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build.c

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00001 /*
00002  *  $Id: build.c,v 1.5 1997/05/19 12:29:58 mj Exp $
00003  *
00004  *  Copyright (C) 1991, 1992  Linus Torvalds
00005  *  Copyright (C) 1997 Martin Mares
00006  */
00007 
00008 /*
00009  * This file builds a disk-image from three different files:
00010  *
00011  * - bootsect: exactly 512 bytes of 8086 machine code, loads the rest
00012  * - setup: 8086 machine code, sets up system parm
00013  * - system: 80386 code for actual system
00014  *
00015  * It does some checking that all files are of the correct type, and
00016  * just writes the result to stdout, removing headers and padding to
00017  * the right amount. It also writes some system data to stderr.
00018  */
00019 
00020 /*
00021  * Changes by tytso to allow root device specification
00022  * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
00023  * Cross compiling fixes by Gertjan van Wingerde, July 1996
00024  * Rewritten by Martin Mares, April 1997
00025  */
00026 
00027 #include <stdio.h>
00028 #include <string.h>
00029 #include <stdlib.h>
00030 #include <stdarg.h>
00031 #include <sys/types.h>
00032 #include <sys/stat.h>
00033 #include <sys/sysmacros.h>
00034 #include <unistd.h>
00035 #include <fcntl.h>
00036 #include <asm/boot.h>
00037 
00038 typedef unsigned char byte;
00039 typedef unsigned short word;
00040 typedef unsigned long u32;
00041 
00042 #define DEFAULT_MAJOR_ROOT 0
00043 #define DEFAULT_MINOR_ROOT 0
00044 
00045 /* Minimal number of setup sectors (see also bootsect.S) */
00046 #define SETUP_SECTS 4
00047 
00048 byte buf[1024];
00049 int fd;
00050 int is_big_kernel;
00051 
00052 void die(const char * str, ...)
00053 {
00054         va_list args;
00055         va_start(args, str);
00056         vfprintf(stderr, str, args);
00057         fputc('\n', stderr);
00058         exit(1);
00059 }
00060 
00061 void file_open(const char *name)
00062 {
00063         if ((fd = open(name, O_RDONLY, 0)) < 0)
00064                 die("Unable to open `%s': %m", name);
00065 }
00066 
00067 void usage(void)
00068 {
00069         die("Usage: build [-b] bootsect setup system [rootdev] [> image]");
00070 }
00071 
00072 int main(int argc, char ** argv)
00073 {
00074         unsigned int i, c, sz, setup_sectors;
00075         u32 sys_size;
00076         byte major_root, minor_root;
00077         struct stat sb;
00078 
00079         if (argc > 2 && !strcmp(argv[1], "-b"))
00080           {
00081             is_big_kernel = 1;
00082             argc--, argv++;
00083           }
00084         if ((argc < 4) || (argc > 5))
00085                 usage();
00086         if (argc > 4) {
00087                 if (!strcmp(argv[4], "CURRENT")) {
00088                         if (stat("/", &sb)) {
00089                                 perror("/");
00090                                 die("Couldn't stat /");
00091                         }
00092                         major_root = major(sb.st_dev);
00093                         minor_root = minor(sb.st_dev);
00094                 } else if (strcmp(argv[4], "FLOPPY")) {
00095                         if (stat(argv[4], &sb)) {
00096                                 perror(argv[4]);
00097                                 die("Couldn't stat root device.");
00098                         }
00099                         major_root = major(sb.st_rdev);
00100                         minor_root = minor(sb.st_rdev);
00101                 } else {
00102                         major_root = 0;
00103                         minor_root = 0;
00104                 }
00105         } else {
00106                 major_root = DEFAULT_MAJOR_ROOT;
00107                 minor_root = DEFAULT_MINOR_ROOT;
00108         }
00109         fprintf(stderr, "Root device is (%d, %d)\n", major_root, minor_root);
00110 
00111         file_open(argv[1]);
00112         i = read(fd, buf, sizeof(buf));
00113         fprintf(stderr,"Boot sector %d bytes.\n",i);
00114         if (i != 512)
00115                 die("Boot block must be exactly 512 bytes");
00116         if (buf[510] != 0x55 || buf[511] != 0xaa)
00117                 die("Boot block hasn't got boot flag (0xAA55)");
00118         buf[508] = minor_root;
00119         buf[509] = major_root;
00120         if (write(1, buf, 512) != 512)
00121                 die("Write call failed");
00122         close (fd);
00123 
00124         file_open(argv[2]);                                 /* Copy the setup code */
00125         for (i=0 ; (c=read(fd, buf, sizeof(buf)))>0 ; i+=c )
00126                 if (write(1, buf, c) != c)
00127                         die("Write call failed");
00128         if (c != 0)
00129                 die("read-error on `setup'");
00130         close (fd);
00131 
00132         setup_sectors = (i + 511) / 512;        /* Pad unused space with zeros */
00133         /* for compatibility with ancient versions of LILO. */
00134         if (setup_sectors < SETUP_SECTS)
00135                 setup_sectors = SETUP_SECTS;
00136         fprintf(stderr, "Setup is %d bytes.\n", i);
00137         memset(buf, 0, sizeof(buf));
00138         while (i < setup_sectors * 512) {
00139                 c = setup_sectors * 512 - i;
00140                 if (c > sizeof(buf))
00141                         c = sizeof(buf);
00142                 if (write(1, buf, c) != c)
00143                         die("Write call failed");
00144                 i += c;
00145         }
00146 
00147         file_open(argv[3]);
00148         if (fstat (fd, &sb))
00149                 die("Unable to stat `%s': %m", argv[3]);
00150         sz = sb.st_size;
00151         fprintf (stderr, "System is %d kB\n", sz/1024);
00152         sys_size = (sz + 15) / 16;
00153         /* 0x28000*16 = 2.5 MB, conservative estimate for the current maximum */
00154         if (sys_size > (is_big_kernel ? 0x28000 : DEF_SYSSIZE))
00155                 die("System is too big. Try using %smodules.",
00156                         is_big_kernel ? "" : "bzImage or ");
00157         if (sys_size > 0xefff)
00158                 fprintf(stderr,"warning: kernel is too big for standalone boot "
00159                     "from floppy\n");
00160         while (sz > 0) {
00161                 int l, n;
00162 
00163                 l = (sz > sizeof(buf)) ? sizeof(buf) : sz;
00164                 if ((n=read(fd, buf, l)) != l) {
00165                         if (n < 0)
00166                                 die("Error reading %s: %m", argv[3]);
00167                         else
00168                                 die("%s: Unexpected EOF", argv[3]);
00169                 }
00170                 if (write(1, buf, l) != l)
00171                         die("Write failed");
00172                 sz -= l;
00173         }
00174         close(fd);
00175 
00176         if (lseek(1, 497, SEEK_SET) != 497)                 /* Write sizes to the bootsector */
00177                 die("Output: seek failed");
00178         buf[0] = setup_sectors;
00179         if (write(1, buf, 1) != 1)
00180                 die("Write of setup sector count failed");
00181         if (lseek(1, 500, SEEK_SET) != 500)
00182                 die("Output: seek failed");
00183         buf[0] = (sys_size & 0xff);
00184         buf[1] = ((sys_size >> 8) & 0xff);
00185         if (write(1, buf, 2) != 2)
00186                 die("Write of image length failed");
00187 
00188         return 0;                                           /* Everything is OK */
00189 }
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