Add OS::is_process_running function.

Adds the is_process_running function to the native OS class and exposes it to script.

This is implemented on Windows and Unix platforms. A stub is provided for other platforms that do not support this function.

Documentation is updated to reflect new API function.

(cherry picked from commit f3c1232c5984a540c33841694469febbe951e7a8)

core/bind/core_bind.cpp

@@ -508,6 +508,10 @@ Error _OS::kill(int p_pid) {
 	return OS::get_singleton()->kill(p_pid);
 }
 
+bool _OS::is_process_running(int p_pid) const {
+	return OS::get_singleton()->is_process_running(p_pid);
+}
+
 int _OS::get_process_id() const {
 	return OS::get_singleton()->get_process_id();
 };
@@ -1343,6 +1347,7 @@ void _OS::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("execute", "path", "arguments", "blocking", "output", "read_stderr", "open_console"), &_OS::execute, DEFVAL(true), DEFVAL(Array()), DEFVAL(false), DEFVAL(false));
 	ClassDB::bind_method(D_METHOD("kill", "pid"), &_OS::kill);
 	ClassDB::bind_method(D_METHOD("shell_open", "uri"), &_OS::shell_open);
+	ClassDB::bind_method(D_METHOD("is_process_running", "pid"), &_OS::is_process_running);
 	ClassDB::bind_method(D_METHOD("get_process_id"), &_OS::get_process_id);
 
 	ClassDB::bind_method(D_METHOD("get_environment", "variable"), &_OS::get_environment);

core/bind/core_bind.h

@@ -249,6 +249,7 @@ public:
 	Error kill(int p_pid);
 	Error shell_open(String p_uri);
 
+	bool is_process_running(int p_pid) const;
 	int get_process_id() const;
 
 	bool has_environment(const String &p_var) const;

core/os/os.h

@@ -324,6 +324,7 @@ public:
 	virtual Error execute(const String &p_path, const List<String> &p_arguments, bool p_blocking = true, ProcessID *r_child_id = nullptr, String *r_pipe = nullptr, int *r_exitcode = nullptr, bool read_stderr = false, Mutex *p_pipe_mutex = nullptr, bool p_open_console = false) = 0;
 	virtual Error kill(const ProcessID &p_pid) = 0;
 	virtual int get_process_id() const;
+	virtual bool is_process_running(const ProcessID &p_pid) const = 0;
 	virtual void vibrate_handheld(int p_duration_ms = 500);
 
 	virtual Error shell_open(String p_uri);

doc/classes/OS.xml

@@ -686,6 +686,15 @@
 				Returns [code]true[/code] if the [b]OK[/b] button should appear on the left and [b]Cancel[/b] on the right.
 			</description>
 		</method>
+		<method name="is_process_running" qualifiers="const">
+			<return type="bool" />
+			<argument index="0" name="pid" type="int" />
+			<description>
+				Returns [code]true[/code] if the child process ID ([code]pid[/code]) is still running or [code]false[/code] if it has terminated.
+				Must be a valid ID generated from [method execute].
+				[b]Note:[/b] This method is implemented on Android, iOS, Linux, macOS and Windows.
+			</description>
+		</method>
 		<method name="is_scancode_unicode" qualifiers="const">
 			<return type="bool" />
 			<argument index="0" name="code" type="int" />

drivers/unix/os_unix.cpp

@@ -363,6 +363,15 @@ int OS_Unix::get_process_id() const {
 	return getpid();
 };
 
+bool OS_Unix::is_process_running(const ProcessID &p_pid) const {
+	int status = 0;
+	if (waitpid(p_pid, &status, WNOHANG) != 0) {
+		return false;
+	}
+
+	return true;
+}
+
 bool OS_Unix::has_environment(const String &p_var) const {
 	return getenv(p_var.utf8().get_data()) != nullptr;
 }

drivers/unix/os_unix.h

@@ -87,6 +87,7 @@ public:
 	virtual Error execute(const String &p_path, const List<String> &p_arguments, bool p_blocking = true, ProcessID *r_child_id = nullptr, String *r_pipe = nullptr, int *r_exitcode = nullptr, bool read_stderr = false, Mutex *p_pipe_mutex = nullptr, bool p_open_console = false);
 	virtual Error kill(const ProcessID &p_pid);
 	virtual int get_process_id() const;
+	virtual bool is_process_running(const ProcessID &p_pid) const;
 
 	virtual bool has_environment(const String &p_var) const;
 	virtual String get_environment(const String &p_var) const;

platform/javascript/os_javascript.cpp

@@ -901,6 +901,10 @@ int OS_JavaScript::get_process_id() const {
 	ERR_FAIL_V_MSG(0, "OS::get_process_id() is not available on the HTML5 platform.");
 }
 
+bool OS_JavaScript::is_process_running(const ProcessID &p_pid) const {
+	return false;
+}
+
 int OS_JavaScript::get_processor_count() const {
 	return godot_js_os_hw_concurrency_get();
 }

platform/javascript/os_javascript.h

@@ -175,6 +175,7 @@ public:
 	virtual Error execute(const String &p_path, const List<String> &p_arguments, bool p_blocking = true, ProcessID *r_child_id = NULL, String *r_pipe = NULL, int *r_exitcode = NULL, bool read_stderr = false, Mutex *p_pipe_mutex = NULL, bool p_open_console = false);
 	virtual Error kill(const ProcessID &p_pid);
 	virtual int get_process_id() const;
+	bool is_process_running(const ProcessID &p_pid) const;
 	int get_processor_count() const;
 
 	virtual void alert(const String &p_alert, const String &p_title = "ALERT!");

platform/uwp/os_uwp.cpp

@@ -673,6 +673,10 @@ Error OS_UWP::kill(const ProcessID &p_pid) {
 	return FAILED;
 };
 
+bool OS_UWP::is_process_running(const ProcessID &p_pid) const {
+	return false;
+}
+
 Error OS_UWP::set_cwd(const String &p_cwd) {
 	return FAILED;
 }

platform/uwp/os_uwp.h

@@ -202,6 +202,7 @@ public:
 
 	virtual Error execute(const String &p_path, const List<String> &p_arguments, bool p_blocking = true, ProcessID *r_child_id = NULL, String *r_pipe = NULL, int *r_exitcode = NULL, bool read_stderr = false, Mutex *p_pipe_mutex = NULL, bool p_open_console = false);
 	virtual Error kill(const ProcessID &p_pid);
+	virtual bool is_process_running(const ProcessID &p_pid) const;
 
 	virtual bool has_environment(const String &p_var) const;
 	virtual String get_environment(const String &p_var) const;

platform/windows/os_windows.cpp

@@ -2913,6 +2913,25 @@ int OS_Windows::get_process_id() const {
 	return _getpid();
 }
 
+bool OS_Windows::is_process_running(const ProcessID &p_pid) const {
+	if (!process_map->has(p_pid)) {
+		return false;
+	}
+
+	const PROCESS_INFORMATION &pi = (*process_map)[p_pid].pi;
+
+	DWORD dw_exit_code = 0;
+	if (!GetExitCodeProcess(pi.hProcess, &dw_exit_code)) {
+		return false;
+	}
+
+	if (dw_exit_code != STILL_ACTIVE) {
+		return false;
+	}
+
+	return true;
+}
+
 Error OS_Windows::set_cwd(const String &p_cwd) {
 	if (_wchdir(p_cwd.c_str()) != 0)
 		return ERR_CANT_OPEN;

platform/windows/os_windows.h

@@ -502,6 +502,7 @@ public:
 	virtual Error execute(const String &p_path, const List<String> &p_arguments, bool p_blocking = true, ProcessID *r_child_id = NULL, String *r_pipe = NULL, int *r_exitcode = NULL, bool read_stderr = false, Mutex *p_pipe_mutex = NULL, bool p_open_console = false);
 	virtual Error kill(const ProcessID &p_pid);
 	virtual int get_process_id() const;
+	virtual bool is_process_running(const ProcessID &p_pid) const;
 
 	virtual bool has_environment(const String &p_var) const;
 	virtual String get_environment(const String &p_var) const;