libc: common: support for C11 thread-specific storage

Add C11 thread-specific storage (tss) support to go with C11 threads
and mutexes.

Signed-off-by: Christopher Friedt <cfriedt@meta.com>

lib/libc/common/CMakeLists.txt

@@ -12,6 +12,7 @@ zephyr_library_sources_ifdef(CONFIG_COMMON_LIBC_THRD
     source/thrd/cnd.c
     source/thrd/mtx.c
     source/thrd/thrd.c
+    source/thrd/tss.c
     )
 
 # Prevent compiler from optimizing calloc into an infinite recursive call

lib/libc/common/include/machine/_threads.h

@@ -14,6 +14,7 @@ extern "C" {
 typedef int cnd_t;
 typedef int mtx_t;
 typedef int thrd_t;
+typedef int tss_t;
 
 #ifdef __cplusplus
 }

lib/libc/common/include/threads.h

@@ -63,6 +63,17 @@ int cnd_signal(cnd_t *cond);
 int cnd_broadcast(cnd_t *cond);
 void cnd_destroy(cnd_t *cond);
 
+#ifndef thread_local
+#define	thread_local _Thread_local
+#endif
+
+typedef void (*tss_dtor_t)(void *val);
+
+int tss_create(tss_t *key, tss_dtor_t destructor);
+void *tss_get(tss_t key);
+int tss_set(tss_t key, void *val);
+void tss_delete(tss_t key);
+
 #ifdef __cplusplus
 }
 #endif

lib/libc/common/source/thrd/tss.c

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2023, Meta
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <errno.h>
+#include <threads.h>
+
+#include <zephyr/kernel.h>
+#include <zephyr/posix/pthread.h>
+
+int tss_create(tss_t *key, tss_dtor_t destructor)
+{
+	switch (pthread_key_create(key, destructor)) {
+	case 0:
+		return thrd_success;
+	case EAGAIN:
+		return thrd_busy;
+	case ENOMEM:
+		return thrd_nomem;
+	default:
+		return thrd_error;
+	}
+}
+
+void *tss_get(tss_t key)
+{
+	return pthread_getspecific(key);
+}
+
+int tss_set(tss_t key, void *val)
+{
+	switch (pthread_setspecific(key, val)) {
+	case 0:
+		return thrd_success;
+	case ENOMEM:
+		return thrd_nomem;
+	default:
+		return thrd_error;
+	}
+}
+
+void tss_delete(tss_t key)
+{
+	(void)pthread_key_delete(key);
+}