[PATCH] emacs: fix infloop in password-store--run

Kai Tetzlaff pwstore at tetzco.de
Sun Feb 27 09:02:47 UTC 2022

Actually, checking the elisp reference manual provided some more

       If a connection from a process contains buffered data,
    ‘accept-process-output’ can return non-‘nil’ even after the process has
    exited.  Therefore, although the following loop:
         ;; This loop contains a bug.
         (while (process-live-p process)
           (accept-process-output process))
    will often read all output from PROCESS, it has a race condition and can
    miss some output if ‘process-live-p’ returns ‘nil’ while the connection
    still contains data.  Better is to write the loop like this:
         (while (accept-process-output process))

So instead of:

>   (let ((output nil)
>         (slept-for 0)
>         (process (apply #'password-store--run-1
>                         (lambda (password)
>                           (setq output password))
>                         (delq nil args))))
>     (accept-process-output process .1 nil t)
>     (while (process-live-p process)
>       (accept-process-output process .1 nil t))
>     output))

it should probably better be:

  (let ((output nil)
        (slept-for 0)
        (process (apply #'password-store--run-1
                        (lambda (password)
                          (setq output password))
                        (delq nil args))))
    ;; wait for output or process termination (max. wait time: 5s)
    (while (accept-process-output process 5.0))

I added a timeout which terminates `accept-process-output' after 5s just
to make sure that a non-responsive pass process doesn't block emacs.
It's debatable if this is needed or even makes any sense.

An updated patch is attached.

Best Regards,

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