Change contains to return true for empty string needles

The behavior of memmem for an empty needle is inconsistent between
implementations of libc.
Our tests imply that we want an empty string needle to be true,
so check for an empty needle before calling memmem.

1 files changed, 7 insertions, 2 deletions

diff --git a/src/jv.c b/src/jv.c
index 06b4e6a2..2427b009 100644
--- a/src/jv.c
+++ b/src/jv.c
@@ -1344,8 +1344,13 @@ int jv_contains(jv a, jv b) {
   } else if (jv_get_kind(a) == JV_KIND_ARRAY) {
     r = jv_array_contains(jv_copy(a), jv_copy(b));
   } else if (jv_get_kind(a) == JV_KIND_STRING) {
-    r = _jq_memmem(jv_string_value(a), jv_string_length_bytes(jv_copy(a)),
-                   jv_string_value(b), jv_string_length_bytes(jv_copy(b))) != 0;
+    int b_len = jv_string_length_bytes(jv_copy(b));
+    if (b_len != 0) {
+      r = _jq_memmem(jv_string_value(a), jv_string_length_bytes(jv_copy(a)),
+                     jv_string_value(b), b_len) != 0;
+    } else {
+      r = 1;
+    }
   } else {
     r = jv_equal(jv_copy(a), jv_copy(b));
   }