On Android, faccessat2 syscall (which supports flags like AT_EACCESS) is
not allowed, so syscall.Faccessat tries to emulate AT_EACCESS check in
userspace using os.Stat, os.Geteuid etc.
Also, according to [1],
> Android doesn't have setuid programs, and never runs code with euid!=uid.
This means on Android the proper AT_EACCESS check is neither possible
nor really needed.
Let's skip the syscall.Faccessat userspace emulation of AT_EACCESS
check and return ENOSYS, so the callers can use a fallback.
This should speed up exec.LookPath on Android.
[1]: 508b2f6e5c/libc/bionic/faccessat.cpp (50)
Change-Id: If7b529fa314480b70e9ae9cdd8c7ce82cd55d233
Reviewed-on: https://go-review.googlesource.com/c/go/+/611298
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
8cd550a232