Bug Fix Request: Add NULL guard to write_quoted_str in civet.

[joshtews]

If a string address is NULL when civet tries to access it the sim crashes

trick/trick_source/web/CivetServer/src/VariableServerVariable.cpp

Lines 60 to 74 in 4a137dd

	static void write_quoted_str( std::ostream& os, const char* s) {
	int ii;
	int len = strlen(s);
	os << "\"" ;
	for (ii=0 ; ii<len ; ii++) {
	switch ((s)[ii]) {
	case '\n': os << "\\n"; break;
	case '\t': os << "\\t"; break;
	case '\b': os << "\\b"; break;
	case '\"': os << "\\\""; break;
	default : os << s[ii] ; break;
	}
	}
	os << "\"" ;
	}

Crash output snippet:

  Thread 4 (MyCivetServer web thread):
  #0  __strlen_evex ()                                     from /lib64/libc.so.6
  #1  write_quoted_str (os=..., s=0x0)                     at src/VariableServerVariable.cpp:62
  #2  VariableServerVariable::writeValue (this=..., outs=...) at src/VariableServerVariable.cpp:188
  #3  VariableServerSession::sendMessage (this=...)        at src/VariableServerSession.cpp:82
  #4  main_loop (S=...)                                    at src/MyCivetServer.cpp:227

Suggested edit:

static void write_quoted_str( std::ostream& os, const char* s) {
    // Return an empty string when s is NULL
    if (!s) { 
        os << "\"\""; return; 
    }

    int ii;
    int len = strlen(s);
    os << "\"" ;
    for (ii=0 ; ii<len ; ii++) {
        switch ((s)[ii]) {
        case '\n': os << "\\n"; break;
        case '\t': os << "\\t"; break;
        case '\b': os << "\\b"; break;
        case '\"': os << "\\\""; break;
        default  : os << s[ii] ; break;
        }
    }
    os << "\"" ;
}

[sharmeye]

Thanks for the issue, we'll investigate this shortly.