scsh-0.5/scsh/bsd/waitcodes.scm

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;;; Scsh routines for analysing exit codes returned by WAIT.
;;; Copyright (c) 1994 by Olin Shivers. See file COPYING.
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;;;
;;; To port these to a new OS, consult /usr/include/sys/wait.h,
;;; and check the WIFEXITED, WEXITSTATUS, WIFSTOPPED, WSTOPSIG,
;;; WIFSIGNALED, and WTERMSIG macros for the magic fields they use.
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;;; These definitions are for BSD4.4-Lite.
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;;;
;;; I could have done a portable version by making C calls for this,
;;; but it's such overkill.
;;; If process terminated normally, return the exit code, otw #f.
(define (status:exit-val status)
(and (zero? (bitwise-and #x7F status))
(arithmetic-shift status -8)))
;;; If the process was suspended, return the suspending signal, otw #f.
(define (status:stop-sig status)
(and (= #x7F (bitwise-and status #x7F))
(arithmetic-shift status -8)))
;;; If the process terminated abnormally,
;;; return the terminating signal, otw #f.
(define (status:term-sig status)
(let ((termsig (bitwise-and status #x7F)))
(and (not (zero? termsig)) ; Didn't exit.
(not (= #x7F)) ; Not suspended.
termsig)))
;;; Flags.
(define wait/poll 1) ; Don't hang if nothing to wait for.
(define wait/stopped-children 2) ; Report on suspended subprocs, too.