xref: /openbsd-src/usr.sbin/installboot/bootstrap.c (revision 33c4b066bb1e3dba50459cc20e55495b3f7b496c)
1 /*
2  * Copyright (c) 2013 Joel Sing <jsing@openbsd.org>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include <sys/param.h>
18 #include <sys/disklabel.h>
19 #include <sys/dkio.h>
20 #include <sys/ioctl.h>
21 #include <sys/stat.h>
22 
23 #include <fcntl.h>
24 #include <stdio.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <unistd.h>
28 
29 #include "installboot.h"
30 
31 int
32 bootstrap(int devfd, char *dev, char *bootfile)
33 {
34 	struct disklabel dl;
35 	struct disklabel *lp;
36 	struct partition *pp;
37 	char *boot, *p, part;
38 	u_int64_t bootend;
39 	struct stat sb;
40 	int bootsize;
41 	int bf, i;
42 
43 	/*
44 	 * Install bootstrap code onto the given disk, preserving the
45 	 * existing disklabel.
46 	 */
47 
48 	/* Read disklabel from disk. */
49 	if (ioctl(devfd, DIOCGDINFO, &dl) == -1)
50 		err(1, "disklabel");
51 	if (dl.d_secsize == 0) {
52 		warnx("disklabel has sector size of 0, assuming %d", DEV_BSIZE);
53 		dl.d_secsize = DEV_BSIZE;
54 	}
55 
56 	/* Read bootstrap file. */
57 	if (verbose)
58 		fprintf(stderr, "reading bootstrap from %s\n", bootfile);
59 	bf = open(bootfile, O_RDONLY);
60 	if (bf < 0)
61 		err(1, "open %s", bootfile);
62 	if (fstat(bf, &sb) != 0)
63 		err(1, "fstat %s", bootfile);
64 	bootsize = sb.st_size;
65 	bootend = howmany((u_int64_t)bootsize, dl.d_secsize);
66 	boot = malloc(bootsize);
67 	if (boot == NULL)
68 		err(1, "malloc");
69 	if (read(bf, boot, bootsize) != bootsize)
70 		err(1, "read");
71 	if (verbose)
72 		fprintf(stderr, "bootstrap is %lld bytes (%llu sectors)\n",
73 		    bootsize, bootend);
74 	close(bf);
75 
76 	/*
77 	 * Check that the bootstrap will fit - partitions must not overlap,
78 	 * or if they do, the partition type must be either FS_BOOT or
79 	 * FS_UNUSED. The 'c' partition will always overlap and is ignored.
80 	 */
81 	if (verbose)
82 		fprintf(stderr, "ensuring used partitions do not overlap "
83 		    "with bootstrap sectors 0-%lld\n", bootend);
84 	for (i = 0; i < dl.d_npartitions; i++) {
85 		part = 'a' + i;
86 		pp = &dl.d_partitions[i];
87 		if (i == RAW_PART)
88 			continue;
89 		if (DL_GETPSIZE(pp) == 0)
90 			continue;
91 		if (bootend <= DL_GETPOFFSET(pp))
92 			continue;
93 		switch (pp->p_fstype) {
94 		case FS_BOOT:
95 			break;
96 		case FS_UNUSED:
97 			warnx("bootstrap overlaps with unused partition %c",
98 			    part);
99 			break;
100 		default:
101 			errx(1, "bootstrap overlaps with partition %c", part);
102 		}
103 	}
104 
105 	/* Make sure the bootstrap has left space for the disklabel. */
106         lp = (struct disklabel *)(boot + (LABELSECTOR * dl.d_secsize) +
107 	    LABELOFFSET);
108 	for (i = 0, p = (char *)lp; i < sizeof(*lp); i++)
109 		if (p[i] != 0)
110 			errx(1, "bootstrap has data in disklabel area");
111 
112 	/* Patch the disklabel into the bootstrap code. */
113 	memcpy(lp, &dl, sizeof(dl));
114 
115 	/* Write the bootstrap out to the disk. */
116 	if (lseek(devfd, 0, SEEK_SET) != 0)
117 		err(1, "lseek");
118 	if (verbose)
119 		fprintf(stderr, "%s bootstrap to disk\n",
120 		    (nowrite ? "would write" : "writing"));
121 	if (nowrite)
122 		return;
123 	if (write(devfd, boot, bootsize) != bootsize)
124 		err(1, "write");
125 }
126