usr.sbin/installboot/install_master.c

   1 /* Based on original installboot from MINIX 3.
   2  *
   3  *      installboot 3.0 - Make a device bootable        Author: Kees J. Bot
   4  *                                                              21 Dec 1991
   5  */
   6 #if HAVE_NBTOOL_CONFIG_H
   7 #include "nbtool_config.h"
   8 #endif
   9
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <string.h>
  13 #include <errno.h>
  14 #include <fcntl.h>
  15 #include <unistd.h>
  16 #include <dirent.h>
  17 #include <sys/stat.h>
  18
  19 #include "installboot.h"
  20
  21 #define BOOTBLOCK       0       /* Of course */
  22 #define BOOT_BLOCK_SIZE 1024
  23 #define SIGNATURE       0xAA55  /* Boot block signature. */
  24 #define SIGPOS          510     /* Where to put signature word. */
  25 #define PARTPOS         446     /* Offset to the partition table in a master
  26                                  * boot block.
  27                                  */
  28
  29
  30 static int rawfd;       /* File descriptor to open device. */
  31 static const char *rawdev;      /* Name of device. */
  32
  33
  34 static void report(const char *label)
  35 /* installboot: label: No such file or directory */
  36 {
  37         fprintf(stderr, "installboot: %s: %s\n", label, strerror(errno));
  38 }
  39
  40 static __dead void fatal(const char *label)
  41 {
  42         report(label);
  43         exit(1);
  44 }
  45
  46 static void bread(FILE *f, char *name, void *buf, size_t len)
  47 /* Read len bytes.  Don't dare return without them. */
  48 {
  49         if (len > 0 && fread(buf, len, 1, f) != 1) {
  50                 if (ferror(f)) fatal(name);
  51                 fprintf(stderr, "installboot: Unexpected EOF on %s\n", name);
  52                 exit(1);
  53         }
  54 }
  55
  56 static void readblock(off_t blk, char *buf, int block_size)
  57 /* For rawfs, so that it can read blocks. */
  58 {
  59         int n;
  60
  61         if (lseek(rawfd, blk * block_size, SEEK_SET) < 0
  62                 || (n= read(rawfd, buf, block_size)) < 0
  63         ) fatal(rawdev);
  64
  65         if (n < block_size) {
  66                 fprintf(stderr, "installboot: Unexpected EOF on %s\n", rawdev);
  67                 exit(1);
  68         }
  69 }
  70
  71 static void writeblock(off_t blk, const char *buf, int block_size)
  72 /* Add a function to write blocks for local use. */
  73 {
  74         if (lseek(rawfd, blk * block_size, SEEK_SET) < 0
  75                 || write(rawfd, buf, block_size) < 0
  76         ) fatal(rawdev);
  77 }
  78
  79
  80 /* A temp stub until fdisk is ported to MINIX */
  81 void install_master(const char *device, char *masterboot, char **guide)
  82 /* Booting a hard disk is a two stage process:  The master bootstrap in sector
  83  * 0 loads the bootstrap from sector 0 of the active partition which in turn
  84  * starts the operating system.  This code installs such a master bootstrap
  85  * on a hard disk.  If guide[0] is non-null then the master bootstrap is
  86  * guided into booting a certain device.
  87  */
  88 {
  89         FILE *masf;
  90         unsigned long size;
  91         static char buf[BOOT_BLOCK_SIZE];
  92
  93         /* Open device. */
  94         if ((rawfd= open(rawdev= device, O_RDWR)) < 0) fatal(device);
  95
  96         /* Open the master boot code. */
  97         if ((masf= fopen(masterboot, "r")) == NULL) fatal(masterboot);
  98
  99         size= PARTPOS;
 100
 101         /* Read the master boot block, patch it, write. */
 102         readblock(BOOTBLOCK, buf, BOOT_BLOCK_SIZE);
 103
 104         memset(buf, 0, PARTPOS);
 105         (void) bread(masf, masterboot, buf, size);
 106
 107         /* Install signature. */
 108         buf[SIGPOS+0]= (SIGNATURE >> 0) & 0xFF;
 109         buf[SIGPOS+1]= (SIGNATURE >> 8) & 0xFF;
 110
 111         writeblock(BOOTBLOCK, buf, BOOT_BLOCK_SIZE);
 112 }
 113
 114 int isoption(const char *option, const char *test)
 115 /* Check if the option argument is equals "test".  Also accept -i as short
 116  * for -image, and the special case -x for -extract.
 117  */
 118 {
 119         if (strcmp(option, test) == 0) return 1;
 120         if (option[0] != '-' && strlen(option) != 2) return 0;
 121         if (option[1] == test[1]) return 1;
 122         if (option[1] == 'x' && test[1] == 'e') return 1;
 123         return 0;
 124 }