0.3.0: converge relibc to upstream 0.6.0 + Red Bear patches

dlmalloc-rs/src/dummy.rs

@@ -0,0 +1,42 @@
+use crate::Allocator;
+use core::ptr;
+
+pub struct System {
+    _priv: (),
+}
+
+impl System {
+    pub const fn new() -> System {
+        System { _priv: () }
+    }
+}
+
+unsafe impl Allocator for System {
+    fn alloc(&self, _size: usize) -> (*mut u8, usize, u32) {
+        (ptr::null_mut(), 0, 0)
+    }
+
+    fn remap(&self, _ptr: *mut u8, _oldsize: usize, _newsize: usize, _can_move: bool) -> *mut u8 {
+        ptr::null_mut()
+    }
+
+    fn free_part(&self, _ptr: *mut u8, _oldsize: usize, _newsize: usize) -> bool {
+        false
+    }
+
+    fn free(&self, _ptr: *mut u8, _size: usize) -> bool {
+        false
+    }
+
+    fn can_release_part(&self, _flags: u32) -> bool {
+        false
+    }
+
+    fn allocates_zeros(&self) -> bool {
+        false
+    }
+
+    fn page_size(&self) -> usize {
+        1
+    }
+}

dlmalloc-rs/src/global.rs

@@ -0,0 +1,56 @@
+use crate::Dlmalloc;
+use core::alloc::{GlobalAlloc, Layout};
+use core::ptr;
+
+pub use crate::sys::enable_alloc_after_fork;
+
+/// An instance of a "global allocator" backed by `Dlmalloc`
+///
+/// This API requires the `global` feature is activated, and this type
+/// implements the `GlobalAlloc` trait in the standard library.
+pub struct GlobalDlmalloc;
+
+static mut DLMALLOC: Dlmalloc = Dlmalloc::new();
+
+unsafe impl GlobalAlloc for GlobalDlmalloc {
+    #[inline]
+    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+        let _guard = lock();
+        let dlmalloc = ptr::addr_of_mut!(DLMALLOC);
+        (*dlmalloc).malloc(layout.size(), layout.align())
+    }
+
+    #[inline]
+    unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
+        let _guard = lock();
+        let dlmalloc = ptr::addr_of_mut!(DLMALLOC);
+        (*dlmalloc).free(ptr, layout.size(), layout.align())
+    }
+
+    #[inline]
+    unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
+        let _guard = lock();
+        let dlmalloc = ptr::addr_of_mut!(DLMALLOC);
+        (*dlmalloc).calloc(layout.size(), layout.align())
+    }
+
+    #[inline]
+    unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
+        let _guard = lock();
+        let dlmalloc = ptr::addr_of_mut!(DLMALLOC);
+        (*dlmalloc).realloc(ptr, layout.size(), layout.align(), new_size)
+    }
+}
+
+unsafe fn lock() -> impl Drop {
+    crate::sys::acquire_global_lock();
+
+    struct Guard;
+    impl Drop for Guard {
+        fn drop(&mut self) {
+            crate::sys::release_global_lock()
+        }
+    }
+
+    Guard
+}

dlmalloc-rs/src/lib.rs

@@ -0,0 +1,230 @@
+//! A Rust port of the `dlmalloc` allocator.
+//!
+//! The `dlmalloc` allocator is described at
+//! <https://gee.cs.oswego.edu/dl/html/malloc.html> and this Rust crate is a straight
+//! port of the C code for the allocator into Rust. The implementation is
+//! wrapped up in a `Dlmalloc` type and has support for Linux, OSX, and Wasm
+//! currently.
+//!
+//! The primary purpose of this crate is that it serves as the default memory
+//! allocator for the `wasm32-unknown-unknown` target in the standard library.
+//! Support for other platforms is largely untested and unused, but is used when
+//! testing this crate.
+
+#![allow(dead_code)]
+#![no_std]
+#![deny(missing_docs)]
+
+#[cfg(feature = "rust_api")]
+use core::{cmp, ptr};
+
+#[cfg(feature = "system")]
+use sys::System;
+
+#[cfg(feature = "global")]
+pub use self::global::{enable_alloc_after_fork, GlobalDlmalloc};
+
+mod dlmalloc;
+
+#[cfg(feature = "c_api")]
+pub use dlmalloc::Dlmalloc as DlmallocCApi;
+
+#[cfg(feature = "global")]
+mod global;
+
+/// In order for this crate to efficiently manage memory, it needs a way to communicate with the
+/// underlying platform. This `Allocator` trait provides an interface for this communication.
+pub unsafe trait Allocator: Send {
+    /// Allocates system memory region of at least `size` bytes
+    /// Returns a triple of `(base, size, flags)` where `base` is a pointer to the beginning of the
+    /// allocated memory region. `size` is the actual size of the region while `flags` specifies
+    /// properties of the allocated region. If `EXTERN_BIT` (bit 0) set in flags, then we did not
+    /// allocate this segment and so should not try to deallocate or merge with others.
+    /// This function can return a `std::ptr::null_mut()` when allocation fails (other values of
+    /// the triple will be ignored).
+    fn alloc(&self, size: usize) -> (*mut u8, usize, u32);
+
+    /// Remaps system memory region at `ptr` with size `oldsize` to a potential new location with
+    /// size `newsize`. `can_move` indicates if the location is allowed to move to a completely new
+    /// location, or that it is only allowed to change in size. Returns a pointer to the new
+    /// location in memory.
+    /// This function can return a `std::ptr::null_mut()` to signal an error.
+    fn remap(&self, ptr: *mut u8, oldsize: usize, newsize: usize, can_move: bool) -> *mut u8;
+
+    /// Frees a part of a memory chunk. The original memory chunk starts at `ptr` with size `oldsize`
+    /// and is turned into a memory region starting at the same address but with `newsize` bytes.
+    /// Returns `true` iff the access memory region could be freed.
+    fn free_part(&self, ptr: *mut u8, oldsize: usize, newsize: usize) -> bool;
+
+    /// Frees an entire memory region. Returns `true` iff the operation succeeded. When `false` is
+    /// returned, the `dlmalloc` may re-use the location on future allocation requests
+    fn free(&self, ptr: *mut u8, size: usize) -> bool;
+
+    /// Indicates if the system can release a part of memory. For the `flags` argument, see
+    /// `Allocator::alloc`
+    fn can_release_part(&self, flags: u32) -> bool;
+
+    /// Indicates whether newly allocated regions contain zeros.
+    fn allocates_zeros(&self) -> bool;
+
+    /// Returns the page size. Must be a power of two
+    fn page_size(&self) -> usize;
+}
+
+/// An allocator instance
+///
+/// Instances of this type are used to allocate blocks of memory. For best
+/// results only use one of these. Currently doesn't implement `Drop` to release
+/// lingering memory back to the OS. That may happen eventually though!
+#[cfg(feature = "rust_api")]
+pub struct Dlmalloc<
+    #[cfg(feature = "system")]
+    A = System,
+    #[cfg(not(feature = "system"))]
+    A,
+>(dlmalloc::Dlmalloc<A>);
+
+cfg_if::cfg_if! {
+    if #[cfg(all(feature = "system", target_family = "wasm"))] {
+        #[path = "wasm.rs"]
+        mod sys;
+    } else if #[cfg(all(feature = "system", target_os = "windows"))] {
+        #[path = "windows.rs"]
+        mod sys;
+    } else if #[cfg(all(feature = "system", target_os = "xous"))] {
+        #[path = "xous.rs"]
+        mod sys;
+    } else if #[cfg(all(feature = "system", any(target_os = "linux", target_os = "macos", target_os = "redox")))] {
+        #[path = "unix.rs"]
+        mod sys;
+    } else {
+        #[path = "dummy.rs"]
+        mod sys;
+    }
+}
+
+#[cfg(feature = "system")]
+#[cfg(feature = "rust_api")]
+impl Dlmalloc<System> {
+    /// Creates a new instance of an allocator
+    pub const fn new() -> Dlmalloc<System> {
+        Dlmalloc(dlmalloc::Dlmalloc::new(System::new()))
+    }
+}
+
+#[cfg(feature = "rust_api")]
+impl<A> Dlmalloc<A> {
+    /// Creates a new instance of an allocator
+    pub const fn new_with_allocator(sys_allocator: A) -> Dlmalloc<A> {
+        Dlmalloc(dlmalloc::Dlmalloc::new(sys_allocator))
+    }
+}
+
+#[cfg(feature = "rust_api")]
+impl<A: Allocator> Dlmalloc<A> {
+    /// Allocates `size` bytes with `align` align.
+    ///
+    /// Returns a null pointer if allocation fails. Returns a valid pointer
+    /// otherwise.
+    ///
+    /// Safety and contracts are largely governed by the `GlobalAlloc::alloc`
+    /// method contracts.
+    #[inline]
+    pub unsafe fn malloc(&mut self, size: usize, align: usize) -> *mut u8 {
+        if align <= self.0.malloc_alignment() {
+            self.0.malloc(size)
+        } else {
+            self.0.memalign(align, size)
+        }
+    }
+
+    /// Same as `malloc`, except if the allocation succeeds it's guaranteed to
+    /// point to `size` bytes of zeros.
+    #[inline]
+    pub unsafe fn calloc(&mut self, size: usize, align: usize) -> *mut u8 {
+        let ptr = self.malloc(size, align);
+        if !ptr.is_null() && self.0.calloc_must_clear(ptr) {
+            ptr::write_bytes(ptr, 0, size);
+        }
+        ptr
+    }
+
+    /// Deallocates a `ptr` with `size` and `align` as the previous request used
+    /// to allocate it.
+    ///
+    /// Safety and contracts are largely governed by the `GlobalAlloc::dealloc`
+    /// method contracts.
+    #[inline]
+    pub unsafe fn free(&mut self, ptr: *mut u8, size: usize, align: usize) {
+        let _ = align;
+        self.0.validate_size(ptr, size);
+        self.0.free(ptr)
+    }
+
+    /// Reallocates `ptr`, a previous allocation with `old_size` and
+    /// `old_align`, to have `new_size` and the same alignment as before.
+    ///
+    /// Returns a null pointer if the memory couldn't be reallocated, but `ptr`
+    /// is still valid. Returns a valid pointer and frees `ptr` if the request
+    /// is satisfied.
+    ///
+    /// Safety and contracts are largely governed by the `GlobalAlloc::realloc`
+    /// method contracts.
+    #[inline]
+    pub unsafe fn realloc(
+        &mut self,
+        ptr: *mut u8,
+        old_size: usize,
+        old_align: usize,
+        new_size: usize,
+    ) -> *mut u8 {
+        self.0.validate_size(ptr, old_size);
+
+        if old_align <= self.0.malloc_alignment() {
+            self.0.realloc(ptr, new_size)
+        } else {
+            let res = self.malloc(new_size, old_align);
+            if !res.is_null() {
+                let size = cmp::min(old_size, new_size);
+                ptr::copy_nonoverlapping(ptr, res, size);
+                self.free(ptr, old_size, old_align);
+            }
+            res
+        }
+    }
+
+    /// If possible, gives memory back to the system if there is unused memory
+    /// at the high end of the malloc pool or in unused segments.
+    ///
+    /// You can call this after freeing large blocks of memory to potentially
+    /// reduce the system-level memory requirements of a program. However, it
+    /// cannot guarantee to reduce memory. Under some allocation patterns, some
+    /// large free blocks of memory will be locked between two used chunks, so
+    /// they cannot be given back to the system.
+    ///
+    /// The `pad` argument represents the amount of free trailing space to
+    /// leave untrimmed. If this argument is zero, only the minimum amount of
+    /// memory to maintain internal data structures will be left. Non-zero
+    /// arguments can be supplied to maintain enough trailing space to service
+    /// future expected allocations without having to re-obtain memory from the
+    /// system.
+    ///
+    /// Returns `true` if it actually released any memory, else `false`.
+    pub unsafe fn trim(&mut self, pad: usize) -> bool {
+        self.0.trim(pad)
+    }
+
+    /// Releases all allocations in this allocator back to the system,
+    /// consuming self and preventing further use.
+    ///
+    /// Returns the number of bytes released to the system.
+    pub unsafe fn destroy(self) -> usize {
+        self.0.destroy()
+    }
+
+    /// Get a reference the underlying [`Allocator`] that this `Dlmalloc` was
+    /// constructed with.
+    pub fn allocator(&self) -> &A {
+        self.0.allocator()
+    }
+}

dlmalloc-rs/src/unix.rs

@@ -0,0 +1,131 @@
+use crate::Allocator;
+use core::ptr;
+
+/// System setting for Linux
+pub struct System {
+    _priv: (),
+}
+
+impl System {
+    pub const fn new() -> System {
+        System { _priv: () }
+    }
+}
+
+#[cfg(feature = "global")]
+static mut LOCK: libc::pthread_mutex_t = libc::PTHREAD_MUTEX_INITIALIZER;
+
+unsafe impl Allocator for System {
+    fn alloc(&self, size: usize) -> (*mut u8, usize, u32) {
+        let addr = unsafe {
+            libc::mmap(
+                ptr::null_mut(),
+                size,
+                libc::PROT_WRITE | libc::PROT_READ,
+                libc::MAP_ANON | libc::MAP_PRIVATE,
+                -1,
+                0,
+            )
+        };
+        if addr == libc::MAP_FAILED {
+            (ptr::null_mut(), 0, 0)
+        } else {
+            (addr.cast(), size, 0)
+        }
+    }
+
+    #[cfg(target_os = "linux")]
+    fn remap(&self, ptr: *mut u8, oldsize: usize, newsize: usize, can_move: bool) -> *mut u8 {
+        let flags = if can_move { libc::MREMAP_MAYMOVE } else { 0 };
+        let ptr = unsafe { libc::mremap(ptr.cast(), oldsize, newsize, flags) };
+        if ptr == libc::MAP_FAILED {
+            ptr::null_mut()
+        } else {
+            ptr.cast()
+        }
+    }
+
+    #[cfg(any(target_os = "redox", target_os = "macos"))]
+    fn remap(&self, _ptr: *mut u8, _oldsize: usize, _newsize: usize, _can_move: bool) -> *mut u8 {
+        ptr::null_mut()
+    }
+
+    #[cfg(target_os = "linux")]
+    fn free_part(&self, ptr: *mut u8, oldsize: usize, newsize: usize) -> bool {
+        unsafe {
+            let rc = libc::mremap(ptr.cast(), oldsize, newsize, 0);
+            if rc != libc::MAP_FAILED {
+                return true;
+            }
+            libc::munmap(ptr.add(newsize).cast(), oldsize - newsize) == 0
+        }
+    }
+
+    #[cfg(any(target_os = "redox", target_os = "macos"))]
+    fn free_part(&self, ptr: *mut u8, oldsize: usize, newsize: usize) -> bool {
+        unsafe { libc::munmap(ptr.add(newsize).cast(), oldsize - newsize) == 0 }
+    }
+
+    fn free(&self, ptr: *mut u8, size: usize) -> bool {
+        unsafe { libc::munmap(ptr.cast(), size) == 0 }
+    }
+
+    fn can_release_part(&self, _flags: u32) -> bool {
+        true
+    }
+
+    fn allocates_zeros(&self) -> bool {
+        true
+    }
+
+    fn page_size(&self) -> usize {
+        4096
+    }
+}
+
+#[cfg(feature = "global")]
+pub fn acquire_global_lock() {
+    unsafe { assert_eq!(libc::pthread_mutex_lock(ptr::addr_of_mut!(LOCK)), 0) }
+}
+
+#[cfg(feature = "global")]
+pub fn release_global_lock() {
+    unsafe { assert_eq!(libc::pthread_mutex_unlock(ptr::addr_of_mut!(LOCK)), 0) }
+}
+
+#[cfg(feature = "global")]
+/// allows the allocator to remain unsable in the child process,
+/// after a call to `fork(2)`
+///
+/// #Safety
+///
+/// if used, this function must be called,
+/// before any allocations are made with the global allocator.
+pub unsafe fn enable_alloc_after_fork() {
+    // atfork must only be called once, to avoid a deadlock,
+    // where the handler attempts to acquire the global lock twice
+    static mut FORK_PROTECTED: bool = false;
+
+    unsafe extern "C" fn _acquire_global_lock() {
+        acquire_global_lock()
+    }
+
+    unsafe extern "C" fn _release_global_lock() {
+        release_global_lock()
+    }
+
+    acquire_global_lock();
+    // if a process forks,
+    // it will acquire the lock before any other thread,
+    // protecting it from deadlock,
+    // due to the child being created with only the calling thread.
+    if !FORK_PROTECTED {
+        libc::pthread_atfork(
+            Some(_acquire_global_lock),
+            Some(_release_global_lock),
+            Some(_release_global_lock),
+        );
+        FORK_PROTECTED = true;
+    }
+    release_global_lock();
+}

dlmalloc-rs/src/wasm.rs

@@ -0,0 +1,76 @@
+use crate::Allocator;
+#[cfg(target_arch = "wasm32")]
+use core::arch::wasm32 as wasm;
+#[cfg(target_arch = "wasm64")]
+use core::arch::wasm64 as wasm;
+use core::ptr;
+
+/// System setting for Wasm
+pub struct System {
+    _priv: (),
+}
+
+impl System {
+    pub const fn new() -> System {
+        System { _priv: () }
+    }
+}
+
+unsafe impl Allocator for System {
+    fn alloc(&self, size: usize) -> (*mut u8, usize, u32) {
+        let pages = size / self.page_size();
+        let prev = wasm::memory_grow(0, pages);
+        if prev == usize::max_value() {
+            return (ptr::null_mut(), 0, 0);
+        }
+        (
+            (prev * self.page_size()) as *mut u8,
+            pages * self.page_size(),
+            0,
+        )
+    }
+
+    fn remap(&self, _ptr: *mut u8, _oldsize: usize, _newsize: usize, _can_move: bool) -> *mut u8 {
+        // TODO: I think this can be implemented near the end?
+        ptr::null_mut()
+    }
+
+    fn free_part(&self, _ptr: *mut u8, _oldsize: usize, _newsize: usize) -> bool {
+        false
+    }
+
+    fn free(&self, _ptr: *mut u8, _size: usize) -> bool {
+        false
+    }
+
+    fn can_release_part(&self, _flags: u32) -> bool {
+        false
+    }
+
+    fn allocates_zeros(&self) -> bool {
+        true
+    }
+
+    fn page_size(&self) -> usize {
+        64 * 1024
+    }
+}
+
+#[cfg(feature = "global")]
+pub fn acquire_global_lock() {
+    // single threaded, no need!
+    assert!(!cfg!(target_feature = "atomics"));
+}
+
+#[cfg(feature = "global")]
+pub fn release_global_lock() {
+    // single threaded, no need!
+    assert!(!cfg!(target_feature = "atomics"));
+}
+
+#[allow(missing_docs)]
+#[cfg(feature = "global")]
+pub unsafe fn enable_alloc_after_fork() {
+    // single threaded, no need!
+    assert!(!cfg!(target_feature = "atomics"));
+}

dlmalloc-rs/src/windows.rs

@@ -0,0 +1,88 @@
+use crate::Allocator;
+use core::mem::MaybeUninit;
+use core::ptr;
+use windows_sys::Win32::System::Memory::*;
+use windows_sys::Win32::System::SystemInformation::*;
+#[cfg(feature = "global")]
+use windows_sys::Win32::System::Threading::*;
+
+pub struct System {
+    _priv: (),
+}
+
+impl System {
+    pub const fn new() -> System {
+        System { _priv: () }
+    }
+}
+
+unsafe impl Allocator for System {
+    fn alloc(&self, size: usize) -> (*mut u8, usize, u32) {
+        let addr = unsafe {
+            VirtualAlloc(
+                ptr::null_mut(),
+                size,
+                MEM_RESERVE | MEM_COMMIT,
+                PAGE_READWRITE,
+            )
+        };
+
+        if addr.is_null() {
+            (ptr::null_mut(), 0, 0)
+        } else {
+            (addr.cast(), size, 0)
+        }
+    }
+
+    fn remap(&self, _ptr: *mut u8, _oldsize: usize, _newsize: usize, _can_move: bool) -> *mut u8 {
+        ptr::null_mut()
+    }
+
+    fn free_part(&self, ptr: *mut u8, oldsize: usize, newsize: usize) -> bool {
+        unsafe { VirtualFree(ptr.add(newsize).cast(), oldsize - newsize, MEM_DECOMMIT) != 0 }
+    }
+
+    fn free(&self, ptr: *mut u8, _size: usize) -> bool {
+        unsafe { VirtualFree(ptr.cast(), 0, MEM_DECOMMIT) != 0 }
+    }
+
+    fn can_release_part(&self, _flags: u32) -> bool {
+        true
+    }
+
+    fn allocates_zeros(&self) -> bool {
+        true
+    }
+
+    fn page_size(&self) -> usize {
+        unsafe {
+            let mut info = MaybeUninit::uninit();
+            GetSystemInfo(info.as_mut_ptr());
+            info.assume_init_ref().dwPageSize as usize
+        }
+    }
+}
+
+// NB: `SRWLOCK_INIT` doesn't appear to be in `windows-sys`
+#[cfg(feature = "global")]
+static mut LOCK: SRWLOCK = SRWLOCK {
+    Ptr: ptr::null_mut(),
+};
+
+#[cfg(feature = "global")]
+pub fn acquire_global_lock() {
+    unsafe {
+        AcquireSRWLockExclusive(ptr::addr_of_mut!(LOCK));
+    }
+}
+
+#[cfg(feature = "global")]
+pub fn release_global_lock() {
+    unsafe {
+        ReleaseSRWLockExclusive(ptr::addr_of_mut!(LOCK));
+    }
+}
+
+/// Not needed on Windows
+#[cfg(feature = "global")]
+pub unsafe fn enable_alloc_after_fork() {}

dlmalloc-rs/src/xous.rs

@@ -0,0 +1,117 @@
+use crate::Allocator;
+use core::ptr;
+
+pub struct System {
+    _priv: (),
+}
+
+impl System {
+    pub const fn new() -> System {
+        System { _priv: () }
+    }
+}
+
+#[cfg(target_arch = "riscv32")]
+mod sys {
+    use core::arch::asm;
+
+    pub fn increase_heap(length: usize) -> Result<(usize, usize), ()> {
+        let syscall_no_increase_heap = 10usize;
+        let memory_flags_read_write = 2usize | 4usize;
+
+        let mut a0 = syscall_no_increase_heap;
+        let mut a1 = length;
+        let mut a2 = memory_flags_read_write;
+
+        unsafe {
+            asm!(
+                "ecall",
+                inlateout("a0") a0,
+                inlateout("a1") a1,
+                inlateout("a2") a2,
+                out("a3") _,
+                out("a4") _,
+                out("a5") _,
+                out("a6") _,
+                out("a7") _,
+            )
+        };
+
+        let result = a0;
+        let address = a1;
+        let length = a2;
+
+        // 3 is the "MemoryRange" type, and the result is only valid
+        // if we get nonzero address and length.
+        if result == 3 && address != 0 && length != 0 {
+            Ok((address, length))
+        } else {
+            Err(())
+        }
+    }
+}
+
+unsafe impl Allocator for System {
+    /// Allocate an additional `size` bytes on the heap, and return a new
+    /// chunk of memory, as well as the size of the allocation and some
+    /// flags. Since flags are unused on this platform, they will always
+    /// be `0`.
+    fn alloc(&self, size: usize) -> (*mut u8, usize, u32) {
+        let size = if size == 0 {
+            4096
+        } else if size & 4095 == 0 {
+            size
+        } else {
+            size + (4096 - (size & 4095))
+        };
+
+        if let Ok((address, length)) = sys::increase_heap(size) {
+            let start = address - size + length;
+            (start as *mut u8, size, 0)
+        } else {
+            (ptr::null_mut(), 0, 0)
+        }
+    }
+
+    fn remap(&self, _ptr: *mut u8, _oldsize: usize, _newsize: usize, _can_move: bool) -> *mut u8 {
+        // TODO
+        ptr::null_mut()
+    }
+
+    fn free_part(&self, _ptr: *mut u8, _oldsize: usize, _newsize: usize) -> bool {
+        false
+    }
+
+    fn free(&self, _ptr: *mut u8, _size: usize) -> bool {
+        false
+    }
+
+    fn can_release_part(&self, _flags: u32) -> bool {
+        false
+    }
+
+    fn allocates_zeros(&self) -> bool {
+        true
+    }
+
+    fn page_size(&self) -> usize {
+        4 * 1024
+    }
+}
+
+#[cfg(feature = "global")]
+pub fn acquire_global_lock() {
+    // global feature should not be enabled
+    unimplemented!()
+}
+
+#[cfg(feature = "global")]
+pub fn release_global_lock() {
+    // global feature should not be enabled
+    unimplemented!()
+}
+
+#[cfg(feature = "global")]
+pub unsafe fn enable_alloc_after_fork() {
+    // platform does not support `fork()` call
+}