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//! ANSI escape sequence sanitization to prevent terminal injection attacks.
use std::fmt::{self, Write};
/// A wrapper that implements `fmt::Debug` and `fmt::Display` and escapes ANSI sequences on-the-fly.
/// This avoids creating intermediate strings while providing security against terminal injection.
pub(super) struct Escape<T>(pub(super) T);
/// Helper struct that escapes ANSI sequences as characters are written
struct EscapingWriter<'a, 'b> {
inner: &'a mut fmt::Formatter<'b>,
}
impl<'a, 'b> fmt::Write for EscapingWriter<'a, 'b> {
fn write_str(&mut self, s: &str) -> fmt::Result {
// Stream the string character by character, escaping ANSI and C1 control sequences
for ch in s.chars() {
match ch {
// C0 control characters that can be used in terminal escape sequences
'\x1b' => self.inner.write_str("\\x1b")?, // ESC
'\x07' => self.inner.write_str("\\x07")?, // BEL
'\x08' => self.inner.write_str("\\x08")?, // BS
'\x0c' => self.inner.write_str("\\x0c")?, // FF
'\x7f' => self.inner.write_str("\\x7f")?, // DEL
// C1 control characters (\x80-\x9f) - 8-bit control codes
// These can be used as alternative escape sequences in some terminals
ch if ch as u32 >= 0x80 && ch as u32 <= 0x9f => {
write!(self.inner, "\\u{{{:x}}}", ch as u32)?
},
_ => self.inner.write_char(ch)?,
}
}
Ok(())
}
}
impl<T: fmt::Debug> fmt::Debug for Escape<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut escaping_writer = EscapingWriter { inner: f };
write!(escaping_writer, "{:?}", self.0)
}
}
impl<T: fmt::Display> fmt::Display for Escape<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut escaping_writer = EscapingWriter { inner: f };
write!(escaping_writer, "{}", self.0)
}
}