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Optionally implement TryFrom in libc_enum! #1484

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Aug 11, 2021
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Optionally implement TryFrom in libc_enum! #1484

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11 changes: 11 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -43,17 +43,28 @@ This project adheres to [Semantic Versioning](https://semver.org/).
- Many more functions, mostly contructors, are now `const`.
(#[1476](https://github.com/nix-rust/nix/pull/1476))

- `sys::event::KEvent::filter` now returns a `Result` instead of being
infalliable. The only cases where it will now return an error are cases
where it previously would've had undefined behavior.
(#[1484](https://github.com/nix-rust/nix/pull/1484))

### Fixed

- Added more errno definitions for better backwards compatibility with
Nix 0.21.0.
(#[1467](https://github.com/nix-rust/nix/pull/1467))

- Fixed potential undefined behavior in `Signal::try_from` on some platforms.
(#[1484](https://github.com/nix-rust/nix/pull/1484))

### Removed

- Removed a couple of termios constants on redox that were never actually
supported.
(#[1483](https://github.com/nix-rust/nix/pull/1483))
- Removed `nix::sys::signal::NSIG`. It was of dubious utility, and not correct
for all platforms.
(#[1484](https://github.com/nix-rust/nix/pull/1484))

## [0.22.0] - 9 July 2021
### Added
Expand Down
128 changes: 117 additions & 11 deletions src/macros.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -83,9 +83,9 @@ macro_rules! libc_bitflags {
macro_rules! libc_enum {
// Exit rule.
(@make_enum
name: $BitFlags:ident,
{
$v:vis
name: $BitFlags:ident,
attrs: [$($attrs:tt)*],
entries: [$($entries:tt)*],
}
Expand All @@ -97,88 +97,171 @@ macro_rules! libc_enum {
}
};

// Exit rule including TryFrom
(@make_enum
name: $BitFlags:ident,
{
$v:vis
attrs: [$($attrs:tt)*],
entries: [$($entries:tt)*],
from_type: $repr:path,
try_froms: [$($try_froms:tt)*]
}
) => {
$($attrs)*
#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
$v enum $BitFlags {
$($entries)*
}
#[allow(unused_doc_comment)]
impl ::std::convert::TryFrom<$repr> for $BitFlags {
type Error = $crate::Error;
fn try_from(x: $repr) -> $crate::Result<Self> {
match x {
$($try_froms)*
_ => Err($crate::Error::EINVAL)
}
}
}
};

// Done accumulating.
(@accumulate_entries
name: $BitFlags:ident,
{
$v:vis
attrs: $attrs:tt,
},
$entries:tt,
$try_froms:tt;
) => {
libc_enum! {
@make_enum
name: $BitFlags,
{
$v
attrs: $attrs,
entries: $entries,
}
}
};

// Done accumulating and want TryFrom
(@accumulate_entries
name: $BitFlags:ident,
{
$v:vis
name: $BitFlags:ident,
attrs: $attrs:tt,
from_type: $repr:path,
},
$entries:tt;
$entries:tt,
$try_froms:tt;
) => {
libc_enum! {
@make_enum
name: $BitFlags,
{
$v
name: $BitFlags,
attrs: $attrs,
entries: $entries,
from_type: $repr,
try_froms: $try_froms
}
}
};

// Munch an attr.
(@accumulate_entries
name: $BitFlags:ident,
$prefix:tt,
[$($entries:tt)*];
[$($entries:tt)*],
[$($try_froms:tt)*];
#[$attr:meta] $($tail:tt)*
) => {
libc_enum! {
@accumulate_entries
name: $BitFlags,
$prefix,
[
$($entries)*
#[$attr]
],
[
$($try_froms)*
#[$attr]
];
$($tail)*
}
};

// Munch last ident if not followed by a comma.
(@accumulate_entries
name: $BitFlags:ident,
$prefix:tt,
[$($entries:tt)*];
[$($entries:tt)*],
[$($try_froms:tt)*];
$entry:ident
) => {
libc_enum! {
@accumulate_entries
name: $BitFlags,
$prefix,
[
$($entries)*
$entry = libc::$entry,
],
[
$($try_froms)*
libc::$entry => Ok($BitFlags::$entry),
];
}
};

// Munch an ident; covers terminating comma case.
(@accumulate_entries
name: $BitFlags:ident,
$prefix:tt,
[$($entries:tt)*];
$entry:ident, $($tail:tt)*
[$($entries:tt)*],
[$($try_froms:tt)*];
$entry:ident,
$($tail:tt)*
) => {
libc_enum! {
@accumulate_entries
name: $BitFlags,
$prefix,
[
$($entries)*
$entry = libc::$entry,
],
[
$($try_froms)*
libc::$entry => Ok($BitFlags::$entry),
];
$($tail)*
}
};

// Munch an ident and cast it to the given type; covers terminating comma.
(@accumulate_entries
name: $BitFlags:ident,
$prefix:tt,
[$($entries:tt)*];
$entry:ident as $ty:ty, $($tail:tt)*
[$($entries:tt)*],
[$($try_froms:tt)*];
$entry:ident as $ty:ty,
$($tail:tt)*
) => {
libc_enum! {
@accumulate_entries
name: $BitFlags,
$prefix,
[
$($entries)*
$entry = libc::$entry as $ty,
],
[
$($try_froms)*
libc::$entry as $ty => Ok($BitFlags::$entry),
];
$($tail)*
}
Expand All @@ -193,11 +276,34 @@ macro_rules! libc_enum {
) => {
libc_enum! {
@accumulate_entries
name: $BitFlags,
{
$v
attrs: [$(#[$attr])*],
},
[],
[];
$($vals)*
}
};

// Entry rule including TryFrom
(
$(#[$attr:meta])*
$v:vis enum $BitFlags:ident {
$($vals:tt)*
}
impl TryFrom<$repr:path>
) => {
libc_enum! {
@accumulate_entries
name: $BitFlags,
{
$v
name: $BitFlags,
attrs: [$(#[$attr])*],
from_type: $repr,
},
[],
[];
$($vals)*
}
Expand Down
25 changes: 21 additions & 4 deletions src/sys/event.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,9 +6,9 @@ use crate::{Errno, Result};
use libc::{timespec, time_t, c_int, c_long, intptr_t, uintptr_t};
#[cfg(target_os = "netbsd")]
use libc::{timespec, time_t, c_long, intptr_t, uintptr_t, size_t};
use std::convert::TryInto;
use std::os::unix::io::RawFd;
use std::ptr;
use std::mem;

// Redefine kevent in terms of programmer-friendly enums and bitfields.
#[repr(C)]
Expand Down Expand Up @@ -76,6 +76,7 @@ libc_enum! {
EVFILT_VNODE,
EVFILT_WRITE,
}
impl TryFrom<type_of_event_filter>
}

#[cfg(any(target_os = "dragonfly", target_os = "freebsd",
Expand Down Expand Up @@ -233,8 +234,8 @@ impl KEvent {
self.kevent.ident
}

pub fn filter(&self) -> EventFilter {
unsafe { mem::transmute(self.kevent.filter as type_of_event_filter) }
pub fn filter(&self) -> Result<EventFilter> {
self.kevent.filter.try_into()
}

pub fn flags(&self) -> EventFlag {
Expand Down Expand Up @@ -313,6 +314,8 @@ pub fn ev_set(ev: &mut KEvent,

#[test]
fn test_struct_kevent() {
use std::mem;

let udata : intptr_t = 12345;

let actual = KEvent::new(0xdead_beef,
Expand All @@ -322,10 +325,24 @@ fn test_struct_kevent() {
0x1337,
udata);
assert_eq!(0xdead_beef, actual.ident());
assert_eq!(libc::EVFILT_READ, actual.filter() as type_of_event_filter);
let filter = actual.kevent.filter;
assert_eq!(libc::EVFILT_READ, filter);
assert_eq!(libc::EV_ONESHOT | libc::EV_ADD, actual.flags().bits());
assert_eq!(libc::NOTE_CHILD | libc::NOTE_EXIT, actual.fflags().bits());
assert_eq!(0x1337, actual.data() as type_of_data);
assert_eq!(udata as type_of_udata, actual.udata() as type_of_udata);
assert_eq!(mem::size_of::<libc::kevent>(), mem::size_of::<KEvent>());
}

#[test]
fn test_kevent_filter() {
let udata : intptr_t = 12345;

let actual = KEvent::new(0xdead_beef,
EventFilter::EVFILT_READ,
EventFlag::EV_ONESHOT | EventFlag::EV_ADD,
FilterFlag::NOTE_CHILD | FilterFlag::NOTE_EXIT,
0x1337,
udata);
assert_eq!(EventFilter::EVFILT_READ, actual.filter().unwrap());
}
18 changes: 3 additions & 15 deletions src/sys/signal.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,6 @@
use crate::{Error, Result};
use crate::errno::Errno;
use crate::unistd::Pid;
use std::convert::TryFrom;
use std::mem;
use std::fmt;
use std::str::FromStr;
Expand Down Expand Up @@ -71,6 +70,7 @@ libc_enum!{
target_os = "redox")))]
SIGINFO,
}
impl TryFrom<i32>
}

impl FromStr for Signal {
Expand Down Expand Up @@ -335,8 +335,6 @@ const SIGNALS: [Signal; 31] = [
SIGEMT,
SIGINFO];

pub const NSIG: libc::c_int = 32;

#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub struct SignalIterator {
next: usize,
Expand All @@ -362,18 +360,6 @@ impl Signal {
}
}

impl TryFrom<libc::c_int> for Signal {
type Error = Error;

fn try_from(signum: libc::c_int) -> Result<Signal> {
if 0 < signum && signum < NSIG {
Ok(unsafe { mem::transmute(signum) })
} else {
Err(Error::from(Errno::EINVAL))
}
}
}

pub const SIGIOT : Signal = SIGABRT;
pub const SIGPOLL : Signal = SIGIO;
pub const SIGUNUSED : Signal = SIGSYS;
Expand Down Expand Up @@ -489,6 +475,8 @@ impl SigSet {
/// signal mask becomes pending, and returns the accepted signal.
#[cfg(not(target_os = "redox"))] // RedoxFS does not yet support sigwait
pub fn wait(&self) -> Result<Signal> {
use std::convert::TryFrom;

let mut signum = mem::MaybeUninit::uninit();
let res = unsafe { libc::sigwait(&self.sigset as *const libc::sigset_t, signum.as_mut_ptr()) };

Expand Down
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