Hello Mike,
2009/1/2 Mike Frysinger vapier@gentoo.org:
From: Bryan Wu bryan.wu@analog.com A couple of buffers in the fat code are declared as an array of bytes. But it is then cast up to a structure with 16bit and 32bit members. Since GCC assumes structure alignment here, we have to force the buffers to be aligned according to the structure usage.
Just curious (because before the Christmas holidays I was also debugging some FAT problems, and maybe this is related) What problem/symptoms does this patch fix? How did the bug show itself?
Kind Regards,
Remy
Signed-off-by: Bryan Wu bryan.wu@analog.com Signed-off-by: Mike Frysinger vapier@gentoo.org
fs/fat/fat.c | 19 +++++++++++++++---- 1 files changed, 15 insertions(+), 4 deletions(-)
diff --git a/fs/fat/fat.c b/fs/fat/fat.c index a9dde7d..06736d9 100644 --- a/fs/fat/fat.c +++ b/fs/fat/fat.c @@ -429,12 +429,16 @@ slot2str(dir_slot *slotptr, char *l_name, int *idx)
/*
- We need align this buffer to 16bit, cause it will be cast up to
- a dir_slot structure
- */
+__u8 get_vfatname_block[MAX_CLUSTSIZE] __attribute__ ((aligned(sizeof(__u16)))); +/*
- Extract the full long filename starting at 'retdent' (which is really
- a slot) into 'l_name'. If successful also copy the real directory entry
- into 'retdent'
- Return 0 on success, -1 otherwise.
*/ -__u8 get_vfatname_block[MAX_CLUSTSIZE]; static int get_vfatname(fsdata *mydata, int curclust, __u8 *cluster, dir_entry *retdent, char *l_name) @@ -517,10 +521,14 @@ mkcksum(const char *str)
/*
- We need align this buffer to 32bit, cause it will be cast up to
- a dir_entry structure
- */
+__u8 get_dentfromdir_block[MAX_CLUSTSIZE] __attribute__ ((aligned(sizeof(__u32)))); +/*
- Get the directory entry associated with 'filename' from the directory
- starting at 'startsect'
*/ -__u8 get_dentfromdir_block[MAX_CLUSTSIZE]; static dir_entry *get_dentfromdir (fsdata * mydata, int startsect, char *filename, dir_entry * retdent, int dols) @@ -725,8 +733,11 @@ read_bootsectandvi(boot_sector *bs, volume_info *volinfo, int *fatsize) return -1; }
-__u8 do_fat_read_block[MAX_CLUSTSIZE]; /* Block buffer */ +/*
- We need align this buffer to 32bit, cause it will be cast up to
- a dir_entry structure
- */
+__u8 do_fat_read_block[MAX_CLUSTSIZE] __attribute__ ((aligned(sizeof(__u32)))); long do_fat_read (const char *filename, void *buffer, unsigned long maxsize, int dols) -- 1.6.0.6
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