cross: add terminal cursor position report

userspace/lib/cross/src/term.rs

@@ -192,6 +192,55 @@ impl TerminalInput {
         self.parse_utf8_from_buffer()
     }
 
+    pub fn read_cursor_position_report(&mut self) -> io::Result<Option<(u32, u32)>> {
+        #[derive(Clone, Copy)]
+        enum State {
+            ReadRow,
+            ReadColumn,
+        }
+
+        // CSI r ; c R
+        let mut ch_buffer = [0];
+
+        let mut state = State::ReadRow;
+        let mut row = 0;
+        let mut column = 0;
+
+        self.stdin.read_exact(&mut ch_buffer)?;
+        if ch_buffer[0] != b'\x1B' {
+            return Ok(None);
+        }
+        self.stdin.read_exact(&mut ch_buffer)?;
+        if ch_buffer[0] != b'[' {
+            return Ok(None);
+        }
+
+        loop {
+            self.stdin.read_exact(&mut ch_buffer)?;
+            let ch = ch_buffer[0];
+
+            match (state, ch) {
+                (State::ReadRow, b';') => {
+                    state = State::ReadColumn;
+                }
+                (State::ReadRow, b'0'..=b'9') => {
+                    row *= 10;
+                    row += (ch - b'0') as u32;
+                }
+                (State::ReadColumn, b'R') => {
+                    return Ok(Some((row, column)));
+                }
+                (State::ReadColumn, b'0'..=b'9') => {
+                    column *= 10;
+                    column += (ch - b'0') as u32;
+                }
+                (_, _) => {
+                    return Ok(None);
+                }
+            }
+        }
+    }
+
     pub fn read_key(&mut self) -> io::Result<TermKey> {
         while self.buffer_len < self.buffer.len() {
             if let Some(key) = self.parse_from_buffer() {

userspace/lib/libterm/src/lib.rs

@@ -28,6 +28,7 @@ pub trait RawTerminal {
     fn raw_leave_alternate_mode(&mut self) -> io::Result<()>;
     fn raw_clear_all(&mut self) -> io::Result<()>;
     fn raw_clear_line(&mut self, what: u32) -> io::Result<()>;
+    fn raw_report_cursor_position(&mut self) -> io::Result<()>;
     fn raw_move_cursor(&mut self, row: usize, column: usize) -> io::Result<()>;
     fn raw_set_cursor_style(&mut self, style: CursorStyle) -> io::Result<()>;
     fn raw_set_color(&mut self, fgbg: u32, color: Color) -> io::Result<()>;
@@ -84,6 +85,10 @@ impl RawTerminal for Stdout {
         write!(self, "\x1B[{}K", what)
     }
 
+    fn raw_report_cursor_position(&mut self) -> io::Result<()> {
+        write!(self, "\x1B[6n")
+    }
+
     fn raw_move_cursor(&mut self, row: usize, column: usize) -> io::Result<()> {
         write!(self, "\x1B[{};{}f", row + 1, column + 1)
     }
@@ -140,9 +145,16 @@ impl Term {
         Ok(Self { stdin, stdout })
     }
 
+    pub fn report_cursor_position(&mut self) -> io::Result<Option<(u32, u32)>> {
+        self.stdout.raw_report_cursor_position()?;
+        self.stdout.flush()?;
+        self.stdin.read_cursor_position_report()
+    }
+
     pub fn set_cursor_position(&mut self, row: usize, column: usize) -> io::Result<()> {
         self.stdout.raw_move_cursor(row, column)
     }
+
     pub fn set_cursor_visible(&mut self, visible: bool) -> io::Result<()> {
         #[cfg(unix)]
         {

userspace/sysutils/src/tst.rs

@@ -13,6 +13,9 @@ fn main() {
             term.set_cursor_position(i, 0).ok();
             write!(term, "{key:?}").ok();
         }
+        let (row, column) = term.report_cursor_position().unwrap().unwrap();
+        term.set_cursor_position(25, 0).ok();
+        write!(term, "row = {row}, column = {column}").ok();
         term.flush().ok();
 
         let key = term.read_key().unwrap();