MFC r359327,359328:
Add property-based filters for syslogd. Property-based filters allow substring and regular expressions (see re_format(7)) matching against various message attributes. Filter specification starts with '#:' or ':' followed by three comma-separated fields property, operator, "value". Value must be double-quoted. A double quote and backslash must be escaped by a backslash. Following properties are supported as test value: o msg - body of the message received; o programname - program name sent the message; o hostname - hostname of message's originator; o source - an alias for hostname. Supported operators: o contains - true if filter value is found as a substring of property; o isequal - true if filter value is equal to property; o startswith - true if property starts with filter value; o regex - true if property matches basic regular expression defined in filter value; o ereregex - true if property matches extended regular expression defined in filter value; Operator may be prefixed by '!' to invert compare logic or by 'icase_' to make comparison function case insensitive. Submitted by: Boris N. Lytochkin <lytboris at gmail com> Relnotes: yes Differential Revision: https://reviews.freebsd.org/D23468