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

[Benoît Thébaudeau]

On Saturday, September 15, 2012 12:02:53 AM, Tom Rini wrote:
> 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.

OK. I took 0 instead of -1 because 0 already had this behavior.

Done here:
http://patchwork.ozlabs.org/patch/184793/

Best regards,
Benoît