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Hermes SMTP Server) with ESMTPA ID 999518821c423a75a84d1cc13c1757c9; Thu, 20 Nov 2025 13:31:30 +0000 (UTC) Message-ID: <0d3f89a8-66c6-2ae2-9cf3-6b2aff8e1f5e@netscape.net> Date: Thu, 20 Nov 2025 05:31:27 -0800 Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: Re: RFC: Serial port DTR/RTS - O_ Content-Language: en-US To: "H. Peter Anvin" , "Maciej W. Rozycki" Cc: Greg KH , Theodore Ts'o , Maarten Brock , "linux-serial@vger.kernel.org" , "linux-api@vger.kernel.org" , LKML References: <20251110201933.GH2988753@mit.edu> <0F8021E8-F288-4669-8195-9948844E36FD@zytor.com> <20251111035143.GJ2988753@mit.edu> <2025111214-doily-anyway-b24b@gregkh> <6DBB5931-ACD4-4174-9FCE-96C45FFC4603@zytor.com> <2025111241-domestic-moonstone-f75f@gregkh> <2025111227-equipment-magnetism-1443@gregkh> <14b1bc5c-83ac-431f-a53b-14872024b969@zytor.com> <6c26eea2-6f90-f48a-9488-e7480f086c70@netscape.net> <2846db90-fb05-41d2-b8de-c678af75a04b@zytor.com> <06279d25-73d6-01f5-dcf8-8667415048d2@netscape.net> From: Ned Ulbricht In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Mailer: WebService/1.1.24652 mail.backend.jedi.jws.acl:role.jedi.acl.token.atz.jws.hermes.aol On 11/18/25 10:05, H. Peter Anvin wrote: >> "(O_EXCL|O_NOFOLLOW)" provokes a thought... >> >> As essential context, fs/open.c build_open_flags() has: >> >> if (flags & O_CREAT) { >>     op->intent |= LOOKUP_CREATE; >>     if (flags & O_EXCL) { >>         op->intent |= LOOKUP_EXCL; >>         flags |= O_NOFOLLOW; >>     } >> } [snip] > I had missed the bit in the spec that says that O_CREAT|O_EXCL is required to > imply O_NOFOLLOW (as Linux indeed does as seen above.) Fwiw, earlier today I had an ultimately unsuccessful series of searches using the Austin Group Issue tracker at: https://austingroupbugs.net/view_all_bug_page.php Searched (serially): "O_EXCL", "O_NOFOLLOW", "EEXIST", "ELOOP"; all with no other filter refinements. Then searched filtering by 'Section' (multiple adjacent selections): 'open' .. 'openat'. In all results, simply eyeball-scanned 'Summary' (w/o opening most). Apparent upshot, unless I'm mistaken, is that the exact error return is a trivial conflict with no appreciable impact on higher levels. In roughly same vein, FreeBSD open(2) man page, specifically at "[EMLINK]" and "STANDARDS", might possibly be stretched to read as implicitly encouraging that assessment. https://man.freebsd.org/cgi/man.cgi?query=open&manpath=FreeBSD+16.0-CURRENT Alhough I don't have a FreeBSD box available to actually test (O_CREAT|O_EXCL|O_NOFOLLOW) symlink behavior on that platform. (Maybe that combo's wired to detonate tnt nasal daemons? Dunno;-) Unfortunately, this does prompt a close re-scrutinization of linux's open(2) man page. Notwithstanding the damn spec, the linux man page should precisely and accurately reflect the observed error return? Ned