dtrace discuss - Oct 2009 - Using dapptrace. Can't seem to trace user functions with defaults or specifying -u<lib>

Hi Folks,
I''m trying to get to grips with dapptrace, running it on my Mac.

Everything seems pretty straightforward, except for - of course - what  
I''m trying to do.

I want to focus in on my code but I can''t seem to be able to output  
just the functions I want, i.e. user functions.

The -U option gives everything. Too much of course.

Leaving that blank means the default which seems to be "a.out",

e.g. sudo -s dapptrace  ~/myexecutable

	: probe description pid31688:a.out::entry does not match any probes

That hits nothing.

If I take a lib from all the output using the -U option, e.g.  
libSystem.B.dylib,

-> libSystem.B.dylib:free(0x300D70, 0x1A, 0xBFFFF258)		
-> libSystem.B.dylib:szone_size(0x22E000, 0x300D70, 0x50)		
<- libSystem.B.dylib:szone_size = 585
-> libSystem.B.dylib:szone_free_definite_size(0x22E000, 0x300D70,  
0x10)		
-> libSystem.B.dylib:tiny_free_list_remove_ptr(0x1, 0x231500,  
0x22E000)		
<- libSystem.B.dylib:tiny_free_list_remove_ptr = 239
<- libSystem.B.dylib:szone_free_de


and try that specifying the -u option as in:

sudo -s dapptrace  -u libSystem.B.dylib ~/myexecutable

that gives...

	: probe description pid31696:libSystem.B.dylib::entry does not match  
any probes



which to me is weird as that is a library it is showing when I run  
with the -U option.

I think I''m missing something obvious here and any advice would be  
much appreciated.

Cheers,
Max


-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://mail.opensolaris.org/pipermail/dtrace-discuss/attachments/20091023/8de60a52/attachment.html>

On Oct 23, 2009, at 8:55 AM, Max wrote:
> Hi Folks,
> I''m trying to get to grips with dapptrace, running it on my Mac.
>
> Everything seems pretty straightforward, except for - of course -  
> what I''m trying to do.
>
> I want to focus in on my code but I can''t seem to be able to
output
> just the functions I want, i.e. user functions.
>
> The -U option gives everything. Too much of course.
>
> Leaving that blank means the default which seems to be "a.out",
>
> e.g. sudo -s dapptrace  ~/myexecutable
>
> 	: probe description pid31688:a.out::entry does not match any probes
>
> That hits nothing.
>
> If I take a lib from all the output using the -U option, e.g.  
> libSystem.B.dylib,
>
> -> libSystem.B.dylib:free(0x300D70, 0x1A, 0xBFFFF258)		
> -> libSystem.B.dylib:szone_size(0x22E000, 0x300D70, 0x50)		
> <- libSystem.B.dylib:szone_size = 585
> -> libSystem.B.dylib:szone_free_definite_size(0x22E000, 0x300D70,  
> 0x10)		
> -> libSystem.B.dylib:tiny_free_list_remove_ptr(0x1, 0x231500,  
> 0x22E000)		
> <- libSystem.B.dylib:tiny_free_list_remove_ptr = 239
> <- libSystem.B.dylib:szone_free_de
>
>
> and try that specifying the -u option as in:
>
> sudo -s dapptrace  -u libSystem.B.dylib ~/myexecutable
>
> that gives...
>
> 	: probe description pid31696:libSystem.B.dylib::entry does not  
> match any probes
>
>
>
> which to me is weird as that is a library it is showing when I run  
> with the -U option.
>
> I think I''m missing something obvious here and any advice would be
> much appreciated.
Max,

	The problem is that the dapptrace script is doing this:
> ### Run DTrace
> if [ $opt_command -eq 1 ]; then
> 	/usr/sbin/dtrace -x dynvarsize=$buf -x evaltime=exec -n
"$dtrace" \
> 	    -c "$command" >&2
> else
> 	/usr/sbin/dtrace -x dynvarsize=$buf -n "$dtrace" -p
"$pid" >&2
> fi
	The -x evaltime=exec option means "start tracing immediately when the  
app is launched",
but at that time, the only libraries loaded are dyld and the target  
executable. There really
aren''t any libSystem.B.dylib functions to probe.

	If you add a "-Z" after the -x evaltime=exec above, your command  
should work.

	I''m not sure what is going on with a.out not working, I believe it  
should work,
and it is a bug that it isn''t.

	James M

Hi James,
that''s great thanks for responding.

It doesn''t seem to match the target executable either with the -u  
option.

Again, I can see that library in use using -U.

Could it be that it is also loaded dynamically?

Everything comes up as expected using -Z.

Many thanks,
Max




On 23 Oct 2009, at 21:42, James McIlree wrote:
>
> On Oct 23, 2009, at 8:55 AM, Max wrote:
>
>> Hi Folks,
>> I''m trying to get to grips with dapptrace, running it on my
Mac.
>>
>> Everything seems pretty straightforward, except for - of course -  
>> what I''m trying to do.
>>
>> I want to focus in on my code but I can''t seem to be able to
output
>> just the functions I want, i.e. user functions.
>>
>> The -U option gives everything. Too much of course.
>>
>> Leaving that blank means the default which seems to be
"a.out",
>>
>> e.g. sudo -s dapptrace  ~/myexecutable
>>
>> 	: probe description pid31688:a.out::entry does not match any probes
>>
>> That hits nothing.
>>
>> If I take a lib from all the output using the -U option, e.g.  
>> libSystem.B.dylib,
>>
>> -> libSystem.B.dylib:free(0x300D70, 0x1A, 0xBFFFF258)		
>> -> libSystem.B.dylib:szone_size(0x22E000, 0x300D70, 0x50)		
>> <- libSystem.B.dylib:szone_size = 585
>> -> libSystem.B.dylib:szone_free_definite_size(0x22E000, 0x300D70,  
>> 0x10)		
>> -> libSystem.B.dylib:tiny_free_list_remove_ptr(0x1, 0x231500,  
>> 0x22E000)		
>> <- libSystem.B.dylib:tiny_free_list_remove_ptr = 239
>> <- libSystem.B.dylib:szone_free_de
>>
>>
>> and try that specifying the -u option as in:
>>
>> sudo -s dapptrace  -u libSystem.B.dylib ~/myexecutable
>>
>> that gives...
>>
>> 	: probe description pid31696:libSystem.B.dylib::entry does not  
>> match any probes
>>
>>
>>
>> which to me is weird as that is a library it is showing when I run  
>> with the -U option.
>>
>> I think I''m missing something obvious here and any advice
would be
>> much appreciated.
>
> Max,
>
> 	The problem is that the dapptrace script is doing this:
>
>> ### Run DTrace
>> if [ $opt_command -eq 1 ]; then
>> 	/usr/sbin/dtrace -x dynvarsize=$buf -x evaltime=exec -n
"$dtrace" \
>> 	    -c "$command" >&2
>> else
>> 	/usr/sbin/dtrace -x dynvarsize=$buf -n "$dtrace" -p
"$pid" >&2
>> fi
>
> 	The -x evaltime=exec option means "start tracing immediately when  
> the app is launched",
> but at that time, the only libraries loaded are dyld and the target  
> executable. There really
> aren''t any libSystem.B.dylib functions to probe.
>
> 	If you add a "-Z" after the -x evaltime=exec above, your command
> should work.
>
> 	I''m not sure what is going on with a.out not working, I believe
it
> should work,
> and it is a bug that it isn''t.
>
> 	James M
>