os: add Process.finalise() and Process.free() methods to cleanup pipe descriptors

cmd/tools/vwatch.v

@@ -245,6 +245,7 @@ fn (mut context Context) compilation_runner_loop() {
 			}
 			if !context.child_process.is_alive() {
 				context.child_process.wait()
+				context.child_process.close()
 				break
 			}
 		}
@@ -315,18 +316,20 @@ fn (mut context Context) manager_main() {
 			time.sleep(200 * time.millisecond)
 		}
 		if !(worker_process.code == 255 && worker_process.status == .exited) {
+			worker_process.close()
 			break
 		}
+		worker_process.close()
 	}
 }
 
 fn (mut context Context) worker_main() {
 	context.rerun_channel = chan RerunCommand{cap: 10}
-	os.signal(C.SIGINT, fn () {
+	os.signal_opt(.int, fn (_ os.Signal) {
 		mut context := unsafe { &Context(voidptr(&ccontext)) }
 		context.is_exiting = true
 		context.kill_pgroup()
-	})
+	}) or { panic(err) }
 	go context.compilation_runner_loop()
 	change_detection_loop(context)
 }

vlib/os/process.v

@@ -5,12 +5,14 @@ module os
 // ProcessState.stopped - the process was running, but was stopped temporarily
 // ProcessState.exited - the process has finished/exited
 // ProcessState.aborted - the process was terminated by a signal
+// ProcessState.closed - the process resources like opened file descriptors were freed/discarded, final state.
 pub enum ProcessState {
 	not_started
 	running
 	stopped
 	exited
 	aborted
+	closed
 }
 
 [heap]
@@ -132,6 +134,34 @@ pub fn (mut p Process) wait() {
 	return
 }
 
+// close - free the OS resources associated with the process.
+// Can be called multiple times, but will free the resources just once.
+// This sets the process state to .closed, which is final.
+pub fn (mut p Process) close() {
+	if p.status in [.not_started, .closed] {
+		return
+	}
+	p.status = .closed
+	$if !windows {
+		for i in 0 .. 3 {
+			if p.stdio_fd[i] != 0 {
+				fd_close(p.stdio_fd[i])
+			}
+		}
+	}
+}
+
+[unsafe]
+pub fn (mut p Process) free() {
+	p.close()
+	unsafe {
+		p.filename.free()
+		p.err.free()
+		p.args.free()
+		p.env.free()
+	}
+}
+
 //
 // _spawn - should not be called directly, but only by p.run()/p.wait() .
 // It encapsulates the fork/execve mechanism that allows the

vlib/os/process_test.v

@@ -52,6 +52,7 @@ fn test_run() {
 	//
 	eprintln('polling iterations: $i')
 	assert i < 50
+	p.close()
 }
 
 fn test_wait() {
@@ -61,6 +62,7 @@ fn test_wait() {
 	assert p.status == .exited
 	assert p.code == 0
 	assert p.pid != os.getpid()
+	p.close()
 }
 
 fn test_slurping_output() {
@@ -73,6 +75,7 @@ fn test_slurping_output() {
 	assert p.code == 0
 	output := p.stdout_slurp().trim_space()
 	errors := p.stderr_slurp().trim_space()
+	p.close()
 	$if trace_process_output ? {
 		eprintln('---------------------------')
 		eprintln('p output: "$output"')