size_t myStringCopy(char *dst, size_t maxlen, const char *src)
{
   assert(dst);
   assert(src);
   
   strncpy(dst, src, maxlen - 1);
   dst[maxlen - 1] = 0;
   return strlen(dst);
}

char buf[256];
myStringCopy(buf, sizeof(buf), someString);

size_t myStringCopy(char *dst, size_t maxlen, const char *src)
{
   assert(dst);
   assert(src);
   
   // null terminate the buffer before copying
   dst[maxlen - 1] = 0;

   // notice 'maxlen' and not 'maxlen-1'
   strncpy(dst, src, maxlen);

   // test for overflow
   if(dst[maxlen-1] != 0)
   {
      // handle error
   }
   
   return strlen(dst);
}

// old code
char path[len + 1];
lsStringCopy(path, len, arg0);

// new code
char path[len + 1];
memcpy(path, arg0, sizeof(path));
path[len] = 0;

static void sSetWorkingDir(const char *arg0)
{
	// find the last path separator
	char *p = strrchr(arg0, '/');
	if(!p)
		p = strrchr(arg0, '\\');
	if(!p)
	{
		/*
		 The log isn't open yet, so just do an assert here so that at least
		 if it fails in dbg mode I'll know. If it fails in the wild then I'll
		 hope there's enough error info logged from other parts of the app
		 to know the problem. Don't know what I'd do about it, though!
		*/
		LS_ASSERTF(p, "Failed to determine working directory: arg0 [%s]", arg0);
		return;
	}
	
	// determine the length of the path sans the filename
	size_t len = p - arg0 + 1;
	len = (len < MAX_OS_PATH) ? len : MAX_OS_PATH;
	
	// copy to a temp buffer
	char path[len + 1];
	lsStringCopy(path, len, arg0);
	
	// set the working directory
	bool ret = lsPlatform_SetWorkingDir(path);
	
	// same as error case above
	LS_ASSERTF(ret, "Failed to set new working directory: path [%s]\n", path);
}