Use std::string for IInput::GetClipboardText

Simplify clipboard handling by returning an `std::string` and freeing the string returned by SDL immediately, so the clipboard data does not stay in memory unnecessarily after the clipboard has been used until the clipboard data is requested again.

Fix possible TOCTOU when pasting from the clipboard into a lineinput, due to the clipboard data being requested twice.

src/engine/client/input.cpp

@@ -68,8 +68,6 @@ CInput::CInput()
 
 	m_MouseFocus = true;
 
-	m_pClipboardText = nullptr;
-
 	m_CompositionCursor = 0;
 	m_CandidateSelectedIndex = -1;
 
@@ -90,7 +88,6 @@ void CInput::Init()
 
 void CInput::Shutdown()
 {
-	SDL_free(m_pClipboardText);
 	CloseJoysticks();
 }
 
@@ -303,11 +300,12 @@ const std::vector<IInput::CTouchFingerState> &CInput::TouchFingerStates() const
 	return m_vTouchFingerStates;
 }
 
-const char *CInput::GetClipboardText()
+std::string CInput::GetClipboardText()
 {
-	SDL_free(m_pClipboardText);
-	m_pClipboardText = SDL_GetClipboardText();
-	return m_pClipboardText;
+	char *pClipboardText = SDL_GetClipboardText();
+	std::string ClipboardText = pClipboardText;
+	SDL_free(pClipboardText);
+	return ClipboardText;
 }
 
 void CInput::SetClipboardText(const char *pText)

src/engine/client/input.h

@@ -74,7 +74,6 @@ private:
 	float GetJoystickDeadzone();
 
 	bool m_InputGrabbed;
-	char *m_pClipboardText;
 
 	bool m_MouseFocus;
 #if defined(CONF_PLATFORM_ANDROID)
@@ -151,7 +150,7 @@ public:
 
 	const std::vector<CTouchFingerState> &TouchFingerStates() const override;
 
-	const char *GetClipboardText() override;
+	std::string GetClipboardText() override;
 	void SetClipboardText(const char *pText) override;
 
 	void StartTextInput() override;

src/engine/input.h

@@ -10,6 +10,7 @@
 
 #include <cstdint>
 #include <functional>
+#include <string>
 #include <vector>
 
 const int g_MaxKeys = 512;
@@ -138,7 +139,7 @@ public:
 	virtual const std::vector<CTouchFingerState> &TouchFingerStates() const = 0;
 
 	// clipboard
-	virtual const char *GetClipboardText() = 0;
+	virtual std::string GetClipboardText() = 0;
 	virtual void SetClipboardText(const char *pText) = 0;
 
 	// text editing

src/game/client/lineinput.cpp

@@ -330,11 +330,10 @@ bool CLineInput::ProcessInput(const IInput::CEvent &Event)
 			KeyHandled = true;
 		}
 		else if(ModPressed && !AltPressed && Event.m_Key == KEY_V)
-		{
-			const char *pClipboardText = Input()->GetClipboardText();
-			if(pClipboardText)
 		{
 			std::string ClipboardText = Input()->GetClipboardText();
+			if(!ClipboardText.empty())
+			{
 				if(m_pfnClipboardLineCallback)
 				{
 					// Split clipboard text into multiple lines. Send all complete lines to callback.

src/game/editor/editor.cpp

@@ -3665,12 +3665,12 @@ void CEditor::DoColorPickerButton(const void *pId, const CUIRect *pRect, ColorRG
 	{
 		if(ButtonResult == 1)
 		{
-			const char *pClipboard = Input()->GetClipboardText();
-			if(*pClipboard == '#' || *pClipboard == '$') // ignore leading # (web color format) and $ (console color format)
-				++pClipboard;
-			if(str_isallnum_hex(pClipboard))
+			std::string Clipboard = Input()->GetClipboardText();
+			if(Clipboard[0] == '#' || Clipboard[0] == '$') // ignore leading # (web color format) and $ (console color format)
+				Clipboard = Clipboard.substr(1);
+			if(str_isallnum_hex(Clipboard.c_str()))
 			{
-				std::optional<ColorRGBA> ParsedColor = color_parse<ColorRGBA>(pClipboard);
+				std::optional<ColorRGBA> ParsedColor = color_parse<ColorRGBA>(Clipboard.c_str());
 				if(ParsedColor)
 				{
 					m_ColorPickerPopupContext.m_State = EEditState::ONE_GO;