From 52c50f9410aabb71286bff74e09f41f9b749615a Mon Sep 17 00:00:00 2001
From: mainzelm <mainzelm>
Date: Wed, 8 Jan 2003 17:59:48 +0000
Subject: [PATCH] Check whether the file is opened non-blocking and call
 read-block with 'immediate in this case.

---
 scsh/rw.scm | 38 +++++++++++++++++++++-----------------
 1 file changed, 21 insertions(+), 17 deletions(-)

diff --git a/scsh/rw.scm b/scsh/rw.scm
index 28b4ade..812153e 100644
--- a/scsh/rw.scm
+++ b/scsh/rw.scm
@@ -17,7 +17,7 @@
 		       (start   0)
 		       (end     (string-length s)))
     (if (bogus-substring-spec? s start end)
-      (error "Bad substring indices" s start end))
+	(error "Bad substring indices" s start end))
 
     (cond ((integer? fd/port)
 	   (let ((port (fdes->inport fd/port)))
@@ -27,19 +27,26 @@
           ((open-input-port? fd/port)
 	   (if (= start end)
 	       0
-	       (let* ((buffer (if (= start 0)
-				  s
-				  (make-string (- end start))))
-		      (needed (if (> (byte-vector-length (port-buffer fd/port)) 1)
-				  'any 
-				  'immediate))   ;bufpol/none may return with 0
-		      (nread (read-block buffer 0 needed fd/port)))
+	       (let* ((needed (if (= 0 (bitwise-and open/non-blocking
+						    (fdes-status fd/port)))
+				  'any
+				  'immediate))
+		      (nread (if (= end (string-length s))
+				 (read-block s start needed fd/port)
+     		      ;;; READ-BLOCK doesn't allow us to specify a
+     		      ;;; maximum number of characters to read/partial
+     		      ;;; but fills the buffer at most to the end.
+		      ;;; Therefore we allocate a new buffer here:
+				 (let* ((buf (make-string (- end start)))
+					(nread-any 
+					 (read-block buf 0 needed fd/port)))
+				   (if (not (eof-object? nread-any))
+				       (copy-bytes! buf 0 s start nread-any))
+				   nread-any))))
+		 
 		 (if (eof-object? nread)
 		     #f
-		     (begin 
-		       (if (not (eq? s buffer))
-			   (copy-bytes! buffer 0 s start nread))
-		       nread)))))
+		     nread))))
 
 	  (else 
 	   (apply error "Not a fd/port in read-string!/partial" s args)))))
@@ -56,11 +63,8 @@
 	   (if (= len 0)
 	       0
 	       (let* ((buffer (make-string len))
-		      (needed (if (> (byte-vector-length (port-buffer fd/port)) 1)
-				  'any
-				  'immediate));; bufpol/none may return with 0
-		      (nread (read-block buffer 0 needed fd/port)))
-		 (cond ((eof-object? nread) #f)
+		      (nread (read-string!/partial buffer fd/port)))
+		 (cond ((not nread) #f)
 		       ((= nread len) buffer)
 		       (else (substring buffer 0 nread))))))
 	  (else