Fix buffer overflow in process_option()

If no value is specified the option name is copied without checking the length.
Avoid the unnecessary copy and eliminate the fixed size buffer completely.

src/host/premake.c

@@ -258,33 +258,26 @@ int process_arguments(lua_State* L, int argc, const char** argv)
  */
 int process_option(lua_State* L, const char* arg)
 {
- char key[512];
- const char* value;
-
  /* If a value is specified, split the option into a key/value pair */
- char* ptr = strchr(arg, '=');
- if (ptr)
+ const char* value = strchr(arg, '=');
+ if (value)
  {
- int len = (int)(ptr - arg);
- if (len > 511) len = 511;
- strncpy(key, arg, len);
- key[len] = '\0';
- value = ptr + 1;
+ /* Store it in the Options table, which is already on the stack */
+ lua_pushlstring(L, arg, value - arg);
+ lua_pushstring(L, ++value);
+ lua_settable(L, -4);
+
+ /* The /scripts option gets picked up here to find the built-in scripts */
+ if (strncmp(arg, "scripts=", value - arg) == 0 && strlen(value) > 0)
+ {
+ scripts_path = value;
+ }
  }
  else
  {
- strcpy(key, arg);
- value = "";
- }
-
- /* Store it in the Options table, which is already on the stack */
- lua_pushstring(L, value);
- lua_setfield(L, -3, key);
-
- /* The /scripts option gets picked up here to find the built-in scripts */
- if (strcmp(key, "scripts") == 0 && strlen(value) > 0)
- {
- scripts_path = value;
+ /* No value, store empty string in the Options table */
+ lua_pushliteral("");
+ lua_setfield(L, -3, arg);
  }
 
  return OKAY;