Date: Mon, 22 Nov 2021 11:58:19 -0600 From: Kyle Evans <kevans@freebsd.org> To: Shawn Webb <shawn.webb@hardenedbsd.org> Cc: Mark Johnston <markj@freebsd.org>, src-committers <src-committers@freebsd.org>, "<dev-commits-src-all@freebsd.org>" <dev-commits-src-all@freebsd.org>, dev-commits-src-branches@freebsd.org Subject: Re: git: 68396709e73a - releng/12.3 - libctf: Improve check for duplicate SOU definitions in ctf_add_type() Message-ID: <CACNAnaF2OYsu1OEhB5FVnrxfwL423tFWgJ7kaVcMBnWyKPjs3Q@mail.gmail.com> In-Reply-To: <20211122172544.a3wi636tajsnsfme@mutt-hbsd> References: <202111221634.1AMGYoK4064366@gitrepo.freebsd.org> <20211122172544.a3wi636tajsnsfme@mutt-hbsd>
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On Mon, Nov 22, 2021 at 11:25 AM Shawn Webb <shawn.webb@hardenedbsd.org> wrote: > > On Mon, Nov 22, 2021 at 04:34:50PM +0000, Mark Johnston wrote: > > The branch releng/12.3 has been updated by markj: > > > > URL: https://cgit.FreeBSD.org/src/commit/?id=68396709e73a4cd392ffc06fde6bfa44d79118a7 > > > > commit 68396709e73a4cd392ffc06fde6bfa44d79118a7 > > Author: Mark Johnston <markj@FreeBSD.org> > > AuthorDate: 2021-10-04 16:28:22 +0000 > > Commit: Mark Johnston <markj@FreeBSD.org> > > CommitDate: 2021-11-22 16:32:18 +0000 > > > > libctf: Improve check for duplicate SOU definitions in ctf_add_type() > > > > When copying a struct or union from one CTF container to another, > > ctf_add_type() checks whether it matches an existing type in the > > destination container. It does so by looking for a type with the same > > name and kind as the new type, and if one exists, it iterates over all > > members of the source type and checks whether a member with matching > > name and offset exists in the matched destination type. This can > > produce false positives, for example because member types are not > > compared, but this is not expected to arise in practice. If the match > > fails, ctf_add_type() returns an error. > > > > The procedure used for member comparison breaks down in the face of > > anonymous struct and union members. ctf_member_iter() visits each > > member in the source definition and looks up the corresponding member in > > the desination definition by name using ctf_member_info(), but this > > function will descend into anonymous members and thus fail to match. > > Fix the problem by introducing a custom comparison routine which does > > not assume member names are unique. This should also be faster for > > types with many members; in the previous scheme, membcmp() would perform > > a linear scan of the desination type's members to perform a lookup by > > name. The new routine steps through the members of both types in a > > single loop. > > Hey Mark, > > Out of curiosity, would commits to releng branches necessitate an EN? > > Thanks, > This is just the in-progress release branch, so not here, at least.
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