dtrace discuss - Feb 2007 - How to get from file descriptor to file name

I am enabling the syscall::write:entry probe on a running process.  Within
dtrace, I have easy access to the file descriptor.  I can also easily
cross-reference this using pfiles to determine the filename.  I am
interested in doing this from within dtrace.  I started with curpsinfo and
from there I was going to access the user struct and follow the trail to the
vnode where I expected I would find the goods I am interested in.  Once I
include <sys/proc.h> I get error messages related to <sys/kstat.h>.

I suspect that there is an easier way.  I''m new to this, so
I''ll appreciate
whatever pointer you can give me.

This is somewhat of a pointless exercise, as I have what I need, but
I''m
using this as an opportunity to learn.  What is the dtrace way?

Given that i didn''t have enabled probes when the file was opened, and
I''m in
the action clause with a file descriptor, how do I get the name of the file?

Thanks,
Chris
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Check out this discussion thread:

http://www.opensolaris.org/jive/thread.jspa?messageID=72813&#72813

And Mike''s blog:

http://blogs.sun.com/mws/entry/dtrace_inlines_translators_and_file

Where he describes the fds[] array, with this example:

$ dtrace -q -s /dev/stdin
syscall::write:entry
/ execname == "ksh" && fds[arg0].fi_oflags & O_APPEND /
{
        printf("ksh %d appending to %s\n", pid,
fds[arg0].fi_pathname);
}


This will accomplish what you wish...

/jim


MC wrote:
>
> I am enabling the syscall::write:entry probe on a running process.  
> Within dtrace, I have easy access to the file descriptor.  I can also 
> easily cross-reference this using pfiles to determine the filename.  I 
> am interested in doing this from within dtrace.  I started with 
> curpsinfo and from there I was going to access the user struct and 
> follow the trail to the vnode where I expected I would find the goods 
> I am interested in.  Once I include <sys/proc.h> I get error messages
> related to <sys/kstat.h>.
>
> I suspect that there is an easier way.  I''m new to this, so
I''ll
> appreciate whatever pointer you can give me.
>
> This is somewhat of a pointless exercise, as I have what I need, but 
> I''m using this as an opportunity to learn.  What is the dtrace
way?
>
> Given that i didn''t have enabled probes when the file was opened,
and
> I''m in the action clause with a file descriptor, how do I get the
name
> of the file?
>
> Thanks,
> Chris
> ------------------------------------------------------------------------
>
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> dtrace-discuss mailing list
> dtrace-discuss at opensolaris.org
>