From 20ca21cb0d0025c69b8bf41d4d93541c289a8ddf Mon Sep 17 00:00:00 2001
From: Nicolas Williams <nico@cryptonector.com>
Date: Sat, 9 Aug 2014 19:04:34 -0500
Subject: [PATCH] Out of bounds negative array indices should raise

---
 jv.c           | 14 +++++++++-----
 tests/all.test |  8 ++++----
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/jv.c b/jv.c
index bf7a0c51..cdd01630 100644
--- a/jv.c
+++ b/jv.c
@@ -230,13 +230,9 @@ static jv* jvp_array_read(jv a, int i) {
 }
 
 static jv* jvp_array_write(jv* a, int i) {
+  assert(i >= 0);
   jvp_array* array = jvp_array_ptr(*a);
 
-  if (i < 0)
-    i = array->length + i;
-  if (i < 0)
-    i = 0;
-
   int pos = i + jvp_array_offset(*a);
   if (pos < array->alloc_length && jvp_refcnt_unshared(a->u.ptr)) {
     // use existing array space
@@ -325,6 +321,14 @@ jv jv_array_get(jv j, int idx) {
 
 jv jv_array_set(jv j, int idx, jv val) {
   assert(jv_get_kind(j) == JV_KIND_ARRAY);
+
+  if (idx < 0)
+    idx = jvp_array_length(j) + idx;
+  if (idx < 0) {
+    jv_free(j);
+    jv_free(val);
+    return jv_invalid_with_msg(jv_string("Out of bounds negative array index"));
+  }
   // copy/free of val,j coalesced
   jv* slot = jvp_array_write(&j, idx);
   jv_free(*slot);
diff --git a/tests/all.test b/tests/all.test
index 99e95b76..d1cdc2ca 100644
--- a/tests/all.test
+++ b/tests/all.test
@@ -156,13 +156,13 @@ null
 # Negative array indices
 #
 
-.foo[-1] = 0
+try (.foo[-1] = 0) catch .
 null
-{"foo":[0]}
+"Out of bounds negative array index"
 
-.foo[-2] = 0
+try (.foo[-2] = 0) catch .
 null
-{"foo":[0]}
+"Out of bounds negative array index"
 
 .[-1] = 5
 [0,1,2]