Print empty quotes ('') when an empty string is passed to outqstr().

This makes a difference for the trap builtin, where after "trap '' 0" we
printed "trap -- quit".  This is wrong, because an empty action means to reset
the action to the default.  A side effect of this commit is that empty
variables are now printed as "variable=''" instead of just "variable=".

1 files changed, 4 insertions, 0 deletions

diff --git a/bin/sh/output.c b/bin/sh/output.c
index 3550cb7..b59e11e 100644
--- a/bin/sh/output.c
+++ b/bin/sh/output.c
@@ -134,6 +134,10 @@ outqstr(const char *p, struct output *file)
 {
 	char ch;
 
+	if (p[0] == '\0') {
+		outstr("''", file);
+		return;
+	}
 	if (p[strcspn(p, "|&;<>()$`\\\"'")] == '\0' && (!ifsset() ||
 	    p[strcspn(p, ifsval())] == '\0')) {
 		outstr(p, file);