[project @ 2000-03-21 17:41:02 by simonmar]

[ghc-hetmet.git] / ghc / lib / std / cbits / readFile.c

diff --git a/ghc/lib/std/cbits/readFile.c b/ghc/lib/std/cbits/readFile.c
index a68f3aa..ee968ff 100644 (file)
--- a/ghc/lib/std/cbits/readFile.c
+++ b/ghc/lib/std/cbits/readFile.c
@@ -1,7 +1,7 @@
 /* 
  * (c) The GRASP/AQUA Project, Glasgow University, 1994-1998
  *
- * $Id: readFile.c,v 1.11 2000/03/10 15:23:40 simonmar Exp $
+ * $Id: readFile.c,v 1.13 2000/03/21 17:41:02 simonmar Exp $
  *
  * hGetContents Runtime Support
  */
@@ -120,7 +120,7 @@ StgInt
 readChunk(StgForeignPtr ptr, StgAddr buf, StgInt off, StgInt len)
 {
     IOFileObject* fo = (IOFileObject*)ptr;
-    int count=0,rc=0, total_count;
+    int count, rc=0, total_count=0;
     int fd;
     char* p;
 
@@ -155,24 +155,29 @@ readChunk(StgForeignPtr ptr, StgAddr buf, StgInt off, StgInt len)
     }
     fo->flags = (fo->flags & ~FILEOBJ_RW_WRITE) | FILEOBJ_RW_READ;
 
+    p = buf+off;
+
     /* copy the unread parts of the file buffer..*/
     if ( FILEOBJ_READABLE(fo) && 
         fo->bufRPtr > 0      &&
         fo->bufWPtr >= fo->bufRPtr ) {
-       count = ( len < (fo->bufWPtr - fo->bufRPtr)) ? len : (fo->bufWPtr - fo->bufRPtr);
-       memcpy(buf,fo->buf, count);
-       fo->bufWPtr=0;
-       fo->bufRPtr=0;
-       
-    }
-
-    if (len - count <= 0)
-       return count;
 
-    len -= count;
-    p = buf+off;
-    p += count;
-    total_count = count;
+        if (fo->bufWPtr - fo->bufRPtr >= len) {
+            /* buffer has enough data to fulfill the request */
+           memcpy(buf, fo->buf + fo->bufRPtr, len);
+            fo->bufRPtr += len;
+            return len;
+        } else {
+            /* can only partially fulfill the request from the buffer */
+            count = fo->bufWPtr - fo->bufRPtr;
+           memcpy(buf, fo->buf + fo->bufRPtr, count);
+            fo->bufWPtr=0;
+           fo->bufRPtr=0;
+            len -= count;
+            p += count;
+            total_count = count;
+        }
+    }
 
     while ((count =
              (