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Date:	Thu, 8 Oct 1992 16:58:33 -0400
From:	Donn Cave <donn@u.washington.edu>
Message-Id: <9210082058.AA03054@carson.u.washington.edu>
Sender: donn@carson.u.washington.edu
To:	rc@hawkwind.utcs.toronto.edu
Subject: rc and null environ strings

Am having this problem with rc version 1.4:

	; A = '' ./rc
		; whatis A
		A=''
		; A = ralph
		segmentation violation--core dumped
	;

In other words, assigning to a zero-length variable is fatal.  However, this
happens only after reading that (zero-length) value (hence the "whatis" in
the example).  Trace back looks like this:

(gdb) where
#0  0xbc2e in free ()
#1  0x68bc in efree (p=(int *) 0x212d) (nalloc.c line 135)
#2  0x5eba in listfree (p=(struct List *) 0x177d8) (list.c line 17)
#3  0x3d31 in get_var_place (s=(char *) 0x167d4 , stack=FALSE) (hash.c line 157)#4  0x8485 in varassign (name=(char *) 0x167d4 , def=(struct List *) 0x16804, stack=FALSE) (var.c line 18)
#5  0x3156 in assign (s1=(struct List *) 0x16810, s2=(struct List *) 0x16804, stack=FALSE) (glom.c line 163)
#6  0x9264 in walk (n=(struct Node *) 0x167f8, parent=TRUE) (walk.c line 160)
#7  0x4cb6 in doit (execit=TRUE) (input.c line 332)
#8  0x63f3 in main (argc=1, argv=(char **) 0x3fffdccc, envp=(char **) 0x3fffdcd4

Platform is DYNIX/ptx on a Sequent 2000/750.  The value of p->w, passed to
efree() at list.c line 17, looks uninitialized to me, but that's as far as
I have taken it.

rc 1.2 doesn't have this problem, although it oddly can't find zero-length
variables passed in in the environment.  "es" works fine.

	Donn Cave, University Computing Services, University of Washington
	donn@cac.washington.edu