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-rw-r--r--fs/adfs/map.c99
1 files changed, 99 insertions, 0 deletions
diff --git a/fs/adfs/map.c b/fs/adfs/map.c
index f44d12cef5be..120e01451e75 100644
--- a/fs/adfs/map.c
+++ b/fs/adfs/map.c
@@ -4,6 +4,7 @@
*
* Copyright (C) 1997-2002 Russell King
*/
+#include <linux/slab.h>
#include <asm/unaligned.h>
#include "adfs.h"
@@ -280,3 +281,101 @@ bad_fragment:
frag_id, zone, asb->s_map_size);
return 0;
}
+
+static unsigned char adfs_calczonecheck(struct super_block *sb, unsigned char *map)
+{
+ unsigned int v0, v1, v2, v3;
+ int i;
+
+ v0 = v1 = v2 = v3 = 0;
+ for (i = sb->s_blocksize - 4; i; i -= 4) {
+ v0 += map[i] + (v3 >> 8);
+ v3 &= 0xff;
+ v1 += map[i + 1] + (v0 >> 8);
+ v0 &= 0xff;
+ v2 += map[i + 2] + (v1 >> 8);
+ v1 &= 0xff;
+ v3 += map[i + 3] + (v2 >> 8);
+ v2 &= 0xff;
+ }
+ v0 += v3 >> 8;
+ v1 += map[1] + (v0 >> 8);
+ v2 += map[2] + (v1 >> 8);
+ v3 += map[3] + (v2 >> 8);
+
+ return v0 ^ v1 ^ v2 ^ v3;
+}
+
+static int adfs_checkmap(struct super_block *sb, struct adfs_discmap *dm)
+{
+ unsigned char crosscheck = 0, zonecheck = 1;
+ int i;
+
+ for (i = 0; i < ADFS_SB(sb)->s_map_size; i++) {
+ unsigned char *map;
+
+ map = dm[i].dm_bh->b_data;
+
+ if (adfs_calczonecheck(sb, map) != map[0]) {
+ adfs_error(sb, "zone %d fails zonecheck", i);
+ zonecheck = 0;
+ }
+ crosscheck ^= map[3];
+ }
+ if (crosscheck != 0xff)
+ adfs_error(sb, "crosscheck != 0xff");
+ return crosscheck == 0xff && zonecheck;
+}
+
+struct adfs_discmap *adfs_read_map(struct super_block *sb, struct adfs_discrecord *dr)
+{
+ struct adfs_discmap *dm;
+ unsigned int map_addr, zone_size, nzones;
+ int i, zone;
+ struct adfs_sb_info *asb = ADFS_SB(sb);
+
+ nzones = asb->s_map_size;
+ zone_size = (8 << dr->log2secsize) - le16_to_cpu(dr->zone_spare);
+ map_addr = (nzones >> 1) * zone_size -
+ ((nzones > 1) ? ADFS_DR_SIZE_BITS : 0);
+ map_addr = signed_asl(map_addr, asb->s_map2blk);
+
+ asb->s_ids_per_zone = zone_size / (asb->s_idlen + 1);
+
+ dm = kmalloc_array(nzones, sizeof(*dm), GFP_KERNEL);
+ if (dm == NULL) {
+ adfs_error(sb, "not enough memory");
+ return ERR_PTR(-ENOMEM);
+ }
+
+ for (zone = 0; zone < nzones; zone++, map_addr++) {
+ dm[zone].dm_startbit = 0;
+ dm[zone].dm_endbit = zone_size;
+ dm[zone].dm_startblk = zone * zone_size - ADFS_DR_SIZE_BITS;
+ dm[zone].dm_bh = sb_bread(sb, map_addr);
+
+ if (!dm[zone].dm_bh) {
+ adfs_error(sb, "unable to read map");
+ goto error_free;
+ }
+ }
+
+ /* adjust the limits for the first and last map zones */
+ i = zone - 1;
+ dm[0].dm_startblk = 0;
+ dm[0].dm_startbit = ADFS_DR_SIZE_BITS;
+ dm[i].dm_endbit = (adfs_disc_size(dr) >> dr->log2bpmb) +
+ (ADFS_DR_SIZE_BITS - i * zone_size);
+
+ if (adfs_checkmap(sb, dm))
+ return dm;
+
+ adfs_error(sb, "map corrupted");
+
+error_free:
+ while (--zone >= 0)
+ brelse(dm[zone].dm_bh);
+
+ kfree(dm);
+ return ERR_PTR(-EIO);
+}