Bug#1051418: Info received (obs-studio: clicking on an xcomposite window source makes obs segfault)

[Michael Neilly <mneilly@yahoo.com>]

For the link provided, the crash occurs because of the presence of the unicode middot character. The wchar_to_utf8() function in libobs utils checks for any char that is less than 0 and returns zero. This results in dstr_to_lower() not updating name_lower in xcompcap_props(). The empty name_lower string is pushed to window_strings which causes qsort() to SEGV.

The following is the check that fails in libobs/utils/utf8.c:

292                  if ((signed char)*w < 0) {
293                          if ((flags & UTF8_IGNORE_ERROR) == 0)
294                                  return 0;                                                                          295                          continue;