arch/alpha/boot/tools/mkbb.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* This utility makes a bootblock suitable for the SRM console/miniloader */
   3
   4 /* Usage:
   5  *      mkbb <device> <lxboot>
   6  *
   7  * Where <device> is the name of the device to install the bootblock on,
   8  * and <lxboot> is the name of a bootblock to merge in.  This bootblock
   9  * contains the offset and size of the bootloader.  It must be exactly
  10  * 512 bytes long.
  11  */
  12
  13 #include <fcntl.h>
  14 #include <unistd.h>
  15 #include <stdlib.h>
  16 #include <stdio.h>
  17
  18 /* Minimal definition of disklabel, so we don't have to include
  19  * asm/disklabel.h (confuses make)
  20  */
  21 #ifndef MAXPARTITIONS
  22 #define MAXPARTITIONS   8                       /* max. # of partitions */
  23 #endif
  24
  25 #ifndef u8
  26 #define u8 unsigned char
  27 #endif
  28
  29 #ifndef u16
  30 #define u16 unsigned short
  31 #endif
  32
  33 #ifndef u32
  34 #define u32 unsigned int
  35 #endif
  36
  37 struct disklabel {
  38     u32 d_magic;                                /* must be DISKLABELMAGIC */
  39     u16 d_type, d_subtype;
  40     u8  d_typename[16];
  41     u8  d_packname[16];
  42     u32 d_secsize;
  43     u32 d_nsectors;
  44     u32 d_ntracks;
  45     u32 d_ncylinders;
  46     u32 d_secpercyl;
  47     u32 d_secprtunit;
  48     u16 d_sparespertrack;
  49     u16 d_sparespercyl;
  50     u32 d_acylinders;
  51     u16 d_rpm, d_interleave, d_trackskew, d_cylskew;
  52     u32 d_headswitch, d_trkseek, d_flags;
  53     u32 d_drivedata[5];
  54     u32 d_spare[5];
  55     u32 d_magic2;                               /* must be DISKLABELMAGIC */
  56     u16 d_checksum;
  57     u16 d_npartitions;
  58     u32 d_bbsize, d_sbsize;
  59     struct d_partition {
  60         u32     p_size;
  61         u32     p_offset;
  62         u32     p_fsize;
  63         u8      p_fstype;
  64         u8      p_frag;
  65         u16     p_cpg;
  66     } d_partitions[MAXPARTITIONS];
  67 };
  68
  69
  70 typedef union __bootblock {
  71     struct {
  72         char                    __pad1[64];
  73         struct disklabel        __label;
  74     } __u1;
  75     struct {
  76         unsigned long           __pad2[63];
  77         unsigned long           __checksum;
  78     } __u2;
  79     char                bootblock_bytes[512];
  80     unsigned long       bootblock_quadwords[64];
  81 } bootblock;
  82
  83 #define bootblock_label         __u1.__label
  84 #define bootblock_checksum      __u2.__checksum
  85
  86 int main(int argc, char ** argv)
  87 {
  88     bootblock           bootblock_from_disk;
  89     bootblock           bootloader_image;
  90     int                 dev, fd;
  91     int                 i;
  92     int                 nread;
  93
  94     /* Make sure of the arg count */
  95     if(argc != 3) {
  96         fprintf(stderr, "Usage: %s device lxboot\n", argv[0]);
  97         exit(0);
  98     }
  99
 100     /* First, open the device and make sure it's accessible */
 101     dev = open(argv[1], O_RDWR);
 102     if(dev < 0) {
 103         perror(argv[1]);
 104         exit(0);
 105     }
 106
 107     /* Now open the lxboot and make sure it's reasonable */
 108     fd = open(argv[2], O_RDONLY);
 109     if(fd < 0) {
 110         perror(argv[2]);
 111         close(dev);
 112         exit(0);
 113     }
 114
 115     /* Read in the lxboot */
 116     nread = read(fd, &bootloader_image, sizeof(bootblock));
 117     if(nread != sizeof(bootblock)) {
 118         perror("lxboot read");
 119         fprintf(stderr, "expected %zd, got %d\n", sizeof(bootblock), nread);
 120         exit(0);
 121     }
 122
 123     /* Read in the bootblock from disk. */
 124     nread = read(dev, &bootblock_from_disk, sizeof(bootblock));
 125     if(nread != sizeof(bootblock)) {
 126         perror("bootblock read");
 127         fprintf(stderr, "expected %zd, got %d\n", sizeof(bootblock), nread);
 128         exit(0);
 129     }
 130
 131     /* Swap the bootblock's disklabel into the bootloader */
 132     bootloader_image.bootblock_label = bootblock_from_disk.bootblock_label;
 133
 134     /* Calculate the bootblock checksum */
 135     bootloader_image.bootblock_checksum = 0;
 136     for(i = 0; i < 63; i++) {
 137         bootloader_image.bootblock_checksum +=
 138                         bootloader_image.bootblock_quadwords[i];
 139     }
 140
 141     /* Write the whole thing out! */
 142     lseek(dev, 0L, SEEK_SET);
 143     if(write(dev, &bootloader_image, sizeof(bootblock)) != sizeof(bootblock)) {
 144         perror("bootblock write");
 145         exit(0);
 146     }
 147
 148     close(fd);
 149     close(dev);
 150     exit(0);
 151 }
 152
 153