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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright (C) 1997 Martin Mares
*/
/*
* This file builds a disk-image from three different files:
*
* - bootsect: exactly 512 bytes of 8086 machine code, loads the rest
* - setup: 8086 machine code, sets up system parm
* - system: 80386 code for actual system
*
* It does some checking that all files are of the correct type, and
* just writes the result to stdout, removing headers and padding to
* the right amount. It also writes some system data to stderr.
*/
/*
* Changes by tytso to allow root device specification
* High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
* Cross compiling fixes by Gertjan van Wingerde, July 1996
* Rewritten by Martin Mares, April 1997
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include <unistd.h>
#include <fcntl.h>
#include <asm/boot.h>
#define DEFAULT_MAJOR_ROOT 0
#define DEFAULT_MINOR_ROOT 0
/* Minimal number of setup sectors (see also bootsect.S) */
#define SETUP_SECTS 4
uint8_t buf[1024];
int fd;
int is_big_kernel;
__attribute__((noreturn))
void die(const char *str, ...)
{
va_list args;
va_start(args, str);
vfprintf(stderr, str, args);
fputc('\n', stderr);
exit(1);
}
void file_open(const char *name)
{
fd = open(name, O_RDONLY, 0);
if (fd < 0)
die("Unable to open `%s': %m", name);
}
__attribute__((noreturn))
void usage(void)
{
die("Usage: build [-b] bootsect setup system [rootdev] [> image]");
}
int main(int argc, char **argv)
{
unsigned int i, c, sz, setup_sectors;
uint32_t sys_size;
uint8_t major_root, minor_root;
struct stat sb;
if (argc > 2 && !strcmp(argv[1], "-b")) {
is_big_kernel = 1;
argc--, argv++;
}
if ((argc < 4) || (argc > 5))
usage();
if (argc > 4) {
if (!strcmp(argv[4], "CURRENT")) {
if (stat("/", &sb)) {
perror("/");
die("Couldn't stat /");
}
major_root = major(sb.st_dev);
minor_root = minor(sb.st_dev);
} else if (strcmp(argv[4], "FLOPPY")) {
if (stat(argv[4], &sb)) {
perror(argv[4]);
die("Couldn't stat root device.");
}
major_root = major(sb.st_rdev);
minor_root = minor(sb.st_rdev);
} else {
major_root = 0;
minor_root = 0;
}
} else {
major_root = DEFAULT_MAJOR_ROOT;
minor_root = DEFAULT_MINOR_ROOT;
}
fprintf(stderr, "Root device is (%d, %d)\n", major_root, minor_root);
file_open(argv[1]);
i = read(fd, buf, sizeof(buf));
fprintf(stderr, "Boot sector %d bytes.\n", i);
if (i != 512)
die("Boot block must be exactly 512 bytes");
if (buf[510] != 0x55 || buf[511] != 0xaa)
die("Boot block hasn't got boot flag (0xAA55)");
buf[508] = minor_root;
buf[509] = major_root;
if (write(1, buf, 512) != 512)
die("Write call failed");
close(fd);
/* Copy the setup code */
file_open(argv[2]);
for (i = 0; (c = read(fd, buf, sizeof(buf))) > 0; i += c)
if (write(1, buf, c) != c)
die("Write call failed");
if (c != 0)
die("read-error on `setup'");
close(fd);
/* Pad unused space with zeros */
setup_sectors = (i + 511) / 512;
/* for compatibility with ancient versions of LILO. */
if (setup_sectors < SETUP_SECTS)
setup_sectors = SETUP_SECTS;
fprintf(stderr, "Setup is %d bytes.\n", i);
memset(buf, 0, sizeof(buf));
while (i < setup_sectors * 512) {
c = setup_sectors * 512 - i;
if (c > sizeof(buf))
c = sizeof(buf);
if (write(1, buf, c) != c)
die("Write call failed");
i += c;
}
file_open(argv[3]);
if (fstat(fd, &sb))
die("Unable to stat `%s': %m", argv[3]);
sz = sb.st_size;
fprintf(stderr, "System is %d kB\n", sz / 1024);
sys_size = (sz + 15) / 16;
/* 0x28000*16 = 2.5 MB, conservative estimate for the current maximum */
if (sys_size > (is_big_kernel ? 0x28000 : DEF_SYSSIZE))
die("System is too big. Try using %smodules.",
is_big_kernel ? "" : "bzImage or ");
if (sys_size > 0xffff)
fprintf(stderr,
"warning: kernel is too big for standalone boot "
"from floppy\n");
while (sz > 0) {
int l, n;
l = (sz > sizeof(buf)) ? sizeof(buf) : sz;
n = read(fd, buf, l);
if (n != l) {
if (n < 0)
die("Error reading %s: %m", argv[3]);
else
die("%s: Unexpected EOF", argv[3]);
}
if (write(1, buf, l) != l)
die("Write failed");
sz -= l;
}
close(fd);
/* Write sizes to the bootsector */
if (lseek(1, 497, SEEK_SET) != 497)
die("Output: seek failed");
buf[0] = setup_sectors;
if (write(1, buf, 1) != 1)
die("Write of setup sector count failed");
if (lseek(1, 500, SEEK_SET) != 500)
die("Output: seek failed");
buf[0] = (sys_size & 0xff);
buf[1] = ((sys_size >> 8) & 0xff);
if (write(1, buf, 2) != 2)
die("Write of image length failed");
return 0;
}
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