/usr/lib/s9fes/spawn-command.scm is in scheme9 2010.11.13-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 | ; Scheme 9 from Empty Space, Function Library
; By Nils M Holm, 2010
; See the LICENSE file of the S9fES package for terms of use
;
; (spawn-command string list) ==> list
; (spawn-command/fd string list) ==> list
;
; (load-from-library "spawn-command.scm")
;
; Spawn a child process running the command STRING with the arguments
; listed in LIST. Return a list of two I/O-ports and the PID of the
; child process:
;
; (input-port output-port integer)
;
; Note that the full path of the command must be spcified and no
; shell operators like <, >, &, etc may be used. When PATH search
; or shell operators are needed, use SPAWN-SHELL-COMMAND instead.
;
; The input-port can be used to read the output of the command and
; the output-port to send input to the command. Error output of the
; child will be redirected to its standard output.
;
; SPAWN-COMMAND/FD is like SPAWN-COMMAND, but delivers raw Unix file
; descriptors instead of input/output ports.
;
; (Example): (spawn-command "/bin/ls -l /bin")
; ==> (#<input-port> #<output-port> 707)
(require-extension sys-unix)
(define (spawn-command/fd command args)
(let* ((from-child (sys:pipe))
(to-child (sys:pipe))
(pid (sys:fork)))
(cond ((zero? pid)
(sys:close (car from-child))
(sys:close (cadr to-child))
(sys:dup2 (cadr from-child) 2)
(sys:dup2 (cadr from-child) 1)
(sys:dup2 (car to-child) 0)
(sys:execv command args)
(error "sys:execv should not return")
(sys:exit 1))
(else
(sys:close (cadr from-child))
(sys:close (car to-child))
(list (car from-child)
(cadr to-child)
pid)))))
(define (spawn-command command args)
(let ((conn (spawn-command/fd command args)))
(list (sys:make-input-port (car conn))
(sys:make-output-port (cadr conn))
(caddr conn))))
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