In IEEE 1003.1-2008 [1] and earlier revisions, BRE/ERE grammar allows for
any character to be escaped, but "ORD_CHAR preceded by an unescaped
<backslash> character [gives undefined results]".
Historically, we've interpreted an escaped ordinary character as the
ordinary character itself. This becomes problematic when some extensions
give special meanings to an otherwise ordinary character
(e.g. GNU's \b, \s, \w), meaning we may have two different valid
interpretations of the same sequence.
To make this easier to deal with and given that the standard calls this
undefined, we should throw an error (EESCAPE) if we run into this scenario
to ease transition into a state where some escaped ordinaries are blessed
with a special meaning -- it will either error out or have extended
behavior, rather than have two entirely different versions of undefined
behavior that leave the consumer of regex(3) guessing as to what behavior
will be used or leaving them with false impressions.
This change bumps the symbol version of regcomp to FBSD_1.6 and provides the
old escape semantics for legacy applications, just in case one has an older
application that would immediately turn into a pumpkin because of an
extraneous escape that's embedded or otherwise critical to its operation.
This is the final piece needed before enhancing libregex with GNU extensions
and flipping the switch on bsdgrep.
[1] http://pubs.opengroup.org/onlinepubs/9699919799.2016edition/
PR: 229925 (exp-run, courtesy of antoine)
Differential Revision: https://reviews.freebsd.org/D10510
Currently, regex(3) exhibits the following wrong behavior as demonstrated
with sed:
- echo "a{1,2,3}b" | sed -r "s/{/_/" (1)
- echo "a{1,2,3}b" | sed "s/\}/_/" (2)
- echo "a{1,2,3}b" | sed -r "s/{}/_/" (3)
Cases (1) and (3) should throw errors but they actually succeed, and (2)
throws an error when it should match the literal '}'. The correct behavior
was decided by comparing to the behavior with the equivalent BRE (1)(3) or
ERE (2) and consulting POSIX, along with some reasonable evaluation.
Tests were also adjusted/added accordingly.
PR: 166861
Reviewed by: emaste, ngie, pfg
Approved by: emaste (mentor)
MFC after: never
Differential Revision: https://reviews.freebsd.org/D10315
BREs recently became prematurely sensitive to the branching operator, which
outright broke expressions that used it instead of failing silently. Test
that \| is matching a literal | for the time being.
Reviewed by: cem, emaste, ngie
Approved by: emaste (mentor)
Differential Revision: https://reviews.freebsd.org/D11577
minus the vendor Makefiles
Provide directions for how to bootstrap the vendor sources in
FREEBSD-upgrade
MFC after 2 weeks
Discussed with: rpaulo
Sponsored by: EMC / Isilon Storage Division
