sh: Save/restore changed variables in optimized command substitution.

In optimized command substitution, save and restore any variables changed by
expansions (${var=value} and $((var=assigned))), instead of trying to
determine if an expansion may cause such changes.

If $! is referenced in optimized command substitution, do not cause jobs to
be remembered longer.

This fixes $(jobs $!) again, simplifies the man page and shortens the code.

1 files changed, 7 insertions, 3 deletions

diff --git a/bin/sh/var.c b/bin/sh/var.c
index f6d7fb1..e405b66 100644
--- a/bin/sh/var.c
+++ b/bin/sh/var.c
@@ -94,6 +94,8 @@ struct var vps4;
 struct var vvers;
 static struct var voptind;
 
+int forcelocal;
+
 static const struct varinit varinit[] = {
 #ifndef NO_HISTORY
 	{ &vhistsize,	VUNSET,				"HISTSIZE=",
@@ -325,6 +327,8 @@ setvareq(char *s, int flags)
 
 	if (aflag)
 		flags |= VEXPORT;
+	if (forcelocal && !(flags & (VNOSET | VNOLOCAL)))
+		mklocal(s);
 	vp = find_var(s, &vpp, &nlen);
 	if (vp != NULL) {
 		if (vp->flags & VREADONLY)
@@ -740,9 +744,9 @@ mklocal(char *name)
 		vp = find_var(name, &vpp, NULL);
 		if (vp == NULL) {
 			if (strchr(name, '='))
-				setvareq(savestr(name), VSTRFIXED);
+				setvareq(savestr(name), VSTRFIXED | VNOLOCAL);
 			else
-				setvar(name, NULL, VSTRFIXED);
+				setvar(name, NULL, VSTRFIXED | VNOLOCAL);
 			vp = *vpp;	/* the new variable */
 			lvp->text = NULL;
 			lvp->flags = VUNSET;
@@ -751,7 +755,7 @@ mklocal(char *name)
 			lvp->flags = vp->flags;
 			vp->flags |= VSTRFIXED|VTEXTFIXED;
 			if (name[vp->name_len] == '=')
-				setvareq(savestr(name), 0);
+				setvareq(savestr(name), VNOLOCAL);
 		}
 	}
 	lvp->vp = vp;