Re: [Chicken-users] greedy (read-string 0)

[felix winkelmann]

On 4/18/07, Andre Kuehne <address@hidden> wrote:
> Hi everyone
>
> I just installed chicken from darcs and got the following:
>
>  > csi -n
>
>   .--. .-.    _       .-.
> : .--': :   :_;      : :.-.
> : :   : `-. .-. .--. : `'.' .--. ,-.,-.
> : :__ : .. :: :'  ..': . `.' '_.': ,. :
> `.__.':_;:_;:_;`.__.':_;:_;`.__.':_;:_;
>
> Version 2.611 - linux-unix-gnu-x86 - [ dload ptables applyhook ]
> (c)2000-2007 Felix L. Winkelmann
> #;1> (with-input-from-file "test" (lambda () (string-length (read-string 0))))
> 1
>
> This only happens inside with-input-from-file.

Argh. Here the patch:


--- old-chicken/extras.scm      2007-04-19 08:02:21.505209216 +0200
+++ new-chicken/extras.scm      2007-04-19 08:02:21.583197360 +0200
@@ -420,23 +420,25 @@
              (doread port) ) ) ) ) ) )

(define (##sys#read-string! n dest port start)
-  (when (##sys#slot port 6)            ; peeked?
-    (##core#inline "C_setsubchar" dest start (##sys#read-char-0 port))
-    (set! start (fx+ start 1)) )
-  (let ((rdstring (##sys#slot (##sys#slot port 2) 7)))
-    (let loop ((start start) (n n) (m 0))
-      (let ((n2 (if rdstring
-                   (rdstring port n dest start) ; *** doesn't update 
port-position!
-                   (let ((c (##sys#read-char-0 port)))
-                     (if (eof-object? c)
-                         0
-                         (begin
-                           (##core#inline "C_setsubchar" dest start c)
-                           1) ) ) ) ) )
-       (cond ((eq? n2 0) m)
-             ((or (not n) (fx< n2 n))
-              (loop (fx+ start n2) (and n (fx- n n2)) (fx+ m n2)) )
-             (else (fx+ n2 m))) ) ) ))
+  (cond ((eq? n 0) 0)
+       (else
+        (when (##sys#slot port 6)      ; peeked?
+          (##core#inline "C_setsubchar" dest start (##sys#read-char-0 port))
+          (set! start (fx+ start 1)) )
+        (let ((rdstring (##sys#slot (##sys#slot port 2) 7)))
+          (let loop ((start start) (n n) (m 0))
+            (let ((n2 (if rdstring
+                          (rdstring port n dest start) ; *** doesn't update 
port-position!
+                          (let ((c (##sys#read-char-0 port)))
+                            (if (eof-object? c)
+                                0
+                                (begin
+                                  (##core#inline "C_setsubchar" dest start c)
+                                  1) ) ) ) ) )
+              (cond ((eq? n2 0) m)
+                    ((or (not n) (fx< n2 n))
+                     (loop (fx+ start n2) (and n (fx- n n2)) (fx+ m n2)) )
+                    (else (fx+ n2 m))) ) ) ))))

(define (read-string! n dest #!optional (port ##sys#standard-input) (start 0))
  (##sys#check-port port 'read-string!)

(also checked into darcs head in a few minutes)

> BTW, is it still considered good practice to post such issues here,
> or do you prefer trac-tickets?

For things like this, trac tickets would be preferable. For issues that
might interest others or where feedback from others might be
useful, a post here is good.

You can always do both.


cheers,
felix