[project @ 1998-08-14 12:42:01 by sof]

Beefed up IO stub functions to not have to rely on stdio any longer

1 files changed, 67 insertions, 10 deletions

diff --git a/ghc/lib/std/cbits/flushFile.lc b/ghc/lib/std/cbits/flushFile.lc
index 6cfd484e74..595dfc01ac 100644
--- a/ghc/lib/std/cbits/flushFile.lc
+++ b/ghc/lib/std/cbits/flushFile.lc
@@ -3,27 +3,84 @@
 %
 \subsection[flushFile.lc]{hFlush Runtime Support}
 
+Empty contents of output buffers.
+
 \begin{code}
 
 #include "rtsdefs.h"
 #include "stgio.h"
 
 StgInt
-flushFile(fp)
-StgForeignObj fp;
+flushFile(ptr)
+StgForeignObj ptr;
 {
-    int rc;
-
-    while ((rc = fflush((FILE *) fp)) != 0) {
-	if (errno != EINTR) {
-	    cvtErrno();
-	    stdErrno();
-	    return rc;
-	}
+    IOFileObject* fo = (IOFileObject*)ptr;
+    int rc = 0;
+
+    if ( (fo->flags & FILEOBJ_FLUSH) && !FILEOBJ_BUFFER_EMPTY(fo) ) {
+       rc = writeBuffer(ptr,fo->bufWPtr - fo->bufRPtr);
+    }
+
+    return rc;
+}
+
+StgInt
+flushBuffer(ptr)
+StgForeignObj ptr;
+{
+    IOFileObject* fo = (IOFileObject*)ptr;
+    int rc = 0;
+
+    /* If the file object is writeable, or if its
+       RW and the last operation on it was a write,
+       flush it.
+    */
+    if ( (!FILEOBJ_READABLE(fo) && FILEOBJ_WRITEABLE(fo)) || (FILEOBJ_RW(fo) && FILEOBJ_JUST_WRITTEN(fo)) ) {
+       rc = flushFile(ptr);
+       if (rc<0) return rc;
+    }
+    
+    /* Reset read & write pointer for input buffers */
+    if ( (fo->flags & FILEOBJ_READ) ) {
+       fo->bufRPtr=0;
+       fo->bufWPtr=0;
     }
     return 0;
 }
 
+/*
+ For RW file objects, flushing input buffers doesn't just involve 
+ resetting the read & write pointers, we also have to change the
+ underlying file position to point to the effective read position.
+
+ (Sigh, I now understand the real reason for why stdio opted for
+ the solution of leaving this to the programmer!)
+*/
+StgInt
+flushReadBuffer(ptr)
+StgForeignObj ptr;
+{
+    IOFileObject* fo = (IOFileObject*)ptr;
+    int delta;
+
+    delta = fo->bufWPtr - fo->bufRPtr;
+
+    if ( delta > 0 ) {
+       while ( lseek(fo->fd, -delta, SEEK_CUR) == -1) {
+	  if (errno != EINTR) {
+	     cvtErrno();
+	     stdErrno();
+	     return -1;
+	  }
+       }
+    }
+
+    fo->bufRPtr=0;
+    fo->bufWPtr=0;
+    return 0;
+}
+
+
 \end{code}