VFS chroot

David Collier-Brown davec-b at rogers.com
Fri Nov 16 08:15:36 MST 2012

On 11/16/2012 09:48 AM, René Klomp wrote:
> Hi all,
> I am developing a VFS module that modifies certain files in a specific
> way that can be different each time that file is opened
> To do this I want to use an external script that takes a file as input
> and then changes it and writes those changes to a temporary file. The
> temporary file then has to be served to the client.
> How could I best do this?
> I tried the following:
> static int my_vfs_open(vfs_handle_struct *handle, struct smb_filename
> *smb_fname,
>              files_struct *fsp, int flags, mode_t mode)
> {
>     if(strcmp(smb_fname->base_name,"test.txt")==0){
>         return open("test2.txt", flags, mode);
>     }
>     return SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, mode);
> }
> This works, but it is not possible to open a file outside the current
> share directory... So I wont be able to let a script write a file to
> another directory so that it wont be visible in the share.
> Another thing I thought about was piping the output of the external
> script to the user. That would probably be more efficient? Is that
> possible? If yes, how?

This sounds a little bit like software copy-on-write, so you perhaps
could do something like
         return open("./.invisible_copy_dir/test.txt", flags, mode);

That's what you're doing, though, not what you *want* to be doing (:-))

What's the thing you want?  In effect, "why?"

David Collier-Brown,         | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
davecb at spamcop.net           |                      -- Mark Twain
(416) 223-8968

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