Handle possible errors in set_virtual_terminal (#105)

Author: madsmtm

CHANGELOG.md

@@ -1,5 +1,6 @@
 # Unreleased
 - Document crate MSRV of `1.70`.
+- Handle errors in `set_virtual_terminal`.
 
 # 2.0.4
 - Switch from `winapi` to `windows-sys`.

src/control.rs

@@ -10,9 +10,6 @@ use std::sync::atomic::{AtomicBool, Ordering};
 /// This is primarily used for Windows 10 environments which will not correctly colorize
 /// the outputs based on ANSI escape codes.
 ///
-/// The returned `Result` is _always_ `Ok(())`, the return type was kept to ensure backwards
-/// compatibility.
-///
 /// # Notes
 /// > Only available to `Windows` build targets.
 ///
@@ -28,15 +25,25 @@ use std::sync::atomic::{AtomicBool, Ordering};
 #[allow(clippy::result_unit_err)]
 #[cfg(windows)]
 pub fn set_virtual_terminal(use_virtual: bool) -> Result<(), ()> {
+    use windows_sys::Win32::Foundation::INVALID_HANDLE_VALUE;
     use windows_sys::Win32::System::Console::{
         GetConsoleMode, GetStdHandle, SetConsoleMode, ENABLE_VIRTUAL_TERMINAL_PROCESSING,
         STD_OUTPUT_HANDLE,
     };
 
     unsafe {
         let handle = GetStdHandle(STD_OUTPUT_HANDLE);
+        if handle == INVALID_HANDLE_VALUE {
+            return Err(());
+        }
+
         let mut original_mode = 0;
-        GetConsoleMode(handle, &mut original_mode);
+        // Return value of 0 means that the function failed:
+        // https://learn.microsoft.com/en-us/windows/console/getconsolemode#return-value
+        if GetConsoleMode(handle, &mut original_mode) == 0 {
+            // TODO: It would be prudent to get the error using `GetLastError` here.
+            return Err(());
+        }
 
         let enabled = original_mode & ENABLE_VIRTUAL_TERMINAL_PROCESSING
             == ENABLE_VIRTUAL_TERMINAL_PROCESSING;