tnfctl_internal_open(3TNF)				       TNF Library Functions					tnfctl_internal_open(3TNF)

NAME

       tnfctl_internal_open - create handle for internal process probe control

SYNOPSIS

       cc [ flag ... ] file ... -ltnfctl [ library ... ]
       #include <tnf/tnfctl.h>

       tnfctl_errcode_t tnfctl_internal_open(tnfctl_handle_t **ret_val);

DESCRIPTION

       tnfctl_internal_open() returns in ret_val a pointer to an opaque handle that can be used to control probes in the same process as the call-
       er (internal process probe control). The process must have  libtnfprobe.so.1 loaded. Probes in libraries that are brought in by	dlopen(3C)
       will  be  visible  after the library has been opened. Probes in libraries closed by a dlclose(3C) will not be visible after the library has
       been disassociated.  See the NOTES section for more details.

RETURN VALUES

       tnfctl_internal_open() returns TNFCTL_ERR_NONE upon success.

ERRORS

       TNFCTL_ERR_ALLOCFAIL	       A memory allocation failure occurred.

       TNFCTL_ERR_BUSY		       Another client is already tracing this program (internally or externally).

       TNFCTL_ERR_NOLIBTNFPROBE        libtnfprobe.so.1 is not linked in the target process.

       TNFCTL_ERR_INTERNAL	       An internal error occurred.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWtnfc			   |
       +-----------------------------+-----------------------------+
       |MT Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       ld(1), prex(1), TNF_PROBE(3TNF), dlopen(3C), dlclose(3C), libtnfctl(3TNF), tracing(3TNF), attributes(5)

       Linker and Libraries Guide

NOTES

       libtnfctl interposes on dlopen(3C) and dlclose(3C) in order to be notified of libraries being dynamically opened and closed. This  interpo-
       sition  is  necessary for internal process probe control to update its list of probes. In these interposition functions, a lock is acquired
       to synchronize on traversal of the library list maintained by the runtime  linker.   To	avoid  deadlocking  on	this  lock,  tnfctl_inter-
       nal_open() should not be called from within the init section of a library that can be opened by dlopen(3C).

       Since interposition does not work as expected when a library is opened dynamically, tnfctl_internal_open() should not be used if the client
       opened  libtnfctl through  dlopen(3C). In this case, the client program should be built with a static dependency on libtnfctl. Also, if the
       client program is explicitly linking in -ldl, it should link -ltnfctl before -ldl.

       Probes  in filtered libraries (see ld(1)) will not be seen because the filtee (backing library) is loaded lazily on the first symbol refer-
       ence and not at process startup or dlopen(3C) time. A workaround is to call tnfctl_check_libs(3TNF) once the caller is sure that the filtee
       has been loaded.

SunOS 5.10							    1 Mar 2004						tnfctl_internal_open(3TNF)