[libcamera-devel] [PATCH 11/30] cam: options: Avoid copies of OptionvValue and KeyValueParser::Options

[Laurent Pinchart]

The OptionValue toKeyValues() and toArray() functions return a copy of
the values. This is unnecessary, and can cause use-after-free issues
when taking references to the return values. Return references instead
to optimize the implementation and avoid issues.

Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
 src/cam/options.cpp | 22 ++++++++++------------
 src/cam/options.h   |  4 ++--
 2 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/src/cam/options.cpp b/src/cam/options.cpp
index 319fab6143c5..9de3dd77fd15 100644
--- a/src/cam/options.cpp
+++ b/src/cam/options.cpp
@@ -632,27 +632,25 @@ std::string OptionValue::toString() const
 
 /**
  * \brief Retrieve the value as a key-value list
- * \return The option value as a KeyValueParser::Options, or an empty list if
- * the value type isn't ValueType::ValueKeyValue
+ *
+ * The behaviour is undefined if the value type isn't ValueType::ValueKeyValue.
+ *
+ * \return The option value as a KeyValueParser::Options
  */
-KeyValueParser::Options OptionValue::toKeyValues() const
+const KeyValueParser::Options &OptionValue::toKeyValues() const
 {
-	if (type_ != ValueKeyValue)
-		return KeyValueParser::Options();
-
 	return keyValues_;
 }
 
 /**
  * \brief Retrieve the value as an array
- * \return The option value as a std::vector of OptionValue, or an empty vector
- * if the value type isn't ValueType::ValueArray
+ *
+ * The behaviour is undefined if the value type isn't ValueType::ValueArray.
+ *
+ * \return The option value as a std::vector of OptionValue
  */
-std::vector<OptionValue> OptionValue::toArray() const
+const std::vector<OptionValue> &OptionValue::toArray() const
 {
-	if (type_ != ValueArray)
-		return std::vector<OptionValue>{};
-
 	return array_;
 }
 
diff --git a/src/cam/options.h b/src/cam/options.h
index 210e502a24e1..09cbc8339dd0 100644
--- a/src/cam/options.h
+++ b/src/cam/options.h
@@ -141,8 +141,8 @@ public:
 
 	int toInteger() const;
 	std::string toString() const;
-	KeyValueParser::Options toKeyValues() const;
-	std::vector<OptionValue> toArray() const;
+	const KeyValueParser::Options &toKeyValues() const;
+	const std::vector<OptionValue> &toArray() const;
 
 	const OptionsParser::Options &children() const;
 
-- 
Regards,

Laurent Pinchart