dtrace discuss - Sep 2005 - DTrace typewriter

G''Day Folks,

I''ve found another use of dtrace, this makes your console keyboard
sound like a typewriter.

   http://www.brendangregg.com/DTrace/typewriter-0.70.tar.gz

I''ve only tested it on an UltraSPARC 5 and a Pentium laptop so far,
more
to follow.

Ok, sorry, not actually a practical use of DTrace. :)

Enjoy!

Brendan

[Sydney, Australia]

I executed following 2 small programs just to check the file open and 
close by a process. The process is running.

##for open

dtrace -n ''syscall::open*:entry
/execname == "esd"/
{printf("%s----> %s", execname,copyinstr(arg0));
}''

This works fine.


## for close


dtrace -n ''syscall::close:entry
/execname == "esd"/
{printf("%s---->  %s", execname,copyinstr(arg0));
}''

for this i am getting following messages...

dtrace: error on enabled probe ID 1 (ID 5677: syscall::close:entry): 
invalid address (0x0) in action #2 at DIF offset 28
dtrace: error on enabled probe ID 1 (ID 5677: syscall::close:entry): 
invalid address (0x0) in action #2 at DIF offset 28
dtrace: error on enabled probe ID 1 (ID 5677: syscall::close:entry): 
invalid address (0x0) in action #2 at DIF offset 28
.............


Did I go wrong somewhere in writing this small code.


Thanks for any help,
-Ganesh

Ganesh,

Ganesh Chaudhari wrote:
> ## for close
> 
> 
> dtrace -n ''syscall::close:entry
> /execname == "esd"/
> {printf("%s---->  %s", execname,copyinstr(arg0));
> }''
> 
> for this i am getting following messages...
> 
> dtrace: error on enabled probe ID 1 (ID 5677: syscall::close:entry): 
> invalid address (0x0) in action #2 at DIF offset 28
> dtrace: error on enabled probe ID 1 (ID 5677: syscall::close:entry): 
> invalid address (0x0) in action #2 at DIF offset 28
> dtrace: error on enabled probe ID 1 (ID 5677: syscall::close:entry): 
> invalid address (0x0) in action #2 at DIF offset 28
> .............
> 
> 
> Did I go wrong somewhere in writing this small code.
close, unlike open, takes as parameter a file descriptor.
Trying to print it as a string will result in the above error.

Try printing it as an integer.
printf("%s---->  %d", execname,arg0);

Manoj

Ganesh Chaudhari wrote:
> 
> I executed following 2 small programs just to check the file open and
> close by a process. The process is running.
> 
> ##for open
> 
> dtrace -n ''syscall::open*:entry
> /execname == "esd"/
> {printf("%s----> %s", execname,copyinstr(arg0));
> }''
> 
> This works fine.
> 
> ## for close
> 
> dtrace -n ''syscall::close:entry
> /execname == "esd"/
> {printf("%s---->  %s", execname,copyinstr(arg0));
> }''
> 
> for this i am getting following messages...
> 
> dtrace: error on enabled probe ID 1 (ID 5677: syscall::close:entry):
> invalid address (0x0) in action #2 at DIF offset 28
> dtrace: error on enabled probe ID 1 (ID 5677: syscall::close:entry):
> invalid address (0x0) in action #2 at DIF offset 28
> dtrace: error on enabled probe ID 1 (ID 5677: syscall::close:entry):
> invalid address (0x0) in action #2 at DIF offset 28

while open()''s first argument is a path name:

     int open(const char *path, int oflag, /* mode_t mode */);

close()''s isn''t

     int close(int fildes);

you''re trying to copyin a "pointer" which is an int (1,2...),
which is
invalid.

if you want to print the name being closed, you''d best do something
like
> dtrace -n ''syscall::open*:entry
> /execname == "esd"/
> {printf("%s----> %s", execname,copyinstr(arg0));
 	this->name = copyinstr(arg0);
> }''
> 
> This works fine.
> 
> ## for close
> 
> dtrace -n ''syscall::close:entry
> /execname == "esd" && this->name /
{ printf ("%s---->  %s", execname, this->name);
this->name = 0;
> }''
>
or some such - check the documentation for syntactical details.

HTH
-- 
Michael Schuster                  (+49 89) 46008-2974 / x62974
visit the online support center:  http://www.sun.com/osc/

Recursion, n.: see ''Recursion''