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From: jgy@hropus.UUCP (John Young)
Newsgroups: comp.unix.questions
Subject: Re: Identify file name given file descriptor
Message-ID: <1037@hropus.UUCP>
Date: Tue, 19-May-87 11:21:27 EDT
Article-I.D.: hropus.1037
Posted: Tue May 19 11:21:27 1987
Date-Received: Sat, 23-May-87 13:25:38 EDT
References: <710@twitch.UUCP> <877@killer.UUCP>
Organization: Bell Labs, Holmdel, NJ
Lines: 41
Keywords: mount, ncheck, partly tested

> main
>     find_file_name ("/", your_fstat_structure) -- start from root directory
> 					       -- with fstat(2) values.
> end
> 
> procedure find_file_name (current_directory, file_fstat)
> 
>     if current_directory.file_stat = file_fstat then
> 				-- was FD this directory?
> 	    putstring (current_directory)
>             return
>     fi
>     for each file_entry in current_directory    -- stat(2) each slot
>         if file_entry.file_type = directory_type then
> 				-- recursively call directories
>             find_file_name (current_directory + file_entry.file_name,
> 						file_fstat)
>         elif file_entry.file_stat = file_fstat then
> 				-- else check to see if it is the file
> 				-- by checking st_ino and st_dev fields.
>             putstring (current_directory + file_entry.file_name)
> 				-- and print the name if you found one.
>             return
>         fi
> end
> 
> 
> There you have it.  All accessible files are checked, which should include
> yourown since you should be able to read you own directory.  The ones you
> can't access can't be accessed :-(.  st_ino and st_dev are all you need to
> compare to see if the files are the same ones.  This should (once written
> in C or something) be as fast or faster than find(1) since find(1) has atleast
> this much work to do.
> 
> - John.
> 

This doesn't seem to handle the case of having a filesystem
mounted on anything but a root level directory.

 - John Young