syslog issues

serhiy-storchaka

There are several issues with corner cases in syslog.openlog().

syslog_get_argv() swallows exceptions, but not in all cases.
if ident is non UTF-8 encodable, syslog.openlog() fails after setting the global reference to ident. Now the C string saved internally in the previous call to openlog() points to the freed memory.
PySys_Audit() can crash if ident is NULL.
There may be a race condition with syslog.syslog(), because the global reference to ident is decrefed before setting the new value.

And, since syslog.syslog() releases the GIL, there may be a race condition syslog.syslog() with syslog.openlog() and syslog.closelog() which can decref the global reference to ident.

P.S. @noamcohen97 noticed yet one issue in syslog.syslog() (potential returning a value from a function while an exception is set #95012 (comment)) and fixed it.