From a1207f1637662ab4c1f18f4d5ddec6060064f9fd Mon Sep 17 00:00:00 2001
From: Bilgin COSKUN <bilgin.coskun@ceng.metu.edu.tr>
Date: Tue, 13 Feb 2024 09:56:57 +0300
Subject: [PATCH] Fix Overlapping src and dest for strcpy in Client Code

---
 code/client/cl_cgame.c |  2 +-
 code/client/cl_main.c  | 18 ++++++++++++++++++
 code/client/cl_ui.c    |  2 +-
 code/client/client.h   |  2 ++
 4 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/code/client/cl_cgame.c b/code/client/cl_cgame.c
index 613d084209..28eaeeae71 100644
--- a/code/client/cl_cgame.c
+++ b/code/client/cl_cgame.c
@@ -618,7 +618,7 @@ intptr_t CL_CgameSystemCalls( intptr_t *args ) {
 		Com_Memcpy( VMA(1), VMA(2), args[3] );
 		return 0;
 	case CG_STRNCPY:
-		strncpy( VMA(1), VMA(2), args[3] );
+		CL_Strncpy( VMA(1), VMA(2), args[3] );
 		return args[1];
 	case CG_SIN:
 		return FloatAsInt( sin( VMF(1) ) );
diff --git a/code/client/cl_main.c b/code/client/cl_main.c
index 6c2579525c..4aa2809914 100644
--- a/code/client/cl_main.c
+++ b/code/client/cl_main.c
@@ -4708,3 +4708,21 @@ qboolean CL_CDKeyValidate( const char *key, const char *checksum ) {
 	return qfalse;
 #endif
 }
+
+/*
+=================
+CL_Strncpy
+=================
+Safe reimplementation of strncpy against overlapping src & dest
+*/
+
+char *CL_Strncpy(char *dest, const char *src, unsigned long n){
+    unsigned long length = strlen(src);
+    if(n > length){
+        memmove(dest, src, length);
+        memset(dest+length,0,n-length);
+    }else{
+        memmove(dest, src, n);
+    }
+    return dest;
+}
diff --git a/code/client/cl_ui.c b/code/client/cl_ui.c
index 714364847f..dc927b52fd 100644
--- a/code/client/cl_ui.c
+++ b/code/client/cl_ui.c
@@ -1005,7 +1005,7 @@ intptr_t CL_UISystemCalls( intptr_t *args ) {
 		return 0;
 
 	case UI_STRNCPY:
-		strncpy( VMA(1), VMA(2), args[3] );
+		CL_Strncpy( VMA(1), VMA(2), args[3] );
 		return args[1];
 
 	case UI_SIN:
diff --git a/code/client/client.h b/code/client/client.h
index 0d3e1c3369..619346addc 100644
--- a/code/client/client.h
+++ b/code/client/client.h
@@ -485,6 +485,8 @@ void CL_InitRef( void );
 qboolean CL_CDKeyValidate( const char *key, const char *checksum );
 int CL_ServerStatus( char *serverAddress, char *serverStatusString, int maxLen );
 
+char *CL_Strncpy(char *dest, const char *src, unsigned long n);
+
 qboolean CL_CheckPaused(void);
 
 //