Overwriting an empty file not created by U-Boot did not work, and it
could even corrupt the FAT. Moreover, creating empty files or emptying
existing files allocated a cluster, which is not standard.

Fix this by always keeping empty files clusterless as specified by
Microsoft (the start cluster must be set to 0 in the directory entry in
that case), and by supporting overwriting such files.

Signed-off-by: Benoît Thébaudeau <benoit@wsystem.com>

Signed-off-by: Benoît Thébaudeau <benoit@wsystem.com>

curclust was used instead of newclust in the debug() calls and in one
CHECK_CLUST() call, which could skip a failure case.

Signed-off-by: Benoît Thébaudeau <benoit@wsystem.com>

set_contents() had uselessly split calls to set_cluster(). Merge these
calls, which removes some cases of set_cluster() being called with a
size of zero.

Signed-off-by: Benoît Thébaudeau <benoit@wsystem.com>

set_cluster() was using a temporary buffer without enforcing its
alignment for DMA and cache. Moreover, it did not check the alignment of
the passed buffer, which can come directly from applicative code or from
the user.

This could cause random data corruption, which has been observed on
i.MX25 writing to an SD card.

Fix this by only passing ARCH_DMA_MINALIGN-aligned buffers to
disk_write(), which requires the introduction of a buffer bouncing
mechanism for the misaligned buffers passed to set_cluster().

By the way, improve the handling of the corresponding return values from
disk_write():
 - print them with debug() in case of error,
 - consider that there is an error is disk_write() returns a smaller
   block count than the requested one, not only if its return value is
   negative.

After this change, set_cluster() and get_cluster() are almost
symmetrical.

Signed-off-by: Benoît Thébaudeau <benoit@wsystem.com>

It is very common that FAT code is using following pattern:
if (disk_{read|write}() < 0)
        return -1;

Up till now the above code was dead, since disk_{read|write) could only
return value >= 0.
As a result some errors from medium layer (i.e. eMMC/SD) were not caught.

The above behavior was caused by block_{read|write|erase} declared at
struct block_dev_desc (@part.h). It returns unsigned long, where 0
indicates error and > 0 indicates that medium operation was correct.

This patch as error regards 0 returned from block_{read|write|erase}
when nr_blocks is grater than zero. Read/Write operation with nr_blocks=0
should return 0 and hence is not considered as an error.

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>

Test HW: Odroid XU3 - Exynos 5433

The changes to introduce loff_t into filesize means that we need to do
64bit math on 32bit platforms.  Make sure we use the right wrappers for
these operations.

Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Cc: Suriyan Ramasami <suriyan.r@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Rini <trini@ti.com>
Tested-by: Pierre Aubert <p.aubert@staubli.com>

Change the internal FAT functions to use loff_t for offsets.

Signed-off-by: Suriyan Ramasami <suriyan.r@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
[trini: Fix fs/fat/fat.c for min3 updates]
Signed-off-by: Tom Rini <trini@ti.com>

- update the comments regarding lbaint_t usage
- cleanup casting of values related to the lbaint_t type
- cleanup of a type that requires a u64

Tested on little endian ARMv7 and ARMv8 configurations

Signed-off-by: Steve Rae <srae@broadcom.com>

When write a file into FAT file system, it will search a match file in
root dir. So the find_directory_entry() will get the first cluster of
root dir content and search the directory item one by one. If the file
is not found, we will call get_fatent_value() to get next cluster of root
dir via lookup the FAT table and continue the search.

The issue is in FAT16/12 system, we cannot get root dir's next clust
from FAT table. The FAT table only be use to find the clust of data
aera in FAT16/12.

In FAT16/12 if the clust is in root dir, the clust number is a negative
number or 0, 1. Since root dir is located in front of the data area.
Data area start clust #2. So the root dir clust number should < 2.

This patch will check above situation before call get_fatenv_value().
If curclust is < 2, include minus number, we just increase one on the
curclust since root dir is in continous cluster.

The patch also add a sanity check for entry in get_fatenv_value().

Signed-off-by: Josh Wu <josh.wu@atmel.com>