minix/lib/libblockdriver/drvlib.c

   1 /* IBM device driver utility functions.                 Author: Kees J. Bot
   2  *                                                              7 Dec 1995
   3  * Entry point:
   4  *   partition: partition a disk to the partition table(s) on it.
   5  */
   6
   7 #include <minix/blockdriver.h>
   8 #include <minix/drvlib.h>
   9 #include <unistd.h>
  10
  11 /* Extended partition? */
  12 #define ext_part(s)     ((s) == 0x05 || (s) == 0x0F)
  13
  14 static void parse_part_table(struct blockdriver *bdp, int device,
  15         int style, int atapi, u8_t *tmp_buf);
  16
  17 static void extpartition(struct blockdriver *bdp, int extdev,
  18         unsigned long extbase, u8_t *tmp_buf);
  19
  20 static int get_part_table(struct blockdriver *bdp, int device,
  21         unsigned long offset, struct part_entry *table, u8_t *tmp_buf);
  22
  23 static void sort(struct part_entry *table);
  24
  25 /*============================================================================*
  26  *                              partition                                     *
  27  *============================================================================*/
  28 void partition(
  29         struct blockdriver *bdp,        /* device dependent entry points */
  30         int device,                     /* device to partition */
  31         int style,                      /* partitioning style: floppy, primary, sub. */
  32         int atapi                       /* atapi device */
  33 )
  34 {
  35 /* This routine is called on first open to initialize the partition tables
  36  * of a device.
  37  */
  38   u8_t *tmp_buf;
  39
  40   if ((*bdp->bdr_part)(device) == NULL)
  41         return;
  42
  43   /* For multithreaded drivers, multiple partition() calls may be made on
  44    * different devices in parallel. Hence we need a separate temporary buffer
  45    * for each request.
  46    */
  47   if (!(tmp_buf = alloc_contig(CD_SECTOR_SIZE, AC_ALIGN4K, NULL)))
  48         panic("partition: unable to allocate temporary buffer");
  49
  50   parse_part_table(bdp, device, style, atapi, tmp_buf);
  51
  52   free_contig(tmp_buf, CD_SECTOR_SIZE);
  53 }
  54
  55 /*============================================================================*
  56  *                              parse_part_table                              *
  57  *============================================================================*/
  58 static void parse_part_table(
  59         struct blockdriver *bdp,        /* device dependent entry points */
  60         int device,                     /* device to partition */
  61         int style,                      /* partitioning style: floppy, primary, sub. */
  62         int atapi,                      /* atapi device */
  63         u8_t *tmp_buf                   /* temporary buffer */
  64 )
  65 {
  66 /* This routine reads and parses a partition table.  It may be called
  67  * recursively.  It makes sure that each partition falls safely within the
  68  * device's limits.  Depending on the partition style we are either making
  69  * floppy partitions, primary partitions or subpartitions.  Only primary
  70  * partitions are sorted, because they are shared with other operating
  71  * systems that expect this.
  72  */
  73   struct part_entry table[NR_PARTITIONS], *pe;
  74   int disk, par;
  75   struct device *dv;
  76   unsigned long base, limit, part_limit;
  77
  78   /* Get the geometry of the device to partition */
  79   if ((dv = (*bdp->bdr_part)(device)) == NULL
  80                                 || dv->dv_size == 0) return;
  81   base = (unsigned long)(dv->dv_base / SECTOR_SIZE);
  82   limit = base + (unsigned long)(dv->dv_size / SECTOR_SIZE);
  83
  84   /* Read the partition table for the device. */
  85   if(!get_part_table(bdp, device, 0L, table, tmp_buf)) {
  86           return;
  87   }
  88
  89   /* Compute the device number of the first partition. */
  90   switch (style) {
  91   case P_FLOPPY:
  92         device += MINOR_fd0p0;
  93         break;
  94   case P_PRIMARY:
  95         sort(table);            /* sort a primary partition table */
  96         device += 1;
  97         break;
  98   case P_SUB:
  99         disk = device / DEV_PER_DRIVE;
 100         par = device % DEV_PER_DRIVE - 1;
 101         device = MINOR_d0p0s0 + (disk * NR_PARTITIONS + par) * NR_PARTITIONS;
 102   }
 103
 104   /* Find an array of devices. */
 105   if ((dv = (*bdp->bdr_part)(device)) == NULL) return;
 106
 107   /* Set the geometry of the partitions from the partition table. */
 108   for (par = 0; par < NR_PARTITIONS; par++, dv++) {
 109         /* Shrink the partition to fit within the device. */
 110         pe = &table[par];
 111         part_limit = pe->lowsec + pe->size;
 112         if (part_limit < pe->lowsec) part_limit = limit;
 113         if (part_limit > limit) part_limit = limit;
 114         if (pe->lowsec < base) pe->lowsec = base;
 115         if (part_limit < pe->lowsec) part_limit = pe->lowsec;
 116
 117         dv->dv_base = (u64_t)pe->lowsec * SECTOR_SIZE;
 118         dv->dv_size = (u64_t)(part_limit - pe->lowsec) * SECTOR_SIZE;
 119
 120         if (style == P_PRIMARY) {
 121                 /* Each Minix primary partition can be subpartitioned. */
 122                 if (pe->sysind == MINIX_PART)
 123                         parse_part_table(bdp, device + par, P_SUB, atapi,
 124                                 tmp_buf);
 125
 126                 /* An extended partition has logical partitions. */
 127                 if (ext_part(pe->sysind))
 128                         extpartition(bdp, device + par, pe->lowsec, tmp_buf);
 129         }
 130   }
 131 }
 132
 133 /*============================================================================*
 134  *                              extpartition                                  *
 135  *============================================================================*/
 136 static void extpartition(
 137         struct blockdriver *bdp,        /* device dependent entry points */
 138         int extdev,                     /* extended partition to scan */
 139         unsigned long extbase,          /* sector offset of the base ext. partition */
 140         u8_t *tmp_buf                   /* temporary buffer */
 141 )
 142 {
 143 /* Extended partitions cannot be ignored alas, because people like to move
 144  * files to and from DOS partitions.  Avoid reading this code, it's no fun.
 145  */
 146   struct part_entry table[NR_PARTITIONS], *pe;
 147   int subdev, disk, par;
 148   struct device *dv;
 149   unsigned long offset, nextoffset;
 150
 151   disk = extdev / DEV_PER_DRIVE;
 152   par = extdev % DEV_PER_DRIVE - 1;
 153   subdev = MINOR_d0p0s0 + (disk * NR_PARTITIONS + par) * NR_PARTITIONS;
 154
 155   offset = 0;
 156   do {
 157         if (!get_part_table(bdp, extdev, offset, table, tmp_buf)) return;
 158         sort(table);
 159
 160         /* The table should contain one logical partition and optionally
 161          * another extended partition.  (It's a linked list.)
 162          */
 163         nextoffset = 0;
 164         for (par = 0; par < NR_PARTITIONS; par++) {
 165                 pe = &table[par];
 166                 if (ext_part(pe->sysind)) {
 167                         nextoffset = pe->lowsec;
 168                 } else
 169                 if (pe->sysind != NO_PART) {
 170                         if ((dv = (*bdp->bdr_part)(subdev)) == NULL) return;
 171
 172                         dv->dv_base = (u64_t)(extbase + offset + pe->lowsec) *
 173                                                                 SECTOR_SIZE;
 174                         dv->dv_size = (u64_t)pe->size * SECTOR_SIZE;
 175
 176                         /* Out of devices? */
 177                         if (++subdev % NR_PARTITIONS == 0) return;
 178                 }
 179         }
 180   } while ((offset = nextoffset) != 0);
 181 }
 182
 183 /*============================================================================*
 184  *                              get_part_table                                *
 185  *============================================================================*/
 186 static int get_part_table(
 187         struct blockdriver *bdp,
 188         int device,
 189         unsigned long offset,           /* sector offset to the table */
 190         struct part_entry *table,       /* four entries */
 191         u8_t *tmp_buf)                  /* temporary buffer */
 192 {
 193 /* Read the partition table for the device, return true iff there were no
 194  * errors.
 195  */
 196   iovec_t iovec1;
 197   u64_t position;
 198   int r;
 199
 200   position = (u64_t)offset * SECTOR_SIZE;
 201   iovec1.iov_addr = (vir_bytes) tmp_buf;
 202   iovec1.iov_size = CD_SECTOR_SIZE;
 203   r = (*bdp->bdr_transfer)(device, FALSE /*do_write*/, position, SELF,
 204         &iovec1, 1, BDEV_NOFLAGS);
 205   if (r != CD_SECTOR_SIZE) {
 206         return 0;
 207   }
 208   if (tmp_buf[510] != 0x55 || tmp_buf[511] != 0xAA) {
 209         /* Invalid partition table. */
 210         return 0;
 211   }
 212   memcpy(table, (tmp_buf + PART_TABLE_OFF), NR_PARTITIONS * sizeof(table[0]));
 213   return 1;
 214 }
 215
 216 /*===========================================================================*
 217  *                              sort                                         *
 218  *===========================================================================*/
 219 static void sort(struct part_entry *table)
 220 {
 221 /* Sort a partition table. */
 222   struct part_entry *pe, tmp;
 223   int n = NR_PARTITIONS;
 224
 225   do {
 226         for (pe = table; pe < table + NR_PARTITIONS-1; pe++) {
 227                 if (pe[0].sysind == NO_PART
 228                         || (pe[0].lowsec > pe[1].lowsec
 229                                         && pe[1].sysind != NO_PART)) {
 230                         tmp = pe[0]; pe[0] = pe[1]; pe[1] = tmp;
 231                 }
 232         }
 233   } while (--n > 0);
 234 }