Matcher function incorrectly assumed that moffset that we get from
findmust is in bytes. Fix this by introducing a stepback function,
taking short path if MB_CUR_MAX is 1, and going back byte-by-byte,
checking if we have a legal character sequence otherwise.
PR: 153502
Reviewed by: pfg, kevans
Approved by: kib (mentor, implicit)
Differential revision: https://reviews.freebsd.org/D18297
The issue found with gcc6 build (originally on illumos, confirmed on FreeBSD).
Mark it __unused.
Differential Revision: https://reviews.freebsd.org/D13109
libc is set for WARNS=2, but the incoming libregex will use WARNS=6.
Sprinkle some casts and (void)bc's to alleviate the warnings that come along
with the higher WARNS level.
These 'bc' parameters could be outright removed, but as of right now they
will be used in some parts of libregex land. Silence the warnings instead
rather than flip-flopping.
Mainly focus on files that use BSD 3-Clause license.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.
Adding features for matching is fairly straightforward, but this requires
some duplication because of this fast/slow setup. They can be fairly
trivially combined into a single walk(), so do it to make future additions
less error prone.
Reviewed by: cem (earlier version), emaste, pfg
Approved by: emaste (mentor)
Differential Revision: https://reviews.freebsd.org/D11233
Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.
Submitted by: Jan Schaumann <jschauma@stevens.edu>
Pull Request: https://github.com/freebsd/freebsd/pull/96
Change the behavior of when REG_STARTEND is combined with REG_NOTBOL.
From the original posting[1]:
"Enable the assumption that pmatch[0].rm_so is a continuation offset
to a string and allows us to do a proper assessment of the character
in regards to it's word position ('^' or '\<'), without risking going
into unallocated memory."
This change makes us similar to how glibc handles REG_STARTEND |
REG_NOTBOL, and is closely related to a soon-to-land fix to sed.
Special thanks to Martijn van Duren and Ingo Schwarze for working
out some consistent behaviour.
Differential Revision: https://reviews.freebsd.org/D6257
Taken from: openbsd-tech 2016-05-24 [1] (Martijn van Duren)
Relnotes: yes
MFC after: 1 month
Fix some rather complex regex issues found on OpenBSD as part of some
ongoing work to fix a sed(1) bug.
Curiously the OpenBSD tests don't trigger segfaults on FreeBSD but the
bugs were confirmed by running a port of FreeBSD's regex under OpenBSD's
malloc. Huge thanks to Ingo for confirming the behavior.
Taken from: Ingo Schwarze (through openbsd-tech 2016-05-15)
MFC after: 1 week
In matcher() we used an integer to index nsub of type size_t.
In print() we used an integer to index nstates of type sopno,
typedef'd long.
In both cases the indexes never take negative values.
Match the types to avoid any error.
MFC after: 5 days
reading past 'stop' in various places when converting multibyte characters.
Reading too far caused truncation to not be detected when it should have
been, eventually causing regexec() to loop infinitely in with certain
combinations of patterns and strings in multibyte locales.
PR: 74020
MFC after: 4 weeks
idea is that we perform multibyte->wide character conversion while parsing
and compiling, then convert byte sequences to wide characters when they're
needed for comparison and stepping through the string during execution.
As with tr(1), the main complication is to efficiently represent sets of
characters in bracket expressions. The old bitmap representation is replaced
by a bitmap for the first 256 characters combined with a vector of individual
wide characters, a vector of character ranges (for [A-Z] etc.), and a vector
of character classes (for [[:alpha:]] etc.).
One other point of interest is that although the Boyer-Moore algorithm had
to be disabled in the general multibyte case, it is still enabled for UTF-8
because of its self-synchronizing nature. This greatly speeds up matching
by reducing the number of multibyte conversions that need to be done.
Only warnings that could be fixed without changing the generated object
code and without restructuring the source code have been handled.
Reviewed by: /sbin/md5
string may be found (from the beginning of the pattern), the point
at which must is found minus that offset may actually point to some
place before the start of the text.
In that case, make start = start.
Alternatively, this could be tested for in the preceding if, but it
did not occur to me. :-)
Caught by: regex(3) test code
use a CHAR_MIN-based array, like elsewhere in the code.
Remove a number of unused variables (some due to the above change, one
that was left after a number of optimizing steps through the source).
Brucified by: bde
previous commits.
At the time we search the pattern for the "must" string, we now compute
the longest offset from the beginning of the pattern at which the must
string might be found. If that offset is found to be infinite (through
use of "+" or "*"), we set it to -1 to disable the heuristics applied
later.
After we are done with pre-matching, we use that offset and the point in
the text at which the must string was found to compute the earliest
point at which the pattern might be found.
Special care should be taken here. The variable "start" is passed to the
automata-processing functions fast() and slow() to indicate the point in
the text at which they should start working from. The real beginning of
the text is passed in a struct match variable m, which is used to check
for anchors. That variable, though, is initialized with "start", so we
must not adjust "start" before "m" is properly initialized.
Simple tests showed a speed increase from 100% to 400%, but they were
biased in that regexec() was called for the whole file instead of line
by line, and parenthized subexpressions were not searched for.
This change adds a single integer to the size of the "guts" structure,
and does not change the ABI.
Further improvements possible:
Since the speed increase observed here is so huge, one intuitive
optimization would be to introduce a bias in the function that computes
the "must" string so as to prefer a smaller string with a finite offset
over a larger one with an infinite offset. Tests have shown this to be a
bad idea, though, as the cost of false pre-matches far outweights the
benefits of a must offset, even in biased situations.
A number of other improvements suggest themselves, though:
* identify the cases where the pattern is identical to the must
string, and avoid entering fast() and slow() in these cases.
* compute the maximum offset from the must string to the end of
the pattern, and use that to set the point at which fast() and
slow() should give up trying to find a match, and return then
return to pre-matching.
* return all the way to pre-matching if a "match" was found and
later invalidated by back reference processing. Since back
references are evil and should be avoided anyway, this is of
little use.
The BM algorithm works by scanning the pattern from right to left,
and jumping as many characters as viable based on the text's mismatched
character and the pattern's already matched suffix.
This typically enable us to test only a fraction of the text's characters,
but has a worse performance than the straight-forward method for small
patterns. Because of this, the BM algorithm will only be used if the
pattern size is at least 4 characters.
Notice that this pre-matching is done on the largest substring of the
regular expression that _must_ be present on the text for a succesful
match to be possible at all.
For instance, "(xyzzy|grues)" will yield a null "must" substring, and,
therefore, not benefit from the BM algorithm at all. Because of the
lack of intelligence of the algorithm that finds the "must" string,
things like "charjump|matchjump" will also yield a null string. To
optimize that, "(char|match)jump" should be used.
The setup time (at regcomp()) for the BM algorithm will most likely
outweight any benefits for one-time matches. Given the slow regex(3)
we have, this is unlikely to be even perceptible, though.
The size of a regex_t structure is increased by 2*sizeof(char*) +
256*sizeof(int) + strlen(must)*sizeof(int). This is all inside the
regex_t's "guts", which is allocated dynamically by regcomp(). If
allocation of either of the two tables fail, the other one is freed.
In this case, the straight-forward algorithm is used for pre-matching.
Tests exercising the code path affected have shown a speed increase of
50% for "must" strings of length four or five.
API and ABI remain unchanged by this commit.
The patch submitted on the PR was not used, as it was non-functional.
PR: 14342
