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, int
  15         style, int atapi, u8_t *tmp_buf);
  16 static void extpartition(struct blockdriver *bdp, int extdev, unsigned
  17         long extbase, u8_t *tmp_buf);
  18 static int get_part_table(struct blockdriver *bdp, int device, unsigned
  19         long offset, struct part_entry *table, u8_t *tmp_buf);
  20 static void sort(struct part_entry *table);
  21
  22 /*============================================================================*
  23  *                              partition                                     *
  24  *============================================================================*/
  25 void partition(bdp, device, style, atapi)
  26 struct blockdriver *bdp;        /* device dependent entry points */
  27 int device;                     /* device to partition */
  28 int style;                      /* partitioning style: floppy, primary, sub. */
  29 int atapi;                      /* atapi device */
  30 {
  31 /* This routine is called on first open to initialize the partition tables
  32  * of a device.
  33  */
  34   u8_t *tmp_buf;
  35
  36   if ((*bdp->bdr_part)(device) == NULL)
  37         return;
  38
  39   /* For multithreaded drivers, multiple partition() calls may be made on
  40    * different devices in parallel. Hence we need a separate temporary buffer
  41    * for each request.
  42    */
  43   if (!(tmp_buf = alloc_contig(CD_SECTOR_SIZE, AC_ALIGN4K, NULL)))
  44         panic("partition: unable to allocate temporary buffer");
  45
  46   parse_part_table(bdp, device, style, atapi, tmp_buf);
  47
  48   free_contig(tmp_buf, CD_SECTOR_SIZE);
  49 }
  50
  51 /*============================================================================*
  52  *                              parse_part_table                              *
  53  *============================================================================*/
  54 static void parse_part_table(bdp, device, style, atapi, tmp_buf)
  55 struct blockdriver *bdp;        /* device dependent entry points */
  56 int device;                     /* device to partition */
  57 int style;                      /* partitioning style: floppy, primary, sub. */
  58 int atapi;                      /* atapi device */
  59 u8_t *tmp_buf;                  /* temporary buffer */
  60 {
  61 /* This routine reads and parses a partition table.  It may be called
  62  * recursively.  It makes sure that each partition falls safely within the
  63  * device's limits.  Depending on the partition style we are either making
  64  * floppy partitions, primary partitions or subpartitions.  Only primary
  65  * partitions are sorted, because they are shared with other operating
  66  * systems that expect this.
  67  */
  68   struct part_entry table[NR_PARTITIONS], *pe;
  69   int disk, par;
  70   struct device *dv;
  71   unsigned long base, limit, part_limit;
  72
  73   /* Get the geometry of the device to partition */
  74   if ((dv = (*bdp->bdr_part)(device)) == NULL
  75                                 || cmp64u(dv->dv_size, 0) == 0) return;
  76   base = div64u(dv->dv_base, SECTOR_SIZE);
  77   limit = base + div64u(dv->dv_size, SECTOR_SIZE);
  78
  79   /* Read the partition table for the device. */
  80   if(!get_part_table(bdp, device, 0L, table, tmp_buf)) {
  81           return;
  82   }
  83
  84   /* Compute the device number of the first partition. */
  85   switch (style) {
  86   case P_FLOPPY:
  87         device += MINOR_fd0p0;
  88         break;
  89   case P_PRIMARY:
  90         sort(table);            /* sort a primary partition table */
  91         device += 1;
  92         break;
  93   case P_SUB:
  94         disk = device / DEV_PER_DRIVE;
  95         par = device % DEV_PER_DRIVE - 1;
  96         device = MINOR_d0p0s0 + (disk * NR_PARTITIONS + par) * NR_PARTITIONS;
  97   }
  98
  99   /* Find an array of devices. */
 100   if ((dv = (*bdp->bdr_part)(device)) == NULL) return;
 101
 102   /* Set the geometry of the partitions from the partition table. */
 103   for (par = 0; par < NR_PARTITIONS; par++, dv++) {
 104         /* Shrink the partition to fit within the device. */
 105         pe = &table[par];
 106         part_limit = pe->lowsec + pe->size;
 107         if (part_limit < pe->lowsec) part_limit = limit;
 108         if (part_limit > limit) part_limit = limit;
 109         if (pe->lowsec < base) pe->lowsec = base;
 110         if (part_limit < pe->lowsec) part_limit = pe->lowsec;
 111
 112         dv->dv_base = mul64u(pe->lowsec, SECTOR_SIZE);
 113         dv->dv_size = mul64u(part_limit - pe->lowsec, SECTOR_SIZE);
 114
 115         if (style == P_PRIMARY) {
 116                 /* Each Minix primary partition can be subpartitioned. */
 117                 if (pe->sysind == MINIX_PART)
 118                         parse_part_table(bdp, device + par, P_SUB, atapi,
 119                                 tmp_buf);
 120
 121                 /* An extended partition has logical partitions. */
 122                 if (ext_part(pe->sysind))
 123                         extpartition(bdp, device + par, pe->lowsec, tmp_buf);
 124         }
 125   }
 126 }
 127
 128 /*============================================================================*
 129  *                              extpartition                                  *
 130  *============================================================================*/
 131 static void extpartition(bdp, extdev, extbase, tmp_buf)
 132 struct blockdriver *bdp;        /* device dependent entry points */
 133 int extdev;                     /* extended partition to scan */
 134 unsigned long extbase;          /* sector offset of the base ext. partition */
 135 u8_t *tmp_buf;                  /* temporary buffer */
 136 {
 137 /* Extended partitions cannot be ignored alas, because people like to move
 138  * files to and from DOS partitions.  Avoid reading this code, it's no fun.
 139  */
 140   struct part_entry table[NR_PARTITIONS], *pe;
 141   int subdev, disk, par;
 142   struct device *dv;
 143   unsigned long offset, nextoffset;
 144
 145   disk = extdev / DEV_PER_DRIVE;
 146   par = extdev % DEV_PER_DRIVE - 1;
 147   subdev = MINOR_d0p0s0 + (disk * NR_PARTITIONS + par) * NR_PARTITIONS;
 148
 149   offset = 0;
 150   do {
 151         if (!get_part_table(bdp, extdev, offset, table, tmp_buf)) return;
 152         sort(table);
 153
 154         /* The table should contain one logical partition and optionally
 155          * another extended partition.  (It's a linked list.)
 156          */
 157         nextoffset = 0;
 158         for (par = 0; par < NR_PARTITIONS; par++) {
 159                 pe = &table[par];
 160                 if (ext_part(pe->sysind)) {
 161                         nextoffset = pe->lowsec;
 162                 } else
 163                 if (pe->sysind != NO_PART) {
 164                         if ((dv = (*bdp->bdr_part)(subdev)) == NULL) return;
 165
 166                         dv->dv_base = mul64u(extbase + offset + pe->lowsec,
 167                                                                 SECTOR_SIZE);
 168                         dv->dv_size = mul64u(pe->size, SECTOR_SIZE);
 169
 170                         /* Out of devices? */
 171                         if (++subdev % NR_PARTITIONS == 0) return;
 172                 }
 173         }
 174   } while ((offset = nextoffset) != 0);
 175 }
 176
 177 /*============================================================================*
 178  *                              get_part_table                                *
 179  *============================================================================*/
 180 static int get_part_table(bdp, device, offset, table, tmp_buf)
 181 struct blockdriver *bdp;
 182 int device;
 183 unsigned long offset;           /* sector offset to the table */
 184 struct part_entry *table;       /* four entries */
 185 u8_t *tmp_buf;                  /* temporary buffer */
 186 {
 187 /* Read the partition table for the device, return true iff there were no
 188  * errors.
 189  */
 190   iovec_t iovec1;
 191   u64_t position;
 192   int r;
 193
 194   position = mul64u(offset, SECTOR_SIZE);
 195   iovec1.iov_addr = (vir_bytes) tmp_buf;
 196   iovec1.iov_size = CD_SECTOR_SIZE;
 197   r = (*bdp->bdr_transfer)(device, FALSE /*do_write*/, position, SELF,
 198         &iovec1, 1, BDEV_NOFLAGS);
 199   if (r != CD_SECTOR_SIZE) {
 200         return 0;
 201   }
 202   if (tmp_buf[510] != 0x55 || tmp_buf[511] != 0xAA) {
 203         /* Invalid partition table. */
 204         return 0;
 205   }
 206   memcpy(table, (tmp_buf + PART_TABLE_OFF), NR_PARTITIONS * sizeof(table[0]));
 207   return 1;
 208 }
 209
 210 /*===========================================================================*
 211  *                              sort                                         *
 212  *===========================================================================*/
 213 static void sort(table)
 214 struct part_entry *table;
 215 {
 216 /* Sort a partition table. */
 217   struct part_entry *pe, tmp;
 218   int n = NR_PARTITIONS;
 219
 220   do {
 221         for (pe = table; pe < table + NR_PARTITIONS-1; pe++) {
 222                 if (pe[0].sysind == NO_PART
 223                         || (pe[0].lowsec > pe[1].lowsec
 224                                         && pe[1].sysind != NO_PART)) {
 225                         tmp = pe[0]; pe[0] = pe[1]; pe[1] = tmp;
 226                 }
 227         }
 228   } while (--n > 0);
 229 }