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authorFrank Gevaerts <frank@gevaerts.be>2014-01-04 21:28:26 +0100
committerFrank Gevaerts <frank@gevaerts.be>2014-01-04 21:28:26 +0100
commit646edc594f9b1ae27390576b4f6b1f08784e32d1 (patch)
treecb61253407b8d147dd8039a72706ae62112a88a2
parentda94b6303ea75f2b7b8e0b08fb9a96c730c894a4 (diff)
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Fix bpb_is_sane() cluster size calculation for non-512 byte sectors.
bpb_is_sane() used to effectively multiplying the sector size (relative to 512 bytes) twice, which meant that filesystems with e.g. 2K sectors and 32 sectors per cluster were rejected because while this adds up to 64K clusters (i.e. the upper limit), the calculation wrongly came to 256K. This bug tends to affect 5.5G ipods when formatted using dosfstools. Change-Id: Ia3f1e1303b2af953f497ccdbf23cd49c3d72e46a
-rw-r--r--firmware/drivers/fat.c13
1 files changed, 9 insertions, 4 deletions
diff --git a/firmware/drivers/fat.c b/firmware/drivers/fat.c
index 0b8451a5c6..fb75355898 100644
--- a/firmware/drivers/fat.c
+++ b/firmware/drivers/fat.c
@@ -624,13 +624,18 @@ static int bpb_is_sane(IF_MV_NONVOID(struct bpb* fat_bpb))
fat_bpb->bpb_bytspersec);
return -1;
}
- if((long)fat_bpb->bpb_secperclus * (long)fat_bpb->bpb_bytspersec
- > 128L*1024L)
+ if((long)fat_bpb->bpb_secperclus * SECTOR_SIZE > 128L*1024L)
{
+ /* We don't multiply by bpb_bytspersec here, because
+ * back in fat_mount_internal() bpb_secperclus has been
+ * "normalised" to 512 byte clusters, by multiplying with
+ * secmult. */
DEBUGF( "bpb_is_sane() - Error: cluster size is larger than 128K "
"(%d * %d = %d)\n",
- fat_bpb->bpb_bytspersec, fat_bpb->bpb_secperclus,
- fat_bpb->bpb_bytspersec * fat_bpb->bpb_secperclus);
+ fat_bpb->bpb_bytspersec,
+ fat_bpb->bpb_secperclus / (fat_bpb->bpb_bytspersec / SECTOR_SIZE),
+ fat_bpb->bpb_bytspersec * fat_bpb->bpb_secperclus /
+ (fat_bpb->bpb_bytspersec / SECTOR_SIZE));
return -2;
}
if(fat_bpb->bpb_numfats != 2)