dtrace discuss - Sep 2005 - how to tracing all the calls to a library?

Is there a method to tracing all the calls to a library?
I know using pid provider can tracing calls to a library,
but It can only tracing a special process, I want to trace all
the calls in the system to a library?
What can I do to reach this?
Thanks,
--Xiliu

This is something I also wanted to do some time back. Clearly it''s not
possible for the PID provider to do this as it stands; if it was possible to
dynamically enable a probe you could potentially do this with a script that
looked at every newly fork/exec''d process (or every process which
loaded
this library, if it''s dynamically linked). But it''s not...

I think the your options are:

* Writing a script to look for "candidate" processes periodically,
invoking
separate D scripts, or
* Just defining some static probe points of your own in the library.

If anyone else has a better solution to this, I''d love to hear it.

Just dreaming for a moment - no idea how practical this is - but given that
the PID provider changes the text of your binary when probes are enabled, is
it possible in theory to do the same thing globally for code in a shared
object? i.e. the provider would instrument the _shared_ text, rather than
copying it and instrumenting it for a single process, as I guess it must do
now?

-- 

Philip Beevers
Fidessa Infrastructure Development

mailto:philip.beevers at fidessa.com
phone: +44 1483 206571

> -----Original Message-----
> From: dtrace-discuss-bounces at opensolaris.org
> [mailto:dtrace-discuss-bounces at opensolaris.org]On Behalf Of 
> Xiliu Tang -
> Sun Microsystems - Beijing China
> Sent: 09 September 2005 10:54
> To: dtrace-discuss at opensolaris.org
> Subject: [dtrace-discuss] how to tracing all the calls to a library?
> 
> 
> Is there a method to tracing all the calls to a library?
> I know using pid provider can tracing calls to a library,
> but It can only tracing a special process, I want to trace all
> the calls in the system to a library?
> What can I do to reach this?
> Thanks,
> --Xiliu
> _______________________________________________
> dtrace-discuss mailing list
> dtrace-discuss at opensolaris.org
> 

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Hi,

not a tracing solution on par with dtrace, but you may want to
try library interpositions.

eg: 

if you''re interested in collecting stats for open(), you
can 

1. code your own version of open() (you''ll need to give it
   the same name, and pass it the same arguments), into a file
   my_open.c

   in the open() in my_open.c, code it to retrieve the symbol
   info for the actual open(), using dlsym().

   collect the stats, and then invoke the actual open by using
   the handle returned from dlsym() earlier.

2. then compile and link it into libmyopen.so.

3. run the programs that you''re investigating after exporting
   LD_PRELOAD to point to your new library.

   $ export LD_PRELOAD=./libmyopen.so.
   $ run_any_programs
   $ ...

hope this helps, cheers,
sam

 | This is something I also wanted to do some time back. Clearly it''s
not
 | possible for the PID provider to do this as it stands; if it was possible to
 | dynamically enable a probe you could potentially do this with a script that
 | looked at every newly fork/exec''d process (or every process which
loaded
 | this library, if it''s dynamically linked). But it''s not...
 | 
 | I think the your options are:
 | 
 | * Writing a script to look for "candidate" processes periodically,
invoking
 | separate D scripts, or
 | * Just defining some static probe points of your own in the library.
 | 
 | If anyone else has a better solution to this, I''d love to hear it.
 | 
 | Just dreaming for a moment - no idea how practical this is - but given that
 | the PID provider changes the text of your binary when probes are enabled, is
 | it possible in theory to do the same thing globally for code in a shared
 | object? i.e. the provider would instrument the _shared_ text, rather than
 | copying it and instrumenting it for a single process, as I guess it must do
 | now?
 | 
 | -- 
 | 
 | Philip Beevers
 | Fidessa Infrastructure Development
 | 
 | mailto:philip.beevers at fidessa.com
 | phone: +44 1483 206571
 | 
 | 
 | > -----Original Message-----
 | > From: dtrace-discuss-bounces at opensolaris.org
 | > [mailto:dtrace-discuss-bounces at opensolaris.org]On Behalf Of 
 | > Xiliu Tang -
 | > Sun Microsystems - Beijing China
 | > Sent: 09 September 2005 10:54
 | > To: dtrace-discuss at opensolaris.org
 | > Subject: [dtrace-discuss] how to tracing all the calls to a library?
 | > 
 | > 
 | > Is there a method to tracing all the calls to a library?
 | > I know using pid provider can tracing calls to a library,
 | > but It can only tracing a special process, I want to trace all
 | > the calls in the system to a library?
 | > What can I do to reach this?
 | > Thanks,
 | > --Xiliu
 | > _______________________________________________
 | > dtrace-discuss mailing list
 | > dtrace-discuss at opensolaris.org
 | > 
 | 
 | 
 | ******************************************************************    
 | This message is intended only for the stated addressee(s) and
 | may be confidential.  Access to this email by anyone else is
 | unauthorised. Any opinions expressed in this email do not
 | necessarily reflect the opinions of royalblue. Any unauthorised
 | disclosure, use or dissemination, either whole or in part is
 | prohibited. If you are not the intended recipient of this message,
 | please notify the sender immediately.
 | ******************************************************************
 | 
 | _______________________________________________
 | dtrace-discuss mailing list
 | dtrace-discuss at opensolaris.org