FreeCalypso > hg > freecalypso-reveng

comparison miscprog/pircksum2.c @ 215:d69f7512e3c1

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Pirelli: documented and verified the checksum scheme used for the factory block
author Mychaela Falconia <falcon@freecalypso.org>
date Sun, 25 Dec 2016 23:48:16 +0000
parents
children
comparison
equal deleted inserted replaced
214:6b40617d00e6 215:d69f7512e3c1
1 /*
2 * This program verifies the correctness of the understanding described in the
3 * ../pirelli/flash2-chksum write-up.
4 */
5
6 #include <sys/types.h>
7 #include <sys/file.h>
8 #include <sys/stat.h>
9 #include <sys/mman.h>
10 #include <stdio.h>
11 #include <stdint.h>
12 #include <endian.h>
13 #include <stdlib.h>
14 #include <unistd.h>
15
16 char *image_filename;
17 u_char *image_map, *endrec;
18 unsigned imgsize, max_imgsize;
19
20 open_and_map_file()
21 {
22 int fd;
23 struct stat st;
24
25 fd = open(image_filename, O_RDONLY);
26 if (fd < 0) {
27 perror(image_filename);
28 exit(1);
29 }
30 fstat(fd, &st);
31 if (!S_ISREG(st.st_mode)) {
32 fprintf(stderr, "error: %s is not a regular file\n",
33 image_filename);
34 exit(1);
35 }
36 if (st.st_size != 0x10000 && st.st_size != 0x360000) {
37 fprintf(stderr, "error: %s has an unexpected size\n",
38 image_filename);
39 exit(1);
40 }
41 max_imgsize = st.st_size - 12;
42 image_map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
43 if (image_map == MAP_FAILED) {
44 perror("mmap");
45 exit(1);
46 }
47 close(fd);
48 endrec = image_map + max_imgsize;
49 return 0;
50 }
51
52 verify_chksum1()
53 {
54 uint16_t sum, ref;
55 unsigned offset;
56
57 sum = 0;
58 for (offset = 0; offset + 1 < imgsize; offset += 2)
59 sum += le16toh(*(uint16_t *)(image_map + offset));
60 if (imgsize & 1)
61 sum += image_map[offset];
62 ref = le16toh(*(uint16_t *)(endrec + 8));
63 if (sum == ref) {
64 printf("Checksum 1 matches (%04X)\n", sum);
65 return 0;
66 } else {
67 printf("Checksum 1 FAILED: computed %04X, stored %04X\n",
68 sum, ref);
69 return 1;
70 }
71 }
72
73 verify_chksum2()
74 {
75 uint16_t sum, ref;
76 unsigned offset;
77
78 sum = 0;
79 for (offset = 0; offset < 10; offset += 2)
80 sum += le16toh(*(uint16_t *)(endrec + offset));
81 ref = le16toh(*(uint16_t *)(endrec + 10));
82 if (sum == ref) {
83 printf("Checksum 2 matches (%04X)\n", sum);
84 return 0;
85 } else {
86 printf("Checksum 2 FAILED: computed %04X, stored %04X\n",
87 sum, ref);
88 return 1;
89 }
90 }
91
92 main(argc, argv)
93 char **argv;
94 {
95 int stat1, stat2;
96
97 if (argc != 2) {
98 fprintf(stderr, "usage: %s image-filename\n", argv[0]);
99 exit(1);
100 }
101 image_filename = argv[1];
102 open_and_map_file();
103 if (le32toh(*(uint32_t *)endrec) != 0x12345678) {
104 printf("Error: 0x12345678 signature missing\n");
105 exit(1);
106 }
107 imgsize = le32toh(*(uint32_t *)(endrec + 4));
108 if (imgsize < 1 || imgsize > max_imgsize) {
109 printf("Error: bogus image size of 0x%x bytes\n", imgsize);
110 exit(1);
111 }
112 printf("Image size: 0x%x bytes\n", imgsize);
113 stat1 = verify_chksum1();
114 stat2 = verify_chksum2();
115 exit(stat1 || stat2);
116 }