libc: common: add support for iso c11 threads

This change capitalizes on newly added support for dynamic
thread stacks and the existing pthread support to provide
an implementation of the ISO C11 `<threads.h>` API.

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

include/zephyr/posix/sys/stat.h

@@ -114,7 +114,7 @@ struct stat {
 #define st_mtime st_mtim.tv_sec
 #define st_ctime st_ctim.tv_sec
 #if defined(__linux) && defined(__x86_64__)
-	__uint64_t __glibc_reserved[3];
+	uint64_t __glibc_reserved[3];
 #endif
 #else
 #if defined(__rtems__)

lib/libc/common/CMakeLists.txt

@@ -1,11 +1,14 @@
 # SPDX-License-Identifier: Apache-2.0
 
+zephyr_system_include_directories(include)
+
 zephyr_library()
 zephyr_library_property(ALLOW_EMPTY TRUE)
 zephyr_library_sources_ifdef(CONFIG_COMMON_LIBC_ABORT source/stdlib/abort.c)
 zephyr_library_sources_ifdef(CONFIG_COMMON_LIBC_TIME source/time/time.c)
 zephyr_library_sources_ifdef(CONFIG_COMMON_LIBC_MALLOC source/stdlib/malloc.c)
 zephyr_library_sources_ifdef(CONFIG_COMMON_LIBC_STRNLEN source/string/strnlen.c)
+zephyr_library_sources_ifdef(CONFIG_COMMON_LIBC_THRD source/thrd/thrd.c)
 
 # Prevent compiler from optimizing calloc into an infinite recursive call
 zephyr_library_compile_options($<TARGET_PROPERTY:compiler,no_builtin_malloc>)

lib/libc/common/Kconfig

@@ -67,3 +67,13 @@ config COMMON_LIBC_STRNLEN
 	bool
 	help
 	  common implementation of strnlen().
+
+config COMMON_LIBC_THRD
+	bool "C11 <threads.h> API support"
+	depends on DYNAMIC_THREAD
+	# Note: the POSIX_API dependency is only necessary until common elements
+	# of C11 threads and POSIX API can be abstracted out to a common library.
+	depends on POSIX_API
+	default y
+	help
+	  Common implementation of C11 <threads.h> API.

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

@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2023, Meta
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_LIB_LIBC_COMMON_INCLUDE_MACHINE__THREADS_H_
+#define ZEPHYR_LIB_LIBC_COMMON_INCLUDE_MACHINE__THREADS_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef int thrd_t;
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ZEPHYR_LIB_LIBC_COMMON_INCLUDE_MACHINE__THREADS_H_ */

lib/libc/common/include/threads.h

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2023, Meta
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_LIB_LIBC_COMMON_INCLUDE_THREADS_H_
+#define ZEPHYR_LIB_LIBC_COMMON_INCLUDE_THREADS_H_
+
+#include <time.h>
+
+#include <machine/_threads.h>
+#include <zephyr/toolchain.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef int (*thrd_start_t)(void *arg);
+
+enum {
+	thrd_success,
+#define thrd_success thrd_success
+	thrd_nomem,
+#define thrd_nomem thrd_nomem
+	thrd_timedout,
+#define thrd_timedout thrd_timedout
+	thrd_busy,
+#define thrd_busy thrd_busy
+	thrd_error,
+#define thrd_error thrd_error
+};
+
+int thrd_create(thrd_t *thr, thrd_start_t func, void *arg);
+int thrd_equal(thrd_t lhs, thrd_t rhs);
+thrd_t thrd_current(void);
+int thrd_sleep(const struct timespec *duration, struct timespec *remaining);
+void thrd_yield(void);
+_Noreturn void thrd_exit(int res);
+int thrd_detach(thrd_t thr);
+int thrd_join(thrd_t thr, int *res);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ZEPHYR_LIB_LIBC_COMMON_INCLUDE_THREADS_H_ */

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

@@ -0,0 +1,85 @@
+/*
+ * 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>
+#include <zephyr/posix/sched.h>
+
+struct thrd_trampoline_arg {
+	thrd_start_t func;
+	void *arg;
+};
+
+int thrd_create(thrd_t *thr, thrd_start_t func, void *arg)
+{
+	typedef void *(*pthread_func_t)(void *arg);
+
+	pthread_func_t pfunc = (pthread_func_t)func;
+
+	switch (pthread_create(thr, NULL, pfunc, arg)) {
+	case 0:
+		return thrd_success;
+	case EAGAIN:
+		return thrd_nomem;
+	default:
+		return thrd_error;
+	}
+}
+
+int thrd_equal(thrd_t lhs, thrd_t rhs)
+{
+	return pthread_equal(lhs, rhs);
+}
+
+thrd_t thrd_current(void)
+{
+	return pthread_self();
+}
+
+int thrd_sleep(const struct timespec *duration, struct timespec *remaining)
+{
+	return nanosleep(duration, remaining);
+}
+
+void thrd_yield(void)
+{
+	(void)sched_yield();
+}
+
+FUNC_NORETURN void thrd_exit(int res)
+{
+	pthread_exit(INT_TO_POINTER(res));
+
+	CODE_UNREACHABLE;
+}
+
+int thrd_detach(thrd_t thr)
+{
+	switch (pthread_detach(thr)) {
+	case 0:
+		return thrd_success;
+	default:
+		return thrd_error;
+	}
+}
+
+int thrd_join(thrd_t thr, int *res)
+{
+	void *ret;
+
+	switch (pthread_join(thr, &ret)) {
+	case 0:
+		if (res != NULL) {
+			*res = POINTER_TO_INT(ret);
+		}
+		return thrd_success;
+	default:
+		return thrd_error;
+	}
+}