Initial import of the CDE 2.1.30 sources from the Open Group.

cde/lib/tt/mini_isam/isfileio.c

@@ -0,0 +1,156 @@
+/*%%  (c) Copyright 1993, 1994 Hewlett-Packard Company			 */
+/*%%  (c) Copyright 1993, 1994 International Business Machines Corp.	 */
+/*%%  (c) Copyright 1993, 1994 Sun Microsystems, Inc.			 */
+/*%%  (c) Copyright 1993, 1994 Novell, Inc. 				 */
+/*%%  $XConsortium: isfileio.c /main/3 1995/10/23 11:39:26 rswiston $ 			 				 */
+#ifndef lint
+static char sccsid[] = "@(#)isfileio.c 1.3 89/07/17 Copyr 1988 Sun Micro";
+#endif
+/*
+ * Copyright (c) 1988 by Sun Microsystems, Inc.
+ */
+
+/*
+ * isfileio.c
+ *
+ * Description:
+ *	I/O operations on UNIX files associated with FCB
+ */
+
+#include "isam_impl.h"
+
+static int _getoffset();
+static Blkno _getblkno();
+
+
+/*
+ * _cp_tofile(fcb, unixfd, data, pos, len)
+ *
+ * Copy data to a file associated with FCB (unixfd distinguishes among 
+ * .rec, .ind., and .var file). The data are copied from buffer data to
+ * the file at offset pos. The number of bytes to copy is in len.
+ */
+
+void
+_cp_tofile(fcb, unixfd, data, pos, len)
+    Fcb		*fcb;
+    int		unixfd;
+    char	*data;
+    long	pos;
+    int		len;
+{
+    int		offset;			     /* Offset within a page */
+    Blkno	blkno;
+    Bufhdr	*bufhdr;
+    int		nbytes;
+
+    /*
+     * Data may span multiple blocks.
+     */
+    while (len > 0) {
+	blkno = _getblkno(pos);
+	offset = _getoffset(pos);
+	nbytes = (len < ISPAGESIZE - offset) ? len : ISPAGESIZE - offset;
+
+	bufhdr = _isdisk_fix(fcb, unixfd, blkno, ISFIXWRITE);
+	memcpy( bufhdr->isb_buffer + offset,data, nbytes);
+	_isdisk_unfix(bufhdr);
+
+	pos  += nbytes;
+	data += nbytes;
+	len  -= nbytes;
+    }
+}
+
+/*
+ * _cp_fromfile(fcb, unixfd, data, pos, len)
+ *
+ * Copy data from a file associated with FCB (unixfd distinguishes among 
+ * .rec, .ind., and .var file). The data are copied to buffer data from
+ * the file at offset pos. The number of bytes to copy is in len.
+ */
+
+void
+_cp_fromfile(fcb, unixfd, data, pos, len)
+    Fcb		*fcb;
+    int		unixfd;
+    char	*data;
+    long	pos;
+    int		len;
+{
+    int		offset;			     /* Offset within a page */
+    Blkno	blkno;
+    Bufhdr	*bufhdr;
+    int		nbytes;
+
+    /*
+     * Data may span multiple blocks.
+     */
+    while (len > 0) {
+	blkno = _getblkno(pos);
+	offset = _getoffset(pos);
+	nbytes = (len < ISPAGESIZE - offset) ? len : ISPAGESIZE - offset;
+
+	bufhdr = _isdisk_fix(fcb, unixfd, blkno, ISFIXREAD);
+	memcpy( data,bufhdr->isb_buffer + offset, nbytes);
+	_isdisk_unfix(bufhdr);
+
+	pos  += nbytes;
+	data += nbytes;
+	len  -= nbytes;
+    }
+}
+
+/*
+ * extend_file(fcb, unixfd, oldsize)
+ *
+ * Extend UNIX file by one block.
+ */
+
+Blkno 
+_extend_file(fcb, unixfd, oldsize)
+    Fcb			*fcb;
+    int			unixfd;
+    Blkno		oldsize;
+{
+    Bufhdr		*bufhdr;
+    char		buf[ISPAGESIZE];
+
+    /* 
+     * We must write something to the buffer, or we will get 
+     * segmentation fault when using mapped I/O.
+     */
+    _isseekpg(unixfd, oldsize);
+    _iswritepg(unixfd, buf);
+
+    bufhdr = _isdisk_fix(fcb, unixfd, oldsize, ISFIXNOREAD); 
+    _isdisk_unfix(bufhdr);
+
+    return (oldsize + 1);
+}
+
+/*
+ * off = _getoffset(pos)
+ *
+ * Calculate offset relative to the beginning of page
+ */
+
+Static int
+_getoffset(pos)
+    long		pos;
+{
+    return ((int)(pos % ISPAGESIZE));
+}
+
+/*
+ * blkno = _getblkno(pos)
+ *
+ * Calculate block number of the block containing position pos.
+ */
+
+Static Blkno
+_getblkno(pos)
+    long		pos;
+{
+    return ((int)(pos / ISPAGESIZE));
+}