perf: Pass parameters by const reference to avoid copies

Fix cppcheck performance warnings by passing function parameters
by const reference instead of by value, preventing unnecessary
copies:
- string parameters in open_device_by_path()
- set<Connector*> parameters in connector finder functions
- vector parameter in FlipState constructor
- range variable in kmscapture loop

These changes improve performance by avoiding object copies while
maintaining the same functionality.

4 files changed, 5 insertions, 5 deletions

diff --git a/kms++/src/card.cpp b/kms++/src/card.cpp
index d0af8a4..c26e4f2 100644
--- a/kms++/src/card.cpp
+++ b/kms++/src/card.cpp
@@ -70,7 +70,7 @@ static int open_first_kms_device()
 	throw runtime_error("No modesetting DRM card found");
 }
 
-static int open_device_by_path(string path)
+static int open_device_by_path(const string& path)
 {
 	int fd = open(path.c_str(), O_RDWR | O_CLOEXEC);
 	if (fd < 0)
diff --git a/kms++util/src/resourcemanager.cpp b/kms++util/src/resourcemanager.cpp
index 5a9f016..424c8f0 100644
--- a/kms++util/src/resourcemanager.cpp
+++ b/kms++util/src/resourcemanager.cpp
@@ -17,7 +17,7 @@ void ResourceManager::reset()
 	m_reserved_planes.clear();
 }
 
-static Connector* find_connector(Card& card, const set<Connector*> reserved)
+static Connector* find_connector(Card& card, const set<Connector*>& reserved)
 {
 	for (Connector* conn : card.get_connectors()) {
 		if (!conn->connected())
@@ -32,7 +32,7 @@ static Connector* find_connector(Card& card, const set<Connector*> reserved)
 	return nullptr;
 }
 
-static Connector* resolve_connector(Card& card, const string& name, const set<Connector*> reserved)
+static Connector* resolve_connector(Card& card, const string& name, const set<Connector*>& reserved)
 {
 	auto connectors = card.get_connectors();
 
diff --git a/utils/kmscapture.cpp b/utils/kmscapture.cpp
index 23941ca..251cc3b 100644
--- a/utils/kmscapture.cpp
+++ b/utils/kmscapture.cpp
@@ -333,7 +333,7 @@ int main(int argc, char** argv)
 
 	vector<int> camera_fds;
 
-	for (string vidpath : glob("/dev/video*")) {
+	for (const string& vidpath : glob("/dev/video*")) {
 		int fd = ::open(vidpath.c_str(), O_RDWR | O_NONBLOCK);
 
 		if (fd < 0)
diff --git a/utils/kmstest.cpp b/utils/kmstest.cpp
index 43dc355..5028e7e 100644
--- a/utils/kmstest.cpp
+++ b/utils/kmstest.cpp
@@ -968,7 +968,7 @@ static bool max_flips_reached;
 class FlipState : private PageFlipHandlerBase
 {
 public:
-	FlipState(Card& card, const string& name, vector<const OutputInfo*> outputs)
+	FlipState(Card& card, const string& name, const vector<const OutputInfo*>& outputs)
 		: m_card(card), m_name(name), m_outputs(outputs)
 	{
 	}