Add code for constructing single-file cpio archives on the fly

src/core/cpio.c

@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2007 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 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+/** @file
+ *
+ * CPIO archives
+ *
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <gpxe/cpio.h>
+
+/**
+ * Set field within a CPIO header
+ *
+ * @v field		Field within CPIO header
+ * @v value		Value to set
+ */
+void cpio_set_field ( char *field, unsigned long value ) {
+	char buf[9];
+
+	snprintf ( buf, sizeof ( buf ), "%08lx", value );
+	memcpy ( field, buf, 8 );
+}