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

[Benoît Thébaudeau]

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?

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"?

Best regards,
Benoît