From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org [79.124.17.100]) by master.gitmailbox.com (Postfix) with ESMTP id BD38743C26 for ; Sat, 23 Jul 2022 14:32:36 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 09ED368B7CF; Sat, 23 Jul 2022 17:32:33 +0300 (EEST) Received: from nef.ens.fr (nef2.ens.fr [129.199.96.40]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id A172168B7B9 for ; Sat, 23 Jul 2022 17:32:26 +0300 (EEST) X-ENS-nef-client: 129.199.129.80 ( name = phare.normalesup.org ) Received: from phare.normalesup.org (phare.normalesup.org [129.199.129.80]) by nef.ens.fr (8.14.4/1.01.28121999) with ESMTP id 26NEWPAO011525 for ; Sat, 23 Jul 2022 16:32:26 +0200 Received: by phare.normalesup.org (Postfix, from userid 1001) id C5408EB5B9; Sat, 23 Jul 2022 16:32:25 +0200 (CEST) Date: Sat, 23 Jul 2022 16:32:25 +0200 From: Nicolas George To: FFmpeg development discussions and patches Message-ID: References: <32p7s1q2-7prs-1189-49p4-30n507437p2@vanv.qr> MIME-Version: 1.0 In-Reply-To: X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.4.3 (nef.ens.fr [129.199.96.32]); Sat, 23 Jul 2022 16:32:26 +0200 (CEST) Subject: Re: [FFmpeg-devel] ABI break in 5.1 X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Content-Type: multipart/mixed; boundary="===============6844313572793471285==" Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: --===============6844313572793471285== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="tn1FUt638RpLcEmO" Content-Disposition: inline --tn1FUt638RpLcEmO Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Jan Engelhardt (12022-07-23): > As I have previously explained, > [ http://ffmpeg.org/pipermail/ffmpeg-devel/2020-July/265705.html ] Read the replies that have been made to you at the time. > (Or, in today's terms, a program built with 5.1 but which is > combined with 5.0 at runtime, then this can happen: >=20 > $ ./a.out=20 > ./a.out: symbol lookup error: ./a.out: undefined symbol: avio_vprintf,=20 > version LIBAVFORMAT_59 This is a perfectly normal outcome. > >"""Running against an older version then the build version is never > >supported > > > >A distribution should never allow this to happen.""" >=20 > This is exactly what we're trying to do. ELF symbol version definitions= =20 > are *the* tool to do this, but we keep getting screwed over by terrible= =20 > symbol version management in ffmpeg. No, the ELF symbol version system cannot prevent you from replacing a file with an older version. The tool to prevent that is the package manager of the distribution, and it obviously depends on the distribution. With Debian, it looks like that: Depends: libavcodec59 (>=3D 7:5.0) What symbol versioning can achieve at most is turn a dangerous late incompatibility, such as accessing a field that was added in the new version, into an immediate harmless crash like the one you quoted above. > libavformat.v advertises a verdef (that one being "LIBAVUTIL_59"=20 > currently), but you keep modifying the set of symbols, such as dropping= =20 > avio_vprintf. Please point the commit where we dropped avio_vprintf. It would be a severe mistake. But to the better of my knowledge we avio_vprintf was added about a month ago and never dropped, and you are mistaken. >=20 > Minus that bug, libavformat.v is but used to do symbol=20 > visibility. For which you don't need a verdef, for starters. Well, make that your lede instead of a dump of a completely useless report of so-called incompatibilities reported by a tool that does not know the specifics. Even better, submit it as an actual patch explaining why and after checking it does not break anything else. Regards, --=20 Nicolas George --tn1FUt638RpLcEmO Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEE6ooRQGBoNzw0KnwPcZVLI8pNxgwFAmLcBncACgkQcZVLI8pN xgwV5w/+OI19CICqjkWV+Vr4Il9NvWO1Vi+zp5scDEezFZapJHW0POnxwJASuR2S JLUr+OJBSUwM4LmK9BLj7i3Cq3cpuOMav5aUW2qwN3xDDg+iqqJ3fvO2O7Qr2CiX Er5B+1HHn9EqXwnRg+Iduxsk6+ESJLHdjkEMLHWSD9mCOPbGHOYYcFNKfiPZCwvL nSvylgTuqwsAzvu6/5ui7pf9KbpXTzvJvWRCabeEoyF0oR8aKr2OGeLumbs1/tRI jpS2PUShMNupskt1H/jq7AOBW+cPpxXS5XQITa47AYKNLO93sIWLSYb+K1PHxsxj XWSRkeCI2Ja7FugtAHeeCX8DwV90dkAegVYwp6dskBz2ebwUwqx8wi0pWYCAEb9k CIm0khwloI4m/T15s8P+qHoZxyqTlrajGLZ/YCxSIaLkcpJglnFPjcBZIumMZNyc RHKDa/PaET1/O5Mctc8Y9gDr+FdttcwNt4X6dpsjB+hEN4Vs+BxbWDklZWpjVd0q kCG72jyuJY40xhfTA0zMLXlJFUMsiyYJPdA1YaiNbJhnibShK5CxzCBwaxmTVGcI he6VI8K5WZkQQjj/IKKlvC6uOyEMDXTB4g8zhsCfTZAACR1bz0ZBYqrGUgSasK/N tpCe4nvNJ265m/faDgoDar1+q4hvggf0mwyv7y0ZyYtLIahgGB8= =GTdk -----END PGP SIGNATURE----- --tn1FUt638RpLcEmO-- --===============6844313572793471285== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe". --===============6844313572793471285==--