setName

pub fn setName(self: Thread, name: []const u8) SetNameError!void {
    if (name.len > max_name_len) return error.NameTooLong;

    const name_with_terminator = blk: {
        var name_buf: [max_name_len:0]u8 = undefined;
        @memcpy(name_buf[0..name.len], name);
        name_buf[name.len] = 0;
        break :blk name_buf[0..name.len :0];
    };

    switch (native_os) {
        .linux => if (use_pthreads) {
            if (self.getHandle() == std.c.pthread_self()) {
                // Set the name of the calling thread (no thread id required).
                const err = try posix.prctl(.SET_NAME, .{@intFromPtr(name_with_terminator.ptr)});
                switch (@as(posix.E, @enumFromInt(err))) {
                    .SUCCESS => return,
                    else => |e| return posix.unexpectedErrno(e),
                }
            } else {
                const err = std.c.pthread_setname_np(self.getHandle(), name_with_terminator.ptr);
                switch (@as(posix.E, @enumFromInt(err))) {
                    .SUCCESS => return,
                    .RANGE => unreachable,
                    else => |e| return posix.unexpectedErrno(e),
                }
            }
        } else {
            var buf: [32]u8 = undefined;
            const path = try std.fmt.bufPrint(&buf, "/proc/self/task/{d}/comm", .{self.getHandle()});

            const file = try std.fs.cwd().openFile(path, .{ .mode = .write_only });
            defer file.close();

            try file.deprecatedWriter().writeAll(name);
            return;
        },
        .windows => {
            var buf: [max_name_len]u16 = undefined;
            const len = try std.unicode.wtf8ToWtf16Le(&buf, name);
            const byte_len = math.cast(c_ushort, len * 2) orelse return error.NameTooLong;

            // Note: NT allocates its own copy, no use-after-free here.
            const unicode_string = windows.UNICODE_STRING{
                .Length = byte_len,
                .MaximumLength = byte_len,
                .Buffer = &buf,
            };

            switch (windows.ntdll.NtSetInformationThread(
                self.getHandle(),
                .ThreadNameInformation,
                &unicode_string,
                @sizeOf(windows.UNICODE_STRING),
            )) {
                .SUCCESS => return,
                .NOT_IMPLEMENTED => return error.Unsupported,
                else => |err| return windows.unexpectedStatus(err),
            }
        },
        .macos, .ios, .watchos, .tvos, .visionos => if (use_pthreads) {
            // There doesn't seem to be a way to set the name for an arbitrary thread, only the current one.
            if (self.getHandle() != std.c.pthread_self()) return error.Unsupported;

            const err = std.c.pthread_setname_np(name_with_terminator.ptr);
            switch (@as(posix.E, @enumFromInt(err))) {
                .SUCCESS => return,
                else => |e| return posix.unexpectedErrno(e),
            }
        },
        .serenity => if (use_pthreads) {
            const err = std.c.pthread_setname_np(self.getHandle(), name_with_terminator.ptr);
            switch (@as(posix.E, @enumFromInt(err))) {
                .SUCCESS => return,
                .NAMETOOLONG => unreachable,
                .SRCH => unreachable,
                else => |e| return posix.unexpectedErrno(e),
            }
        },
        .netbsd, .solaris, .illumos => if (use_pthreads) {
            const err = std.c.pthread_setname_np(self.getHandle(), name_with_terminator.ptr, null);
            switch (@as(posix.E, @enumFromInt(err))) {
                .SUCCESS => return,
                .INVAL => unreachable,
                .SRCH => unreachable,
                .NOMEM => unreachable,
                else => |e| return posix.unexpectedErrno(e),
            }
        },
        .freebsd, .openbsd => if (use_pthreads) {
            // Use pthread_set_name_np for FreeBSD because pthread_setname_np is FreeBSD 12.2+ only.
            // TODO maybe revisit this if depending on FreeBSD 12.2+ is acceptable because
            // pthread_setname_np can return an error.

            std.c.pthread_set_name_np(self.getHandle(), name_with_terminator.ptr);
            return;
        },
        .dragonfly => if (use_pthreads) {
            const err = std.c.pthread_setname_np(self.getHandle(), name_with_terminator.ptr);
            switch (@as(posix.E, @enumFromInt(err))) {
                .SUCCESS => return,
                .INVAL => unreachable,
                .FAULT => unreachable,
                .NAMETOOLONG => unreachable, // already checked
                .SRCH => unreachable,
                else => |e| return posix.unexpectedErrno(e),
            }
        },
        else => {},
    }
    return error.Unsupported;
}