[project @ 1998-12-02 13:17:09 by simonm]

Move 4.01 onto the main trunk.

1 files changed, 80 insertions, 0 deletions

diff --git a/ghc/lib/std/cbits/flushFile.c b/ghc/lib/std/cbits/flushFile.c
new file mode 100644
index 0000000000..7390b27ec2
--- /dev/null
+++ b/ghc/lib/std/cbits/flushFile.c
@@ -0,0 +1,80 @@
+/* 
+ * (c) The GRASP/AQUA Project, Glasgow University, 1994-1998
+ *
+ * $Id: flushFile.c,v 1.3 1998/12/02 13:27:32 simonm Exp $
+ *
+ * hFlush Runtime Support
+ */
+
+#include "Rts.h"
+#include "stgio.h"
+
+StgInt
+flushFile(ptr)
+StgForeignPtr ptr;
+{
+    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)
+StgForeignPtr 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)
+StgForeignPtr 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;
+}