drivers: net: nsos: add F_GETFL and F_SETFL support

This allows to use Zephyr TLS subsystem with Native Sim offloaded sockets.

Signed-off-by: Marcin Niestroj <m.niestroj@emb.dev>

drivers/net/CMakeLists.txt

@@ -15,9 +15,11 @@ if(CONFIG_NET_NATIVE_OFFLOADED_SOCKETS)
     ${ZEPHYR_BASE}/subsys/net/lib/sockets
   )
   zephyr_library_sources(nsos_errno.c)
+  zephyr_library_sources(nsos_fcntl.c)
   zephyr_library_sources(nsos_netdb.c)
   zephyr_library_sources(nsos_sockets.c)
   target_sources(native_simulator INTERFACE nsos_adapt.c)
   target_sources(native_simulator INTERFACE nsos_errno.c)
+  target_sources(native_simulator INTERFACE nsos_fcntl.c)
   target_sources(native_simulator INTERFACE nsos_netdb.c)
 endif()

drivers/net/nsos.h

@@ -110,6 +110,9 @@ int nsos_adapt_recvfrom(int fd, void *buf, size_t len, int flags,
 			struct nsos_mid_sockaddr *addr, size_t *addrlen);
 
 
+int nsos_adapt_fcntl_getfl(int fd);
+int nsos_adapt_fcntl_setfl(int fd, int flags);
+
 int nsos_adapt_getaddrinfo(const char *node, const char *service,
 			   const struct nsos_mid_addrinfo *hints,
 			   struct nsos_mid_addrinfo **res,

drivers/net/nsos_adapt.c

@@ -11,6 +11,7 @@
  */
 
 #include <errno.h>
+#include <fcntl.h>
 #include <netdb.h>
 #include <netinet/in.h>
 #include <poll.h>
@@ -21,6 +22,7 @@
 
 #include "nsos.h"
 #include "nsos_errno.h"
+#include "nsos_fcntl.h"
 #include "nsos_netdb.h"
 
 #include "nsi_tracing.h"
@@ -596,3 +598,24 @@ void nsos_adapt_freeaddrinfo(struct nsos_mid_addrinfo *res_mid)
 	freeaddrinfo(wrap->addrinfo);
 	free(wrap);
 }
+
+int nsos_adapt_fcntl_getfl(int fd)
+{
+	int flags;
+
+	flags = fcntl(fd, F_GETFL);
+
+	return fl_to_nsos_mid(flags);
+}
+
+int nsos_adapt_fcntl_setfl(int fd, int flags)
+{
+	int ret;
+
+	ret = fcntl(fd, F_SETFL, fl_from_nsos_mid(flags));
+	if (ret < 0) {
+		return -errno_to_nsos_mid(errno);
+	}
+
+	return 0;
+}

drivers/net/nsos_fcntl.c

@@ -0,0 +1,84 @@
+/**
+ * Copyright (c) 2023-2024 Marcin Niestroj
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * @file
+ *
+ * fcntl.h related code common to Zephyr (top: nsos_sockets.c) and Linux
+ * (bottom: nsos_adapt.c).
+ *
+ * It is needed by both sides to share the same macro definitions/values
+ * (prefixed with NSOS_MID_), which is not possible to achieve with two separate
+ * standard libc libraries, since they use different values for the same
+ * symbols.
+ */
+
+#include <fcntl.h>
+
+#include "nsos_errno.h"
+#include "nsos_fcntl.h"
+
+#include <stdbool.h>
+
+static int fl_to_nsos_mid_(int flags, bool strict)
+{
+	int flags_mid = 0;
+
+#define TO_NSOS_MID(_flag)				\
+	if (flags & (_flag)) {				\
+		flags &= ~(_flag);			\
+		flags_mid |= NSOS_MID_ ## _flag;	\
+	}
+
+	TO_NSOS_MID(O_RDONLY);
+	TO_NSOS_MID(O_WRONLY);
+	TO_NSOS_MID(O_RDWR);
+
+	TO_NSOS_MID(O_APPEND);
+	TO_NSOS_MID(O_EXCL);
+	TO_NSOS_MID(O_NONBLOCK);
+
+#undef TO_NSOS_MID
+
+	if (strict && flags != 0) {
+		return -NSOS_MID_EINVAL;
+	}
+
+	return flags_mid;
+}
+
+int fl_to_nsos_mid(int flags)
+{
+	return fl_to_nsos_mid_(flags, false);
+}
+
+int fl_to_nsos_mid_strict(int flags)
+{
+	return fl_to_nsos_mid_(flags, true);
+}
+
+int fl_from_nsos_mid(int flags_mid)
+{
+	int flags = 0;
+
+#define FROM_NSOS_MID(_flag)				\
+	if (flags_mid & NSOS_MID_ ## _flag) {		\
+		flags_mid &= ~NSOS_MID_ ## _flag;	\
+		flags |= _flag;				\
+	}
+
+	FROM_NSOS_MID(O_RDONLY);
+	FROM_NSOS_MID(O_WRONLY);
+	FROM_NSOS_MID(O_RDWR);
+
+	FROM_NSOS_MID(O_APPEND);
+	FROM_NSOS_MID(O_EXCL);
+	FROM_NSOS_MID(O_NONBLOCK);
+
+#undef FROM_NSOS_MID
+
+	return flags;
+}

drivers/net/nsos_fcntl.h

@@ -0,0 +1,22 @@
+/**
+ * Copyright (c) 2023-2024 Marcin Niestroj
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef __DRIVERS_NET_NSOS_FCNTL_H__
+#define __DRIVERS_NET_NSOS_FCNTL_H__
+
+#define NSOS_MID_O_RDONLY	00
+#define NSOS_MID_O_WRONLY	01
+#define NSOS_MID_O_RDWR		02
+
+#define NSOS_MID_O_APPEND	0x0400
+#define NSOS_MID_O_EXCL		0x0800
+#define NSOS_MID_O_NONBLOCK	0x4000
+
+int fl_to_nsos_mid(int flags);
+int fl_to_nsos_mid_strict(int flags);
+int fl_from_nsos_mid(int flags);
+
+#endif /* __DRIVERS_NET_NSOS_FCNTL_H__ */

drivers/net/nsos_sockets.c

@@ -18,11 +18,13 @@
 #include <zephyr/net/net_ip.h>
 #include <zephyr/net/offloaded_netdev.h>
 #include <zephyr/net/socket_offload.h>
+#include <zephyr/posix/fcntl.h>
 #include <zephyr/sys/fdtable.h>
 
 #include "sockets_internal.h"
 #include "nsos.h"
 #include "nsos_errno.h"
+#include "nsos_fcntl.h"
 #include "nsos_netdb.h"
 
 #include "nsi_host_trampolines.h"
@@ -227,6 +229,28 @@ static int nsos_ioctl(void *obj, unsigned int request, va_list args)
 
 	case ZFD_IOCTL_POLL_OFFLOAD:
 		return -EOPNOTSUPP;
+
+	case F_GETFL: {
+		int flags;
+
+		flags = nsos_adapt_fcntl_getfl(OBJ_TO_FD(obj));
+
+		return fl_from_nsos_mid(flags);
+	}
+
+	case F_SETFL: {
+		int flags = va_arg(args, int);
+		int ret;
+
+		ret = fl_to_nsos_mid_strict(flags);
+		if (ret < 0) {
+			return -errno_from_nsos_mid(-ret);
+		}
+
+		ret = nsos_adapt_fcntl_setfl(OBJ_TO_FD(obj), flags);
+
+		return -errno_from_nsos_mid(-ret);
+	}
 	}
 
 	return -EINVAL;