[U-Boot] [PATCH v2 8/8] FAT: Make it possible to read from any file position

[Tom Rini]

On 09/14/2012 03:03 PM, Benoît Thébaudeau wrote:
> On Friday, September 14, 2012 10:49:04 PM, Tom Rini wrote:
>> On Mon, Sep 03, 2012 at 04:17:09PM +0200, Beno??t Th??baudeau wrote:
>>> Dear Wolfgang Denk,
>>>
>>> On Sunday, September 2, 2012 5:28:09 PM, Wolfgang Denk wrote:
>>>> Dear Beno??t Th??baudeau,
>>>>
>>>> In message
>>>> <1285759492.332736.1342790529256.JavaMail.root at advansee.com> you
>>>> wrote:
>>>>> When storage devices contain files larger than the embedded
>>>>> RAM, it
>>>>> is usef> ul to
>>>>> be able to read these files by chunks, e.g. for a software
>>>>> update
>>>>> to the
>>>>> embedded NAND Flash from an external storage device (USB stick,
>>>>> SD
>>>>> card, et> c.).
>>>>>
>>>>> Hence, this patch makes it possible by adding a new FAT API to
>>>>> read
>>>>> files f> rom a
>>>>> given position.
>>>>>
>>>>> Signed-off-by: Beno??t Th??baudeau
>>>>> <benoit.thebaudeau at advansee.com>
>>>>> Cc: Wolfgang Denk <wd at denx.de>
>>>>> ---
>>>>> Changes for v2:
>>>>>  - Patch renumbering because of the new v2 1/8.
>>>>>  - Possible code style changes due to the new v2 1/8.
>>>>>  - Add missing vairable renaming to fat_write.c.
>>>>>
>>>>>  .../fs/fat/fat.c                                   |   88
>>>>>  ++++++++++++++++> ----
>>>>>  .../fs/fat/fat_write.c                             |   18 ++--
>>>>>  2 files changed, 80 insertions(+), 26 deletions(-)
>>>>
>>>> I don't see any command line interface to actually use this code.
>>>>
>>>> How would I put this to use?
>>>
>>> Here is the current "fatload" command line interface:
>>> fatload <interface> <dev[:part]>  <addr> <filename> [bytes]
>>>
>>> Do you prefer to change it to:
>>> fatload <interface> <dev[:part]>  <addr> <filename> [offset]
>>> [bytes]
>>>
>>> or to have a new dedicated command, or something else?
>>
>> Lets go with:
>> fatload <interface> <dev[:part]>  <addr> <filename> [bytes] [offset]
>> and
>> update the long help text to mention both bytes and offset and that
>> offset requires bytes.
> 
> OK. Do you want that in an update of this patch or in a separate patch?

New patch to replace this.

> You're right: Having [bytes] before [offset] will avoid breaking the current
> users of this command. However, this has one drawback: fatls first has to be
> used to get the file size (with [offset] first, 0 could be easily used for
> offset to access [bytes]). Hence, still with [bytes] first, would you like to
> have some special bytes value (let's say -1 or any negative value) meaning "from
> offset to end of file"?

Lets go with -1 meaning until end of file since we don't have a good way
today to determine total filesize.

-- 
Tom