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Conference noted::hackers_v1

Title:	-={ H A C K E R S }=-
Notice:	Write locked - see NOTED::HACKERS
Moderator:	DIEHRD::MORRIS

Created:	Thu Feb 20 1986
Last Modified:	Mon Aug 03 1992
Last Successful Update:	Fri Jun 06 1997
Number of topics:	680
Total number of notes:	5456

328.0. "Who called me?" by REGENT::MINOW (Martin Minow -- DECtalk Engineering) Mon Oct 06 1986 12:36

Many years ago, I implemented the "caller()" function in Decus C --
it returned a string that named the routine that called the current
function.  For example,

	main() {
		foo();
	}

	foo() {
		printf("%s\n", caller());
	}

would print "main".

This should be easy to do in VMS -- could any kind soul point me to
the proper incantation?

Thanks.

Martin.

T.R	Title	User	Personal Name	Date	Lines
328.1	easy in VMS?	BLITZN::PALO	Computer-friendly liveware	`Mon Oct 06 1986 23:38`	5
	why would this be easy in VMS? What about the case where the program is linked/notrace (ie no DST information in the .exe). Granted you could code a lot of the garbage, but that's not VMS. \rik
328.2	huh?	REGENT::MINOW	Martin Minow -- DECtalk Engineering	`Tue Oct 07 1986 09:49`	7
	It should be easy in VMS because, if I abort the program, I get a traceback with exactly the information I want -- module, routine, and line number. (I finally fixed the bug by crashing the program at different places until I found the offending caller in the traceback.) Martin.
328.3	keyword: TRACEBACK	FROST::HARRIMAN	DEC 41-BLANK-03, Harriman,Paul J., qty 1	`Tue Oct 07 1986 10:17`	11
	re: .-1 Sure, it's easy if you have traceback... But if you don't (.-2's scenario) you have a bigger problem... Even though you don't have the symbolic information, the address of the caller should be on the stack somewhere, shouldn't it? Or the FP? Could someone refresh my memory? /pjh
328.4		ULTRA::PRIBORSKY	Tony Priborsky	`Tue Oct 07 1986 13:08`	6
	Look at facility TRACE in the fiche. If your image is linked /NOTRACE, you can't get there from here. This will affect INSTALLed images, since with V4, you can INSTALL only if linked /NOTRACE. [Has this been relaxed? I seem to recall that shareable images can now be linked /DEBUG. /NOTRACE => /NODEBUG. Does the /NOTRACE on installed images now apply only to executable images?]
328.5	What is the conflict?	SKYLAB::FISHER	Burns Fisher 381-1466, ZKO1-1/D42	`Tue Oct 07 1986 13:22`	6
	re .4: I don't know the answer to your question, but I don't see a conflict. One need not install a sharable image in order to debug it. Burns
328.6	No fair debugging installed PRIVED images	TLE::AMARTIN	Alan H. Martin	`Thu Oct 09 1986 13:21`	4
	Re .4: Maybe you can only install an image with privs if it was linked /NOTRACE? /AHM
328.7	INSTALL with privs <> LINK/TRACE	WHOARU::MCCARTHY	Error Message #000000	`Thu Oct 09 1986 21:24`	11
	> Maybe you can only install an image with privs if it was linked /NOTRACE? Is this a question? I know INSTALL does not allow installation of an image with privs that has been linked with trace. I don't use install alot and therefore get caught by this once in a while. mac
328.8	An incantation of sorts	CASEE::COWAN	Ken Cowan	`Sun Oct 12 1986 10:59`	32
	RE: .0 It is very difficult to mung the DST records to get the information you want, however, you have easy access to the PC of the person who called you. The VAX Architecture Handbook describes the format of the call frame on page 278. In BLISS the incantation is: LIBRARY 'SYS$LIBRARY:STARLET'; BUILTIN FP; LOCAL PC, FMP : REF BLOCK[, BYTE]; FMP = .FP; PC = .FMP [SF$L_SAVE_PC]; Re: the other topic A privileged executable image has to be /NOTRACE for security, however, a sharable image it uses can have /TRACE enabled. Since the executable is /NOTRACE, you won't get traceback, but other things using it will. I'm not sure how privileged sharable images behave. KC