How to get filename of an open file descriptor

[Skip Ford]

Robert Watson wrote:
> On Sun, 18 Nov 2007, Skip Ford wrote:
>>
>>As for the procstat(1) code itself, I've found one bug and have two 
>>sugestions:
>>
>>1)  procstat_args() doesn't use a local variable and the buffer doesn't
>>get cleared between calls:
>>
>>$ procstat -a 797
>> PID ARGS
>> 797 audacious
>>$ procstat -a 795 797
>> PID ARGS
>> 795 xterm -xtsessionID 11c0a80103000118536826300000007680000
>> 797 audacious essionID 11c0a80103000118536826300000007680000
>>$
>>
>>Other option's functions are not similarly affected.
>>
>>2)  I think it should handle requests for information about pid 0 instead 
>>of requiring at least pid 1 as it currently does.  Solaris suggests 
>>'/proc/*' to see all processes.  If we use `ps axopid=` then it aborts on 
>>the swapper (pid 0) immediately.
>>
>>3)  Similarly, I think all of the sysctl(3) calls within the individual 
>>option functions (procstat_bin(), procstat_args(), etc.) should just go 
>>ahead and print the header and pid, then print any sysctl(3) error in the 
>>PID's row instead of erroring out.  We're either about to finish executing 
>>anyway if that was the only pid requested, or we're moving on to another 
>>pid that has nothing to do with the previous pid.  There's not really any 
>>reason to stop processing further pids.  This also affects attempting to 
>>list all pids since it currently stops processing pids as soon as one 
>>doesn't exist. A global error variable could just be incremented with 
>>every call and returned at process exit, that way it'd still be meaningful 
>>for single PIDs.
> 
> Actually, I think I've fixed all of the above in p4 with some changes 
> yesterday; I'll do a new code drop for you to try:
> 
>   http://www.watson.org/~robert/freebsd/20071118-procstat.tgz

Yes, I like it.  We must be thinking alike, which is ultimately
bad news for you, I'm afraid.

The bug mentioned first above is still present, and the other bug I
mentioned outside of this thread also is, AFAIK.  Other than those, I like
it.

-- 
Skip