91 lines
3.2 KiB
Rust
91 lines
3.2 KiB
Rust
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use ptr;
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use libc;
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use sys_common::alloc::{MIN_ALIGN, realloc_fallback};
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use alloc::{GlobalAlloc, Layout, System};
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#[stable(feature = "alloc_system_type", since = "1.28.0")]
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unsafe impl GlobalAlloc for System {
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#[inline]
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unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
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if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
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libc::malloc(layout.size()) as *mut u8
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} else {
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#[cfg(target_os = "macos")]
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{
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if layout.align() > (1 << 31) {
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return ptr::null_mut()
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}
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}
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aligned_malloc(&layout)
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}
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}
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#[inline]
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unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
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if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
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libc::calloc(layout.size(), 1) as *mut u8
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} else {
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let ptr = self.alloc(layout.clone());
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if !ptr.is_null() {
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ptr::write_bytes(ptr, 0, layout.size());
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}
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ptr
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}
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}
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#[inline]
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unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
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libc::free(ptr as *mut libc::c_void)
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}
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#[inline]
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unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
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if layout.align() <= MIN_ALIGN && layout.align() <= new_size {
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libc::realloc(ptr as *mut libc::c_void, new_size) as *mut u8
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} else {
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realloc_fallback(self, ptr, layout, new_size)
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}
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}
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}
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#[cfg(any(target_os = "android",
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target_os = "hermit",
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target_os = "redox",
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target_os = "solaris"))]
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#[inline]
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unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
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// On android we currently target API level 9 which unfortunately
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// doesn't have the `posix_memalign` API used below. Instead we use
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// `memalign`, but this unfortunately has the property on some systems
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// where the memory returned cannot be deallocated by `free`!
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//
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// Upon closer inspection, however, this appears to work just fine with
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// Android, so for this platform we should be fine to call `memalign`
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// (which is present in API level 9). Some helpful references could
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// possibly be chromium using memalign [1], attempts at documenting that
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// memalign + free is ok [2] [3], or the current source of chromium
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// which still uses memalign on android [4].
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//
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// [1]: https://codereview.chromium.org/10796020/
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// [2]: https://code.google.com/p/android/issues/detail?id=35391
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// [3]: https://bugs.chromium.org/p/chromium/issues/detail?id=138579
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// [4]: https://chromium.googlesource.com/chromium/src/base/+/master/
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// /memory/aligned_memory.cc
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libc::memalign(layout.align(), layout.size()) as *mut u8
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}
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#[cfg(not(any(target_os = "android",
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target_os = "hermit",
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target_os = "redox",
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target_os = "solaris")))]
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#[inline]
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unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
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let mut out = ptr::null_mut();
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let ret = libc::posix_memalign(&mut out, layout.align(), layout.size());
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if ret != 0 {
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ptr::null_mut()
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} else {
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out as *mut u8
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}
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}
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