From fda274ddd297a53110d43189c2d69fee8f748da9 Mon Sep 17 00:00:00 2001
From: Billy Donahue <BillyDonahue@users.noreply.github.com>
Date: Tue, 9 Feb 2021 23:50:37 -0500
Subject: [PATCH] Fix Value::resize to fill all array elements (#1265)

* Fix Value::resize to fill all array elements

Fixes #1264
---
 src/lib_json/json_value.cpp |  3 ++-
 src/test_lib_json/main.cpp  | 13 +++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/lib_json/json_value.cpp b/src/lib_json/json_value.cpp
index bfa9263..378ea79 100644
--- a/src/lib_json/json_value.cpp
+++ b/src/lib_json/json_value.cpp
@@ -912,7 +912,8 @@ void Value::resize(ArrayIndex newSize) {
   if (newSize == 0)
     clear();
   else if (newSize > oldSize)
-    this->operator[](newSize - 1);
+    for (ArrayIndex i = oldSize; i < newSize; ++i)
+      (*this)[i];
   else {
     for (ArrayIndex index = newSize; index < oldSize; ++index) {
       value_.map_->erase(index);
diff --git a/src/test_lib_json/main.cpp b/src/test_lib_json/main.cpp
index be9c4a7..e8bc7bc 100644
--- a/src/test_lib_json/main.cpp
+++ b/src/test_lib_json/main.cpp
@@ -12,6 +12,7 @@
 
 #include "fuzz.h"
 #include "jsontest.h"
+#include <algorithm>
 #include <cmath>
 #include <cstring>
 #include <functional>
@@ -24,6 +25,7 @@
 #include <memory>
 #include <sstream>
 #include <string>
+#include <vector>
 
 using CharReaderPtr = std::unique_ptr<Json::CharReader>;
 
@@ -347,6 +349,17 @@ JSONTEST_FIXTURE_LOCAL(ValueTest, resizeArray) {
     JSONTEST_ASSERT_EQUAL(array.size(), 0);
   }
 }
+
+JSONTEST_FIXTURE_LOCAL(ValueTest, resizePopulatesAllMissingElements) {
+  int n = 10;
+  Json::Value v;
+  v.resize(n);
+  JSONTEST_ASSERT_EQUAL(n, v.size());
+  JSONTEST_ASSERT_EQUAL(n, std::distance(v.begin(), v.end()));
+  for (const Json::Value& e : v)
+    JSONTEST_ASSERT_EQUAL(e, Json::Value{});
+}
+
 JSONTEST_FIXTURE_LOCAL(ValueTest, getArrayValue) {
   Json::Value array;
   for (Json::ArrayIndex i = 0; i < 5; i++)