mavlink/mavlink_shell: Move mavlink shell to its own process in NuttX…

… build

Move the mavlink shell to its own process and launch it via px4_exec.

The task is very simple and does not need anything from the MavlinkShell
class, it is defined as a static function anyway in order to be passed
as pointer-to-function to px4_task_spawn.

The shell application is now compiled as its own module, and added to
the builtin list or list of module binaries, and can / is started via
px4_exec instead.

src/modules/mavlink/CMakeLists.txt

@@ -144,6 +144,14 @@ px4_add_module(
 	UNITY_BUILD
 	)
 
+px4_add_module(
+	MODULE modules__mavlink_shell
+	MAIN mavlink_shell
+	NO_DAEMON
+	SRCS
+		mavlink_shell_main.cpp
+	)
+
 if(PX4_TESTING)
 	add_subdirectory(mavlink_tests)
 endif()

src/modules/mavlink/mavlink_shell.cpp

@@ -141,6 +141,9 @@ int MavlinkShell::start()
 #endif
 
 	if (ret == 0) {
+#ifdef __PX4_NUTTX
+		_task = px4_exec("mavlink_shell", nullptr, nullptr, 0);
+#else
 		_task = px4_task_spawn_cmd("mavlink_shell",
 					   SCHED_DEFAULT,
 					   SCHED_PRIORITY_DEFAULT,
@@ -150,6 +153,7 @@ int MavlinkShell::start()
 					   argv);
 #else
 					   nullptr);
+#endif
 #endif
 
 		if (_task < 0) {
@@ -183,12 +187,6 @@ int MavlinkShell::start()
 
 int MavlinkShell::shell_start_thread(int argc, char *argv[])
 {
-#ifdef __PX4_NUTTX
-	dup2(1, 2); //redirect stderror to stdout
-
-	nsh_consolemain(0, NULL);
-#endif /* __PX4_NUTTX */
-
 #ifdef __PX4_POSIX
 
 	if (argc != 3) {

src/modules/mavlink/mavlink_shell_main.cpp

@@ -0,0 +1,53 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2023 Technology Innovation Institute. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file mavlink_shell_main.cpp
+ * Main thread of mavlink shell
+ */
+
+#include <unistd.h>
+
+#ifdef __PX4_NUTTX
+#include <nshlib/nshlib.h>
+#endif /* __PX4_NUTTX */
+
+extern "C" __EXPORT int mavlink_shell_main(int argc, char *argv[])
+{
+#ifdef __PX4_NUTTX
+	dup2(1, 2); //redirect stderror to stdout
+
+	nsh_consolemain(0, NULL);
+#endif /* __PX4_NUTTX */
+	return 0;
+}