bjoernager/rust
bjoernager/rust
1
Fork 0
Code Issues Pull requests Activity

Auto merge of #97802 - Enselic:add-no_ignore_sigkill-feature, r=joshtriplett

Browse source 
Support `#[unix_sigpipe = "inherit|sig_dfl"]` on `fn main()` to prevent ignoring `SIGPIPE`

When enabled, programs don't have to explicitly handle `ErrorKind::BrokenPipe` any longer. Currently, the program

```rust
fn main() { loop { println!("hello world"); } }
```

will print an error if used with a short-lived pipe, e.g.

    % ./main | head -n 1
    hello world
    thread 'main' panicked at 'failed printing to stdout: Broken pipe (os error 32)', library/std/src/io/stdio.rs:1016:9
    note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

by enabling `#[unix_sigpipe = "sig_dfl"]` like this

```rust
#![feature(unix_sigpipe)]
#[unix_sigpipe = "sig_dfl"]
fn main() { loop { println!("hello world"); } }
```

there is no error, because `SIGPIPE` will not be ignored and thus the program will be killed appropriately:

    % ./main | head -n 1
    hello world

The current libstd behaviour of ignoring `SIGPIPE` before `fn main()` can be explicitly requested by using `#[unix_sigpipe = "sig_ign"]`.

With `#[unix_sigpipe = "inherit"]`, no change at all is made to `SIGPIPE`, which typically means the behaviour will be the same as `#[unix_sigpipe = "sig_dfl"]`.

See https://github.com/rust-lang/rust/issues/62569 and referenced issues for discussions regarding the `SIGPIPE` problem itself

See the [this](https://rust-lang.zulipchat.com/#narrow/stream/219381-t-libs/topic/Proposal.3A.20First.20step.20towards.20solving.20the.20SIGPIPE.20problem) Zulip topic for more discussions, including about this PR.

Tracking issue: https://github.com/rust-lang/rust/issues/97889
This commit is contained in:
bors 2022-09-02 21:08:08 +00:00
commit 8c6ce6b91b
46 changed files with 482 additions and 43 deletions
Download patch file Download diff file Expand all files Collapse all files

2
compiler/rustc_feature/src/active.rs
View file

@ -519,6 +519,8 @@ declare_features! (
/// Allows creation of instances of a struct by moving fields that have
/// not changed from prior instances of the same struct (RFC #2528)
(active, type_changing_struct_update, "1.58.0", Some(86555), None),
/// Enables rustc to generate code that instructs libstd to NOT ignore SIGPIPE.
(active, unix_sigpipe, "CURRENT_RUSTC_VERSION", Some(97889), None),
/// Allows unsized fn parameters.
(active, unsized_fn_params, "1.49.0", Some(48055), None),
/// Allows unsized rvalues at arguments and parameters.

1
compiler/rustc_feature/src/builtin_attrs.rs
View file

@ -359,6 +359,7 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
),
// Entry point:
gated!(unix_sigpipe, Normal, template!(Word, NameValueStr: "inherit|sig_ign|sig_dfl"), ErrorFollowing, experimental!(unix_sigpipe)),
ungated!(start, Normal, template!(Word), WarnFollowing),
ungated!(no_start, CrateLevel, template!(Word), WarnFollowing),
ungated!(no_main, CrateLevel, template!(Word), WarnFollowing),