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path: root/src/backend/regex/regc_lex.c
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* Pre-beta mechanical code beautification.Tom Lane2023-05-19
| | | | | | | | | | | | | | | Run pgindent, pgperltidy, and reformat-dat-files. This set of diffs is a bit larger than typical. We've updated to pg_bsd_indent 2.1.2, which properly indents variable declarations that have multi-line initialization expressions (the continuation lines are now indented one tab stop). We've also updated to perltidy version 20230309 and changed some of its settings, which reduces its desire to add whitespace to lines to make assignments etc. line up. Going forward, that should make for fewer random-seeming changes to existing code. Discussion: https://postgr.es/m/20230428092545.qfb3y5wcu4cm75ur@alvherre.pgsql
* Avoid character classification in regex escape parsing.Jeff Davis2023-04-21
| | | | | | | | | | | | | For regex escape sequences, just test directly for the relevant ASCII characters rather than using locale-sensitive character classification. This fixes an assertion failure when a locale considers a non-ASCII character, such as "൧", to be a digit. Reported-by: Richard Guo Discussion: https://postgr.es/m/CAMbWs49Q6UoKGeT8pBkMtJGJd+16CBFZaaWUk9Du+2ERE5g_YA@mail.gmail.com Backpatch-through: 11
* Defend against stack overrun in a few more places.Tom Lane2022-08-24
| | | | | | | | | | | | | | | | | | | SplitToVariants() in the ispell code, lseg_inside_poly() in geo_ops.c, and regex_selectivity_sub() in selectivity estimation could recurse until stack overflow; fix by adding check_stack_depth() calls. So could next() in the regex compiler, but that case is better fixed by converting its tail recursion to a loop. (We probably get better code that way too, since next() can now be inlined into its sole caller.) There remains a reachable stack overrun in the Turkish stemmer, but we'll need some advice from the Snowball people about how to fix that. Per report from Egor Chindyaskin and Alexander Lakhin. These mistakes are old, so back-patch to all supported branches. Richard Guo and Tom Lane Discussion: https://postgr.es/m/1661334672.728714027@f473.i.mail.ru
* Avoid determining regexp subexpression matches, when possible.Tom Lane2021-08-09
| | | | | | | | | | | | | | | | | | | | | Identifying the precise match locations for parenthesized subexpressions is a fairly expensive task given the way our regexp engine works, both at regexp compile time (where we must create an optimized NFA for each parenthesized subexpression) and at runtime (where determining exact match locations requires laborious search). Up to now we've made little attempt to optimize this situation. This patch identifies cases where we know at compile time that we won't need to know subexpression match locations, and teaches the regexp compiler to not bother creating per-subexpression regexps for parenthesis pairs that are not referenced by backrefs elsewhere in the regexp. (To preserve semantics, we obviously still have to pin down the match locations of backref references.) Users could have obtained the same results before this by being careful to write "non capturing" parentheses wherever possible, but few people bother with that. Discussion: https://postgr.es/m/2219936.1628115334@sss.pgh.pa.us
* Allow complemented character class escapes within regex brackets.Tom Lane2021-02-25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The complement-class escapes \D, \S, \W are now allowed within bracket expressions. There is no semantic difficulty with doing that, but the rather hokey macro-expansion-based implementation previously used here couldn't cope. Also, invent "word" as an allowed character class name, thus "\w" is now equivalent to "[[:word:]]" outside brackets, or "[:word:]" within brackets. POSIX allows such implementation-specific extensions, and the same name is used in e.g. bash. One surprising compatibility issue this raises is that constructs such as "[\w-_]" are now disallowed, as our documentation has always said they should be: character classes can't be endpoints of a range. Previously, because \w was just a macro for "[:alnum:]_", such a construct was read as "[[:alnum:]_-_]", so it was accepted so long as the character after "-" was numerically greater than or equal to "_". Some implementation cleanup along the way: * Remove the lexnest() hack, and in consequence clean up wordchrs() to not interact with the lexer. * Fix colorcomplement() to not be O(N^2) in the number of colors involved. * Get rid of useless-as-far-as-I-can-see calls of element() on single-character character element names in brackpart(). element() always maps these to the character itself, and things would be quite broken if it didn't --- should "[a]" match something different than "a" does? Besides, the shortcut path in brackpart() wasn't doing this anyway, making it even more inconsistent. Discussion: https://postgr.es/m/2845172.1613674385@sss.pgh.pa.us Discussion: https://postgr.es/m/3220564.1613859619@sss.pgh.pa.us
* Fix another ancient bug in parsing of BRE-mode regular expressions.Tom Lane2021-02-18
| | | | | | | | | | | | | | While poking at the regex code, I happened to notice that the bug squashed in commit afcc8772e had a sibling: next() failed to return a specific value associated with the '}' token for a "\{m,n\}" quantifier when parsing in basic RE mode. Again, this could result in treating the quantifier as non-greedy, which it never should be in basic mode. For that to happen, the last character before "\}" that sets "nextvalue" would have to set it to zero, or it'd have to have accidentally been zero from the start. The failure can be provoked repeatably with, for example, a bound ending in digit "0". Like the previous patch, back-patch all the way.
* Fix ancient bug in parsing of BRE-mode regular expressions.Tom Lane2021-01-08
| | | | | | | | | | | | | | | | | brenext(), when parsing a '*' quantifier, forgot to return any "value" for the token; per the equivalent case in next(), it should return value 1 to indicate that greedy rather than non-greedy behavior is wanted. The result is that the compiled regexp could behave like 'x*?' rather than the intended 'x*', if we were unlucky enough to have a zero in v->nextvalue at this point. That seems to happen with some reliability if we have '.*' at the beginning of a BRE-mode regexp, although that depends on the initial contents of a stack-allocated struct, so it's not guaranteed to fail. Found by Alexander Lakhin using valgrind testing. This bug seems to be aboriginal in Spencer's code, so back-patch all the way. Discussion: https://postgr.es/m/16814-6c5e3edd2bdf0d50@postgresql.org
* Clean up warnings from -Wimplicit-fallthrough.Tom Lane2018-05-01
| | | | | | | | | | | | | | | | | | | | | | | | | Recent gcc can warn about switch-case fall throughs that are not explicitly labeled as intentional. This seems like a good thing, so clean up the warnings exposed thereby by labeling all such cases with comments that gcc will recognize. In files that already had one or more suitable comments, I generally matched the existing style of those. Otherwise I went with /* FALLTHROUGH */, which is one of the spellings approved at the more-restrictive-than-default level -Wimplicit-fallthrough=4. (At the default level you can also spell it /* FALL ?THRU */, and it's not picky about case. What you can't do is include additional text in the same comment, so some existing comments containing versions of this aren't good enough.) Testing with gcc 8.0.1 (Fedora 28's current version), I found that I also had to put explicit "break"s after elog(ERROR) or ereport(ERROR); apparently, for this purpose gcc doesn't recognize that those don't return. That seems like possibly a gcc bug, but it's fine because in most places we did that anyway; so this amounts to a visit from the style police. Discussion: https://postgr.es/m/15083.1525207729@sss.pgh.pa.us
* Phase 2 of pgindent updates.Tom Lane2017-06-21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Change pg_bsd_indent to follow upstream rules for placement of comments to the right of code, and remove pgindent hack that caused comments following #endif to not obey the general rule. Commit e3860ffa4dd0dad0dd9eea4be9cc1412373a8c89 wasn't actually using the published version of pg_bsd_indent, but a hacked-up version that tried to minimize the amount of movement of comments to the right of code. The situation of interest is where such a comment has to be moved to the right of its default placement at column 33 because there's code there. BSD indent has always moved right in units of tab stops in such cases --- but in the previous incarnation, indent was working in 8-space tab stops, while now it knows we use 4-space tabs. So the net result is that in about half the cases, such comments are placed one tab stop left of before. This is better all around: it leaves more room on the line for comment text, and it means that in such cases the comment uniformly starts at the next 4-space tab stop after the code, rather than sometimes one and sometimes two tabs after. Also, ensure that comments following #endif are indented the same as comments following other preprocessor commands such as #else. That inconsistency turns out to have been self-inflicted damage from a poorly-thought-through post-indent "fixup" in pgindent. This patch is much less interesting than the first round of indent changes, but also bulkier, so I thought it best to separate the effects. Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
* Initial pgindent run with pg_bsd_indent version 2.0.Tom Lane2017-06-21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The new indent version includes numerous fixes thanks to Piotr Stefaniak. The main changes visible in this commit are: * Nicer formatting of function-pointer declarations. * No longer unexpectedly removes spaces in expressions using casts, sizeof, or offsetof. * No longer wants to add a space in "struct structname *varname", as well as some similar cases for const- or volatile-qualified pointers. * Declarations using PG_USED_FOR_ASSERTS_ONLY are formatted more nicely. * Fixes bug where comments following declarations were sometimes placed with no space separating them from the code. * Fixes some odd decisions for comments following case labels. * Fixes some cases where comments following code were indented to less than the expected column 33. On the less good side, it now tends to put more whitespace around typedef names that are not listed in typedefs.list. This might encourage us to put more effort into typedef name collection; it's not really a bug in indent itself. There are more changes coming after this round, having to do with comment indentation and alignment of lines appearing within parentheses. I wanted to limit the size of the diffs to something that could be reviewed without one's eyes completely glazing over, so it seemed better to split up the changes as much as practical. Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
* Remove typedef celt from the regex library, along with macro NOCELT.Tom Lane2016-08-19
| | | | | | | | | | | | | | | | | | | | | The regex library used to have a notion of a "collating element" that was distinct from a "character", but Henry Spencer never actually implemented his planned support for multi-character collating elements, and the Tcl crew ripped out most of the stubs for that years ago. The only thing left that distinguished the "celt" typedef from the "chr" typedef was that "celt" was supposed to also be able to hold the not-a-character "NOCELT" value. However, NOCELT was not used anywhere after the MCCE stub removal changes, which means there's no need for celt to be different from chr. Removing the separate typedef simplifies matters and also removes a trap for the unwary, in that celt is signed while chr may not be, so comparisons could mean different things. There's no bug there today because we restrict CHR_MAX to be less than INT_MAX, but I think there may have been such bugs before we did that, and there could be again if anyone ever decides to fool with the range of chr. This patch also removes assorted unnecessary casts to "chr" of values that are already chrs. Many of these seem to be leftover from days when the code was compatible with pre-ANSI C.
* Suppress compiler warnings about useless comparison of unsigned to zero.Tom Lane2016-02-15
| | | | | | | | | | | | Reportedly, some compilers warn about tests like "c < 0" if c is unsigned, and hence complain about the character range checks I added in commit 3bb3f42f3749d40b8d4de65871e8d828b18d4a45. This is a bit of a pain since the regex library doesn't really want to assume that chr is unsigned. However, since any such reconfiguration would involve manual edits of regcustom.h anyway, we can put it on the shoulders of whoever wants to do that to adjust this new range-checking macro correctly. Per gripes from Coverity and Andres.
* Fix some regex issues with out-of-range characters and large char ranges.Tom Lane2016-02-08
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Previously, our regex code defined CHR_MAX as 0xfffffffe, which is a bad choice because it is outside the range of type "celt" (int32). Characters approaching that limit could lead to infinite loops in logic such as "for (c = a; c <= b; c++)" where c is of type celt but the range bounds are chr. Such loops will work safely only if CHR_MAX+1 is representable in celt, since c must advance to beyond b before the loop will exit. Fortunately, there seems no reason not to restrict CHR_MAX to 0x7ffffffe. It's highly unlikely that Unicode will ever assign codes that high, and none of our other backend encodings need characters beyond that either. In addition to modifying the macro, we have to explicitly enforce character range restrictions on the values of \u, \U, and \x escape sequences, else the limit is trivially bypassed. Also, the code for expanding case-independent character ranges in bracket expressions had a potential integer overflow in its calculation of the number of characters it could generate, which could lead to allocating too small a character vector and then overwriting memory. An attacker with the ability to supply arbitrary regex patterns could easily cause transient DOS via server crashes, and the possibility for privilege escalation has not been ruled out. Quite aside from the integer-overflow problem, the range expansion code was unnecessarily inefficient in that it always produced a result consisting of individual characters, abandoning the knowledge that we had a range to start with. If the input range is large, this requires excessive memory. Change it so that the original range is reported as-is, and then we add on any case-equivalent characters that are outside that range. With this approach, we can bound the number of individual characters allowed without sacrificing much. This patch allows at most 100000 individual characters, which I believe to be more than the number of case pairs existing in Unicode, so that the restriction will never be hit in practice. It's still possible for range() to take awhile given a large character code range, so also add statement-cancel detection to its loop. The downstream function dovec() also lacked cancel detection, and could take a long time given a large output from range(). Per fuzz testing by Greg Stark. Back-patch to all supported branches. Security: CVE-2016-0773
* Implement lookbehind constraints in our regular-expression engine.Tom Lane2015-10-30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A lookbehind constraint is like a lookahead constraint in that it consumes no text; but it checks for existence (or nonexistence) of a match *ending* at the current point in the string, rather than one *starting* at the current point. This is a long-requested feature since it exists in many other regex libraries, but Henry Spencer had never got around to implementing it in the code we use. Just making it work is actually pretty trivial; but naive copying of the logic for lookahead constraints leads to code that often spends O(N^2) time to scan an N-character string, because we have to run the match engine from string start to the current probe point each time the constraint is checked. In typical use-cases a lookbehind constraint will be written at the start of the regex and hence will need to be checked at every character --- so O(N^2) work overall. To fix that, I introduced a third copy of the core DFA matching loop, paralleling the existing longest() and shortest() loops. This version, matchuntil(), can suspend and resume matching given a couple of pointers' worth of storage space. So we need only run it across the string once, stopping at each interesting probe point and then resuming to advance to the next one. I also put in an optimization that simplifies one-character lookahead and lookbehind constraints, such as "(?=x)" or "(?<!\w)", into AHEAD and BEHIND constraints, which already existed in the engine. This avoids the overhead of the LACON machinery entirely for these rather common cases. The net result is that lookbehind constraints run a factor of three or so slower than Perl's for multi-character constraints, but faster than Perl's for one-character constraints ... and they work fine for variable-length constraints, which Perl gives up on entirely. So that's not bad from a competitive perspective, and there's room for further optimization if anyone cares. (In reality, raw scan rate across a large input string is probably not that big a deal for Postgres usage anyway; so I'm happy if it's linear.)
* Sync regex code with Tcl 8.6.4.Tom Lane2015-09-16
| | | | | | | | | | | | | | | | | | | Sync our regex code with upstream changes since last time we did this, which was Tcl 8.5.11 (see commit 08fd6ff37f71485e2fc04bc6ce07d2a483c36702). The only functional change here is to disbelieve that an octal escape is three digits long if it would exceed \377. That's a bug fix, but it's a minor one and could change the interpretation of working regexes, so don't back-patch. In addition to that, s/INFINITY/DUPINF/ to eliminate the risk of collisions with <math.h>'s macro, and s/LOCAL/NOPROP/ because that also seems like an unnecessarily collision-prone macro name. There were some other cosmetic changes in their copy that I did not adopt, notably a rather half-hearted attempt at renaming some of the C functions in a more verbose style. (I'm not necessarily against the concept, but renaming just a few functions in the package is not an improvement.)
* pgindent run for 9.4Bruce Momjian2014-05-06
| | | | | This includes removing tabs after periods in C comments, which was applied to back branches, so this change should not effect backpatching.
* Make various variables const (read-only).Tom Lane2014-01-18
| | | | | | | | | | | | | | | | | | These changes should generally improve correctness/maintainability. A nice side benefit is that several kilobytes move from initialized data to text segment, allowing them to be shared across processes and probably reducing copy-on-write overhead while forking a new backend. Unfortunately this doesn't seem to help libpq in the same way (at least not when it's compiled with -fpic on x86_64), but we can hope the linker at least collects all nominally-const data together even if it's not actually part of the text segment. Also, make pg_encname_tbl[] static in encnames.c, since there seems no very good reason for any other code to use it; per a suggestion from Wim Lewis, who independently submitted a patch that was mostly a subset of this one. Oskari Saarenmaa, with some editorialization by me
* Fix comparisons of pointers with zero to compare with NULL instead.Tom Lane2010-10-29
| | | | | | | Per C standard, these are semantically the same thing; but saying NULL when you mean NULL is good for readability. Marti Raudsepp, per results of INRIA's Coccinelle.
* Remove cvs keywords from all files.Magnus Hagander2010-09-20
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* 8.4 pgindent run, with new combined Linux/FreeBSD/MinGW typedef listBruce Momjian2009-06-11
| | | | provided by Andrew.
* Sync our regex code with upstream changes since last time we did this, whichTom Lane2008-02-14
| | | | | | | | | | | | | was Tcl 8.4.8. The main changes are to remove the never-fully-implemented code for multi-character collating elements, and to const-ify some stuff a bit more fully. In combination with the recent security patch, this commit brings us into line with Tcl 8.5.0. Note that I didn't make any effort to duplicate a lot of cosmetic changes that they made to bring their copy into line with their own style guidelines, such as adding braces around single-line IF bodies. Most of those we either had done already (such as ANSI-fication of function headers) or there is no point because pgindent would undo the change anyway.
* Fix assorted security-grade bugs in the regex engine. All of these problemsTom Lane2008-01-03
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | are shared with Tcl, since it's their code to begin with, and the patches have been copied from Tcl 8.5.0. Problems: CVE-2007-4769: Inadequate check on the range of backref numbers allows crash due to out-of-bounds read. CVE-2007-4772: Infinite loop in regex optimizer for pattern '($|^)*'. CVE-2007-6067: Very slow optimizer cleanup for regex with a large NFA representation, as well as crash if we encounter an out-of-memory condition during NFA construction. Part of the response to CVE-2007-6067 is to put a limit on the number of states in the NFA representation of a regex. This seems needed even though the within-the-code problems have been corrected, since otherwise the code could try to use very large amounts of memory for a suitably-crafted regex, leading to potential DOS by driving the system into swap, activating a kernel OOM killer, etc. Although there are certainly plenty of ways to drive the system into effective DOS with poorly-written SQL queries, these problems seem worth treating as security issues because many applications might accept regex search patterns from untrustworthy sources. Thanks to Will Drewry of Google for reporting these problems. Patches by Will Drewry and Tom Lane. Security: CVE-2007-4769, CVE-2007-4772, CVE-2007-6067
* Add a useless return statement to suppress a warning seen with someTom Lane2007-10-22
| | | | | | versions of gcc (I'm seeing it with Apple's gcc 4.0.1). I think the reason we did not see this before was that the assert() macros in the regex code were all no-ops till recently.
* Standard pgindent run for 8.1.Bruce Momjian2005-10-15
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* $Header: -> $PostgreSQL Changes ...PostgreSQL Daemon2003-11-29
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* Another pgindent run with updated typedefs.Bruce Momjian2003-08-08
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* pgindent run.Bruce Momjian2003-08-04
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* Replace regular expression package with Henry Spencer's latest versionTom Lane2003-02-05
(extracted from Tcl 8.4.1 release, as Henry still hasn't got round to making it a separate library). This solves a performance problem for multibyte, as well as upgrading our regexp support to match recent Tcl and nearly match recent Perl.