fix(permissions): fallback to denied access if the permission prompt fails (#14235)

runtime/permissions.rs

@@ -1885,13 +1885,15 @@ fn permission_prompt(message: &str, name: &str) -> bool {
   };
 
   #[cfg(unix)]
-  fn clear_stdin() {
+  fn clear_stdin() -> Result<(), AnyError> {
     let r = unsafe { libc::tcflush(0, libc::TCIFLUSH) };
     assert_eq!(r, 0);
+    Ok(())
   }
 
   #[cfg(not(unix))]
-  fn clear_stdin() {
+  fn clear_stdin() -> Result<(), AnyError> {
+    use deno_core::anyhow::bail;
     use winapi::shared::minwindef::TRUE;
     use winapi::shared::minwindef::UINT;
     use winapi::shared::minwindef::WORD;
@@ -1911,31 +1913,34 @@ fn permission_prompt(message: &str, name: &str) -> bool {
     unsafe {
       let stdin = GetStdHandle(STD_INPUT_HANDLE);
       // emulate an enter key press to clear any line buffered console characters
-      emulate_enter_key_press(stdin);
+      emulate_enter_key_press(stdin)?;
       // read the buffered line or enter key press
-      read_stdin_line();
+      read_stdin_line()?;
       // check if our emulated key press was executed
-      if is_input_buffer_empty(stdin) {
+      if is_input_buffer_empty(stdin)? {
         // if so, move the cursor up to prevent a blank line
-        move_cursor_up();
+        move_cursor_up()?;
       } else {
         // the emulated key press is still pending, so a buffered line was read
         // and we can flush the emulated key press
-        flush_input_buffer(stdin);
+        flush_input_buffer(stdin)?;
       }
     }
 
-    unsafe fn flush_input_buffer(stdin: HANDLE) {
+    return Ok(());
+
+    unsafe fn flush_input_buffer(stdin: HANDLE) -> Result<(), AnyError> {
       let success = FlushConsoleInputBuffer(stdin);
       if success != TRUE {
-        panic!(
-          "Error flushing console input buffer: {}",
+        bail!(
+          "Could not flush the console input buffer: {}",
           std::io::Error::last_os_error()
         )
       }
+      Ok(())
     }
 
-    unsafe fn emulate_enter_key_press(stdin: HANDLE) {
+    unsafe fn emulate_enter_key_press(stdin: HANDLE) -> Result<(), AnyError> {
       // https://github.com/libuv/libuv/blob/a39009a5a9252a566ca0704d02df8dabc4ce328f/src/win/tty.c#L1121-L1131
       let mut input_record: INPUT_RECORD = std::mem::zeroed();
       input_record.EventType = KEY_EVENT;
@@ -1951,42 +1956,48 @@ fn permission_prompt(message: &str, name: &str) -> bool {
       let success =
         WriteConsoleInputW(stdin, &input_record, 1, &mut record_written);
       if success != TRUE {
-        panic!(
-          "Error emulating enter key press: {}",
+        bail!(
+          "Could not emulate enter key press: {}",
           std::io::Error::last_os_error()
-        )
+        );
       }
+      Ok(())
     }
 
-    unsafe fn is_input_buffer_empty(stdin: HANDLE) -> bool {
+    unsafe fn is_input_buffer_empty(stdin: HANDLE) -> Result<bool, AnyError> {
       let mut buffer = Vec::with_capacity(1);
       let mut events_read = 0;
       let success =
         PeekConsoleInputW(stdin, buffer.as_mut_ptr(), 1, &mut events_read);
       if success != TRUE {
-        panic!(
-          "Error peeking console input buffer: {}",
+        bail!(
+          "Could not peek the console input buffer: {}",
           std::io::Error::last_os_error()
         )
       }
-      events_read == 0
+      Ok(events_read == 0)
     }
 
-    fn move_cursor_up() {
+    fn move_cursor_up() -> Result<(), AnyError> {
       use std::io::Write;
-      write!(std::io::stderr(), "\x1B[1A").expect("expected to move cursor up");
+      write!(std::io::stderr(), "\x1B[1A")?;
+      Ok(())
     }
 
-    fn read_stdin_line() {
+    fn read_stdin_line() -> Result<(), AnyError> {
       let mut input = String::new();
       let stdin = std::io::stdin();
-      stdin.read_line(&mut input).expect("expected to read line");
+      stdin.read_line(&mut input)?;
+      Ok(())
     }
   }
 
   // For security reasons we must consume everything in stdin so that previously
   // buffered data cannot effect the prompt.
-  clear_stdin();
+  if let Err(err) = clear_stdin() {
+    eprintln!("Error clearing stdin for permission prompt. {:#}", err);
+    return false; // don't grant permission if this fails
+  }
 
   let opts = "[y/n (y = yes allow, n = no deny)] ";
   let msg = format!(