usr.sbin/installboot/minixfs3.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <stdint.h>
   4 #include <errno.h>
   5 #include <sys/stat.h>
   6 #include <sys/bootblock.h>
   7 #include <fcntl.h>
   8 #include <unistd.h>
   9 #include <string.h>
  10
  11 #ifndef DFL_SECSIZE
  12 #define DFL_SECSIZE     512
  13 #endif
  14
  15 #define MFS_FIRST_SUBP_OFFSET   32
  16
  17 static int minixfs3_read_mbr(const char* device, char* buf)
  18 {
  19         int fd;
  20         int bytes;
  21         int n;
  22
  23         fd = open(device, O_RDONLY);
  24         if (fd == -1) {
  25                 fprintf(stderr, "Can't open %s: %s\n", device, strerror(errno));
  26                 return 1;
  27         }
  28
  29         if (lseek(fd, MBR_PART_OFFSET, SEEK_SET) != MBR_PART_OFFSET) {
  30                 fprintf(stderr, "Can't seek in %s to %d: %s\n",
  31                         device, MBR_PART_OFFSET, strerror(errno));
  32                 close(fd);
  33                 return 1;
  34         }
  35
  36         bytes = DFL_SECSIZE - MBR_PART_OFFSET;
  37
  38         if ((n = read(fd, buf, bytes)) != bytes) {
  39                 fprintf(stderr, "Can't read %d bytes from %s, %d read instead"
  40                         ": %s\n",
  41                         bytes, device, n, strerror(errno));
  42                 close(fd);
  43                 return 1;
  44         }
  45
  46         if ((uint8_t)buf[bytes-2] != 0x55 || (uint8_t)buf[bytes-1] != 0xAA) {
  47                 fprintf(stderr, "No MBR on %s, signature is %x\n",
  48                         device, *(uint16_t*)(&buf[bytes-2]));
  49                 close(fd);
  50                 return 1;
  51         }
  52
  53         close(fd);
  54         return 0;
  55 }
  56
  57
  58 int minixfs3_is_minix_partition(const char* partition)
  59 {
  60         char buf[DFL_SECSIZE]; /* part table + signature */
  61         int name_length = strlen(partition);
  62
  63         /* partition must be 0-3 */
  64         if (atol(&partition[name_length-1]) >= 4) {
  65                 fprintf(stderr, "Wrong device %s, must be /.../cxdyp[0-3]\n",
  66                         partition);
  67                 return 0;
  68         }
  69
  70         /* it should be partition device, not disk */
  71         if (partition[name_length-2] != 'p') {
  72                 fprintf(stderr, "Wrong device %s, must be /.../cxdyp[0-3]\n",
  73                         partition);
  74                 return 0;
  75         }
  76
  77         /* MINIX 3 partition with current scheme *must* have subpartitions,
  78          * thus MBR has signature. minixfs3_read_mbr checks the signature.
  79          */
  80         if (minixfs3_read_mbr(partition, buf))
  81                 return 0;
  82         return 1;
  83 }
  84
  85 /* bootxx from NetBSD is ~8Kb, and old MINIX installations have just
  86  * 1Kb of space for their bootblock. Check if there is enough space
  87  * to install bootxx_minixfs3. New installation should have 16Kb before
  88  * the first subpartition.
  89  */
  90 int minixfs3_has_bootblock_space(const char* partition)
  91 {
  92         char buf[DFL_SECSIZE]; /* part table + signature */
  93         char disk[NAME_MAX];
  94         struct mbr_partition *part;
  95         uint32_t first_subpartition = (uint32_t) ~0;
  96         uint32_t parent_partition = 0;
  97         int i;
  98         int name_length = strlen(partition);
  99
 100         /* partition must be 0-3 */
 101         if (atol(&partition[name_length-1]) >= 4) {
 102                 fprintf(stderr, "Wrong device %s, must be /.../cxdyp[0-3]\n",
 103                         partition);
 104                 exit(1);
 105         }
 106         /* it should be partition device, not disk */
 107         if (partition[name_length-2] != 'p') {
 108                 fprintf(stderr, "Wrong device %s, must be /.../cxdyp[0-3]\n",
 109                         partition);
 110                 exit(1);
 111         }
 112
 113         if (minixfs3_read_mbr(partition, buf))
 114                 exit(1);
 115
 116         part = (struct mbr_partition *) buf;
 117
 118         for (i = 0; i < 4; i++) {
 119                 if (part[i].mbrp_size && part[i].mbrp_start < first_subpartition)
 120                         first_subpartition = part[i].mbrp_start;
 121         }
 122
 123         strncpy(disk, partition, name_length - 2);
 124         disk[name_length - 2] = '\0';
 125
 126         if (minixfs3_read_mbr(disk, buf))
 127                 exit(1);
 128
 129         for (i = 0; i < 4; i++) {
 130                 struct mbr_partition *p = &part[i];
 131                 if (p->mbrp_size && p->mbrp_start <= first_subpartition
 132                     && (p->mbrp_start + p->mbrp_size) > first_subpartition) {
 133                         parent_partition = p->mbrp_start;
 134                         break;
 135                 }
 136         }
 137
 138         if ((first_subpartition - parent_partition) < MFS_FIRST_SUBP_OFFSET)
 139                 return 0;
 140         else
 141                 return 1;
 142 }