Hi Pintu,
On Sat, 22 Oct 2011, Pintu Kumar wrote:
> I already did some work for scanning only top level directory in vvfat.
> Using the following logic in read_directory()
>
> if(parent_index >= 0 & (!dot & !dotdot))
> {
> free(buffer);
> break;
> }
Sorry, this is way too deep in the code (and I'd have to guess because you
did not grace me with exact locations), I cannot afford to dive into it
that far. But what I can say is that it is not all that easy; you'll need
to refactor the code.
You _will_ need to reserve sectors for future directory parsing. You
_will_ need to add code that intercepts reads to those sectors. You _will_
have to read the directories in question when those sectors are accessed
and thereby commit the sectors to a final state.
BTW both Kevin and I said that before.
> Hope this is correct logic for skipping sub-directories content by just
> scanning only dot and dotdot entries inside it.
It would be, if all you want are empty directories.
> But as per the recent analysis it was observed that there is some
> problem in skipping sub-directory scanning itself. Because when I issue
> "df" command on VVFAT partition I get read_cluster errors during these
> sector location.
When you issue "df", you need to commit to which sectors are reserved. By
that, you take almost all the advantage of lazy directory parsing away.
> Mr. Johannes, can you clarify on this first.
>
> Then we will look into the dynamic mapping part later.
I am very sorry, but I do get the impression that the intent is to lure me
into doing all the work, including the investigation what it would take to
turn the code into a version that reads just the top-level first and only
later the subdirectories.
This will not happen. I have enough projects that I want to tackle myself,
and I am extremely unwilling to do the work for somebody else when that
somebody else is paid to do the work. For the things I _want_ to do I
already have too little time, given that my day job is quite demanding and
asks software design and architecture of me already.
So: you _will_ have to acquaint yourself with the FAT and then the VFAT
specification. You _will_ have to make a proper plan how the client may be
fooled into believing that there is a fixed filesystem when there is
actually just directories of files. And you _will_ have to write that code
yourself.
I hope this clarified it?
Ciao,
Johannes
