hush: fix a corner case of empty "do \n done" structure

The structure is:

    while cmd; do
    done

bash doesn't accept it at all. We were accepting it but execution
was buggy.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

3 files changed, 9 insertions, 1 deletions

diff --git a/shell/hush.c b/shell/hush.c
index c3a4afb5a..c7971b0ce 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -7498,7 +7498,10 @@ static int run_list(struct pipe *pi)
 #endif
 #if ENABLE_HUSH_LOOPS
                 /* Beware of "while false; true; do ..."! */
-                if (pi->next && pi->next->res_word == RES_DO) {
+                if (pi->next
+                 && (pi->next->res_word == RES_DO || pi->next->res_word == RES_DONE)
+                /* (the second check above is needed for "while ...; do \n done" case) */
+                ) {
                         if (rword == RES_WHILE) {
                                 if (rcode) {
                                         /* "while false; do...done" - exitcode 0 */
diff --git a/shell/hush_test/hush-misc/while3.right b/shell/hush_test/hush-misc/while3.right
new file mode 100644
index 000000000..7c4d7beb0
--- /dev/null
+++ b/shell/hush_test/hush-misc/while3.right
@@ -0,0 +1 @@
+OK:0
diff --git a/shell/hush_test/hush-misc/while3.tests b/shell/hush_test/hush-misc/while3.tests
new file mode 100755
index 000000000..9132b5f4d
--- /dev/null
+++ b/shell/hush_test/hush-misc/while3.tests
@@ -0,0 +1,4 @@
+while false; do
+    # bash will require at least ":" here...
+done
+echo OK:$?