text: /*
   *  linux/tools/build.c
   *
   *  Copyright (C) 1991, 1992  Linus Torvalds
   */
  
  /*
   * This file builds a disk-image from three different files:
   *
   * - bootsect: max 510 bytes of 8086 machine code, loads the rest
   * - setup: max 4 sectors of 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
   */
  
  #include <stdio.h>	/* fprintf */
  #include <string.h>
  #include <stdlib.h>	/* contains exit */
  #include <sys/types.h>	/* unistd.h needs this */
  #include <sys/stat.h>
  #include <sys/sysmacros.h>
  #include <unistd.h>	/* contains read/write */
  #include <fcntl.h>
  #include <linux/config.h>
  #include <linux/a.out.h>
  
  #define MINIX_HEADER 32
  #define GCC_HEADER 1024
  
  #define SYS_SIZE DEF_SYSSIZE
  
  #define DEFAULT_MAJOR_ROOT 0
  #define DEFAULT_MINOR_ROOT 0
  
  /* max nr of sectors of setup: don't change unless you also change
   * bootsect etc */
  #define SETUP_SECTS 4
  
  #define STRINGIFY(x) #x
  
  typedef union {
  	long l;
  	short s[2];
  	char b[4];
  } conv;
  
  long intel_long(long l)
  {
  	conv t;
  
  	t.b[0] = l & 0xff; l >>= 8;
  	t.b[1] = l & 0xff; l >>= 8;
  	t.b[2] = l & 0xff; l >>= 8;
  	t.b[3] = l & 0xff; l >>= 8;
  	return t.l;
  }
  
  short intel_short(short l)
  {
  	conv t;
  
  	t.b[0] = l & 0xff; l >>= 8;
  	t.b[1] = l & 0xff; l >>= 8;
  	return t.s[0];
  }
  
  void die(char * str)
  {
  	fprintf(stderr,"%s\n",str);
  	exit(1);
  }
  
  void usage(void)
  {
  	die("Usage: build bootsect setup system [rootdev] [> image]");
  }
  
  int main(int argc, char ** argv)
  {
  	int i,c,id, sz;
  	unsigned long sys_size;
  	char buf[1024];
  	struct exec *ex = (struct exec *)buf;
  	char major_root, minor_root;
  	struct stat sb;
  
  	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);
  	for (i=0;i<sizeof buf; i++) buf[i]=0;
  	if ((id=open(argv[1],O_RDONLY,0))<0)
  		die("Unable to open 'boot'");
  	if (read(id,buf,MINIX_HEADER) != MINIX_HEADER)
  		die("Unable to read header of 'boot'");
  	if (((long *) buf)[0]!=intel_long(0x04100301))
  		die("Non-Minix header of 'boot'");
  	if (((long *) buf)[1]!=intel_long(MINIX_HEADER))
  		die("Non-Minix header of 'boot'");
  	if (((long *) buf)[3] != 0)
  		die("Illegal data segment in 'boot'");
  	if (((long *) buf)[4] != 0)
  		die("Illegal bss in 'boot'");
  	if (((long *) buf)[5] != 0)
  		die("Non-Minix header of 'boot'");
  	if (((long *) buf)[7] != 0)
  		die("Illegal symbol table in 'boot'");
  	i=read(id,buf,sizeof buf);
  	fprintf(stderr,"Boot sector %d bytes.\n",i);
  	if (i != 512)
  		die("Boot block must be exactly 512 bytes");
  	if ((*(unsigned short *)(buf+510)) != (unsigned short)intel_short(0xAA55))
  		die("Boot block hasn't got boot flag (0xAA55)");
  	buf[508] = (char) minor_root;
  	buf[509] = (char) major_root;	
  	i=write(1,buf,512);
  	if (i!=512)
  		die("Write call failed");
  	close (id);
  	
  	if ((id=open(argv[2],O_RDONLY,0))<0)
  		die("Unable to open 'setup'");
  	if (read(id,buf,MINIX_HEADER) != MINIX_HEADER)
  		die("Unable to read header of 'setup'");
  	if (((long *) buf)[0]!=intel_long(0x04100301))
  		die("Non-Minix header of 'setup'");
  	if (((long *) buf)[1]!=intel_long(MINIX_HEADER))
  		die("Non-Minix header of 'setup'");
  	if (((long *) buf)[3] != 0)
  		die("Illegal data segment in 'setup'");
  	if (((long *) buf)[4] != 0)
  		die("Illegal bss in 'setup'");
  	if (((long *) buf)[5] != 0)
  		die("Non-Minix header of 'setup'");
  	if (((long *) buf)[7] != 0)
  		die("Illegal symbol table in 'setup'");
  	for (i=0 ; (c=read(id,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 (id);
  	if (i > SETUP_SECTS*512)
  		die("Setup exceeds " STRINGIFY(SETUP_SECTS)
  			" sectors - rewrite build/boot/setup");
  	fprintf(stderr,"Setup is %d bytes.\n",i);
  	for (c=0 ; c<sizeof(buf) ; c++)
  		buf[c] = '\0';
  	while (i<SETUP_SECTS*512) {
  		c = SETUP_SECTS*512-i;
  		if (c > sizeof(buf))
  			c = sizeof(buf);
  		if (write(1,buf,c) != c)
  			die("Write call failed");
  		i += c;
  	}
  	
  	if ((id=open(argv[3],O_RDONLY,0))<0)
  		die("Unable to open 'system'");
  	if (read(id,buf,GCC_HEADER) != GCC_HEADER)
  		die("Unable to read header of 'system'");
  	if (N_MAGIC(*ex) != ZMAGIC)
  		die("Non-GCC header of 'system'");
  	fprintf(stderr,"System is %d kB (%d kB code, %d kB data and %d kB bss)\n",
  		(ex->a_text+ex->a_data+ex->a_bss)/1024,
  		ex->a_text /1024,
  		ex->a_data /1024,
  		ex->a_bss  /1024);
  	sz = N_SYMOFF(*ex) - GCC_HEADER + 4;
  	sys_size = (sz + 15) / 16;
  	if (sys_size > SYS_SIZE)
  		die("System is too big");
  	while (sz > 0) {
  		int l, n;
  
  		l = sz;
  		if (l > sizeof(buf))
  			l = sizeof(buf);
  		if ((n=read(id, buf, l)) != l) {
  			if (n == -1) 
  				perror(argv[1]);
  			else
  				fprintf(stderr, "Unexpected EOF\n");
  			die("Can't read 'system'");
  		}
  		if (write(1, buf, l) != l)
  			die("Write failed");
  		sz -= l;
  	}
  	close(id);
  	if (lseek(1,500,0) == 500) {
  		buf[0] = (sys_size & 0xff);
  		buf[1] = ((sys_size >> 8) & 0xff);
  		if (write(1, buf, 2) != 2)
  			die("Write failed");
  	}
  	return(0);
  }
  