+/*
+ * RouterBoot helper routines
+ *
+ * Copyright (C) 2012 Gabor Juhos <juhosg@openwrt.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/routerboot.h>
+
+#include "routerboot.h"
+
+static u32 get_u32(void *buf)
+{
+ u8 *p = buf;
+
+ return ((u32) p[3] + ((u32) p[2] << 8) + ((u32) p[1] << 16) +
+ ((u32) p[0] << 24));
+}
+
+static u16 get_u16(void *buf)
+{
+ u8 *p = buf;
+
+ return (u16) p[1] + ((u16) p[0] << 8);
+}
+
+__init int
+routerboot_find_tag(u8 *buf, unsigned int buflen, u16 tag_id,
+ u8 **tag_data, u16 *tag_len)
+{
+ uint32_t magic;
+ int ret;
+
+ if (buflen < 4)
+ return -EINVAL;
+
+ magic = get_u32(buf);
+ switch (magic) {
+ case RB_MAGIC_HARD:
+ /* skip magic value */
+ buf += 4;
+ buflen -= 4;
+ break;
+
+ case RB_MAGIC_SOFT:
+ if (buflen < 8)
+ return -EINVAL;
+
+ /* skip magic and CRC value */
+ buf += 8;
+ buflen -= 8;
+
+ break;
+
+ default:
+ return -EINVAL;
+ }
+
+ ret = -ENOENT;
+ while (buflen > 2) {
+ u16 id;
+ u16 len;
+
+ len = get_u16(buf);
+ buf += 2;
+ buflen -= 2;
+
+ if (buflen < 2)
+ break;
+
+ id = get_u16(buf);
+ buf += 2;
+ buflen -= 2;
+
+ if (id == RB_ID_TERMINATOR)
+ break;
+
+ if (buflen < len)
+ break;
+
+ if (id == tag_id) {
+ if (tag_len)
+ *tag_len = len;
+ if (tag_data)
+ *tag_data = buf;
+ ret = 0;
+ break;
+ }
+
+ buf += len;
+ buflen -= len;
+ }
+
+ return ret;
+}
projects / openwrt / openwrt.git / commitdiff