Fix for an underflow on some type conversions (#1715)

CHANGELOG.md

@@ -20,6 +20,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Extra padding is not evenly spread around the terminal by default anymore
 
+### Fixed
+
+- Fixed a bad type conversion which could cause underflow on a window resize
+
 ## Version 0.2.3
 
 ### Fixed

src/term/mod.rs

@@ -865,8 +865,8 @@ impl SizeInfo {
         let line = Line(y.saturating_sub(self.padding_y as usize) / (self.cell_height as usize));
 
         Point {
-            line: min(line, self.lines() - 1),
+            line: min(line, Line(self.lines().saturating_sub(1))),
-            col: min(col, self.cols() - 1)
+            col: min(col, Column(self.cols().saturating_sub(1)))
         }
     }
 }

src/tty/windows.rs

@@ -19,6 +19,7 @@ use std::os::windows::io::{FromRawHandle, IntoRawHandle};
 use std::os::windows::fs::OpenOptionsExt;
 use std::env;
 use std::cell::UnsafeCell;
+use std::u16;
 
 use dunce::canonicalize;
 use mio;
@@ -276,8 +277,9 @@ impl<'a> EventedReadWrite for Pty<'a, NamedPipe, NamedPipe> {
 
 impl<'a> OnResize for Winpty<'a> {
     fn on_resize(&mut self, sizeinfo: &SizeInfo) {
-        if sizeinfo.cols().0 > 0 && sizeinfo.lines().0 > 0 {
+        let (cols, lines) = (sizeinfo.cols().0, sizeinfo.lines().0);
-            self.set_size(sizeinfo.cols().0, sizeinfo.lines().0)
+        if cols > 0 && cols <= u16::MAX as usize && lines > 0 && lines <= u16::MAX as usize {
+            self.set_size(cols as u16, lines as u16)
                 .unwrap_or_else(|_| info!("Unable to set winpty size, did it die?"));
         }
     }

winpty/src/windows.rs

@@ -201,12 +201,12 @@ impl<'a, 'b> Winpty<'a> {
     /// Change the size of the Windows console window.
     /// 
     /// cols & rows MUST be greater than 0
-    pub fn set_size(&mut self, cols: usize, rows: usize) -> Result<(), Err> {
+    pub fn set_size(&mut self, cols: u16, rows: u16) -> Result<(), Err> {
         assert!(cols > 0 && rows > 0);
         let mut err = null_mut() as *mut winpty_error_t;
 
         unsafe {
-            winpty_set_size(self.0, cols as i32, rows as i32, &mut err);
+            winpty_set_size(self.0, i32::from(cols), i32::from(rows), &mut err);
         }
 
         if let Some(err) = check_err(err) {