Android: <sys/random.h> not available until API 28

[rcdailey]

According to the NDK r17b code, in sysroot/usr/include/sys/random.h, it has:

#if __ANDROID_API__ >= 28
int getentropy(void* __buffer, size_t __buffer_size) __wur __INTRODUCED_IN(28);

ssize_t getrandom(void* __buffer, size_t __buffer_size, unsigned int __flags) __wur __INTRODUCED_IN(28);
#endif /* __ANDROID_API__ >= 28 */

Looks like the ::getrandom() function that is used by Boost.UUID in boost/uuid/detail/random_provider_getrandom.ipp is not valid to use. At the moment, with no additional configuration, the UUID library cannot be used on Android (My API is set to 15). I think the fix for this would probably be to have some preprocessor logic that checks if we're on Android, and API less than 28, we do not define BOOST_UUID_RANDOM_PROVIDER_GETRANDOM_HAS_LIBC_WRAPPER, maybe?

[jeking3]

Your assessment is likely correct; unfortunately android is not one of the environments in our standard set of CI builds that we can test.

The selector logic can be found here: https://github.com/boostorg/uuid/blob/develop/include/boost/uuid/detail/random_provider_detect_platform.hpp

A workaround for you would be to define BOOST_UUID_RANDOM_PROVIDER_FORCE_POSIX. If you are able to submit a pull request that modifies that file to properly avoid it, for example wrapping the two getentropy/getrandom blocks with something to avoid android if the api is less than 28. Alternately, perhaps there's a Boost.Predef like way to handle this.

[Lastique]

I can make a PR in a few days.

[jeking3]

How can we add android build support to CI?

[Lastique]

On August 15, 2018 9:40:38 PM "James E. King III" notifications@github.com wrote:

How can we add android build support to CI?

I don't think we can, unless we install Android SDK every time tests are run. There are Android testers in the official Boost testing table.

[rcdailey]

You don't need the Android SDK, just 1 installation of the NDK. The SDK is only needed for Java stuff. You can get away with pure NDK + build system to cross compile native libraries for Android.

[rcdailey]

Also if your CI pipeline can use docker containers for your build environment, you could use a premade image for the NDK, I think some are available. Again just throwing some thoughts out there, I'm not at all familiar with your environment.

[Lastique]

On August 15, 2018 10:50:28 PM Robert Dailey notifications@github.com wrote:

You don't need the Android SDK, just 1 installation of the NDK. The SDK is only needed for Java stuff. You can get away with pure NDK + build system to cross compile native libraries for Android.

Doesn't matter. Travis CI and AppVeyor images are not under our control and have fixed contents. So the only way we could add Android cross-compilation is to download and install NDK every time tests are run. Which is not good for testing times and IMHO not worth it.

Maybe it is possible to configure custom images on some paid plan, but that is not something we can do locally for Boost.UUID.

[Lastique]

Please, see if https://github.com/boostorg/uuid/pull/77 fixes the problem.