Throwing when trying to access TooFar elements in DataBuf

src/types.cpp

@@ -172,9 +172,8 @@ int Exiv2::DataBuf::cmpBytes(size_t offset, const void* buf, size_t bufsize) con
 }
 
 byte* Exiv2::DataBuf::data(size_t offset) {
-  /// \todo this first check should be for <= offset
-  if (pData_.size() < offset) {
-    throw std::overflow_error("Overflow in Exiv2::DataBuf::c_data");
+  if (offset >= pData_.size()) {
+    throw std::out_of_range("Overflow in Exiv2::DataBuf::c_data");
   }
   if (pData_.empty() || pData_.size() == offset) {
     return nullptr;
@@ -183,9 +182,8 @@ byte* Exiv2::DataBuf::data(size_t offset) {
 }
 
 const byte* Exiv2::DataBuf::c_data(size_t offset) const {
-  /// \todo this first check should be for <= offset
-  if (pData_.size() < offset) {
-    throw std::overflow_error("Overflow in Exiv2::DataBuf::c_data");
+  if (offset >= pData_.size()) {
+    throw std::out_of_range("Overflow in Exiv2::DataBuf::c_data");
   }
   if (pData_.empty() || pData_.size() == offset) {
     return nullptr;

unitTests/test_types.cpp

@@ -1,9 +1,13 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
+#include <exiv2/types.hpp>
+
 #include <gtest/gtest.h>
+
+#include <algorithm>
 #include <cmath>
-#include <exiv2/types.hpp>
 #include <limits>
+
 using namespace Exiv2;
 
 // More info about tm : http://www.cplusplus.com/reference/ctime/tm/
@@ -24,10 +28,9 @@ TEST(ExivTime, doesNotGetTimeWithBadFormedString) {
   ASSERT_EQ(1, exifTime("007:a5:24 aa:bb:cc", &tmInstance));
 }
 
-TEST(DataBuf, pointsToNullByDefault) {
+TEST(DataBuf, defaultInstanceIsEmpty) {
   DataBuf instance;
-  ASSERT_EQ(nullptr, instance.c_data());
-  ASSERT_EQ(0, instance.size());
+  ASSERT_TRUE(instance.empty());
 }
 
 TEST(DataBuf, allocatesDataWithNonEmptyConstructor) {
@@ -36,6 +39,18 @@ TEST(DataBuf, allocatesDataWithNonEmptyConstructor) {
   ASSERT_EQ(5, instance.size());
 }
 
+TEST(DataBuf, canBeConstructedFromExistingData) {
+  const std::array<byte, 4> data {'h', 'o', 'l', 'a'};
+  DataBuf instance(data.data(), data.size());
+  ASSERT_TRUE(std::equal(data.begin(), data.end(), instance.begin()));
+}
+
+TEST(DataBuf, tryingToAccessTooFarElementThrows) {
+  const std::array<byte, 4> data {'h', 'o', 'l', 'a'};
+  DataBuf instance(data.data(), data.size());
+  ASSERT_THROW(instance.data(4), std::out_of_range);
+}
+
 // Test methods like DataBuf::read_uint32 and DataBuf::write_uint32.
 TEST(DataBuf, read_write_endianess) {
   DataBuf buf(4 + 1 + 2 + 4 + 8);