[Chicken-users] Possible stack problem with fork

[Peter Bex]

Hi all,

I've encountered a really strange bug, and I'm wondering if it's my
own mistake or there's a bug somewhere in chicken.

The code I have is this:

(define (run-and-catch-output program args)
  (call-with-values
    create-pipe
    (lambda (in out)
      (let* ([child (lambda ()
                      (file-close in)                           ; Close read end
                      (duplicate-fileno out fileno/stdout)      ; out = stdout
                      (process-execute program args))]
             [child-pid (process-fork child)])
        (file-close out)                        ; Close write end
        (let ([str (read-string in)])           ; Read out entire file as string
          (process-wait child-pid)              ; Clean up zombie
          str) )) ))                            ; Return string

This should run a program with the supplied arguments, and then return the
standard output in a string.  This seems overly complex maybe, but as
far as I see it's the only way when you want to use a `safe' exec, where
the commandline isn't simply blindly to the shell.
(and hand-parsing the string for special shell characters is evil, IMHO)

After making the above definition, I observed the following:
csi> (display (run-and-catch-output "/bin/ls" '()))
Error: (values) continuation can not receive multiple values: #<procedure>
Error: unbound variable: splay
csi> (display (run-and-catch-output "/bin/ls" '()))
Error: (values) continuation can not receive multiple values: #<procedure>
Error: unbound variable: isplay

Note the second error message.  Somehow the string "display" is getting
mangled.

Any ideas?

Regards,
Peter
-- 
http://www.student.kun.nl/peter.bex
--
"The process of preparing programs for a digital computer
 is especially attractive, not only because it can be economically
 and scientifically rewarding, but also because it can be an aesthetic
 experience much like composing poetry or music."
                                                        -- Donald Knuth

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