[xferbuf] Add generic data-transfer buffer

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/core/xferbuf.c

@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <ipxe/xfer.h>
+#include <ipxe/iobuf.h>
+#include <ipxe/xferbuf.h>
+
+/** @file
+ *
+ * Data transfer buffer
+ *
+ */
+
+/**
+ * Finish using data transfer buffer
+ *
+ * @v xferbuf		Data transfer buffer
+ */
+void xferbuf_done ( struct xfer_buffer *xferbuf ) {
+	free ( xferbuf->data );
+	xferbuf->data = NULL;
+	xferbuf->len = 0;
+	xferbuf->pos = 0;
+}
+
+/**
+ * Ensure that data transfer buffer is large enough for the specified size
+ *
+ * @v xferbuf		Data transfer buffer
+ * @v len		Required minimum size
+ * @ret rc		Return status code
+ */
+static int xferbuf_ensure_size ( struct xfer_buffer *xferbuf, size_t len ) {
+	void *new_data;
+
+	/* If buffer is already large enough, do nothing */
+	if ( len <= xferbuf->len )
+		return 0;
+
+	/* Extend buffer */
+	new_data = realloc ( xferbuf->data, len );
+	if ( ! new_data ) {
+		DBGC ( xferbuf, "XFERBUF %p could not extend buffer to "
+		       "%zd bytes\n", xferbuf, len );
+		return -ENOSPC;
+	}
+	xferbuf->data = new_data;
+	xferbuf->len = len;
+
+	return 0;
+}
+
+/**
+ * Add received data to data transfer buffer
+ *
+ * @v xferbuf		Data transfer buffer
+ * @v iobuf		I/O buffer
+ * @v meta		Data transfer metadata
+ * @ret rc		Return status code
+ */
+int xferbuf_deliver ( struct xfer_buffer *xferbuf, struct io_buffer *iobuf,
+		      struct xfer_metadata *meta ) {
+	size_t len;
+	size_t max;
+	int rc;
+
+	/* Calculate new buffer position */
+	if ( meta->flags & XFER_FL_ABS_OFFSET )
+		xferbuf->pos = 0;
+	xferbuf->pos += meta->offset;
+
+	/* Ensure that we have enough buffer space for this data */
+	len = iob_len ( iobuf );
+	max = ( xferbuf->pos + len );
+	if ( ( rc = xferbuf_ensure_size ( xferbuf, max ) ) != 0 )
+		goto done;
+
+	/* Copy data to buffer */
+	memcpy ( ( xferbuf->data + xferbuf->pos ), iobuf->data, len );
+
+	/* Update current buffer position */
+	xferbuf->pos += len;
+
+ done:
+	free_iob ( iobuf );
+	return rc;
+}