Fix crash in Buffer with null pointer and non-zero length

Author: accelerated

Diff for: src/buffer.cpp

@@ -67,11 +67,11 @@ Buffer::const_iterator Buffer::end() const {
 }
 
 Buffer::operator bool() const {
-    return size_ != 0;
+    return (data_ != nullptr) && (size_ != 0);
 }
 
 Buffer::operator string() const {
-    return string(data_, data_ + size_);
+    return (bool)(*this) ? string(data_, data_ + size_) : string();
 }
 
 ostream& operator<<(ostream& output, const Buffer& rhs) {

Diff for: tests/buffer_test.cpp

@@ -14,16 +14,22 @@ TEST_CASE("conversions", "[buffer]") {
     const string data = "Hello world!";
     const Buffer buffer(data);
     const Buffer empty_buffer;
+    const Buffer null_data((const char*)nullptr, 5);
+    const Buffer null_size(data.c_str(), 0);
 
 
     SECTION("bool conversion") {
         CHECK(!!buffer == true);
         CHECK(!!empty_buffer == false);
+        CHECK(!!null_data == false);
+        CHECK(!!null_size == false);
     }
 
     SECTION("string conversion") {
         CHECK(static_cast<string>(buffer) == data);
         CHECK(static_cast<string>(empty_buffer).empty());
+        CHECK(static_cast<string>(null_data).empty());
+        CHECK(static_cast<string>(null_size).empty());
     }
 
     SECTION("vector conversion") {