lts build failing on fontconfig for android

[contendar]

Description
While building lts build for android it fails

Expected behavior
It should compile successfully and create aar files in respective folder.

Current behavior
Build failed with fontconfig: failed message

To Reproduce
Execute following command
./android.sh --lts --enable-gpl --enable-android-media-codec --enable-android-zlib --enable-fontconfig --enable-freetype --enable-fribidi --enable-lame --enable-libvorbis --enable-libvpx --enable-libwebp --enable-x264

Expected behavior
It should compile successfully and create aar files in respective folder.

Screenshots

Logs
build.log

Environment

• Platform: Android
• Architecture: arm-v7a, arm-v7a-neon, arm64-v8a, x86, x86_64
• Version (if applicable) Latest
• Source branch master
• Android NDK version:22.0.7026061

[tanersener]

build.log shows that an unsupported NDK version is used during the build. Please use one of the versions listed in NDK Compatibility wiki page.

INFO: Using Android NDK v21.1.6352462 provided at /Users/zainali/Library/Android/sdk/ndk/21.1.6352462

[contendar]

I am sorry I attached the wrong build.log(I was testing if using the NDK v21 fixed the issue), I am attaching the
correct build.log file.

After analysing the error in build.log file(undefined symbol: posix_fadvise referenced by fccache.c), I think may be ffmpeg-kit/src/fontconfig/src/fccache.c needs to be patched
Like replace following line

if defined(HAVE_POSIX_FADVISE) && defined(POSIX_FADV_WILLNEED)
	posix_fadvise (fd, 0, fd_stat->st_size, POSIX_FADV_WILLNEED);
#endif

With

#if defined(__ANDROID__) && defined(__ANDROID_API__) && (__ANDROID_API__ < 21)
        // 'posix_fadvise' introduced in API 21:
#elif defined(HAVE_POSIX_FADVISE) && defined(POSIX_FADV_WILLNEED)
	posix_fadvise (fd, 0, fd_stat->st_size, POSIX_FADV_WILLNEED);
#endif

Do you think this will be ok(I verified that this patch let this library compile) or this may cause some performance issues?

[tanersener]

As far as I see, posix_fadvise is an optional component for fontconfig. configure script of fontconfig checks it and enables it only if it is available.

This is what I have about it in the config.log file of fontconfig. As you can understand, I don't have it too, so my builds don't try to link it and I don't get any linking errors.

configure:17022: checking for posix_fadvise in fcntl.h
configure:17052: result: no

I suggest analysing why it is enabled in your system. You can also patch it if it is easier for you. But I don't know whether it will affect the performance or not.

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[tanersener]

My tests show that some macOS hosts are affected from this. It seems like although HAVE_POSIX_FADVISE define is detected as 0, clang still sets it to 1.

[tanersener]

Patched in the development branch.