59 lines
1.9 KiB
Scheme
59 lines
1.9 KiB
Scheme
;;; select(2) syscall for scsh. -*- Scheme -*-
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;;; Copyright (c) 1995 by Olin Shivers.
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;;; TIMEOUT is 0 for immediate, >0 for timeout, #f for infinite;
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;;; default is #f.
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;;; The sets are vectors of file descriptors & fd ports.
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;;; You get three new vectors back.
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(define (select read-set write-set exception-set . maybe-timeout)
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(receive (errno rs ws es)
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(apply select/errno read-set write-set exception-set maybe-timeout)
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(if errno
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(apply errno-error errno select read-set write-set exception-set
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maybe-timeout)
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(values rs ws es))))
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(define (select/errno read-set write-set exception-set . maybe-timeout)
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(let ((timeout (optional-arg maybe-timeout #f))
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(vec-ok? (lambda (v)
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(vector-every? (lambda (elt)
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(or (and (integer? elt) (>= elt 0))
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(fdport? elt)))
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v))))
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;; Type-check input vectors.
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(check-arg vec-ok? read-set select/errno)
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(check-arg vec-ok? write-set select/errno)
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(check-arg vec-ok? exception-set select/errno)
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(check-arg (lambda (x) (or (not x) (integer? x))) timeout select/errno)
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(let lp ()
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(receive (errno rsize wsize esize)
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(%select/errno read-set write-set exception-set timeout)
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(cond ((not errno)
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(values errno
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(vector-take read-set rsize)
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(vector-take write-set wsize)
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(vector-take exception-set esize)))
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((= errno errno/intr) (lp))
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(else (values errno '#() '#() '#())))))))
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(define-foreign %select/errno
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(scm_select (vector-desc rvec)
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(vector-desc wvec)
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(vector-desc evec)
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(desc nsecs)) ; Integer or #f for infinity.
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desc ; errno or #f
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fixnum ; nread - number of hits in RVEC
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fixnum ; nwrite - number of hits in WVEC
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fixnum) ; nexcept - number of hits in EVEC
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(define (vector-take vec nelts)
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(let ((short (make-vector nelts)))
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(do ((i (- nelts 1) (- i 1)))
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((< i 0))
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(vector-set! short i (vector-ref vec i)))
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short))
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