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std: Use memalign, not posix_memalign, on Android

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We've gotten requests to move our Android support as far back as API level 9
where unfortunately the `posix_memalign` API wasn't implemented yet. Thankfully,
however, the `memalign` API was and it appears to be usable with `free` on the
Android platform (see comments included in commit).

This should help fix some of the last few test failures when compiling against
API level 9.
This commit is contained in:
Alex Crichton 2016-05-23 22:29:17 -07:00
parent 1ccada6cd3
commit 33dfd0fb16
1 changed files with 34 additions and 7 deletions
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41
src/liballoc_system/lib.rs
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@ -80,13 +80,40 @@ mod imp {
if align <= MIN_ALIGN { if align <= MIN_ALIGN {
libc::malloc(size as libc::size_t) as *mut u8 libc::malloc(size as libc::size_t) as *mut u8
} else { } else {
let mut out = ptr::null_mut(); aligned_malloc(size, align)
let ret = libc::posix_memalign(&mut out, align as libc::size_t, size as libc::size_t); }
if ret != 0 { }
ptr::null_mut()
} else { #[cfg(target_os = "android")]
out as *mut u8 unsafe fn aligned_malloc(size: usize, align: usize) -> *mut u8 {
} // On android we currently target API level 9 which unfortunately
// doesn't have the `posix_memalign` API used below. Instead we use
// `memalign`, but this unfortunately has the property on some systems
// where the memory returned cannot be deallocated by `free`!
//
// Upon closer inspection, however, this appears to work just fine with
// Android, so for this platform we should be fine to call `memalign`
// (which is present in API level 9). Some helpful references could
// possibly be chromium using memalign [1], attempts at documenting that
// memalign + free is ok [2] [3], or the current source of chromium
// which still uses memalign on android [4].
//
// [1]: https://codereview.chromium.org/10796020/
// [2]: https://code.google.com/p/android/issues/detail?id=35391
// [3]: https://bugs.chromium.org/p/chromium/issues/detail?id=138579
// [4]: https://chromium.googlesource.com/chromium/src/base/+/master/
// /memory/aligned_memory.cc
libc::memalign(align as libc::size_t, size as libc::size_t) as *mut u8
}
#[cfg(not(target_os = "android"))]
unsafe fn aligned_malloc(size: usize, align: usize) -> *mut u8 {
let mut out = ptr::null_mut();
let ret = libc::posix_memalign(&mut out, align as libc::size_t, size as libc::size_t);
if ret != 0 {
ptr::null_mut()
} else {
out as *mut u8
} }
} }