fix(pthread/tls): destructors

Also added tests for it.

Signed-off-by: Anhad Singh <andypython@protonmail.com>

tests/pthread/tls.c

@@ -0,0 +1,71 @@
+#include <assert.h>
+// PTHREAD_KEYS_MAX
+#include <limits.h>
+#include <pthread.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+pthread_key_t key_a;
+pthread_key_t key_b;
+size_t total_destructor_runs = 0;
+
+void drop_key_a(void *val_a) {
+    assert(pthread_getspecific(key_a) == NULL && val_a == (void *)0xaaaa);
+    total_destructor_runs++;
+
+    void *val_b = pthread_getspecific(key_b);
+    printf("drop_key_a(a=%p, b=%p)\n", val_a, val_b);
+
+    if (total_destructor_runs <= 2) {
+        pthread_setspecific(key_a, val_a);
+        return;
+    }
+
+    if (val_b != NULL) {
+        assert(val_b == (void *)0xbbbb);
+    } else {
+        pthread_setspecific(key_b, (void *)0xbbbb);
+    }
+}
+
+void drop_key_b(void *val_b) {
+    assert(pthread_getspecific(key_b) == NULL && val_b == (void *)0xbbbb);
+    total_destructor_runs++;
+
+    void *val_a = pthread_getspecific(key_a);
+    printf("drop_key_b(a=%p, b=%p)\n", val_a, val_b);
+
+    if (total_destructor_runs <= 2) {
+        pthread_setspecific(key_b, val_b);
+        return;
+    }
+
+    if (val_a != NULL) {
+        assert(val_a == (void *)0xaaaa);
+    } else {
+        pthread_setspecific(key_a, (void *)0xaaaa);
+    }
+}
+
+void *test_tls_destructors(void *arg) {
+    (void)arg;
+    assert(!pthread_key_create(&key_a, drop_key_a));
+    assert(!pthread_key_create(&key_b, drop_key_b));
+    assert(!pthread_setspecific(key_a, (void *)0xaaaa));
+    assert(!pthread_setspecific(key_b, (void *)0xbbbb));
+    return NULL;
+}
+
+int main(void) {
+    pthread_t t1;
+    assert(!pthread_create(&t1, NULL, test_tls_destructors, NULL));
+    assert(!pthread_join(t1, NULL));
+    printf("total_destructor_iterations: %zu\n", total_destructor_runs);
+    // There are two destructors (i.e., `drop_key_{a, b}`), so the total number
+    // of iterations will be `2 * PTHREAD_DESTRUCTOR_ITERATIONS`.
+    assert((total_destructor_runs / 2) == PTHREAD_DESTRUCTOR_ITERATIONS);
+
+    assert(pthread_getspecific(PTHREAD_KEYS_MAX) == NULL);
+    return EXIT_SUCCESS;
+}