From a7576f0b6c71880bd410475682f52db2a85f538d Mon Sep 17 00:00:00 2001
From: Klaus Schmidinger <vdr@tvdr.de>
Date: Wed, 15 Jan 2025 08:57:45 +0100
Subject: [PATCH] Added parameter checks to strn0cpy() and Utf8Strn0Cpy()

---
 CONTRIBUTORS |  1 +
 HISTORY      |  1 +
 tools.c      | 33 ++++++++++++++++++++-------------
 3 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index ffad2c81..24f2cf90 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -3374,6 +3374,7 @@ Stefan Hofmann <stefan.hofmann@t-online.de>
  for fixing some typos in the translation files
  for adding 1 to Utf8BufSize() for worst case
  for adding a header to the backtrace
+ for adding parameter checks to strn0cpy()
 
 Stefan Blochberger <Stefan.Blochberger@gmx.de>
  for suggesting to automatically display the progress display whenever replay of a
diff --git a/HISTORY b/HISTORY
index db6b548b..f6430326 100644
--- a/HISTORY
+++ b/HISTORY
@@ -10053,3 +10053,4 @@ Video Disk Recorder Revision History
 - Fixed handling margins for timers that are not VPS controlled and not spawned (thanks
   to Markus Ehrnsperger).
 - Added a header to the backtrace (thanks to Stefan Hofmann).
+- Added parameter checks to strn0cpy() (thanks to Stefan Hofmann). Same for Utf8Strn0Cpy().
diff --git a/tools.c b/tools.c
index bb9433c1..f189bb0f 100644
--- a/tools.c
+++ b/tools.c
@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: tools.c 5.14 2024/09/01 20:43:40 kls Exp $
+ * $Id: tools.c 5.15 2025/01/15 08:57:45 kls Exp $
  */
 
 #include "tools.h"
@@ -131,8 +131,11 @@ char *strcpyrealloc(char *dest, const char *src)
 char *strn0cpy(char *dest, const char *src, size_t n)
 {
   char *s = dest;
-  for ( ; --n && (*dest = *src) != 0; dest++, src++) ;
-  *dest = 0;
+  if (dest && n) {
+     if (src)
+        for ( ; --n && (*dest = *src) != 0; dest++, src++) ;
+     *dest = 0;
+     }
   return s;
 }
 
@@ -914,17 +917,21 @@ char *Utf8Strn0Cpy(char *Dest, const char *Src, int n)
   if (cCharSetConv::SystemCharacterTable())
      return strn0cpy(Dest, Src, n);
   char *d = Dest;
-  while (*Src) {
-        int sl = Utf8CharLen(Src);
-        n -= sl;
-        if (n > 0) {
-           while (sl--)
-                 *d++ = *Src++;
-           }
-        else
-           break;
+  if (Dest && n > 0) {
+     if (Src) {
+        while (*Src) {
+              int sl = Utf8CharLen(Src);
+              n -= sl;
+              if (n > 0) {
+                 while (sl--)
+                       *d++ = *Src++;
+                 }
+              else
+                 break;
+              }
         }
-  *d = 0;
+     *d = 0;
+     }
   return Dest;
 }