json_pointer: move array out-of-bounds check outside of is_valid_index()

The out-of-bounds check is useful when trying to index/obtain a value from
an array.
However, when we set a value to a specific JSON pointer, we can allow
values that are outside the length of the current array.
The RFC6901 doc isn't clear on that aspect, and doing so is a bit more
in-line with how json_object_array_{put,insert}_idx() functions behave.

This changes the behavior of json_pointer_set{f}() because now a value can
be set anywhere in the array.

Also, added a test-case for this behavior change.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

diff --git a/json_pointer.c b/json_pointer.c
index f04b487ccc236a37779fe04b21884ca506789837..e834c3b514389cee08a7e04b942b2ae1f93d84f0 100644 (file)
--- a/json_pointer.c
+++ b/json_pointer.c
@@ -42,7 +42,7 @@ static void string_replace_all_occurrences_with_char(char *s, const char *occur,
        }
 }
 
-static int is_valid_index(struct json_object *jo, const char *path, size_t *idx)
+static int is_valid_index(const char *path, size_t *idx)
 {
        size_t i, len = strlen(path);
        /* this code-path optimizes a bit, for when we reference the 0-9 index range
@@ -53,7 +53,7 @@ static int is_valid_index(struct json_object *jo, const char *path, size_t *idx)
                if (is_plain_digit(path[0]))
                {
                        *idx = (path[0] - '0');
-                       goto check_oob;
+                       return 1;
                }
                errno = EINVAL;
                return 0;
@@ -77,13 +77,6 @@ static int is_valid_index(struct json_object *jo, const char *path, size_t *idx)
        // We know it's all digits, so the only error case here is overflow,
        // but ULLONG_MAX will be longer than any array length so that's ok.
        *idx = strtoull(path, NULL, 10);
-check_oob:
-       len = json_object_array_length(jo);
-       if (*idx >= len)
-       {
-               errno = ENOENT;
-               return 0;
-       }
 
        return 1;
 }
@@ -93,8 +86,14 @@ static int json_pointer_get_single_path(struct json_object *obj, char *path,
 {
        if (json_object_is_type(obj, json_type_array))
        {
-               if (!is_valid_index(obj, path, idx))
+               if (!is_valid_index(path, idx))
                        return -1;
+               if (*idx >= json_object_array_length(obj))
+               {
+                       errno = ENOENT;
+                       return -1;
+               }
+
                obj = json_object_array_get_idx(obj, *idx);
                if (obj)
                {
@@ -129,7 +128,7 @@ static int json_pointer_set_single_path(struct json_object *parent, const char *
                /* RFC (Chapter 4) states that '-' may be used to add new elements to an array */
                if (path[0] == '-' && path[1] == '\0')
                        return json_object_array_add(parent, value);
-               if (!is_valid_index(parent, path, &idx))
+               if (!is_valid_index(path, &idx))
                        return -1;
                return json_object_array_put_idx(parent, idx, value);
        }

diff --git a/tests/test_json_pointer.c b/tests/test_json_pointer.c
index 4ac78cb81f01f6865161ab910333a45aea7c9901..09c195a2fbd63eb0dc34969ea10484e8b5f25e45 100644 (file)
--- a/tests/test_json_pointer.c
+++ b/tests/test_json_pointer.c
@@ -269,6 +269,22 @@ static void test_example_set(void)
        printf("%s\n", json_object_get_string(jo1));
 
        json_object_put(jo1);
+
+       jo1 = json_tokener_parse("[0, 1, 2, 3]");
+       jo2 = json_tokener_parse("[0, 1, 2, 3, null, null, null, 7]");
+
+       assert(0 == json_pointer_set(&jo1, "/7", json_object_new_int(7)));
+       assert(1 == json_object_equal(jo1, jo2));
+
+       json_object_put(jo1);
+
+       jo1 = json_tokener_parse("[0, 1, 2, 3]");
+
+       assert(0 == json_pointer_setf(&jo1, json_object_new_int(7), "/%u", 7));
+       assert(1 == json_object_equal(jo1, jo2));
+
+       json_object_put(jo1);
+       json_object_put(jo2);
 }
 
 static void test_wrong_inputs_set(void)