all: change optional to result of io (#16075)

vlib/net/ftp/ftp.v

@@ -42,7 +42,7 @@ mut:
 	port   int
 }
 
-fn (mut dtp DTP) read() ?[]u8 {
+fn (mut dtp DTP) read() ![]u8 {
 	mut data := []u8{}
 	mut buf := []u8{len: 1024}
 	for {
@@ -75,15 +75,15 @@ pub fn new() FTP {
 	return f
 }
 
-fn (mut zftp FTP) write(data string) ?int {
+fn (mut zftp FTP) write(data string) !int {
 	$if debug {
 		println('FTP.v >>> $data')
 	}
 	return zftp.conn.write('$data\r\n'.bytes())
 }
 
-fn (mut zftp FTP) read() ?(int, string) {
-	mut data := zftp.reader.read_line()?
+fn (mut zftp FTP) read() !(int, string) {
+	mut data := zftp.reader.read_line()!
 	$if debug {
 		println('FTP.v <<< $data')
 	}
@@ -93,7 +93,7 @@ fn (mut zftp FTP) read() ?(int, string) {
 	code := data[..3].int()
 	if data[3] == `-` {
 		for {
-			data = zftp.reader.read_line()?
+			data = zftp.reader.read_line()!
 			if data[..3].int() == code && data[3] != `-` {
 				break
 			}
@@ -103,10 +103,10 @@ fn (mut zftp FTP) read() ?(int, string) {
 }
 
 // connect establishes an FTP connection to the host at `ip` port 21.
-pub fn (mut zftp FTP) connect(ip string) ?bool {
-	zftp.conn = net.dial_tcp('$ip:21')?
+pub fn (mut zftp FTP) connect(ip string) !bool {
+	zftp.conn = net.dial_tcp('$ip:21')!
 	zftp.reader = io.new_buffered_reader(reader: zftp.conn)
-	code, _ := zftp.read()?
+	code, _ := zftp.read()!
 	if code == ftp.connected {
 		return true
 	}
@@ -114,14 +114,14 @@ pub fn (mut zftp FTP) connect(ip string) ?bool {
 }
 
 // login sends the "USER `user`" and "PASS `passwd`" commands to the remote host.
-pub fn (mut zftp FTP) login(user string, passwd string) ?bool {
+pub fn (mut zftp FTP) login(user string, passwd string) !bool {
 	zftp.write('USER $user') or {
 		$if debug {
 			println('ERROR sending user')
 		}
 		return false
 	}
-	mut code, _ := zftp.read()?
+	mut code, _ := zftp.read()!
 	if code == ftp.logged_in {
 		return true
 	}
@@ -134,7 +134,7 @@ pub fn (mut zftp FTP) login(user string, passwd string) ?bool {
 		}
 		return false
 	}
-	code, _ = zftp.read()?
+	code, _ = zftp.read()!
 	if code == ftp.logged_in {
 		return true
 	}
@@ -142,15 +142,15 @@ pub fn (mut zftp FTP) login(user string, passwd string) ?bool {
 }
 
 // close closes the FTP connection.
-pub fn (mut zftp FTP) close() ? {
-	zftp.write('QUIT')?
-	zftp.conn.close()?
+pub fn (mut zftp FTP) close() ! {
+	zftp.write('QUIT')!
+	zftp.conn.close()!
 }
 
 // pwd returns the current working directory on the remote host for the logged in user.
-pub fn (mut zftp FTP) pwd() ?string {
-	zftp.write('PWD')?
-	_, data := zftp.read()?
+pub fn (mut zftp FTP) pwd() !string {
+	zftp.write('PWD')!
+	_, data := zftp.read()!
 	spl := data.split('"') // "
 	if spl.len >= 2 {
 		return spl[1]
@@ -159,9 +159,9 @@ pub fn (mut zftp FTP) pwd() ?string {
 }
 
 // cd changes the current working directory to the specified remote directory `dir`.
-pub fn (mut zftp FTP) cd(dir string) ? {
+pub fn (mut zftp FTP) cd(dir string) ! {
 	zftp.write('CWD $dir') or { return }
-	mut code, mut data := zftp.read()?
+	mut code, mut data := zftp.read()!
 	match int(code) {
 		ftp.denied {
 			$if debug {
@@ -169,7 +169,7 @@ pub fn (mut zftp FTP) cd(dir string) ? {
 			}
 		}
 		ftp.complete {
-			code, data = zftp.read()?
+			code, data = zftp.read()!
 		}
 		else {}
 	}
@@ -178,7 +178,7 @@ pub fn (mut zftp FTP) cd(dir string) ? {
 	}
 }
 
-fn new_dtp(msg string) ?&DTP {
+fn new_dtp(msg string) !&DTP {
 	if !is_dtp_message_valid(msg) {
 		return error('Bad message')
 	}
@@ -194,32 +194,32 @@ fn new_dtp(msg string) ?&DTP {
 	return dtp
 }
 
-fn (mut zftp FTP) pasv() ?&DTP {
-	zftp.write('PASV')?
-	code, data := zftp.read()?
+fn (mut zftp FTP) pasv() !&DTP {
+	zftp.write('PASV')!
+	code, data := zftp.read()!
 	$if debug {
 		println('pass: $data')
 	}
 	if code != ftp.passive_mode {
 		return error('pasive mode not allowed')
 	}
-	dtp := new_dtp(data)?
+	dtp := new_dtp(data)!
 	return dtp
 }
 
 // dir returns a list of the files in the current working directory.
-pub fn (mut zftp FTP) dir() ?[]string {
+pub fn (mut zftp FTP) dir() ![]string {
 	mut dtp := zftp.pasv() or { return error('Cannot establish data connection') }
-	zftp.write('LIST')?
-	code, _ := zftp.read()?
+	zftp.write('LIST')!
+	code, _ := zftp.read()!
 	if code == ftp.denied {
 		return error('`LIST` denied')
 	}
 	if code != ftp.open_data_connection {
 		return error('Data channel empty')
 	}
-	list_dir := dtp.read()?
-	result, _ := zftp.read()?
+	list_dir := dtp.read()!
+	result, _ := zftp.read()!
 	if result != ftp.close_data_connection {
 		println('`LIST` not ok')
 	}
@@ -235,17 +235,17 @@ pub fn (mut zftp FTP) dir() ?[]string {
 }
 
 // get retrieves `file` from the remote host.
-pub fn (mut zftp FTP) get(file string) ?[]u8 {
+pub fn (mut zftp FTP) get(file string) ![]u8 {
 	mut dtp := zftp.pasv() or { return error('Cannot stablish data connection') }
-	zftp.write('RETR $file')?
-	code, _ := zftp.read()?
+	zftp.write('RETR $file')!
+	code, _ := zftp.read()!
 	if code == ftp.denied {
 		return error('Permission denied')
 	}
 	if code != ftp.open_data_connection {
 		return error('Data connection not ready')
 	}
-	blob := dtp.read()?
+	blob := dtp.read()!
 	dtp.close()
 	return blob
 }