From: Chris Hanson <org/chris-hanson/cph>
Date: Wed, 18 Aug 1993 22:52:46 +0000 (+0000)
Subject: Guarantee that CHANNEL-READ not return #f if the argument channel is
X-Git-Tag: 20090517-FFI~8053
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=ff55b37c5c24bf827fc51df35855e37af609677c;p=mit-scheme.git

Guarantee that CHANNEL-READ not return #f if the argument channel is
set to blocking mode.
---

diff --git a/v7/src/runtime/io.scm b/v7/src/runtime/io.scm
index 4e482acdd..5f2a0f543 100644
--- a/v7/src/runtime/io.scm
+++ b/v7/src/runtime/io.scm
@@ -1,6 +1,6 @@
 #| -*-Scheme-*-
 
-$Id: io.scm,v 14.35 1993/06/16 15:00:21 gjr Exp $
+$Id: io.scm,v 14.36 1993/08/18 22:52:46 cph Exp $
 
 Copyright (c) 1988-1993 Massachusetts Institute of Technology
 
@@ -235,17 +235,27 @@ MIT in each case. |#
 	(ucode-primitive terminal-set-state 2)))
 
 (define (channel-read channel buffer start end)
-  (if (and have-select? (not (channel-type=file? channel)))
-      (let ((block-events? (block-thread-events)))
-	(let ((result
-	       (and (eq? 'INPUT-AVAILABLE (test-for-input-on-channel channel))
-		    ((ucode-primitive channel-read 4)
-		     (channel-descriptor channel) buffer start end))))
-	  (if (not block-events?)
-	      (unblock-thread-events))
-	  result))
-      ((ucode-primitive channel-read 4) (channel-descriptor channel)
-					buffer start end)))
+  (let ((do-read
+	 (lambda ()
+	   ((ucode-primitive channel-read 4) (channel-descriptor channel)
+					     buffer start end)))
+	(do-test
+	 (lambda ()
+	   (eq? 'INPUT-AVAILABLE (test-for-input-on-channel channel)))))
+    (declare (integrate-operator do-read do-test))
+    (if (and have-select? (not (channel-type=file? channel)))
+	(let ((block-events? (block-thread-events)))
+	  (let ((result
+		 (if (channel-blocking? channel)
+		     (begin
+		       (do () ((do-test)))
+		       (do-read))
+		     (and (do-test)
+			  (do-read)))))
+	    (if (not block-events?)
+		(unblock-thread-events))
+	    result))
+	(do-read))))
 
 (define (channel-read-block channel buffer start end)
   (let loop ()