Added an exit code to the blocking mode of OS::execute

Updated documentation accordingly.

Fixes #31881.

core/bind/core_bind.cpp

@@ -481,15 +481,18 @@ Error _OS::shell_open(String p_uri) {
 int _OS::execute(const String &p_path, const Vector<String> &p_arguments, bool p_blocking, Array p_output, bool p_read_stderr) {
 
 	OS::ProcessID pid = -2;
+	int exitcode = 0;
 	List<String> args;
 	for (int i = 0; i < p_arguments.size(); i++)
 		args.push_back(p_arguments[i]);
 	String pipe;
-	Error err = OS::get_singleton()->execute(p_path, args, p_blocking, &pid, &pipe, NULL, p_read_stderr);
+	Error err = OS::get_singleton()->execute(p_path, args, p_blocking, &pid, &pipe, &exitcode, p_read_stderr);
 	p_output.clear();
 	p_output.push_back(pipe);
 	if (err != OK)
 		return -1;
+	else if (p_blocking)
+		return exitcode;
 	else
 		return pid;
 }

doc/classes/OS.xml

@@ -105,11 +105,11 @@
 				This method has slightly different behavior based on whether the [code]blocking[/code] mode is enabled.
 				If [code]blocking[/code] is [code]true[/code], the Godot thread will pause its execution while waiting for the process to terminate. The shell output of the process will be written to the [code]output[/code] array as a single string. When the process terminates, the Godot thread will resume execution.
 				If [code]blocking[/code] is [code]false[/code], the Godot thread will continue while the new process runs. It is not possible to retrieve the shell output in non-blocking mode, so [code]output[/code] will be empty.
-				The return value also depends on the blocking mode. When blocking, the method will return -2 (no process ID information is available in blocking mode). When non-blocking, the method returns a process ID, which you can use to monitor the process (and potentially terminate it with [method kill]). If the process forking (non-blocking) or opening (blocking) fails, the method will return [code]-1[/code].
+				The return value also depends on the blocking mode. When blocking, the method will return an exit code of the process. When non-blocking, the method returns a process ID, which you can use to monitor the process (and potentially terminate it with [method kill]). If the process forking (non-blocking) or opening (blocking) fails, the method will return [code]-1[/code] or another exit code.
 				Example of blocking mode and retrieving the shell output:
 				[codeblock]
 				var output = []
-				OS.execute("ls", ["-l", "/tmp"], true, output)
+				var exit_code = OS.execute("ls", ["-l", "/tmp"], true, output)
 				[/codeblock]
 				Example of non-blocking mode, running another instance of the project and storing its process ID:
 				[codeblock]

drivers/unix/os_unix.cpp

@@ -314,7 +314,7 @@ Error OS_Unix::execute(const String &p_path, const List<String> &p_arguments, bo
 		}
 		int rv = pclose(f);
 		if (r_exitcode)
-			*r_exitcode = rv;
+			*r_exitcode = WEXITSTATUS(rv);
 
 		return OK;
 	}