Aucbvax.6909
fa.info-vax
utzoo!decvax!ucbvax!info-vax
Sun Apr 25 10:26:34 1982
Examining .EXE files linked /NOTRACE
>From EPS@MIT-AI Sun Apr 25 10:15:53 1982
Most of the stuff that comes from DEC is linked /NOTRACE,
so RUN/DEBUG doesn't work.  You can use PATCH, but I find
DEBUG better suited for general hackery.
				      * * *
	.title	debugable	make /NOTRACE image DEBUGable
	$dscdef
	$fabdef
	$rabdef
	$rmsdef
	.library	/sys$library:lib/
	$ihddef
	$ihadef
	.psect	debugable,nowrt,shr,pic,long
	.entry	debugable,^m
	clrl	-(sp)
	pushl	#<DSC$K_DTYPE_T@16>!<DSC$K_CLASS_D@24>
	pushaq	prompt
	pushaq	4(sp)
	calls	#2,g^lib$get_foreign
	cmpl	r0,#rms$_eof
	bneq	3$
	brw	done
3$:	blbc	r0,death
	$fab_store	fab=exefab,-
		fns=(sp),fna=@4(sp)
	$open	fab=exefab
	blbc	r0,death
	cmpb	exefab+fab$b_rfm,#fab$c_fix
	beql	docon
	brw	notexe
docon:	movab	-512(sp),sp
	$rab_store	rab=exerab,-
		rbf=(sp),ubf=(sp)
	$connect	rab=exerab
	blbc	r0,death
	$read	rab=exerab
	blbs	r0,check
death:	$exit_s	r0
check:	cmpw	exerab+rab$w_rsz,#512
	bneq	notexe
	cmpw	ihd$w_majorid(sp),#^a/02/
	bneq	notexe
	cmpb	ihd$b_imgtype(sp),#ihd$k_exe
	bneq	notexe
	bbs	#ihd$v_lnknotfr,ihd$l_lnkflags(sp),noxfer
	movzwl	ihd$w_activoff(sp),r0
	addl2	sp,r0
	cmpl	iha$l_tfradr1(r0),#sys$imgsta
	beql	doesst
	tstl	iha$l_tfradr3(r0)
	bneq	notclr
	movq	iha$l_tfradr1(r0),iha$l_tfradr2(r0)
	movaw	@#sys$imgsta,iha$l_tfradr1(r0)
	$write	rab=exerab
	blbc	r0,die1
	$close	fab=exefab
	blbc	r0,die1
done:	movzwl	#1,r0
	ret
notexe:	pushaq	notex1
scream:	calls	#1,g^lib$put_output
	blbs	r0,done
die1:	brw	death
noxfer:	pushaq	noxfe1
	brb	scream
doesst:	pushaq	doess1
	brb	scream
notclr:	pushaq	notcl1
	brb	scream
	.psect	constants,nowrt,noexe,shr,long
prompt:	.ascid	/.EXE file: /
	.align	long
notex1:	.ascid	/?Not an executable file/
	.align	long
noxfe1:	.ascid	/?No transfer address/
	.align	long
doess1:	.ascid	/?Already DEBUGable/
	.align	long
notcl1:	.ascid	/?Activation section full/
	.psect	exefab,wrt,noexe,long
exefab::	$fab	fac=<BIO,GET,PUT>,-
			dnm=<.EXE>,-
			mrs=512,-
			rfm=fix
	.psect	exerab,wrt,noexe,long
exerab::	$rab	fab=exefab,-
			bkt=1,-
			rop=<BIO>,-
			usz=512
	.end	debugable
				      * * *
This will not work for .EXE files created by TKB.
Since the .EXE file will have no symbols, you should
make a 'SYSDEF.COM' file containing lines like
	DEFINE SYS$QIOW = ^X80000000
to define all the symbols in SYSVECTOR.  Then RUN/DEBUG
your .EXE file and type '@SYSDEF' to load the symbols.
Most images load at ^X200.  I have a program that dumps
all the interesting things in .EXE files (everything
but the code) so I use that to get the start address
and locations of the various image sections.  Before
you attack a program with DEBUG, an ASCII dump should
be made.  RUN the program and immediately type ^Y.
Then $ EXAMINE/ASCII 200:7FFFFFFF to get a general idea
of where things are.  You can't do this with programs
INSTALLed with privileges; make a copy of the known
.EXE and ^Y out of that.  Good luck as always.

					--Eric

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