fix: implement signalfd

[yoinspiration]

• Add Signalfd file descriptor implementation (api/src/file/signalfd.rs)
• Implement signalfd4 system call handler (api/src/syscall/fs/signalfd.rs)
• Register signalfd4 in syscall router (api/src/syscall/mod.rs)
• Export signalfd module in file/mod.rs and syscall/fs/mod.rs

This fixes the panic when reading from signalfd4 file descriptor. Previously, signalfd4 returned a DummyFd which would panic on read. Now it returns a proper Signalfd that can read signals correctly.

Fixes #15

[AsakuraMizu]

Please refer to https://docs.github.com/zh/get-started/git-basics/configuring-git-to-handle-line-endings and update your commit. I can not identify your changes in diff.

[yoinspiration]

I've updated the commit according to the GitHub documentation on configuring Git to handle line endings.

What I've Done

1. Added .gitattributes file to ensure consistent line endings (LF)
2. Reorganized the commit to clearly show only the actual code changes

Result

The commit now displays clean, readable diffs:

• 6 files changed, 300 insertions(+), 3 deletions(-)
• New files: api/src/file/signalfd.rs (194 lines) and api/src/syscall/fs/signalfd.rs (65 lines)
• Modified files show only relevant changes (e.g., api/src/file/mod.rs shows just 1 line: +pub mod signalfd;)

The diff statistics are consistent with or without whitespace ignored, confirming the line ending issue is resolved. You should now be able to clearly identify all code changes in the diff.

[Copilot]

Pull Request Overview

This PR implements the signalfd4 system call to fix Issue #15, which was causing a panic when reading from signalfd4 file descriptors. The implementation replaces the previous DummyFd with a fully functional Signalfd that can properly read signals.

Key changes:

• Implements Signalfd struct with signal dequeuing and polling capabilities
• Adds sys_signalfd4 syscall handler with proper flag handling and signal mask validation
• Registers signalfd4 in the syscall router, removing it from the dummy fd list

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
api/src/file/signalfd.rs	New file implementing the Signalfd file descriptor with read, poll, and signal handling logic
api/src/syscall/fs/signalfd.rs	New file implementing sys_signalfd4 syscall handler with flag parsing and fd creation
api/src/syscall/mod.rs	Registers signalfd4 syscall and removes it from dummy fd list
api/src/syscall/fs/mod.rs	Exports signalfd module
api/src/file/mod.rs	Exports signalfd module
.gitattributes	Adds line ending normalization rules (unrelated to signalfd implementation)

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[yoinspiration]

Thank you for the thorough review! I've addressed all the comments:

1. SFD flag constants: Updated to use O_CLOEXEC and O_NONBLOCK from linux_raw_sys::general instead of hardcoded values, following the same pattern as pipe.rs and event.rs.

2. Chinese comments: Translated all Chinese comments to English for consistency with the codebase.

3. Unsafe block formatting: Removed the empty line and updated the comment to use singular "field" since only one field is accessed.

All changes have been committed and pushed. The implementation now correctly handles the signalfd4 flags and maintains consistency with the rest of the codebase.

[Copilot]

Pull Request Overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 6 comments.

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[yoinspiration]

Thanks for the additional feedback! I've addressed each comment in the latest commit:

• Updated SignalfdSiginfo to avoid packed-struct UB and added helper for the union access.
• Signalfd now allows mask updates when fd != -1, matching the Linux spec.
• Byte serialization uses ptr::addr_of! to avoid unaligned references.

Please let me know if anything else needs adjustment!

[yoinspiration]

need to accept this pull request Starry-OS/starry-signal#5 first in starry-signal repository, or it will encounter CI errors without SignalInfo::errno() method

[AsakuraMizu]

You forgot to update Cargo.lock xd

[yoinspiration]

True, my bad — thanks for updating it!

[yoinspiration]

True, my bad ― thanks for updating it!

…

________________________________ 发件人: 朝�}水希 ***@***.***> 发送时间: 2025年11月20日 12:12 收件人: Starry-OS/StarryOS ***@***.***> 抄送: yoinspiration ***@***.***>; State change ***@***.***> 主题: Re: [Starry-OS/StarryOS] fix: implement signalfd (PR #31) [https://avatars.githubusercontent.com/u/17076564?s=20&v=4]AsakuraMizu left a comment (Starry-OS/StarryOS#31)<#31 (comment)> You forgot to update Cargo.lock xd ― Reply to this email directly, view it on GitHub<#31 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AWA53WZRIJJIFKMTMZEV2VL35U5TRAVCNFSM6AAAAACMI467LWVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTKNJVGY4DCNJRHA>. You are receiving this because you modified the open/close state.Message ID: ***@***.***>