1 /* ----------------------------------------------------------------------- *
2 *
3 * Copyright 2007-2008 H. Peter Anvin - All Rights Reserved
4 *
5 * Permission is hereby granted, free of charge, to any person
6 * obtaining a copy of this software and associated documentation
7 * files (the "Software"), to deal in the Software without
8 * restriction, including without limitation the rights to use,
9 * copy, modify, merge, publish, distribute, sublicense, and/or
10 * sell copies of the Software, and to permit persons to whom
11 * the Software is furnished to do so, subject to the following
12 * conditions:
13 *
14 * The above copyright notice and this permission notice shall
15 * be included in all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
18 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
19 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
20 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
21 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
22 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
23 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
24 * OTHER DEALINGS IN THE SOFTWARE.
25 *
26 * ----------------------------------------------------------------------- */
27
28 /*
29 * syslinux/getadv.c
30 *
31 * Get a data item from the auxilliary data vector. Returns a pointer
32 * and sets *size on success; NULL on failure.
33 */
34
35 #include <syslinux/adv.h>
36 #include <klibc/compiler.h>
37 #include <inttypes.h>
38
syslinux_getadv(int tag,size_t * size)39 __export const void *syslinux_getadv(int tag, size_t * size)
40 {
41 const uint8_t *p;
42 size_t left;
43
44 p = syslinux_adv_ptr();
45 left = syslinux_adv_size();
46
47 while (left >= 2) {
48 uint8_t ptag = *p++;
49 size_t plen = *p++;
50 left -= 2;
51
52 if (ptag == ADV_END)
53 return NULL; /* Not found */
54
55 if (left < plen)
56 return NULL; /* Item overrun */
57
58 if (ptag == tag) {
59 *size = plen;
60 return p;
61 }
62
63 p += plen;
64 left -= plen;
65 }
66
67 return NULL;
68 }
69