mirror of
https://github.com/microsoft/edit.git
synced 2026-06-17 00:19:58 -05:00
8d9b1ede11
The main change is adding multithreading support in order to make JSON unit tests work properly. The TLS overhead is not _that bad. Other changes: * Switch to `io::Result`, because `AllocError` doesn't transmit error codes (meh!) * Reduce x86 commit chunk size to 32KiB * Improved performance slightly by inlining harder (`alloc_uninit`) and outlining the result unwrap (`alloc_raw_bump`)
74 lines
2.3 KiB
Rust
74 lines
2.3 KiB
Rust
// Copyright (c) Microsoft Corporation.
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// Licensed under the MIT License.
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use std::ffi::c_int;
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use std::io;
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use std::ptr::{self, NonNull, null_mut};
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/// Reserves a virtual memory region of the given size.
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/// To commit the memory, use `virtual_commit`.
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/// To release the memory, use `virtual_release`.
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///
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/// # Safety
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///
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/// This function is unsafe because it uses raw pointers.
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/// Don't forget to release the memory when you're done with it or you'll leak it.
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pub unsafe fn virtual_reserve(size: usize) -> io::Result<NonNull<u8>> {
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unsafe {
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let ptr = libc::mmap(
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null_mut(),
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size,
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desired_mprotect(libc::PROT_READ | libc::PROT_WRITE),
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libc::MAP_PRIVATE | libc::MAP_ANONYMOUS,
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-1,
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0,
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);
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if ptr.is_null() || ptr::eq(ptr, libc::MAP_FAILED) {
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Err(io::Error::last_os_error())
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} else {
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Ok(NonNull::new_unchecked(ptr as *mut u8))
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}
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}
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}
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#[cfg(target_os = "netbsd")]
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const fn desired_mprotect(flags: c_int) -> c_int {
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// NetBSD allows an mmap(2) caller to specify what protection flags they
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// will use later via mprotect. It does not allow a caller to move from
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// PROT_NONE to PROT_READ | PROT_WRITE.
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//
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// see PROT_MPROTECT in man 2 mmap
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flags << 3
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}
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#[cfg(not(target_os = "netbsd"))]
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const fn desired_mprotect(_: c_int) -> c_int {
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libc::PROT_NONE
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}
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/// Releases a virtual memory region of the given size.
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///
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/// # Safety
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///
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/// This function is unsafe because it uses raw pointers.
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/// Make sure to only pass pointers acquired from `virtual_reserve`.
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pub unsafe fn virtual_release(base: NonNull<u8>, size: usize) {
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unsafe {
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libc::munmap(base.cast().as_ptr(), size);
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}
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}
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/// Commits a virtual memory region of the given size.
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///
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/// # Safety
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///
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/// This function is unsafe because it uses raw pointers.
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/// Make sure to only pass pointers acquired from `virtual_reserve`
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/// and to pass a size less than or equal to the size passed to `virtual_reserve`.
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pub unsafe fn virtual_commit(base: NonNull<u8>, size: usize) -> io::Result<()> {
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unsafe {
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let status = libc::mprotect(base.cast().as_ptr(), size, libc::PROT_READ | libc::PROT_WRITE);
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if status != 0 { Err(io::Error::last_os_error()) } else { Ok(()) }
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}
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}
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