1 files changed, 66 insertions, 0 deletions
diff --git a/grub-core/kern/disk_common.c b/grub-core/kern/disk_common.c
new file mode 100644
index 0000000..e09fba8
--- /dev/null
+++ b/grub-core/kern/disk_common.c
@@ -0,0 +1,66 @@
+/* This function performs three tasks:
+   - Make sectors disk relative from partition relative.
+   - Normalize offset to be less than the sector size.
+   - Verify that the range is inside the partition.  */
+static grub_err_t
+grub_disk_adjust_range (grub_disk_t disk, grub_disk_addr_t *sector,
+			grub_off_t *offset, grub_size_t size)
+{
+  grub_partition_t part;
+  grub_disk_addr_t total_sectors;
+
+  *sector += *offset >> GRUB_DISK_SECTOR_BITS;
+  *offset &= GRUB_DISK_SECTOR_SIZE - 1;
+
+  for (part = disk->partition; part; part = part->parent)
+    {
+      grub_disk_addr_t start;
+      grub_uint64_t len;
+
+      start = part->start;
+      len = part->len;
+
+      if (*sector >= len
+	  || len - *sector < ((*offset + size + GRUB_DISK_SECTOR_SIZE - 1)
+			      >> GRUB_DISK_SECTOR_BITS))
+	return grub_error (GRUB_ERR_OUT_OF_RANGE,
+			   N_("attempt to read or write outside of partition"));
+
+      *sector += start;
+    }
+
+  /* Transform total_sectors to number of 512B blocks.  */
+  total_sectors = disk->total_sectors << (disk->log_sector_size - GRUB_DISK_SECTOR_BITS);
+
+  /*
+   * Some drivers have problems with disks above reasonable sizes.
+   * Clamp the size to GRUB_DISK_MAX_SECTORS. Just one condition is enough
+   * since GRUB_DISK_SIZE_UNKNOWN is always above GRUB_DISK_MAX_SECTORS,
+   * assuming a maximum 4 KiB sector size.
+   */
+  if (total_sectors > GRUB_DISK_MAX_SECTORS)
+    total_sectors = GRUB_DISK_MAX_SECTORS;
+
+  if ((total_sectors <= *sector
+       || ((*offset + size + GRUB_DISK_SECTOR_SIZE - 1)
+	   >> GRUB_DISK_SECTOR_BITS) > total_sectors - *sector))
+    return grub_error (GRUB_ERR_OUT_OF_RANGE,
+		       N_("attempt to read or write outside of disk `%s'"), disk->name);
+
+  return GRUB_ERR_NONE;
+}
+
+static inline grub_disk_addr_t
+transform_sector (grub_disk_t disk, grub_disk_addr_t sector)
+{
+  return sector >> (disk->log_sector_size - GRUB_DISK_SECTOR_BITS);
+}
+
+static unsigned
+grub_disk_cache_get_index (unsigned long dev_id, unsigned long disk_id,
+			   grub_disk_addr_t sector)
+{
+  return ((dev_id * 524287UL + disk_id * 2606459UL
+	   + ((unsigned) (sector >> GRUB_DISK_CACHE_BITS)))
+	  % GRUB_DISK_CACHE_NUM);
+}