    assert(pthread_rwlock_unlock(&global_rwlock) == 0);
+    assert(pthread_once(&global_once, once_callback) == 0);
+    assert(pthread_cond_signal(&global_cond) == 0);
+
+    pthread_t thread_id;
+    int create_res = pthread_create(&thread_id, NULL, thread_func, NULL);
+    assert(create_res == 0);
+    pthread_mutex_t dynamic_mutex;
+    int mutex_res = pthread_mutex_init(&dynamic_mutex, NULL);
+    assert(mutex_res == 0);
+    assert(pthread_join(thread_id, NULL) == 0);
+    assert(tls_counter == 100);
+
+    return 0;
+}