disk: dos: add code for creating MBR partition layout

Add a code for creating and writing MBR partition layout. The code generates
similar layout of EBRs (Exteneded Block Records) and logical volumes as
Linux's fdisk utility.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

diff --git a/disk/part_dos.c b/disk/part_dos.c
index c9c9c5fc28d26bab83127e279932918642738bba..f431925745c1c568890c8e48fa22a51c169f6b23 100644 (file)
--- a/disk/part_dos.c
+++ b/disk/part_dos.c
@@ -320,6 +320,173 @@ int is_valid_dos_buf(void *buf)
        return test_block_type(buf) == DOS_MBR ? 0 : -1;
 }
 
+#if CONFIG_IS_ENABLED(CMD_MBR)
+static void lba_to_chs(lbaint_t lba, unsigned char *rc, unsigned char *rh,
+                      unsigned char *rs)
+{
+       unsigned int c, h, s;
+       /* use fixed CHS geometry */
+       unsigned int sectpertrack = 63;
+       unsigned int heads = 255;
+
+       c = (lba + 1) / sectpertrack / heads;
+       h = (lba + 1) / sectpertrack - c * heads;
+       s = (lba + 1) - (c * heads + h) * sectpertrack;
+
+       if (c > 1023) {
+               c = 1023;
+               h = 254;
+               s = 63;
+       }
+
+       *rc = c & 0xff;
+       *rh = h;
+       *rs = s + ((c & 0x300) >> 2);
+}
+
+static void mbr_fill_pt_entry(dos_partition_t *pt, lbaint_t start,
+               lbaint_t relative, lbaint_t size, uchar sys_ind, bool bootable)
+{
+       pt->boot_ind = bootable ? 0x80 : 0x00;
+       pt->sys_ind = sys_ind;
+       lba_to_chs(start, &pt->cyl, &pt->head, &pt->sector);
+       lba_to_chs(start + size - 1, &pt->end_cyl, &pt->end_head, &pt->end_sector);
+       put_unaligned_le32(relative, &pt->start4);
+       put_unaligned_le32(size, &pt->size4);
+}
+
+int write_mbr_partitions(struct blk_desc *dev,
+               struct disk_partition *p, int count, unsigned int disksig)
+{
+       ALLOC_CACHE_ALIGN_BUFFER(unsigned char, buffer, dev->blksz);
+       lbaint_t ext_part_start = 0, ext_part_size = 0, ext_part_sect = 0;
+       dos_partition_t *pt;
+       int i;
+
+       memset(buffer, 0, dev->blksz);
+       buffer[DOS_PART_MAGIC_OFFSET] = 0x55;
+       buffer[DOS_PART_MAGIC_OFFSET + 1] = 0xaa;
+       put_unaligned_le32(disksig, &buffer[DOS_PART_DISKSIG_OFFSET]);
+       pt = (dos_partition_t *) (buffer + DOS_PART_TBL_OFFSET);
+
+       /* create all primary partitions */
+       for (i = 0; i < 4 && i < count; i++, pt++) {
+               mbr_fill_pt_entry(pt, p[i].start, p[i].start, p[i].size,
+                                 p[i].sys_ind, p[i].bootable);
+               if (is_extended(p[i].sys_ind)) {
+                       ext_part_start = p[i].start;
+                       ext_part_size = p[i].size;
+                       ext_part_sect = p[i].start;
+               }
+       }
+
+       if (i < count && !ext_part_start) {
+               printf("%s: extended partition is needed for more than 4 partitions\n",
+                       __func__);
+               return -1;
+       }
+
+       /* write MBR */
+       if (blk_dwrite(dev, 0, 1, buffer) != 1) {
+               printf("%s: failed writing 'MBR' (1 blks at 0x0)\n",
+                      __func__);
+               return -1;
+       }
+
+       /* create extended volumes */
+       for (; i < count; i++) {
+               lbaint_t next_ebr = 0;
+
+               memset(buffer, 0, dev->blksz);
+               buffer[DOS_PART_MAGIC_OFFSET] = 0x55;
+               buffer[DOS_PART_MAGIC_OFFSET + 1] = 0xaa;
+               pt = (dos_partition_t *) (buffer + DOS_PART_TBL_OFFSET);
+
+               mbr_fill_pt_entry(pt, p[i].start, p[i].start - ext_part_sect,
+                                 p[i].size, p[i].sys_ind, p[i].bootable);
+
+               if (i + 1 < count) {
+                       pt++;
+                       next_ebr = p[i].start + p[i].size;
+                       mbr_fill_pt_entry(pt, next_ebr,
+                                         next_ebr - ext_part_start,
+                                         p[i+1].start + p[i+1].size - next_ebr,
+                                         DOS_PART_TYPE_EXTENDED, 0);
+               }
+
+               /* write EBR */
+               if (blk_dwrite(dev, ext_part_sect, 1, buffer) != 1) {
+                       printf("%s: failed writing 'EBR' (1 blks at 0x%lx)\n",
+                              __func__, ext_part_sect);
+                       return -1;
+               }
+               ext_part_sect = next_ebr;
+       }
+
+       return 0;
+}
+
+int layout_mbr_partitions(struct disk_partition *p, int count,
+                         lbaint_t total_sectors)
+{
+       struct disk_partition *ext = NULL;
+       int i, j;
+       lbaint_t ext_vol_start;
+
+       /* calculate primary partitions start and size if needed */
+       if (!p[0].start)
+               p[0].start = DOS_PART_DEFAULT_GAP;
+       for (i = 0; i < 4 && i < count; i++) {
+               if (!p[i].start)
+                       p[i].start = p[i - 1].start + p[i - 1].size;
+               if (!p[i].size) {
+                       lbaint_t end = total_sectors;
+                       lbaint_t allocated = 0;
+
+                       for (j = i + 1; j < 4 && j < count; j++) {
+                               if (p[j].start) {
+                                       end = p[j].start;
+                                       break;
+                               }
+                               allocated += p[j].size;
+                       }
+                       p[i].size = end - allocated - p[i].start;
+               }
+               if (p[i].sys_ind == 0x05)
+                       ext = &p[i];
+       }
+
+       if (i >= 4 && !ext) {
+               printf("%s: extended partition is needed for more than 4 partitions\n",
+                       __func__);
+               return -1;
+       }
+
+       /* calculate extended volumes start and size if needed */
+       ext_vol_start = ext->start;
+       for (i = 4; i < count; i++) {
+               if (!p[i].start)
+                       p[i].start = ext_vol_start + DOS_PART_DEFAULT_GAP;
+               if (!p[i].size) {
+                       lbaint_t end = ext->start + ext->size;
+                       lbaint_t allocated = 0;
+
+                       for (j = i + 1; j < count; j++) {
+                               if (p[j].start) {
+                                       end = p[j].start - DOS_PART_DEFAULT_GAP;
+                                       break;
+                               }
+                               allocated += p[j].size + DOS_PART_DEFAULT_GAP;
+                       }
+                       p[i].size = end - allocated - p[i].start;
+               }
+               ext_vol_start = p[i].start + p[i].size;
+       }
+
+       return 0;
+}
+#endif
+
 int write_mbr_sector(struct blk_desc *dev_desc, void *buf)
 {
        if (is_valid_dos_buf(buf))

diff --git a/disk/part_dos.h b/disk/part_dos.h
index dd909a9317dba13d0d2f3f82024b5dd2ca99a5ae..505582242281afa66df27fd3cf8263aa0caa6a38 100644 (file)
--- a/disk/part_dos.h
+++ b/disk/part_dos.h
@@ -19,6 +19,8 @@
 #define DOS_PART_TYPE_EXTENDED_LBA     0x0F
 #define DOS_PART_TYPE_EXTENDED_LINUX   0x85
 
+#define DOS_PART_DEFAULT_GAP           2048
+
 typedef struct dos_partition {
        unsigned char boot_ind;         /* 0x80 - active                        */
        unsigned char head;             /* starting head                        */

diff --git a/include/part.h b/include/part.h
index 67b8b2a5cc27f4f2df8f324859ce3245ea4ed59b..fac36364bd4b544a64e77be884154cfc8dfd9d5c 100644 (file)
--- a/include/part.h
+++ b/include/part.h
@@ -474,6 +474,11 @@ int is_valid_dos_buf(void *buf);
  */
 int write_mbr_sector(struct blk_desc *dev_desc, void *buf);
 
+int write_mbr_partitions(struct blk_desc *dev,
+               struct disk_partition *p, int count, unsigned int disksig);
+int layout_mbr_partitions(struct disk_partition *p, int count,
+                         lbaint_t total_sectors);
+
 #endif