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mmap non-zero length #1873

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Merged
merged 1 commit into from
Nov 21, 2022
Merged

mmap non-zero length #1873

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2 changes: 2 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,8 @@ This project adheres to [Semantic Versioning](https://semver.org/).
([#1792](https://github.com/nix-rust/nix/pull/1792))
- The `addr` argument of `sys::mman::mmap` is now of type `Option<NonZeroUsize>`.
([#1870](https://github.com/nix-rust/nix/pull/1870))
- The `length` argument of `sys::mman::mmap` is now of type `NonZeroUsize`.
([#1873](https://github.com/nix-rust/nix/pull/1873))

### Fixed

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9 changes: 5 additions & 4 deletions src/sys/mman.rs
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Expand Up @@ -418,7 +418,7 @@ pub fn munlockall() -> Result<()> {
/// [`mmap(2)`]: https://man7.org/linux/man-pages/man2/mmap.2.html
pub unsafe fn mmap(
addr: Option<NonZeroUsize>,
length: size_t,
length: NonZeroUsize,
prot: ProtFlags,
flags: MapFlags,
fd: RawFd,
Expand All @@ -428,8 +428,8 @@ pub unsafe fn mmap(
std::ptr::null_mut(),
|a| usize::from(a) as *mut c_void
);

let ret = libc::mmap(ptr, length, prot.bits(), flags.bits(), fd, offset);
let ret = libc::mmap(ptr, length.into(), prot.bits(), flags.bits(), fd, offset);

if ret == libc::MAP_FAILED {
Err(Errno::last())
Expand Down Expand Up @@ -520,8 +520,9 @@ pub unsafe fn madvise(
/// # use nix::sys::mman::{mmap, mprotect, MapFlags, ProtFlags};
/// # use std::ptr;
/// const ONE_K: size_t = 1024;
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ONE_K is no longer used

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Updated to fix this.

/// let one_k_non_zero = std::num::NonZeroUsize::new(ONE_K).unwrap();
/// let mut slice: &mut [u8] = unsafe {
/// let mem = mmap(None, ONE_K, ProtFlags::PROT_NONE,
/// let mem = mmap(None, one_k_non_zero, ProtFlags::PROT_NONE,
/// MapFlags::MAP_ANON | MapFlags::MAP_PRIVATE, -1, 0).unwrap();
/// mprotect(mem, ONE_K, ProtFlags::PROT_READ | ProtFlags::PROT_WRITE).unwrap();
/// std::slice::from_raw_parts_mut(mem as *mut u8, ONE_K)
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13 changes: 9 additions & 4 deletions test/sys/test_mman.rs
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@@ -1,11 +1,12 @@
use nix::sys::mman::{mmap, MapFlags, ProtFlags};
use std::num::NonZeroUsize;

#[test]
fn test_mmap_anonymous() {
unsafe {
let ptr = mmap(
None,
1,
NonZeroUsize::new(1).unwrap(),
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Do you think it would be worthwhile to bring in the nonzero_ext crate just for these tests?

Suggested change
NonZeroUsize::new(1).unwrap(),
nonzero_ext::nonzero!(1)

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At this point no, but if NonZeroUsize sees wider usage it may become worthwhile.

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BTW, I took a look through my other crates and found exactly zero places where nonzero_ext would help. It turns out that Option<NonZeroXXX> is a lot more common than NonZeroXXX.

ProtFlags::PROT_READ | ProtFlags::PROT_WRITE,
MapFlags::MAP_PRIVATE | MapFlags::MAP_ANONYMOUS,
-1,
Expand All @@ -25,10 +26,12 @@ fn test_mremap_grow() {
use nix::sys::mman::{mremap, MRemapFlags};

const ONE_K: size_t = 1024;
let one_k_non_zero = NonZeroUsize::new(ONE_K).unwrap();

let slice: &mut [u8] = unsafe {
let mem = mmap(
None,
ONE_K,
one_k_non_zero,
ProtFlags::PROT_READ | ProtFlags::PROT_WRITE,
MapFlags::MAP_ANONYMOUS | MapFlags::MAP_PRIVATE,
-1,
Expand Down Expand Up @@ -79,12 +82,14 @@ fn test_mremap_grow() {
fn test_mremap_shrink() {
use nix::libc::{c_void, size_t};
use nix::sys::mman::{mremap, MRemapFlags};
use std::num::NonZeroUsize;

const ONE_K: size_t = 1024;
let ten_one_k = NonZeroUsize::new(10 * ONE_K).unwrap();
let slice: &mut [u8] = unsafe {
let mem = mmap(
None,
10 * ONE_K,
ten_one_k,
ProtFlags::PROT_READ | ProtFlags::PROT_WRITE,
MapFlags::MAP_ANONYMOUS | MapFlags::MAP_PRIVATE,
-1,
Expand All @@ -100,7 +105,7 @@ fn test_mremap_shrink() {
let slice: &mut [u8] = unsafe {
let mem = mremap(
slice.as_mut_ptr() as *mut c_void,
10 * ONE_K,
ten_one_k.into(),
ONE_K,
MRemapFlags::empty(),
None,
Expand Down