dtrace discuss - Sep 2005 - How to get full path name of execname?

Hi,

Is there a way to print out full path name of execname when the following
probe is touched?

proc:genunix:exec_common:exec-success

Thanks.

************************************************
* C P Lin, Common Technology Project Lead.     *
* Sun Microsystems Inc.                        *                        
* E-Mail:  c.lin at sun.com                       *
* Address: 4150 Network Circle, M/S UMPK12-210 *
* Santa Clara, CA 95054                        *
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On 9/14/05, C Lin <c.lin at sun.com> wrote:
> Hi,
> 
> Is there a way to print out full path name of execname when the following
> probe is touched?
> 
> proc:genunix:exec_common:exec-success
It''s passed as args[0] to proc:::exec; something like:

proc:::exec
{
    self->path = args[0];
}

proc:::exec-success
/self->path/
{
    printf("execed %s\n", self->path);
    self->path = 0;
}

proc:::exec-failure
{
    self->path = 0;
}

should do the trick.

Cheers,

On 9/14/05, Jonathan Adams <jwadams at gmail.com>
wrote:
> 
> On 9/14/05, C Lin <c.lin at sun.com> wrote:
> > Hi,
> >
> > Is there a way to print out full path name of execname when the 
> following
> > probe is touched?
> >
> > proc:genunix:exec_common:exec-success
> 
> It''s passed as args[0] to proc:::exec; something like:
> 
> printf("execed %s\n", self->path);

Having the _full_ pathname in _one_ string seems to be tricky, although you 
can of course
print out both ''cwd'' and ''self->path''
separately.

For example, 

/ # cd /bin
/bin # ./ls
...
in this case, ''cwd'' is "/usr/bin/" , self-path is
"ls"

/bin # ls
...
in this case, self->path is "/usr/xpg6/bin/ls" ( because I have
xpg6 in
front of /usr/bin in PATH ).

You can''t simply add them into one string, because in the second case, 
"/usr/bin//usr/xpg6/bin/ls" would not be a valid path ...

Tao
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On Wed, Sep 14, 2005 at 06:02:58PM -0500, Tao Chen
wrote:
> On 9/14/05, Jonathan Adams <jwadams at gmail.com> wrote:
> > 
> > On 9/14/05, C Lin <c.lin at sun.com> wrote:
> > > Hi,
> > >
> > > Is there a way to print out full path name of execname when the 
> > following
> > > probe is touched?
> > >
> > > proc:genunix:exec_common:exec-success
> > 
> > It''s passed as args[0] to proc:::exec; something like:
> > 
> > printf("execed %s\n", self->path);
> 
> 
> Having the _full_ pathname in _one_ string seems to be tricky, although you
> can of course
> print out both ''cwd'' and
''self->path'' separately.
> 
> For example, 
> 
> / # cd /bin
> /bin # ./ls
> ...
> in this case, ''cwd'' is "/usr/bin/" , self-path
is "ls"
> 
> /bin # ls
> ...
> in this case, self->path is "/usr/xpg6/bin/ls" ( because I
have xpg6 in
> front of /usr/bin in PATH ).
> 
> You can''t simply add them into one string, because in the second
case,
> "/usr/bin//usr/xpg6/bin/ls" would not be a valid path ...
Ah, that''s a wrinkle I''d missed.  You could do something like:

	self->path = (((char *)arg0)[0] == ''/'') ? args[0] :
	   strjoin(cwd, strjoin("/", self->name));

Or, on a recent OpenSolaris build (or when the new S10 dtrace patch is
available):

	self->path = (index(arg0, "/") == 0) ? args[0] :
	   strjoin(cwd, strjoin("/", self->name));

Cheers,
- jonathan

-- 
Jonathan Adams, Solaris Kernel Development

On 9/14/05, Jonathan Adams <jonathan.adams at sun.com>
wrote:
> 
> 
> self->path = (((char *)arg0)[0] == ''/'') ? args[0] :
> strjoin(cwd, strjoin("/", self->name));
> 
> Or, on a recent OpenSolaris build (or when the new S10 dtrace patch is
> available):
> 
> self->path = (index(arg0, "/") == 0) ? args[0] :
> strjoin(cwd, strjoin("/", self->name));
> 
> 
I didn''t get "(((char *)arg0)[0] == ''/'')"
right when I first tried.

"args[0][0]" or "(args[0])[0]" gives error:

... args has not yet been declared or assigned

Also about arg0 v.s. args[0] :
1. arg0 in index() should be args[0] or (char *)arg0 instead.
2. if you assign args[0] to self->path, you cannot use self->path 
as a predicate since it''s not a scalar value.

(Just for the sake of thread completeness.)

Thanks,
Tao
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