Close socket with :abort T after error

[vibs29]

clisp (or less likely usocket) doesn't allow socket operations, other than close, after an error; it exits with code 141. CL+SSL might produce an error e.g. during implicit force-outputs. DRAKMA's http-request then calls its close method in an unwind-protect cleanup form, which calls force-output again. This second call causes clisp to exit. The following semantics for close seem sensible: If you've received an error operating with a plain-text or CL+SSL socket, then call close with :abort T. Use :abort NIL only when you've encountered no errors. When close is used that way, the problem gets solved. CL+SSL's close doesn't call force-output when :abort is T.

[hanshuebner]

I would like to see this fixed, but the logic was already difficult to understand, and now with the additional flet and cond it really exceeds my brain capacity. Can you find a way to make this easier to review?

[stassats]

Or maybe clisp should be fixed?

[vibs29]

I don't fully understand the original cleanup clause, but here is what I did. The changed version is equivalent to the original except that in one case it closes with abort T instead of abort NIL.

This was the original cleanup clause.

(when (and http-stream
           (or (not done)
               (and must-close
                    (not want-stream)))
           (not (eq content :continuation)))
  (ignore-errors (close http-stream)))

which, swapping the last two outer AND terms, is equivalent to

(when (and http-stream
           (not (eq content :continuation))
           (or (not done)
               (and must-close
                    (not want-stream))))
  (ignore-errors (close http-stream)))

which is

(when (and http-stream
           (not (eq content :continuation)))
  (when (or (not done)
            (and must-close
                 (not want-stream)))
    (ignore-errors (close http-stream))))

which is

(when (and http-stream
           (not (eq content :continuation)))
  (cond ((not done) (ignore-errors ...))
        ((and must-close (not want-stream)) (ignore-errors ...))))

which is

(when (and http-stream
           (not (eq content :continuation)))
  (flet ((close-aborting (a) (ignore-errors (close http-stream :abort a))))
    (cond ((not done) (close-aborting nil))
          ((and must-close (not want-stream)) (close-aborting nil)))))

I then finally changed the behaviour to what I wanted, which was to change the NIL to T in the (not done) situation. (That situation represents that an error occurred in the unwind-protect's body.)