root/tools/build.c

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DEFINITIONS

This source file includes following definitions.
  1. intel_long
  2. intel_short
  3. die
  4. usage
  5. main

   1 /*
   2  *  linux/tools/build.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 /*
   8  * This file builds a disk-image from three different files:
   9  *
  10  * - bootsect: exactly 512 bytes of 8086 machine code, loads the rest
  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  */
  22 
  23 #include <stdio.h>      /* fprintf */
  24 #include <string.h>
  25 #include <stdlib.h>     /* contains exit */
  26 #include <sys/types.h>  /* unistd.h needs this */
  27 #include <sys/stat.h>
  28 #include <sys/sysmacros.h>
  29 #include <unistd.h>     /* contains read/write */
  30 #include <fcntl.h>
  31 #include <linux/config.h>
  32 #include <linux/a.out.h>
  33 
  34 #define MINIX_HEADER 32
  35 
  36 #define N_MAGIC_OFFSET 1024
  37 static int GCC_HEADER = sizeof(struct exec);
  38 
  39 #define SYS_SIZE DEF_SYSSIZE
  40 
  41 #define DEFAULT_MAJOR_ROOT 0
  42 #define DEFAULT_MINOR_ROOT 0
  43 
  44 /* max nr of sectors of setup: don't change unless you also change
  45  * bootsect etc */
  46 #define SETUP_SECTS 4
  47 
  48 #define STRINGIFY(x) #x
  49 
  50 typedef union {
  51         long l;
  52         short s[2];
  53         char b[4];
  54 } conv;
  55 
  56 long intel_long(long l)
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  57 {
  58         conv t;
  59 
  60         t.b[0] = l & 0xff; l >>= 8;
  61         t.b[1] = l & 0xff; l >>= 8;
  62         t.b[2] = l & 0xff; l >>= 8;
  63         t.b[3] = l & 0xff; l >>= 8;
  64         return t.l;
  65 }
  66 
  67 short intel_short(short l)
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  68 {
  69         conv t;
  70 
  71         t.b[0] = l & 0xff; l >>= 8;
  72         t.b[1] = l & 0xff; l >>= 8;
  73         return t.s[0];
  74 }
  75 
  76 void die(char * str)
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  77 {
  78         fprintf(stderr,"%s\n",str);
  79         exit(1);
  80 }
  81 
  82 void usage(void)
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  83 {
  84         die("Usage: build bootsect setup system [rootdev] [> image]");
  85 }
  86 
  87 int main(int argc, char ** argv)
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  88 {
  89         int i,c,id, sz;
  90         unsigned long sys_size;
  91         char buf[1024];
  92         struct exec *ex = (struct exec *)buf;
  93         char major_root, minor_root;
  94         struct stat sb;
  95         unsigned char setup_sectors;
  96 
  97         if ((argc < 4) || (argc > 5))
  98                 usage();
  99         if (argc > 4) {
 100                 if (!strcmp(argv[4], "CURRENT")) {
 101                         if (stat("/", &sb)) {
 102                                 perror("/");
 103                                 die("Couldn't stat /");
 104                         }
 105                         major_root = major(sb.st_dev);
 106                         minor_root = minor(sb.st_dev);
 107                 } else if (strcmp(argv[4], "FLOPPY")) {
 108                         if (stat(argv[4], &sb)) {
 109                                 perror(argv[4]);
 110                                 die("Couldn't stat root device.");
 111                         }
 112                         major_root = major(sb.st_rdev);
 113                         minor_root = minor(sb.st_rdev);
 114                 } else {
 115                         major_root = 0;
 116                         minor_root = 0;
 117                 }
 118         } else {
 119                 major_root = DEFAULT_MAJOR_ROOT;
 120                 minor_root = DEFAULT_MINOR_ROOT;
 121         }
 122         fprintf(stderr, "Root device is (%d, %d)\n", major_root, minor_root);
 123         for (i=0;i<sizeof buf; i++) buf[i]=0;
 124         if ((id=open(argv[1],O_RDONLY,0))<0)
 125                 die("Unable to open 'boot'");
 126         if (read(id,buf,MINIX_HEADER) != MINIX_HEADER)
 127                 die("Unable to read header of 'boot'");
 128         if (((long *) buf)[0]!=intel_long(0x04100301))
 129                 die("Non-Minix header of 'boot'");
 130         if (((long *) buf)[1]!=intel_long(MINIX_HEADER))
 131                 die("Non-Minix header of 'boot'");
 132         if (((long *) buf)[3] != 0)
 133                 die("Illegal data segment in 'boot'");
 134         if (((long *) buf)[4] != 0)
 135                 die("Illegal bss in 'boot'");
 136         if (((long *) buf)[5] != 0)
 137                 die("Non-Minix header of 'boot'");
 138         if (((long *) buf)[7] != 0)
 139                 die("Illegal symbol table in 'boot'");
 140         i=read(id,buf,sizeof buf);
 141         fprintf(stderr,"Boot sector %d bytes.\n",i);
 142         if (i != 512)
 143                 die("Boot block must be exactly 512 bytes");
 144         if ((*(unsigned short *)(buf+510)) != (unsigned short)intel_short(0xAA55))
 145                 die("Boot block hasn't got boot flag (0xAA55)");
 146         buf[508] = (char) minor_root;
 147         buf[509] = (char) major_root;   
 148         i=write(1,buf,512);
 149         if (i!=512)
 150                 die("Write call failed");
 151         close (id);
 152         
 153         if ((id=open(argv[2],O_RDONLY,0))<0)
 154                 die("Unable to open 'setup'");
 155         if (read(id,buf,MINIX_HEADER) != MINIX_HEADER)
 156                 die("Unable to read header of 'setup'");
 157         if (((long *) buf)[0]!=intel_long(0x04100301))
 158                 die("Non-Minix header of 'setup'");
 159         if (((long *) buf)[1]!=intel_long(MINIX_HEADER))
 160                 die("Non-Minix header of 'setup'");
 161         if (((long *) buf)[3] != 0)
 162                 die("Illegal data segment in 'setup'");
 163         if (((long *) buf)[4] != 0)
 164                 die("Illegal bss in 'setup'");
 165         if (((long *) buf)[5] != 0)
 166                 die("Non-Minix header of 'setup'");
 167         if (((long *) buf)[7] != 0)
 168                 die("Illegal symbol table in 'setup'");
 169         for (i=0 ; (c=read(id,buf,sizeof buf))>0 ; i+=c )
 170                 if (write(1,buf,c)!=c)
 171                         die("Write call failed");
 172         if (c != 0)
 173                 die("read-error on 'setup'");
 174         close (id);
 175         setup_sectors = (unsigned char)((i + 511) / 512);
 176         /* for compatibility with LILO */
 177         if (setup_sectors < SETUP_SECTS)
 178                 setup_sectors = SETUP_SECTS;
 179         fprintf(stderr,"Setup is %d bytes.\n",i);
 180         for (c=0 ; c<sizeof(buf) ; c++)
 181                 buf[c] = '\0';
 182         while (i < setup_sectors * 512) {
 183                 c = setup_sectors * 512 - i;
 184                 if (c > sizeof(buf))
 185                         c = sizeof(buf);
 186                 if (write(1,buf,c) != c)
 187                         die("Write call failed");
 188                 i += c;
 189         }
 190         
 191         if ((id=open(argv[3],O_RDONLY,0))<0)
 192                 die("Unable to open 'system'");
 193         if (read(id,buf,GCC_HEADER) != GCC_HEADER)
 194                 die("Unable to read header of 'system'");
 195         if (N_MAGIC(*ex) == ZMAGIC) {
 196                 GCC_HEADER = N_MAGIC_OFFSET;
 197                 lseek(id, GCC_HEADER, SEEK_SET);
 198         } else if (N_MAGIC(*ex) != QMAGIC)
 199                 die("Non-GCC header of 'system'");
 200         fprintf(stderr,"System is %d kB (%d kB code, %d kB data and %d kB bss)\n",
 201                 (ex->a_text+ex->a_data+ex->a_bss)/1024,
 202                 ex->a_text /1024,
 203                 ex->a_data /1024,
 204                 ex->a_bss  /1024);
 205         sz = N_SYMOFF(*ex) - GCC_HEADER + 4;
 206         sys_size = (sz + 15) / 16;
 207         if (sys_size > SYS_SIZE)
 208                 die("System is too big");
 209         while (sz > 0) {
 210                 int l, n;
 211 
 212                 l = sz;
 213                 if (l > sizeof(buf))
 214                         l = sizeof(buf);
 215                 if ((n=read(id, buf, l)) != l) {
 216                         if (n == -1) 
 217                                 perror(argv[1]);
 218                         else
 219                                 fprintf(stderr, "Unexpected EOF\n");
 220                         die("Can't read 'system'");
 221                 }
 222                 if (write(1, buf, l) != l)
 223                         die("Write failed");
 224                 sz -= l;
 225         }
 226         close(id);
 227         if (lseek(1, 497, 0) == 497) {
 228                 if (write(1, &setup_sectors, 1) != 1)
 229                         die("Write of setup sectors failed");
 230         }
 231         if (lseek(1,500,0) == 500) {
 232                 buf[0] = (sys_size & 0xff);
 233                 buf[1] = ((sys_size >> 8) & 0xff);
 234                 if (write(1, buf, 2) != 2)
 235                         die("Write failed");
 236         }
 237         return(0);
 238 }

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