Re: open-pipe fd duplications

[Kevin Ryde <user42@zip.com.au>]

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Marius Vollmer <mvo@zagadka.de> writes:
>
> Can you make that change?

Yep, applied.

I realized I botched the first effort actually, didn't pay attention
to the comment ...

        * popen.scm (open-process): Correction to previous fdes closing
        change, need to watch out for stdin==stderr or stdout==stderr.

I added some tests, both of this and of the original problem.


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--- popen.scm.~1.12.~	1970-01-01 10:00:01.000000000 +1000
+++ popen.scm	2003-09-16 21:46:52.000000000 +1000
@@ -81,9 +81,8 @@
 						(= pt-fileno error-fdes)))
 				       (close-fdes pt-fileno))))))
 
-	       ;; copy the three selected descriptors to the standard
-	       ;; descriptors 0, 1, 2.  note that it's possible that
-	       ;; output-fdes or input-fdes is equal to error-fdes.
+	       ;; Copy the three selected descriptors to the standard
+	       ;; descriptors 0, 1, 2, if not already there
 
 	       (cond ((not (= input-fdes 0))
 		      (if (= output-fdes 0)
@@ -91,13 +90,17 @@
 		      (if (= error-fdes 0)
 			  (set! error-fdes (dup->fdes 0)))
 		      (dup2 input-fdes 0)
-		      (close-fdes input-fdes)))
-
+		      ;; it's possible input-fdes is error-fdes
+		      (if (not (= input-fdes error-fdes))
+			  (close-fdes input-fdes))))
+	       
 	       (cond ((not (= output-fdes 1))
 		      (if (= error-fdes 1)
 			  (set! error-fdes (dup->fdes 1)))
 		      (dup2 output-fdes 1)
-		      (close-fdes output-fdes)))
+		      ;; it's possible output-fdes is error-fdes
+		      (if (not (= output-fdes error-fdes))
+			  (close-fdes output-fdes))))
 
 	       (cond ((not (= error-fdes 2))
 		      (dup2 error-fdes 2)

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;;;; popen.test --- exercise ice-9/popen.scm      -*- scheme -*-
;;;;
;;;; Copyright 2003 Free Software Foundation, Inc.
;;;;
;;;; This library is free software; you can redistribute it and/or
;;;; modify it under the terms of the GNU Lesser General Public
;;;; License as published by the Free Software Foundation; either
;;;; version 2.1 of the License, or (at your option) any later version.
;;;; 
;;;; This library is distributed in the hope that it will be useful,
;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
;;;; Lesser General Public License for more details.
;;;; 
;;;; You should have received a copy of the GNU Lesser General Public
;;;; License along with this library; if not, write to the Free Software
;;;; Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

(define-module (test-suite test-ice-9-popen)
  #:use-module (test-suite lib)
  #:use-module (ice-9 popen))


;; read from PORT until eof is reached, return what's read as a string
(define (read-string-to-eof port)
  (do ((lst '() (cons c lst))
       (c (read-char port) (read-char port)))
      ((eof-object? c)
       (list->string (reverse! lst)))))

;; call (THUNK), with SIGPIPE set to SIG_IGN so that an EPIPE error is
;; generated rather than a SIGPIPE signal
(define (with-epipe thunk)
  (dynamic-wind
      (lambda ()
	(sigaction SIGPIPE SIG_IGN))
      thunk
      restore-signals))


;;
;; open-input-pipe
;;

(with-test-prefix "open-input-pipe"
  
  (pass-if-exception "no args" exception:wrong-num-args
    (open-input-pipe))
  
  (pass-if "port?"
    (port? (open-input-pipe "echo hello")))
  
  (pass-if "echo hello"
    (string=? "hello\n" (read-string-to-eof (open-input-pipe "echo hello"))))
  
  ;; exercise file descriptor setups when stdin is the same as stderr  
  (pass-if "stdin==stderr"
    (let ((port (open-file "/dev/null" "r+")))
      (with-input-from-port port
	(lambda ()
	  (with-error-to-port port
	    (lambda ()
	      (open-input-pipe "echo hello"))))))
    #t)
  
  ;; exercise file descriptor setups when stdout is the same as stderr  
  (pass-if "stdout==stderr"
    (let ((port (open-file "/dev/null" "r+")))
      (with-output-to-port port
	(lambda ()
	  (with-error-to-port port
	    (lambda ()
	      (open-input-pipe "echo hello"))))))
    #t)
  
  ;; After the child closes stdout (which it indicates here by writing
  ;; "closed" to stderr), the parent should see eof.  In Guile 1.6.4 and
  ;; earlier a duplicate of stdout existed in the child, meaning eof was not
  ;; seen.
  (pass-if "no duplicate"
    (let* ((pair (pipe))
	   (port (with-error-to-port (cdr pair)
		   (lambda ()
		     (open-input-pipe
		      "exec 1>/dev/null; echo closed 1>&2; sleep 999")))))
      (read-char (car pair)) ;; wait for child to do its thing
      (and (char-ready? port)
	   (eof-object? (read-char port))))))

;;
;; open-output-pipe
;;

(with-test-prefix "open-output-pipe"
  
  (pass-if-exception "no args" exception:wrong-num-args
    (open-output-pipe))
  
  (pass-if "port?"
    (port? (open-output-pipe "exit 0")))
  
  ;; exercise file descriptor setups when stdout is the same as stderr  
  (pass-if "stdin==stderr"
    (let ((port (open-file "/dev/null" "r+")))
      (with-input-from-port port
	(lambda ()
	  (with-error-to-port port
	    (lambda ()
	      (open-output-pipe "exit 0"))))))
    #t)
  
  ;; exercise file descriptor setups when stdout is the same as stderr
  (pass-if "stdout==stderr"
    (let ((port (open-file "/dev/null" "r+")))
      (with-output-to-port port
	(lambda ()
	  (with-error-to-port port
	    (lambda ()
	      (open-output-pipe "exit 0"))))))
    #t)
  
  ;; After the child closes stdin (which it indicates here by writing
  ;; "closed" to stderr), the parent should see a broken pipe.  We setup to
  ;; see this as EPIPE (rather than SIGPIPE).  In Guile 1.6.4 and earlier a
  ;; duplicate of stdin existed in the child, preventing the broken pipe
  ;; occurring.
  (pass-if "no duplicate"
    (with-epipe
     (lambda ()
       (let* ((pair (pipe))
	      (port (with-error-to-port (cdr pair)
		      (lambda ()
			(open-output-pipe
			 "exec 0</dev/null; echo closed 1>&2; sleep 999")))))
	 (read-char (car pair)) ;; wait for child to do its thing
	 (catch 'system-error
		(lambda ()
		  (write-char #\x port)
		  (force-output port)
		  #f)
		(lambda (key name fmt args errno-list)
		  (= (car errno-list) EPIPE))))))))

;;
;; close-pipe
;;

(with-test-prefix "open-output-pipe"
  
  (pass-if-exception "no args" exception:wrong-num-args
    (close-pipe))
  
  (pass-if "exit 0"
    (let ((st (close-pipe (open-output-pipe "exit 0"))))
      (and (status:exit-val st)
	   (= 0 (status:exit-val st)))))
  
  (pass-if "exit 1"
    (let ((st (close-pipe (open-output-pipe "exit 1"))))
      (and (status:exit-val st)
	   (= 1 (status:exit-val st))))))


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