Fix #1690 - mg_json_get for keys with the same prefix

mongoose.c

@@ -2565,8 +2565,10 @@ int mg_json_get(struct mg_str json, const char *path, int *toklen) {
           int n = mg_pass_string(&s[i + 1], len - i - 1);
           if (n < 0) return n;
           if (i + 1 + n >= len) return MG_JSON_NOT_FOUND;
-          // printf("K[%.*s] %d %d\n", n, &s[i + 1], depth, ed);
+          // printf("K[%.*s] %d %d %d\n", n, &s[i + 1], n, depth, ed);
           if (depth == ed && path[pos - 1] == '.' &&
+              (path[pos + n] == '\0' || path[pos + n] == '.' ||
+               path[pos + n] == '[') &&
               strncmp(&s[i + 1], &path[pos], (size_t) n) == 0) {
             pos += n;
           }

src/json.c

@@ -169,8 +169,10 @@ int mg_json_get(struct mg_str json, const char *path, int *toklen) {
           int n = mg_pass_string(&s[i + 1], len - i - 1);
           if (n < 0) return n;
           if (i + 1 + n >= len) return MG_JSON_NOT_FOUND;
-          // printf("K[%.*s] %d %d\n", n, &s[i + 1], depth, ed);
+          // printf("K[%.*s] %d %d %d\n", n, &s[i + 1], n, depth, ed);
           if (depth == ed && path[pos - 1] == '.' &&
+              (path[pos + n] == '\0' || path[pos + n] == '.' ||
+               path[pos + n] == '[') &&
               strncmp(&s[i + 1], &path[pos], (size_t) n) == 0) {
             pos += n;
           }

test/unit_test.c

@@ -2490,6 +2490,11 @@ static void test_json(void) {
     ASSERT((str = mg_json_get_hex(json, "$[1]", &len)) != NULL);
     ASSERT(len == 5 && memcmp(str, "\x01\x00\x02hi", (size_t) len) == 0);
     free(str);
+
+    json = mg_str("{\"a\":[1,2,3], \"ab\": 2}");
+    ASSERT(mg_json_get_long(json, "$.a[0]", -42) == 1);
+    ASSERT(mg_json_get_long(json, "$.ab", -42) == 2);
+    ASSERT(mg_json_get_long(json, "$.ac", -42) == -42);
   }
 }