1 /* This utility makes a bootblock suitable for the SRM console/miniloader */
2
3 /* Usage:
4 * mkbb <device> <lxboot>
5 *
6 * Where <device> is the name of the device to install the bootblock on,
7 * and <lxboot> is the name of a bootblock to merge in. This bootblock
8 * contains the offset and size of the bootloader. It must be exactly
9 * 512 bytes long.
10 */
11
12 #include <fcntl.h>
13 #include <unistd.h>
14 #include <stdio.h>
15
16 /* Minimal definition of disklabel, so we don't have to include
17 * asm/disklabel.h (confuses make)
18 */
19 #ifndef MAXPARTITIONS
20 #define MAXPARTITIONS 8 /* max. # of partitions */
21 #endif
22
23 #ifndef u8
24 #define u8 unsigned char
25 #endif
26
27 #ifndef u16
28 #define u16 unsigned short
29 #endif
30
31 #ifndef u32
32 #define u32 unsigned int
33 #endif
34
35 struct disklabel {
36 u32 d_magic; /* must be DISKLABELMAGIC */
37 u16 d_type, d_subtype;
38 u8 d_typename[16];
39 u8 d_packname[16];
40 u32 d_secsize;
41 u32 d_nsectors;
42 u32 d_ntracks;
43 u32 d_ncylinders;
44 u32 d_secpercyl;
45 u32 d_secprtunit;
46 u16 d_sparespertrack;
47 u16 d_sparespercyl;
48 u32 d_acylinders;
49 u16 d_rpm, d_interleave, d_trackskew, d_cylskew;
50 u32 d_headswitch, d_trkseek, d_flags;
51 u32 d_drivedata[5];
52 u32 d_spare[5];
53 u32 d_magic2; /* must be DISKLABELMAGIC */
54 u16 d_checksum;
55 u16 d_npartitions;
56 u32 d_bbsize, d_sbsize;
57 struct d_partition {
58 u32 p_size;
59 u32 p_offset;
60 u32 p_fsize;
61 u8 p_fstype;
62 u8 p_frag;
63 u16 p_cpg;
64 } d_partitions[MAXPARTITIONS];
65 };
66
67
68 typedef union __bootblock {
69 struct {
70 char __pad1[64];
71 struct disklabel __label;
72 } __u1;
73 struct {
74 unsigned long __pad2[63];
75 unsigned long __checksum;
76 } __u2;
77 char bootblock_bytes[512];
78 unsigned long bootblock_quadwords[64];
79 } bootblock;
80
81 #define bootblock_label __u1.__label
82 #define bootblock_checksum __u2.__checksum
83
main(int argc,char ** argv)84 main(int argc, char ** argv)
85 {
86 bootblock bootblock_from_disk;
87 bootblock bootloader_image;
88 int dev, fd;
89 int i;
90 int nread;
91
92 /* Make sure of the arg count */
93 if(argc != 3) {
94 fprintf(stderr, "Usage: %s device lxboot\n", argv[0]);
95 exit(0);
96 }
97
98 /* First, open the device and make sure it's accessible */
99 dev = open(argv[1], O_RDWR);
100 if(dev < 0) {
101 perror(argv[1]);
102 exit(0);
103 }
104
105 /* Now open the lxboot and make sure it's reasonable */
106 fd = open(argv[2], O_RDONLY);
107 if(fd < 0) {
108 perror(argv[2]);
109 close(dev);
110 exit(0);
111 }
112
113 /* Read in the lxboot */
114 nread = read(fd, &bootloader_image, sizeof(bootblock));
115 if(nread != sizeof(bootblock)) {
116 perror("lxboot read");
117 fprintf(stderr, "expected %d, got %d\n", sizeof(bootblock), nread);
118 exit(0);
119 }
120
121 /* Read in the bootblock from disk. */
122 nread = read(dev, &bootblock_from_disk, sizeof(bootblock));
123 if(nread != sizeof(bootblock)) {
124 perror("bootblock read");
125 fprintf(stderr, "expected %d, got %d\n", sizeof(bootblock), nread);
126 exit(0);
127 }
128
129 /* Swap the bootblock's disklabel into the bootloader */
130 bootloader_image.bootblock_label = bootblock_from_disk.bootblock_label;
131
132 /* Calculate the bootblock checksum */
133 bootloader_image.bootblock_checksum = 0;
134 for(i = 0; i < 63; i++) {
135 bootloader_image.bootblock_checksum +=
136 bootloader_image.bootblock_quadwords[i];
137 }
138
139 /* Write the whole thing out! */
140 lseek(dev, 0L, SEEK_SET);
141 if(write(dev, &bootloader_image, sizeof(bootblock)) != sizeof(bootblock)) {
142 perror("bootblock write");
143 exit(0);
144 }
145
146 close(fd);
147 close(dev);
148 exit(0);
149 }
150
151
152