Use strn functions and improve error handling. Even if we know the strings are NULL terminated we use length terminated string functions after a first strlen this makes it easier to assert that at one point we know the string is terminated and afterwards use the length of that.

#ifndef ERRORCODES_H
#define ERRORCODES_H

/* No begin certificate / end certificate could be found */
#define ERR_INVALID_INPUT_NO_LIST 2
/* Too much input for the installer process */
#define ERR_TOO_MUCH_INPUT 3

#endif