TR : DOSFS unlink problem

[Etienne Fortin]

Hi Thomas,
Maybe sometimes I should look at the mailing list archive before jumping
to asking yet another question :) RTFM as they say :)

Anyway, looking at unlink.c:unlink(), I find it strange to have to look
at the parent directory of of the directory containing the file we want
to unlink. Only the parent directory of the file should be looked at.
This way, the call to rtems_filesystem_evaluate_parent() of the parent
dir of the file to unlink seems unecessary. Looks like too much
indirection. But I don't quite completely understand what is going on so
I may be totally wrong. 

For now I just commented out the call to
rtems_filesystem_evaluate_parent() (thank god RTEMS is open source!!!)
until a solution is found.

Etienne




-----Message d'origine-----
De : Thomas Doerfler [mailto:Thomas.Doerfler at imd-systems.de] 
Envoyé : 25 novembre, 2004 13:39
À : Etienne Fortin; Jennifer averett
Cc : rtems-users at rtems.com
Objet : Re: TR : DOSFS unlink problem


Etienne,

as you mentioned in another message, somebody else already found 
this problem. The reason is, that the unlink call want to check, 
that the directory, where the file is located, is writable. 

Unfortunately, DOSFS does niot keep track of parents, so in the 
structure maintained to manage a file, there is no pointer back 
to the directory, where the file is located in. Therefore, a 
basic operation to "move up one level in the directory tree" 
fails in DOSFS and this makes unlink fail aswell.

I havve already investigated a bit about this problem :-)

I also have the feeling, that DOSFS currently does NOT implement 
file attributes (is this right? sorry if I make wrong 
assumptions here). Then it really does not make sense to walk 
back to the parent directory of the file, and check the access 
attributes (which are not meaningful at all).

I have filed a PR on this.

And I have no clue on how to solve this. Adding "go back to 
parent" support seems a bit difficult. I have started in 
maintaining a "parent_cln" field  in the fat_file_fd_t 
structure, but this is only a start.

Any ideas? 

wkr,
Thomas.


> 
> -----Message d'origine-----
> De : Etienne Fortin [mailto:etienne.fortin at sensio.tv]
> Envoyé : 25 novembre, 2004 13:02
> À : rtems-users at rtems.com
> Objet : DOSFS unlink problem
> 
> 
> Hi everyone,
> Me again, with my problems :)
> 
> I mounted a filesystem (DOSFS) on /storage.
> 
> In /storage I have a directory named bitstr.
> 
> So the basepath is /storage/bitstr.
> 
> I can create files in /storage/bitstr.
> 
> I can list the files with opendir/readdir...
> 
> BUT, I can't remove files in /storage/bitstr.
> 
> Somewhere in unlink, there's a call to 
> rtems_filesystem_evaluate_parent(). It searchs for parent of 
> /storage/bitstr (or so it seems). It finds the parent, and it's type 
> is RTEMS_FILESYSTEM_MEMORY_FILE and not FAT_DIRECTORY. So, it throws 
> up an error saying that it's not a directory.
> 
> Quite strange...
> 
> Any idea?
> 
> Etienne Fortin
> Sensio
> 

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