[android] Enable tests for FileManager in Android.

[drodriguez]

Many tests were disabled in Android, but they actually work without
almost changes.

• Android uses /proc/mounts as Linux. Enabling that code path gives good
  results in Android.
• attributesOfFileSystem works on Android once glibc.modulemap
  includes the right headers (see [android] Add missing POSIX/Linux headers to Android build. swift#24286).
• However, since Process is still not available in Android, the test
  that relies on xdgTestHelper tool will not work, and have been
  disabled (but instead of causing the test to fail, they are simply not
  run in Android, which probably will never conform to XDG).

[millenomi]

Note that xdgTestHelper is used in other tests and is increasingly misnamed.

Is there a way we can spawn processes programmatically on Android?

[drodriguez]

I’m looking into it. Some of the POSIX APIs used by Foundation appeared in very recent Androids (ref: https://android.googlesource.com/platform/bionic/+/master/libc/include/spawn.h), so I don’t think they are a possibility. I don’t know if I can do fork/exec instead. I don’t know if Process will be possible to bring to Android at all (and so the tests that depend on it will probably never pass in Android).

[finagolfin]

I had made the first two changes when building Foundation natively on Android AArch64. I also had to disable three other Android-specific blocks in FileManager because they wouldn't compile: the two mode_t & conversion functions and the TimeInterval conversion in attributesOfItem.

[finagolfin]

I don’t know if I can do fork/exec instead.

The posix_spawn added in Pie last year is a wrapper around fork, it has been backported to older Android versions too.

[spevans]

@swift-ci test

[drodriguez]

@swift-ci please test linux platform

[spevans]

@swift-ci test linux

[drodriguez]

@buttaface: I haven’t had problems with mode_t or TimeInterval. It seems to compile fine with NDK r18 and r16. There's a workaround at the top of the files for mode_t, I wonder if that's what’s creating the problem in your setup.

Re spawn vs. fork/exec. It is completely possible to replicate spawn, but the code also uses actions and other pieces of the API that will have to be branched out or duplicated. I think it is not impossible, but I don’t think it is easy either.

@swift-ci please test linux platform

[finagolfin]

I haven’t had problems with mode_t or TimeInterval. It seems to compile fine with NDK r18 and r16.

Hmm, I'm using the latest NDK r19, with the Android API set to 21, could be why.

There's a workaround at the top of the files for mode_t, I wonder if that's what’s creating the problem in your setup.

Yes, that bitwise & function for Android makes other code not compile: I haven't looked into why, just disabled it.

It is completely possible to replicate spawn

I'll try it with the backported posix_spawn from Bionic and see how it goes.

[spevans]

@swift-ci test linux