Change "-f <file>" to not support patterns with a NUL-byte in them
under --fixed-strings. We'll now only support these under
"--perl-regexp" with PCRE v2.
A previous change to grep's documentation changed the description of
"-f <file>" to be vague enough as to not promise that this would work.
By dropping support for this we make it a whole lot easier to move
away from the kwset backend, which we'll do in a subsequent change.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The behavior of "grep" when patterns contained a NUL-byte has always
been haphazard, and has served the vagaries of the implementation more
than anything else. A pattern containing a NUL-byte can only be
provided via "-f <file>". Since pickaxe (log search) has no such flag
the NUL-byte in patterns has only ever been supported by "grep" (and
not "log --grep").
Since 9eceddeec6 ("Use kwset in grep", 2011-08-21) patterns containing
"\0" were considered fixed. In 966be95549 ("grep: add tests to fix
blind spots with \0 patterns", 2017-05-20) I added tests for this
behavior.
Change the behavior to do the obvious thing, i.e. don't silently
discard a regex pattern and make it implicitly fixed just because they
contain a NUL-byte. Instead die if the backend in question can't
handle them, e.g. --basic-regexp is combined with such a pattern.
This is desired because from a user's point of view it's the obvious
thing to do. Whether we support BRE/ERE/Perl syntax is different from
whether our implementation is limited by C-strings. These patterns are
obscure enough that I think this behavior change is OK, especially
since we never documented the old behavior.
Doing this also makes it easier to replace the kwset backend with
something else, since we'll no longer strictly need it for anything we
can't easily use another fixed-string backend for.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Move the tests for "-f <file>" where "<file>" contains a NUL byte
pattern into their own file. I added most of these tests in
966be95549 ("grep: add tests to fix blind spots with \0 patterns",
2017-05-20).
Whether a regex engine supports matching binary content is very
different from whether it matches binary patterns. Since
2f8952250a ("regex: add regexec_buf() that can work on a non
NUL-terminated string", 2016-09-21) we've required REG_STARTEND of our
regex engines so we can match binary content, but only the PCRE v2
engine can sensibly match binary patterns.
Since 9eceddeec6 ("Use kwset in grep", 2011-08-21) we've been punting
patterns containing NUL-byte and considering them fixed, except in
cases where "--ignore-case" is provided and they're non-ASCII, see
5c1ebcca4d ("grep/icase: avoid kwsset on literal non-ascii strings",
2016-06-25). Subsequent commits will change this behavior.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Ævar Arnfjörð Bjarmason