1/*
2 *  $Id: build.c,v 1.1.1.1 2008/10/15 03:26:02 james26_jang Exp $
3 *
4 *  Copyright (C) 1991, 1992  Linus Torvalds
5 *  Copyright (C) 1997 Martin Mares
6 */
7
8/*
9 * This file builds a disk-image from three different files:
10 *
11 * - bootsect: exactly 512 bytes of 8086 machine code, loads the rest
12 * - setup: 8086 machine code, sets up system parm
13 * - system: 80386 code for actual system
14 *
15 * It does some checking that all files are of the correct type, and
16 * just writes the result to stdout, removing headers and padding to
17 * the right amount. It also writes some system data to stderr.
18 */
19
20/*
21 * Changes by tytso to allow root device specification
22 * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
23 * Cross compiling fixes by Gertjan van Wingerde, July 1996
24 * Rewritten by Martin Mares, April 1997
25 */
26
27#include <stdio.h>
28#include <string.h>
29#include <stdlib.h>
30#include <stdarg.h>
31#include <sys/types.h>
32#include <sys/stat.h>
33#include <sys/sysmacros.h>
34#include <unistd.h>
35#include <fcntl.h>
36#include <asm/boot.h>
37
38typedef unsigned char byte;
39typedef unsigned short word;
40typedef unsigned long u32;
41
42#define DEFAULT_MAJOR_ROOT 0
43#define DEFAULT_MINOR_ROOT 0
44
45/* Minimal number of setup sectors (see also bootsect.S) */
46#define SETUP_SECTS 4
47
48byte buf[1024];
49int fd;
50int is_big_kernel;
51
52void die(const char * str, ...)
53{
54	va_list args;
55	va_start(args, str);
56	vfprintf(stderr, str, args);
57	fputc('\n', stderr);
58	exit(1);
59}
60
61void file_open(const char *name)
62{
63	if ((fd = open(name, O_RDONLY, 0)) < 0)
64		die("Unable to open `%s': %m", name);
65}
66
67void usage(void)
68{
69	die("Usage: build [-b] bootsect setup system [rootdev] [> image]");
70}
71
72int main(int argc, char ** argv)
73{
74	unsigned int i, c, sz, setup_sectors;
75	u32 sys_size;
76	byte major_root, minor_root;
77	struct stat sb;
78
79	if (argc > 2 && !strcmp(argv[1], "-b"))
80	  {
81	    is_big_kernel = 1;
82	    argc--, argv++;
83	  }
84	if ((argc < 4) || (argc > 5))
85		usage();
86	if (argc > 4) {
87		if (!strcmp(argv[4], "CURRENT")) {
88			if (stat("/", &sb)) {
89				perror("/");
90				die("Couldn't stat /");
91			}
92			major_root = major(sb.st_dev);
93			minor_root = minor(sb.st_dev);
94		} else if (strcmp(argv[4], "FLOPPY")) {
95			if (stat(argv[4], &sb)) {
96				perror(argv[4]);
97				die("Couldn't stat root device.");
98			}
99			major_root = major(sb.st_rdev);
100			minor_root = minor(sb.st_rdev);
101		} else {
102			major_root = 0;
103			minor_root = 0;
104		}
105	} else {
106		major_root = DEFAULT_MAJOR_ROOT;
107		minor_root = DEFAULT_MINOR_ROOT;
108	}
109	fprintf(stderr, "Root device is (%d, %d)\n", major_root, minor_root);
110
111	file_open(argv[1]);
112	i = read(fd, buf, sizeof(buf));
113	fprintf(stderr,"Boot sector %d bytes.\n",i);
114	if (i != 512)
115		die("Boot block must be exactly 512 bytes");
116	if (buf[510] != 0x55 || buf[511] != 0xaa)
117		die("Boot block hasn't got boot flag (0xAA55)");
118	buf[508] = minor_root;
119	buf[509] = major_root;
120	if (write(1, buf, 512) != 512)
121		die("Write call failed");
122	close (fd);
123
124	file_open(argv[2]);				    /* Copy the setup code */
125	for (i=0 ; (c=read(fd, buf, sizeof(buf)))>0 ; i+=c )
126		if (write(1, buf, c) != c)
127			die("Write call failed");
128	if (c != 0)
129		die("read-error on `setup'");
130	close (fd);
131
132	setup_sectors = (i + 511) / 512;	/* Pad unused space with zeros */
133	/* for compatibility with ancient versions of LILO. */
134	if (setup_sectors < SETUP_SECTS)
135		setup_sectors = SETUP_SECTS;
136	fprintf(stderr, "Setup is %d bytes.\n", i);
137	memset(buf, 0, sizeof(buf));
138	while (i < setup_sectors * 512) {
139		c = setup_sectors * 512 - i;
140		if (c > sizeof(buf))
141			c = sizeof(buf);
142		if (write(1, buf, c) != c)
143			die("Write call failed");
144		i += c;
145	}
146
147	file_open(argv[3]);
148	if (fstat (fd, &sb))
149		die("Unable to stat `%s': %m", argv[3]);
150	sz = sb.st_size;
151	fprintf (stderr, "System is %d kB\n", sz/1024);
152	sys_size = (sz + 15) / 16;
153	/* 0x28000*16 = 2.5 MB, conservative estimate for the current maximum */
154	if (sys_size > (is_big_kernel ? 0x28000 : DEF_SYSSIZE))
155		die("System is too big. Try using %smodules.",
156			is_big_kernel ? "" : "bzImage or ");
157	if (sys_size > 0xefff)
158		fprintf(stderr,"warning: kernel is too big for standalone boot "
159		    "from floppy\n");
160	while (sz > 0) {
161		int l, n;
162
163		l = (sz > sizeof(buf)) ? sizeof(buf) : sz;
164		if ((n=read(fd, buf, l)) != l) {
165			if (n < 0)
166				die("Error reading %s: %m", argv[3]);
167			else
168				die("%s: Unexpected EOF", argv[3]);
169		}
170		if (write(1, buf, l) != l)
171			die("Write failed");
172		sz -= l;
173	}
174	close(fd);
175
176	if (lseek(1, 497, SEEK_SET) != 497)		    /* Write sizes to the bootsector */
177		die("Output: seek failed");
178	buf[0] = setup_sectors;
179	if (write(1, buf, 1) != 1)
180		die("Write of setup sector count failed");
181	if (lseek(1, 500, SEEK_SET) != 500)
182		die("Output: seek failed");
183	buf[0] = (sys_size & 0xff);
184	buf[1] = ((sys_size >> 8) & 0xff);
185	if (write(1, buf, 2) != 2)
186		die("Write of image length failed");
187
188	return 0;					    /* Everything is OK */
189}
190