The code was using u32 and usize interchangably, which doesn't work on
64-bit systems. This:
`pub const sigset_t = [1024 / 32]u32;`
is not consistent with this:
`const shift = @as(u5, @intCast(s & (usize_bits - 1)));`
However, normal signal numbers are less than 31, so the bad math doesn't matter much. Also, despite support for 1024 signals in the set, only setting signals between 1 and NSIG (which is mostly 65, but sometimes 128) is defined. The existing tests only exercised signal numbers in the first 31 bits so they didn't trip over this:
The C library `sigaddset` will return `EINVAL` if given an out of bounds signal number. I made the Zig code just silently ignore any out of bounds signal numbers.
Moved all the `sigset` related declarations next to each in the source, too.
The `filled_sigset` seems non-standard to me. I think it is meant to be used like `empty_sigset`, but it only contains 31 set signals, which seems wrong (should be 64 or 128, aka `NSIG`). It's also unused. The oddly named but similar `all_mask` is used (by posix.zig) but sets all 1024 bits (which I understood to be undefined behavior but seems to work just fine). For comparison the musl `sigfillset` fills in 65 bits or 128 bits.
Linux kernel syscalls expect to be given the number of bits of sigset that
they're built for, not the full 1024-bit sigsets that glibc supports.
I audited the other syscalls in here that use `sigset_t` and they're all
using `NSIG / 8`.
Fixes#12715
These started failing with LLVM 20 for unclear reasons:
test-std
└─ run test std-mips64-linux.4.19...6.13.4-gnuabi64.2.28-mips64r2-Debug-libc 2798/2878 passed, 2 failed, 78 skipped
error: 'posix.test.test.link with relative paths' failed: expected 2, found 0
/home/alexrp/Source/ziglang/zig-llvm20/lib/std/testing.zig:103:17: 0x1d9e5bf in expectEqualInner__anon_47031 (test)
return error.TestExpectedEqual;
^
/home/alexrp/Source/ziglang/zig-llvm20/lib/std/posix/test.zig:311:9: 0x3650f57 in test.link with relative paths (test)
try testing.expectEqual(@as(@TypeOf(nstat.nlink), 2), nstat.nlink);
^
error: 'posix.test.test.linkat with different directories' failed: expected 2, found 0
/home/alexrp/Source/ziglang/zig-llvm20/lib/std/testing.zig:103:17: 0x1d9e5bf in expectEqualInner__anon_47031 (test)
return error.TestExpectedEqual;
^
/home/alexrp/Source/ziglang/zig-llvm20/lib/std/posix/test.zig:355:9: 0x3653377 in test.linkat with different directories (test)
try testing.expectEqual(@as(@TypeOf(nstat.nlink), 2), nstat.nlink);
^
error: while executing test 'zig.system.darwin.macos.test.detect', the following test command failed:
qemu-mips64 -L /opt/glibc/mips64-linux-gnu-n64 /home/alexrp/Source/ziglang/zig-llvm20/.zig-cache/o/22a8c3762ea56ae3a674fa9ad15f6657/test --seed=0xa1dbb43c --cache-dir=/home/alexrp/Source/ziglang/zig-llvm20/.zig-cache --listen=-
test-std
└─ run test std-mips64-linux.4.19...6.13.4-gnuabi64.2.28-mips64r2-Debug-libc 2798/2878 passed, 1 failed, 79 skipped
error: 'posix.test.test.linkat with different directories' failed: expected 2, found 0
/home/alexrp/Source/ziglang/zig-llvm20/lib/std/testing.zig:103:17: 0x1d9e22f in expectEqualInner__anon_47031 (test)
return error.TestExpectedEqual;
^
/home/alexrp/Source/ziglang/zig-llvm20/lib/std/posix/test.zig:356:9: 0x3650b47 in test.linkat with different directories (test)
try testing.expectEqual(@as(@TypeOf(nstat.nlink), 2), nstat.nlink);
^
error: while executing test 'zig.system.darwin.macos.test.detect', the following test command failed:
qemu-mips64 -L /opt/glibc/mips64-linux-gnu-n64 /home/alexrp/Source/ziglang/zig-llvm20/.zig-cache/o/22a8c3762ea56ae3a674fa9ad15f6657/test --seed=0xa1dbb43c --cache-dir=/home/alexrp/Source/ziglang/zig-llvm20/.zig-cache --listen=-
Unfortunately, neither GDB nor LLDB want to play nice with qemu-mips64(el) at
the moment, so I can't easily debug these failures.
