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 A4DB8410EC for ; Mon, 3 Jan 2022 11:04:08 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 1073668AF7E; Mon, 3 Jan 2022 13:04:06 +0200 (EET) Received: from mail-vk1-f180.google.com (mail-vk1-f180.google.com [209.85.221.180]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id 67F0C68AE34 for ; Mon, 3 Jan 2022 13:03:59 +0200 (EET) Received: by mail-vk1-f180.google.com with SMTP id 70so18583539vkx.7 for ; Mon, 03 Jan 2022 03:03:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=UfCg9M8SoYv+YvUEKqpVqDP7KogKtN09u7TuUvXRnZ8=; b=CB8iRc9MIBUunpQBEFm5R3JUrDFYsVmNjC0FuFcKa9yVwvZXhOOJrOFkXdImrjuxVp z3GkUhwmpirElPAjYIRBelGIG4gNk6TJNmjTWbFsjGAcUGTybiLqUxAYkO5EtnGW+xEM FcLuUGzQlBf2GB4fpklppc/XLHl8zFanJSizcC6H1AqmpPE6xyLFGCuPmohLCYCdvgyU s35kfjGNzvT2qCRNfU3BbG92zx59bNoPNU9b6rX3476eXbICfKB+Nbuy2b1K8ZdZi3cK cYynhhitoB8IynsBeC3ZclF0PZFCxBUzEJNEozL+WwOMRFuzId40Q3vsq4+3HRU1MX0L 3FNg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=UfCg9M8SoYv+YvUEKqpVqDP7KogKtN09u7TuUvXRnZ8=; b=h/PCmBQ6fsSXBDJksWg0Cbe4aXncDR/d249+tfkuuqzwFIzSNByN+EpcWlYQaQKmYe 943JkDEzfCzTWPPcIBsGYUC84/bEBCGsh96bRf5x3cPRe/Dp9itIc7n8ZPWw3qunz8ry 5UE38++lAQcYprcrxmZP+Bchzz1tasfLD8tlqP3KN5qZqoqVednctm7P86qD3KJhvd+2 VmwHqVrdiOX+2b65603vYGAWJNDSRDjjVTUEfVjDfLdYuIG9G6lKd/IglQYjMywpVBWD 0cdDzNgg03dTxj8IQd8pCu4yF7xuClsUy85MY1ijpFd+gdA/p6RYa4e2WKbChPBefZfp mUgA== X-Gm-Message-State: AOAM530SIyQCeMF99MG03/nwVJUt2UeHgWN644xmnBR3u8EhOq0jMJaB 96FeT8B5HhbB4EGAfth7+rLKTXmZJ0mhOimfXZW0yWBn6bnrVw== X-Google-Smtp-Source: ABdhPJxYVz3HDr7eN5blduJKq57ZXFWbGIpdMOVxaF/r39/wUH/drYInEwsDDYTzquQSeN6Mj94xFUBFBS0OQ7nIt1o= X-Received: by 2002:a1f:130a:: with SMTP id 10mr6635356vkt.28.1641207837271; Mon, 03 Jan 2022 03:03:57 -0800 (PST) MIME-Version: 1.0 References: <20211228150703.1228-1-dcnieho@gmail.com> In-Reply-To: From: "Diederick C. Niehorster" Date: Mon, 3 Jan 2022 12:03:40 +0100 Message-ID: To: FFmpeg development discussions and patches Subject: Re: [FFmpeg-devel] [RFC v2] avdevice: lock to minor version of avformat 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: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: Hi Andreas, Thanks for the comments! On Mon, Jan 3, 2022 at 11:02 AM Andreas Rheinhardt wrote: > > Diederick Niehorster: > > As per discussion on the list ( > > https://ffmpeg.org/pipermail/ffmpeg-devel/2021-June/281513.html, see > > especially https://ffmpeg.org/pipermail/ffmpeg-devel/2021-June/281586.html), > > to resolve the the unholy ABI-relationship between libavdevice and > > libavformat and allow easier working on the part of the avdevice API > > that lives in avformat, lock avdevice to a specific major and minor > > version of avformat. > > > > Signed-off-by: Diederick Niehorster > > --- > > 1. If this patch intends to make it illegal to use libavdevice together > with libavformat with a different minor version than it was compiled > against, then the most basic requirement of this is to actually properly > document it and not add stuff that might cause linking failure if used > in a way that runs afoul of your undocumented new requirements. Absolutely, documentation is required. Should that be in (amongst local to the function in the header)? I wanted to have the discussion first, or would docs be good to have ready to help the discussion? > 2. Is avdevice_version_same_minor() supposed to cause linking failures > by virtue of its AV_MAKE_MAJOR_MINOR_FUNC_NAME generated symbol name? Or > is the user actually supposed to run this function explicitly? > Anyway, it is not clear from the documentation that this function calls > abort on failure. The implementation is as suggested by Nicolas as suggested here https://ffmpeg.org/pipermail/ffmpeg-devel/2021-August/284492.html (And thanks for letting me know about preprocessor rescan, my v2 fixes most except ppc, see https://patchwork.ffmpeg.org/check/49132/, and now i know why :p). The idea is that it causes linker failure. I've tested this indeed, when trying to load incompatible avformat and avdevice dlls the dynamic linker throws an error. So strictly the function doesn't have to abort, nor does it have to be called at all, but it's nicely documenting. > > libavdevice/avdevice.c | 10 ++++++++++ > > libavdevice/version.h | 10 ++++++++++ > > libavformat/utils.c | 5 +++++ > > libavformat/version.h | 11 +++++++++++ > > libavutil/macros.h | 3 +++ > > 5 files changed, 39 insertions(+) > > > > diff --git a/libavdevice/avdevice.c b/libavdevice/avdevice.c > > index 8f460c7564..0c9b702eda 100644 > > --- a/libavdevice/avdevice.c > > +++ b/libavdevice/avdevice.c > > @@ -38,6 +38,16 @@ unsigned avdevice_version(void) > > return LIBAVDEVICE_VERSION_INT; > > } > > > > +unsigned avdevice_version_same_minor() > > +{ > > + // check version of loaded lavf has same major and minor version as > > + // this library was compiled against > > + if ((avformat_version_same_minor()) & ~0xFF != (LIBAVFORMAT_VERSION_INT & ~0xFF)) > > + abort(); > > + > > + return avdevice_version(); > > +} > > + > > const char * avdevice_configuration(void) > > { > > return FFMPEG_CONFIGURATION; > > diff --git a/libavdevice/version.h b/libavdevice/version.h > > index 41f568d6b0..83d8c67511 100644 > > --- a/libavdevice/version.h > > +++ b/libavdevice/version.h > > @@ -26,6 +26,7 @@ > > */ > > > > #include "libavutil/version.h" > > +#include "libavutil/macros.h" > > > > #define LIBAVDEVICE_VERSION_MAJOR 59 > > #define LIBAVDEVICE_VERSION_MINOR 1 > > @@ -48,4 +49,13 @@ > > */ > > #define FF_API_DEVICE_CAPABILITIES (LIBAVDEVICE_VERSION_MAJOR < 60) > > > > +/** > > + * avdevice_version_same_minor() expands to a function with > > + * the same minor and major version it was compiled against > > + * encoded in it. Enables locking to the minor version of > > + * other libraries they were compiled against. > > + */ > > +#define avdevice_version_same_minor AV_MAKE_MAJOR_MINOR_FUNC_NAME(device,LIBAVFORMAT_VERSION_MAJOR,LIBAVFORMAT_VERSION_MINOR) > > +unsigned avdevice_version_same_minor(); > > + > > #endif /* AVDEVICE_VERSION_H */ > > diff --git a/libavformat/utils.c b/libavformat/utils.c > > index 332ba534d2..607a777c3f 100644 > > --- a/libavformat/utils.c > > +++ b/libavformat/utils.c > > @@ -63,6 +63,11 @@ unsigned avformat_version(void) > > return LIBAVFORMAT_VERSION_INT; > > } > > > > +unsigned avformat_version_same_minor() > > +{ > > + return avformat_version(); > > +} > > + > > const char *avformat_configuration(void) > > { > > return FFMPEG_CONFIGURATION; > > diff --git a/libavformat/version.h b/libavformat/version.h > > index 379a68cc7c..661d074b12 100644 > > --- a/libavformat/version.h > > +++ b/libavformat/version.h > > @@ -28,6 +28,7 @@ > > */ > > > > #include "libavutil/version.h" > > +#include "libavutil/macros.h" > > > > // Major bumping may affect Ticket5467, 5421, 5451(compatibility with Chromium) > > // Also please add any ticket numbers that you believe might be affected here > > @@ -63,4 +64,14 @@ > > > > > > #define FF_API_R_FRAME_RATE 1 > > + > > +/** > > + * avformat_version_same_minor() expands to a function with > > + * the same minor and major version it was compiled against > > + * encoded in it. Enables locking to the minor version of > > + * other libraries they were compiled against. > > + */ > > +#define avformat_version_same_minor AV_MAKE_MAJOR_MINOR_FUNC_NAME(format,LIBAVFORMAT_VERSION_MAJOR,LIBAVFORMAT_VERSION_MINOR) > > +unsigned avformat_version_same_minor(); > > + > > #endif /* AVFORMAT_VERSION_H */ > > diff --git a/libavutil/macros.h b/libavutil/macros.h > > index 2a7567c3ea..dab530a8a0 100644 > > --- a/libavutil/macros.h > > +++ b/libavutil/macros.h > > @@ -73,6 +73,9 @@ > > * @} > > */ > > > > +#define AV_MAKE_MAJOR_MINOR_FUNC_NAME_IMPL(name,major,minor) av ## name ## _version_ ## major ## _ ## minor > > +#define AV_MAKE_MAJOR_MINOR_FUNC_NAME(name,major,minor) AV_MAKE_MAJOR_MINOR_FUNC_NAME_IMPL(name,major,minor) > > + > > #define AV_PRAGMA(s) _Pragma(#s) > > > > #define FFALIGN(x, a) (((x)+(a)-1)&~((a)-1)) > > > > _______________________________________________ > 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". _______________________________________________ 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".