Type Error Risk in `pwnlib.term.readline`: `rstrip(b'\n')` Called on String

[chenyangyc]

Description

File & line: pwnlib/term/readline.py:382.

if not term_mode:
  print(prompt, end='', flush=True)
  return getattr(sys.stdin, 'buffer', sys.stdin).readline(_size).rstrip(b'\n')

pwnlib.term.readline calls rstrip(b'\n') on the result of sys.stdin.readline(...).

Because rstrip() is defined for str and its overloads only accept str | None, passing a bytes literal (b'\n') may trigger a type error :

Versions:

• pwntools :4.12.0
• python: 3.9.13
• system: Ubuntu 22.04

[peace-maker]

True, good catch. It doesn't appear to be triggered in practice since sys.stdin.buffer.readline() returns bytes and a .buffer attribute seems to always be available when people run pwntools scripts.

We should properly handle the fallback case though. It makes me wonder if we can assume any return types when the execution environment replaced sys.stdin in the first place though.