[xXPBSXx]

What

raise_nid_postfix (and kill on the own process, which calls it) failed with EINVAL for a signal without a host equivalent and without a guest handler, also when the guest had set it to SIG_IGN. FreeBSD 11.4 defines SIGURG, SIGCONT, SIGCHLD, SIGIO, SIGWINCH and SIGINFO as ignored by default (sys/kern/kern_sig.c:205-240), so sending one succeeds, and tdsendsignal forgets such a signal at once, also when it is blocked (kern_sig.c:2178-2187), except SIGCONT, which stays pending while blocked. A signal set to SIG_IGN is forgotten the same way. All of these now return 0. Signals whose default action ends the process, such as SIGUSR1, are unchanged.

Fixes #8466

Overlap: the open signal PRs #3986, #6044 and #7201 rewrite large parts of Signals.cpp and conflict with this change (git merge-tree: 3, 26 and 25 conflicts); the PRs #8407, #8411 and #8414 are clean against it. Whichever lands second rebases. pr_overlap was not run.

Tested

Windows 10 (19045), MinGW-w64 GCC 15.2.0, Release, on upstream/main 44e3389 + this commit:

• guest_signals: Exit code 0xc0000409 with System/src/Signals.cpp taken back to main (new test lines kept), passes with the change (3 of 3 runs). New cases: raise and kill(getpid(), ...) return 0 for 16, 19, 20, 23, 28 and 29 with errno untouched and no handler called; with those signals blocked, 16, 20, 23, 28 and 29 are not pending afterwards; signal 30 set to SIG_IGN returns 0 from raise and kill, also blocked, without becoming pending.
• guest_sigtimedwait, guest_itimer, guest_itimer_pending_default, guest_kill, guest_signal_sets, guest_sigaltstack, guest_getitimer pass.
• python tools/check_conventions.py --base upstream/main: passes.
• Not tested: Linux (shared code, not built there), a console, a title run, pthread_kill to another thread (it still remembers such a signal as pending). No title is known to send these signals to itself.

Checklist

• Based on current main; no other open PR implements the same functions
• One topic per PR; follow-ups go in a new PR
• No comments in code except technical debt
• Unimplemented paths throw; no silent stubs added
• No notes, investigation .md files or images added to the repository
• New third-party code is a submodule built from source (none added)
• Generic behaviour, not specific to one title
• Depends on: none
• Unblocks: none
• AI-assisted: yes

AI-assisted (Claude Code).

🤖 Generated with Claude Code

[github-actions]

Some comparisons could not be completed because a pull request conflicts with the base branch. Review these shared files manually before concluding that there is no overlap.

Pull request	Shared files not compared
PR 3986	core/libs/prx/libkernel/System/src/Signals.cpp core/libs/tests/GuestSignals.cpp
PR 6044	core/libs/tests/GuestSignals.cpp
PR 7201	core/libs/prx/libkernel/System/src/Signals.cpp