1 /*
2  * Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
3  * Use of this source code is governed by a BSD-style license that can be
4  * found in the LICENSE file.
5  */
6 
7 #include <stdio.h>
8 #include <string.h>
9 
10 #include "fmap.h"
11 
is_fmap(uint8_t * ptr)12 static int is_fmap(uint8_t *ptr)
13 {
14 	FmapHeader *fmap_header = (FmapHeader *)ptr;
15 
16 	if (0 != memcmp(ptr, FMAP_SIGNATURE, FMAP_SIGNATURE_SIZE))
17 		return 0;
18 
19 	if (fmap_header->fmap_ver_major == FMAP_VER_MAJOR)
20 		return 1;
21 
22 	fprintf(stderr, "Found FMAP, but major version is %u instead of %u\n",
23 		fmap_header->fmap_ver_major, FMAP_VER_MAJOR);
24 	return 0;
25 }
26 
27 /* Find and point to the FMAP header within the buffer */
fmap_find(uint8_t * ptr,size_t size)28 FmapHeader *fmap_find(uint8_t *ptr, size_t size)
29 {
30 	ssize_t offset, align;
31 	ssize_t lim = size - sizeof(FmapHeader);
32 
33 	if (lim >= 0 && is_fmap(ptr))
34 		return (FmapHeader *)ptr;
35 
36 	/* Search large alignments before small ones to find "right" FMAP. */
37 	for (align = FMAP_SEARCH_STRIDE; align <= lim; align *= 2);
38 	for (; align >= FMAP_SEARCH_STRIDE; align /= 2)
39 		for (offset = align; offset <= lim; offset += align * 2)
40 			if (is_fmap(ptr + offset))
41 				return (FmapHeader *)(ptr + offset);
42 
43 	return NULL;
44 }
45 
46 /* Search for an area by name, return pointer to its beginning */
fmap_find_by_name(uint8_t * ptr,size_t size,FmapHeader * fmap,const char * name,FmapAreaHeader ** ah_ptr)47 uint8_t *fmap_find_by_name(uint8_t *ptr, size_t size, FmapHeader *fmap,
48 			   const char *name, FmapAreaHeader **ah_ptr)
49 {
50 	int i;
51 	FmapAreaHeader *ah;
52 
53 	if (!fmap)
54 		fmap = fmap_find(ptr, size);
55 	if (!fmap)
56 		return NULL;
57 
58 	ah = (FmapAreaHeader*)((void *)fmap + sizeof(FmapHeader));
59 	for (i = 0; i < fmap->fmap_nareas; i++)
60 		if (!strncmp(ah[i].area_name, name, FMAP_NAMELEN)) {
61 			if (ah_ptr)
62 				*ah_ptr = ah + i;
63 			return ptr + ah[i].area_offset;
64 		}
65 
66 	return NULL;
67 }
68