1/*
2 *  Copyright (C) 1991, 1992  Linus Torvalds
3 *  Copyright (C) 1997 Martin Mares
4 */
5
6/*
7 * This file builds a disk-image from three different files:
8 *
9 * - bootsect: compatibility mbr which prints an error message if
10 *             someone tries to boot the kernel directly.
11 * - setup: 8086 machine code, sets up system parm
12 * - system: 80386 code for actual system
13 *
14 * It does some checking that all files are of the correct type, and
15 * just writes the result to stdout, removing headers and padding to
16 * the right amount. It also writes some system data to stderr.
17 */
18
19/*
20 * Changes by tytso to allow root device specification
21 * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
22 * Cross compiling fixes by Gertjan van Wingerde, July 1996
23 * Rewritten by Martin Mares, April 1997
24 */
25
26#include <stdio.h>
27#include <string.h>
28#include <stdlib.h>
29#include <stdarg.h>
30#include <sys/types.h>
31#include <sys/stat.h>
32#include <sys/sysmacros.h>
33#include <unistd.h>
34#include <fcntl.h>
35#include <asm/boot.h>
36
37typedef unsigned char byte;
38typedef unsigned short word;
39typedef unsigned long u32;
40
41#define DEFAULT_MAJOR_ROOT 0
42#define DEFAULT_MINOR_ROOT 0
43
44/* Minimal number of setup sectors (see also bootsect.S) */
45#define SETUP_SECTS 4
46
47byte buf[1024];
48int fd;
49int is_big_kernel;
50
51void die(const char * str, ...)
52{
53	va_list args;
54	va_start(args, str);
55	vfprintf(stderr, str, args);
56	fputc('\n', stderr);
57	exit(1);
58}
59
60void file_open(const char *name)
61{
62	if ((fd = open(name, O_RDONLY, 0)) < 0)
63		die("Unable to open `%s': %m", name);
64}
65
66void usage(void)
67{
68	die("Usage: build [-b] bootsect setup system [rootdev] [> image]");
69}
70
71int main(int argc, char ** argv)
72{
73	unsigned int i, c, sz, setup_sectors;
74	u32 sys_size;
75	byte major_root, minor_root;
76	struct stat sb;
77
78	if (argc > 2 && !strcmp(argv[1], "-b"))
79	  {
80	    is_big_kernel = 1;
81	    argc--, argv++;
82	  }
83	if ((argc < 4) || (argc > 5))
84		usage();
85	if (argc > 4) {
86		if (!strcmp(argv[4], "CURRENT")) {
87			if (stat("/", &sb)) {
88				perror("/");
89				die("Couldn't stat /");
90			}
91			major_root = major(sb.st_dev);
92			minor_root = minor(sb.st_dev);
93		} else if (strcmp(argv[4], "FLOPPY")) {
94			if (stat(argv[4], &sb)) {
95				perror(argv[4]);
96				die("Couldn't stat root device.");
97			}
98			major_root = major(sb.st_rdev);
99			minor_root = minor(sb.st_rdev);
100		} else {
101			major_root = 0;
102			minor_root = 0;
103		}
104	} else {
105		major_root = DEFAULT_MAJOR_ROOT;
106		minor_root = DEFAULT_MINOR_ROOT;
107	}
108	fprintf(stderr, "Root device is (%d, %d)\n", major_root, minor_root);
109
110	file_open(argv[1]);
111	i = read(fd, buf, sizeof(buf));
112	fprintf(stderr,"Boot sector %d bytes.\n",i);
113	if (i != 512)
114		die("Boot block must be exactly 512 bytes");
115	if (buf[510] != 0x55 || buf[511] != 0xaa)
116		die("Boot block hasn't got boot flag (0xAA55)");
117	buf[508] = minor_root;
118	buf[509] = major_root;
119	if (write(1, buf, 512) != 512)
120		die("Write call failed");
121	close (fd);
122
123	file_open(argv[2]);				    /* Copy the setup code */
124	for (i=0 ; (c=read(fd, buf, sizeof(buf)))>0 ; i+=c )
125		if (write(1, buf, c) != c)
126			die("Write call failed");
127	if (c != 0)
128		die("read-error on `setup'");
129	close (fd);
130
131	setup_sectors = (i + 511) / 512;	/* Pad unused space with zeros */
132	/* for compatibility with ancient versions of LILO. */
133	if (setup_sectors < SETUP_SECTS)
134		setup_sectors = SETUP_SECTS;
135	fprintf(stderr, "Setup is %d bytes.\n", i);
136	memset(buf, 0, sizeof(buf));
137	while (i < setup_sectors * 512) {
138		c = setup_sectors * 512 - i;
139		if (c > sizeof(buf))
140			c = sizeof(buf);
141		if (write(1, buf, c) != c)
142			die("Write call failed");
143		i += c;
144	}
145
146	file_open(argv[3]);
147	if (fstat (fd, &sb))
148		die("Unable to stat `%s': %m", argv[3]);
149	sz = sb.st_size;
150	fprintf (stderr, "System is %d kB\n", sz/1024);
151	sys_size = (sz + 15) / 16;
152	if (!is_big_kernel && sys_size > DEF_SYSSIZE)
153		die("System is too big. Try using bzImage or modules.");
154	while (sz > 0) {
155		int l, n;
156
157		l = (sz > sizeof(buf)) ? sizeof(buf) : sz;
158		if ((n=read(fd, buf, l)) != l) {
159			if (n < 0)
160				die("Error reading %s: %m", argv[3]);
161			else
162				die("%s: Unexpected EOF", argv[3]);
163		}
164		if (write(1, buf, l) != l)
165			die("Write failed");
166		sz -= l;
167	}
168	close(fd);
169
170	if (lseek(1, 497, SEEK_SET) != 497)		    /* Write sizes to the bootsector */
171		die("Output: seek failed");
172	buf[0] = setup_sectors;
173	if (write(1, buf, 1) != 1)
174		die("Write of setup sector count failed");
175	if (lseek(1, 500, SEEK_SET) != 500)
176		die("Output: seek failed");
177	buf[0] = (sys_size & 0xff);
178	buf[1] = ((sys_size >> 8) & 0xff);
179	buf[2] = ((sys_size >> 16) & 0xff);
180	buf[3] = ((sys_size >> 24) & 0xff);
181	if (write(1, buf, 4) != 4)
182		die("Write of image length failed");
183
184	return 0;					    /* Everything is OK */
185}
186