Fix crash on setting attribute to variable with getn discipline

The 'getn' discipline is experimental and undocumented, the only mention of it being an old mailing list post from David Korn: https://www.mail-archive.com/[email protected]/msg00601.html But it still should not crash. $ LC_NUMERIC=C ENV=/./dev/null arch/*/bin/ksh $ foo.getn() { .sh.value=2.3*4.5; } $ typeset -F foo Memory fault src/cmd/ksh93/sh/nvdisc.c: assign(): - Check that the nvalue union has a non-NULL pointer before using it. Progresses: #435
ksh93 · Jun 7, 2022 · bafff8e · bafff8e
1 parent 2f779e1
commit bafff8e
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diff --git a/src/cmd/ksh93/sh/nvdisc.c b/src/cmd/ksh93/sh/nvdisc.c
@@ -367,7 +367,7 @@ static void	assign(Namval_t *np,const char* val,int flags,Namfun_t *handle)
 done:
 	if(bp== &block)
 		block_done(bp);
-	if(nq && nq->nvalue.rp->running==1)
+	if(nq && nq->nvalue.rp && nq->nvalue.rp->running==1)
 	{
 		nq->nvalue.rp->running=0;
 		_nv_unset(nq,0);

diff --git a/src/cmd/ksh93/tests/variables.sh b/src/cmd/ksh93/tests/variables.sh
@@ -1369,5 +1369,13 @@ got=$("$SHELL" -c $'foo=baz; foo+=_foo "$SHELL" -c \'print $foo\'; print $foo')
 [[ $exp == "$got" ]] || err_exit "using the += operator for invocation-local assignments changes variables outside of the invocation-local scope" \
 	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
 
+# ======
+# Crash when setting attribute after getn (numeric get) discipline
+# https://github.com/ksh93/ksh/issues/435#issuecomment-1148813866
+got=$("$SHELL" -c 'foo.getn() { .sh.value=2.3*4.5; }; typeset -F2 foo; typeset -p foo' 2>&1)
+exp='typeset -F 2 foo=10.35'
+[[ $got == "$exp" ]] || err_exit "Setting attribute after setting getn discipline fails" \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+
 # ======
 exit $((Errors<125?Errors:125))