feat(core): highlight unprintable chars in permission prompts (#22468)

If we strip out unprintable chars, we don't see the full filename being
requested by permission prompts. Instead, we highlight and escape them
to make them visible.

Author: mmastrac

runtime/permissions/prompter.rs

@@ -11,12 +11,24 @@ use std::io::StderrLock;
 use std::io::StdinLock;
 use std::io::Write as IoWrite;
 
-/// Helper function to strip ansi codes and ASCII control characters.
-fn strip_ansi_codes_and_ascii_control(s: &str) -> std::borrow::Cow<str> {
-  console_static_text::ansi::strip_ansi_codes(s)
-    .chars()
-    .filter(|c| !c.is_ascii_control())
-    .collect()
+/// Helper function to make control characters visible so users can see the underlying filename.
+fn escape_control_characters(s: &str) -> std::borrow::Cow<str> {
+  if !s.contains(|c: char| c.is_ascii_control() || c.is_control()) {
+    return std::borrow::Cow::Borrowed(s);
+  }
+  let mut output = String::with_capacity(s.len() * 2);
+  for c in s.chars() {
+    match c {
+      c if c.is_ascii_control() => output.push_str(
+        &colors::white_bold_on_red(c.escape_debug().to_string()).to_string(),
+      ),
+      c if c.is_control() => output.push_str(
+        &colors::white_bold_on_red(c.escape_debug().to_string()).to_string(),
+      ),
+      c => output.push(c),
+    }
+  }
+  output.into()
 }
 
 pub const PERMISSION_EMOJI: &str = "⚠️";
@@ -249,9 +261,9 @@ impl PermissionPrompter for TtyPrompter {
       return PromptResponse::Deny; // don't grant permission if this fails
     }
 
-    let message = strip_ansi_codes_and_ascii_control(message);
-    let name = strip_ansi_codes_and_ascii_control(name);
-    let api_name = api_name.map(strip_ansi_codes_and_ascii_control);
+    let message = escape_control_characters(message);
+    let name = escape_control_characters(name);
+    let api_name = api_name.map(escape_control_characters);
 
     // print to stderr so that if stdout is piped this is still displayed.
     let opts: String = if is_unary {

tests/integration/run_tests.rs

@@ -4725,19 +4725,19 @@ fn stdio_streams_are_locked_in_permission_prompt() {
 }
 
 #[test]
-fn permission_prompt_strips_ansi_codes_and_control_chars() {
+fn permission_prompt_escapes_ansi_codes_and_control_chars() {
   util::with_pty(&["repl"], |mut console| {
     console.write_line(
         r#"Deno.permissions.request({ name: "env", variable: "\rDo you like ice cream? y/n" });"#
       );
     // will be uppercase on windows
     let env_name = if cfg!(windows) {
-      "DO YOU LIKE ICE CREAM? Y/N"
+      "\\rDO YOU LIKE ICE CREAM? Y/N"
     } else {
-      "Do you like ice cream? y/n"
+      "\\rDo you like ice cream? y/n"
     };
     console.expect(format!(
-      "┌ ⚠️  Deno requests env access to \"{}\".",
+      "\u{250c} \u{26a0}\u{fe0f}  Deno requests env access to \"{}\".",
       env_name
     ))
   });
@@ -4747,14 +4747,10 @@ fn permission_prompt_strips_ansi_codes_and_control_chars() {
     console.expect("undefined");
     console.write_line_raw(r#"const unboldANSI = "\u001b[22m";"#);
     console.expect("undefined");
-    console.write_line_raw(r#"const prompt = `┌ ⚠️  ${boldANSI}Deno requests run access to "echo"${unboldANSI}\n ├ Requested by \`Deno.Command().output()`"#);
-    console.expect("undefined");
-    console.write_line_raw(r#"const moveANSIUp = "\u001b[1A";"#);
-    console.expect("undefined");
-    console.write_line_raw(r#"const clearANSI = "\u001b[2K";"#);
-    console.expect("undefined");
-    console.write_line_raw(r#"const moveANSIStart = "\u001b[1000D";"#);
-    console.expect("undefined");
+    console.write_line_raw(
+      r#"new Deno.Command(`${boldANSI}cat${unboldANSI}`).spawn();"#,
+    );
+    console.expect("\u{250c} \u{26a0}\u{fe0f}  Deno requests run access to \"\\u{1b}[1mcat\\u{1b}[22m\".");
   });
 }