Date: Sat, 13 Feb 2021 11:10:49 -0500 From: Mark Johnston <markj@freebsd.org> To: Jung-uk Kim <jkim@freebsd.org> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r362333 - in head: contrib/flex contrib/flex/src usr.bin/lex usr.bin/lex/lib Message-ID: <YCf6CVhryv/6Ju2E@raichu> In-Reply-To: <68440f27-7b70-cc1f-d646-9669c4093838@FreeBSD.org> References: <202006181809.05II9G8p054025@repo.freebsd.org> <YCbeabF%2BBSrpQep0@raichu> <0a0ac901-c1d2-54d7-d585-2856ae4fe6ea@FreeBSD.org> <68440f27-7b70-cc1f-d646-9669c4093838@FreeBSD.org>
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On Sat, Feb 13, 2021 at 02:39:56AM -0500, Jung-uk Kim wrote: > On 21. 2. 13., Jung-uk Kim wrote: > > On 21. 2. 12., Mark Johnston wrote: > >> On Thu, Jun 18, 2020 at 06:09:16PM +0000, Jung-uk Kim wrote: > >>> Author: jkim > >>> Date: Thu Jun 18 18:09:16 2020 > >>> New Revision: 362333 > >>> URL: https://svnweb.freebsd.org/changeset/base/362333 > >>> > >>> Log: > >>> MFV: r362286 > >>> > >>> Merge flex 2.6.4. > >> > >> This seems to have introduced a regression: input() now returns 0 > >> instead of EOF to indicate that the end of input was reached. This has > >> been reported in a few places: > >> > >> https://github.com/westes/flex/issues/448 > >> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=911415 > >> > >> It breaks the scanner used by libdtrace, and as a result dtrace is > >> unable to resolve some probe argument types: > >> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=253440 > >> > >> I have a small patch to libdtrace which works around this. The upstream > >> commit that introduced the change is fairly old at this point, and > >> upstream seems somewhat unresponsive, so I'm not sure it'll get > >> reverted. Some other scanners in the tree look like they'd be affected, > >> like crypto/heimdal/lib/asn1/lex.l or > >> sys/contrib/dev/acpica/compiler/aslsupport.l, so I'm wondering if we > >> should revert this particular change for 13.0. Certainly we should fix > >> the DTrace bug one way or another for 13.0. > > > > I think it does not make much sense and we should revert the upstream > > change. Does the attached patch work for you? The original patch fixes it, the updated one does not since libdtrace sets -l in LFLAGS. :) Removing it causes a build failure but it is trivial to resolve. I am running some tests now to see if anything regressed. > Now I believe the author wanted Lex compatibility. Maybe we should do > the attached patch instead? Is it common to use the base system's flex for ports and out-of-tree code generally? I have no real idea. I'd be worried about configure scripts that use the flex version to determine whether or not to apply a workaround for this change. I also note that Debian does not seem to have patched this. Looking through consumers in the tree (all *.l files), the following scanners could be affected: - libdtrace - contrib/com_err/lex.l - contrib/ipfilter/iplang/iplang_l.l - does not appear to be built - crypto/heimdal/lib/asn1/lex.l - crypto/heimdal/lib/com_err/lex.l - crypto/heimdal/lib/hx509/sel-lex.l - crypto/heimdal/lib/sl/slc-lex.l - sys/contrib/dev/acpica/compiler/aslsupport.l - sys/contrib/dev/acpica/compiler/prparser.l It would not be too difficult to patch them, and I think in most cases the problem is not very severe and is only triggered by invalid input. For instance, asn1_compile enters an infinite loop if the input file contains an unterminated comment. So for 13.0 I am kind of inclined to just patch consumers. If you think we should revert the change in flex, I'm ok with that too and will remove the use of -l in libdtrace. > diff --git a/contrib/flex/src/flex.skl b/contrib/flex/src/flex.skl > index 242645f53245..c23b944ea473 100644 > --- a/contrib/flex/src/flex.skl > +++ b/contrib/flex/src/flex.skl > @@ -1863,7 +1863,11 @@ m4_ifdef( [[M4_YY_USE_LINENO]], > case EOB_ACT_END_OF_FILE: > { > if ( yywrap( M4_YY_CALL_ONLY_ARG ) ) > +#ifdef YY_FLEX_LEX_COMPAT > return 0; > +#else > + return EOF; > +#endif > > if ( ! YY_G(yy_did_buffer_switch_on_eof) ) > YY_NEW_FILE;
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