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|
;;
;; SCSH process form notation
;;
;; See http://www.scsh.net/docu/html/man-Z-H-3.html#node_chap_2
;;
;; Some minor changes due to Chicken- and R7RS-incompatible identifiers:
;; | was changed to pipe, |+ was changed to pipe+
;;
;; || wasn't changed, but it's really the zero-length symbol
;;
;; BIG FAT WARNING: Don't mix this with threading, or Bad Things will happen
(module scsh-process
(;; procedures
exec-path fork/pipe %fork/pipe fork/pipe+ %fork/pipe+
run/collecting* run/string* run/strings* run/port* run/file* run/sexp* run/sexps*
;; macros
run/collecting run/string run/strings run/port run/file run/sexp run/sexps
(& maybe-symbol->string) (run maybe-symbol->string) (exec-epf maybe-symbol->string))
(import chicken scheme data-structures)
(use extras utils files ports posix srfi-1)
;; TODO: Perhaps expose environment, and mess around with the path so that
;; execve can be used in a sensible way? Scsh has its own PATH, so we could
;; use something similar to that, but it's more work.
(define (exec-path prog . args)
;; Args can include numbers and such, too! That's why we're using ->string
(process-execute (maybe-symbol->string prog) (map ->string args)))
;; TODO: continue-threads argument
(define (fork/pipe #!optional thunk)
(fork/pipe+ '((1 2 0)) thunk))
(define (fork/pipe+ conns #!optional thunk)
;; Blergh, this is silly overhead we don't really need
(let* ((from-fds (map (lambda (x) (drop-right x 1)) conns))
(to-fds (map last conns))
(pipe-pairs (map (lambda _ (receive (create-pipe))) to-fds))
(pid (process-fork)))
(if (zero? pid) ; Child
(begin
(for-each (lambda (p from-fds-for-this-p)
;; Close receiving ends of pipes in child.
(file-close (car p))
;; Set up linkage from output fds to created pipes.
(for-each (lambda (from-fd)
(duplicate-fileno (cadr p) from-fd))
from-fds-for-this-p)
;; Not needed anymore after duplication is complete.
(file-close (cadr p)))
pipe-pairs from-fds)
(if thunk (thunk) pid))
(begin ; Parent
(for-each (lambda (p to-fd)
;; Close sending end in parent.
(file-close (cadr p))
;; Set up linkage from created pipes to the input fds.
(duplicate-fileno (car p) to-fd)
;; No longer needed after duplication.
(file-close (car p)))
pipe-pairs to-fds)
pid))))
;; TODO: Differentiate between fork and %fork
(define %fork/pipe fork/pipe)
(define %fork/pipe+ fork/pipe+)
(define (maybe-symbol->string s)
(if (symbol? s) (symbol->string s) s))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Baroque procedural interface ;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Documented under http://www.scsh.net/docu/html/man-Z-H-3.html#node_sec_2.4.2
(define (run/collecting* fds thunk)
(let* ((temp-files (map (lambda () (open-input-file (create-temporary-file)))
fds))
(conns (map (lambda (temp-fd from-fd)
(list from-fd (open-input-file* temp-fd)))
temp-files fds)))
(apply values (fork/pipe+ conns thunk) temp-files)))
(define (run/port* thunk)
(fork/pipe (lambda () (with-output-to-port (open-output-file* 1) thunk)))
(open-input-file* 0))
(define (run/file* thunk)
(error "not yet implemented"))
(define (run/string* thunk)
(read-string #f (run/port* thunk)))
(define (run/strings* thunk)
(read-lines (run/port* thunk)))
(define (run/sexp* thunk)
(read (run/port* thunk)))
(define (run/sexps* thunk)
(read-file (run/port* thunk)))
;;;;;;;;;;;;
;; Syntax ;;
;;;;;;;;;;;;
(define-syntax run/collecting
(syntax-rules ()
((_ ?fds ?epf ...) (run/collecting* `?fds (lambda () (exec-epf ?epf ...))))))
(define-syntax run/file
(syntax-rules ()
((_ ?epf ...) (run/file* (lambda () (exec-epf ?epf ...))))))
(define-syntax run/port
(syntax-rules ()
((_ ?epf ...) (run/port* (lambda () (exec-epf ?epf ...))))))
(define-syntax run/string
(syntax-rules ()
((_ ?epf ...) (run/string* (lambda () (exec-epf ?epf ...))))))
(define-syntax run/strings
(syntax-rules ()
((_ ?epf ...) (run/strings* (lambda () (exec-epf ?epf ...))))))
(define-syntax run/sexp
(syntax-rules ()
((_ ?epf ...) (run/sexp* (lambda () (exec-epf ?epf ...))))))
(define-syntax run/sexps
(syntax-rules ()
((_ ?epf ...) (run/sexps* (lambda () (exec-epf ?epf ...))))))
(define-syntax &
(syntax-rules ()
((_ ?epf ...)
(process-fork (lambda ()
(handle-exceptions exn
;; TODO: Figure out how SCSH does this. It shows the error
;; on stderr in the REPL, but then still quits it.
;; If we just invoke current-handler, it'll get a second REPL
(begin (print-error-message exn) (exit 1))
(exec-epf ?epf ...)))))))
(define-syntax run
(syntax-rules ()
((_ ?epf ...)
;; We reorder the values as they make more sense this way for SCSH compat:
;; scsh returns just the exit code, and conveniently we allow MV in single
;; value continuations, which makes it compatible.
(receive (pid normal-exit? exit-status)
(process-wait (& ?epf ...))
(values exit-status normal-exit? pid)))))
;; Perhaps this should really be a procedure?
(define-syntax setup-redirection
(syntax-rules (< > << >> = - stdports)
((_ (< ?file-name)) (setup-redirection (< 0 ?file-name)))
((_ (> ?file-name)) (setup-redirection (> 1 ?file-name)))
((_ (<< ?object)) (setup-redirection (<< 0 ?object)))
((_ (>> ?object)) (setup-redirection (>> 1 ?object)))
((_ (< ?fd ?file-name))
(duplicate-fileno (file-open (maybe-symbol->string `?file-name)
open/rdonly)
`?fd))
((_ (> ?fd ?file-name))
(duplicate-fileno (file-open (maybe-symbol->string `?file-name)
(fx+ open/wronly open/creat))
`?fd))
((_ (<< ?fd ?object)) (error "<< currently not implemented"))
((_ (>> ?fd ?object)) (error ">> currently not implemented"))
((_ (= ?fd-from ?fd/port-to))
(let* ((fd/port-to ?fd/port-to) ; Evaluate once
(fd-to (if (port? fd/port-to)
(port->fileno fd/port-to)
fd/port-to)))
(duplicate-fileno ?fd-from fd-to)))
((_ (- ?fd/port))
(let ((o `?fd/port))
(cond
((fixnum? ?fd/port) (file-close o))
((output-port? ?fd/port) (close-output-port o))
((input-port? ?fd/port) (close-input-port o))
(else (error "Can only close i/o-ports and file descriptor numbers" o)))))
((_ stdports)
(begin (setup-redirection (= 0 (current-input-port)))
(setup-redirection (= 1 (current-output-port)))
(setup-redirection (= 2 (current-error-port)))))
((_ ?arg0 ...)
(syntax-error "Invalid redirection pattern: " `?arg0 ...))))
;; The most "core" syntax form
(define-syntax exec-epf
;; The nested let-syntaxes exist to let us pre-empt the fallthrough
;; whenever we see one of the recognised special rules so we don't end up
;; with the generic one if we happen to make a small mistake
(syntax-rules (pipe pipe+ begin epf)
((_ (pipe ?pf0 ...) ?redir0 ...)
(exec-epf (pipe+ ((1 2 0)) ?pf0 ...) ?redir0 ...))
((_ (pipe+ ?args ...) ?redir0 ...)
(let-syntax
((pipe+
(syntax-rules ___ ()
((_ ((?from0 ?from1 ___ ?to) ___) ?pf0 ___ ?last-pf)
(let ((conns `((?from0 ?from1 ___ ?to) ___)))
(setup-redirection ?redir0) ...
(begin (fork/pipe+ conns (lambda () (exec-epf (epf ?pf0))))
___
(exec-epf (epf ?last-pf))))))))
(pipe+ ?args ...)))
((_ (begin ?expr0 ...))
(begin (setup-redirection (= 0 (current-input-port)))
(setup-redirection (= 1 (current-output-port)))
(setup-redirection (= 2 (current-error-port)))
?expr0 ...))
((_ (epf ?args ...)) ; TODO: Figure out the point of this
(exec-epf ?args ...))
;; This is purely for convenience, so you don't need the (epf ...) wrapper
((_ (?prog ?arg0 ...) ?redir0 ...)
(begin
(setup-redirection ?redir0) ...
(exec-path `?prog `?arg0 ...)))))
)
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