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.

12 files changed, 56 insertions, 0 deletions

diff --git a/core/core_bind.cpp b/core/core_bind.cpp
index 0f0b8ed63f..7c3cbfe48d 100644
--- a/core/core_bind.cpp
+++ b/core/core_bind.cpp
@@ -269,6 +269,10 @@ 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();
 }
@@ -571,6 +575,7 @@ void OS::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("create_instance", "arguments"), &OS::create_instance);
 	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);
diff --git a/core/core_bind.h b/core/core_bind.h
index f6f2791006..76313dc1a8 100644
--- a/core/core_bind.h
+++ b/core/core_bind.h
@@ -173,6 +173,7 @@ 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;
diff --git a/core/os/os.h b/core/os/os.h
index a7cf3f1679..5eac77d634 100644
--- a/core/os/os.h
+++ b/core/os/os.h
@@ -152,6 +152,7 @@ public:
 	virtual Error create_instance(const List<String> &p_arguments, ProcessID *r_child_id = nullptr) { return create_process(get_executable_path(), p_arguments, r_child_id); };
 	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);
diff --git a/doc/classes/OS.xml b/doc/classes/OS.xml
index f45bee4db4..266a2573de 100644
--- a/doc/classes/OS.xml
+++ b/doc/classes/OS.xml
@@ -434,6 +434,15 @@
 				Returns [code]true[/code] if the input keycode corresponds to a Unicode character.
 			</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 create_process].
+				[b]Note:[/b] This method is implemented on Android, iOS, Linux, macOS and Windows.
+			</description>
+		</method>
 		<method name="is_stdout_verbose" qualifiers="const">
 			<return type="bool" />
 			<description>
diff --git a/drivers/unix/os_unix.cpp b/drivers/unix/os_unix.cpp
index 12e2113364..52a4d538e1 100644
--- a/drivers/unix/os_unix.cpp
+++ b/drivers/unix/os_unix.cpp
@@ -412,6 +412,15 @@ 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;
 }
diff --git a/drivers/unix/os_unix.h b/drivers/unix/os_unix.h
index 6116574528..a1ed4bd501 100644
--- a/drivers/unix/os_unix.h
+++ b/drivers/unix/os_unix.h
@@ -76,6 +76,7 @@ public:
 	virtual Error create_process(const String &p_path, const List<String> &p_arguments, ProcessID *r_child_id = nullptr, bool p_open_console = false) override;
 	virtual Error kill(const ProcessID &p_pid) override;
 	virtual int get_process_id() const override;
+	virtual bool is_process_running(const ProcessID &p_pid) const override;
 
 	virtual bool has_environment(const String &p_var) const override;
 	virtual String get_environment(const String &p_var) const override;
diff --git a/platform/javascript/os_javascript.cpp b/platform/javascript/os_javascript.cpp
index 79c2b2fefb..1686353229 100644
--- a/platform/javascript/os_javascript.cpp
+++ b/platform/javascript/os_javascript.cpp
@@ -131,6 +131,10 @@ 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();
 }
diff --git a/platform/javascript/os_javascript.h b/platform/javascript/os_javascript.h
index 09497ebc5d..0c672111cc 100644
--- a/platform/javascript/os_javascript.h
+++ b/platform/javascript/os_javascript.h
@@ -79,6 +79,7 @@ public:
 	Error create_process(const String &p_path, const List<String> &p_arguments, ProcessID *r_child_id = nullptr, bool p_open_console = false) override;
 	Error kill(const ProcessID &p_pid) override;
 	int get_process_id() const override;
+	bool is_process_running(const ProcessID &p_pid) const override;
 	int get_processor_count() const override;
 	int get_default_thread_pool_size() const override { return 1; }
 
diff --git a/platform/uwp/os_uwp.cpp b/platform/uwp/os_uwp.cpp
index f002e47f2d..1614bfdcc3 100644
--- a/platform/uwp/os_uwp.cpp
+++ b/platform/uwp/os_uwp.cpp
@@ -647,6 +647,10 @@ 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;
 }
diff --git a/platform/uwp/os_uwp.h b/platform/uwp/os_uwp.h
index bde65257be..bddf63ff18 100644
--- a/platform/uwp/os_uwp.h
+++ b/platform/uwp/os_uwp.h
@@ -198,6 +198,7 @@ public:
 	virtual Error execute(const String &p_path, const List<String> &p_arguments, String *r_pipe = nullptr, int *r_exitcode = nullptr, bool read_stderr = false, Mutex *p_pipe_mutex = nullptr, bool p_open_console = false);
 	virtual Error create_process(const String &p_path, const List<String> &p_arguments, ProcessID *r_child_id = nullptr, 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;
diff --git a/platform/windows/os_windows.cpp b/platform/windows/os_windows.cpp
index 6b4e455197..d43ab47004 100644
--- a/platform/windows/os_windows.cpp
+++ b/platform/windows/os_windows.cpp
@@ -517,6 +517,25 @@ 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((LPCWSTR)(p_cwd.utf16().get_data())) != 0) {
 		return ERR_CANT_OPEN;
diff --git a/platform/windows/os_windows.h b/platform/windows/os_windows.h
index 81cc7c3fc1..378438a075 100644
--- a/platform/windows/os_windows.h
+++ b/platform/windows/os_windows.h
@@ -132,6 +132,7 @@ public:
 	virtual Error create_process(const String &p_path, const List<String> &p_arguments, ProcessID *r_child_id = nullptr, bool p_open_console = false) override;
 	virtual Error kill(const ProcessID &p_pid) override;
 	virtual int get_process_id() const override;
+	virtual bool is_process_running(const ProcessID &p_pid) const override;
 
 	virtual bool has_environment(const String &p_var) const override;
 	virtual String get_environment(const String &p_var) const override;