kovidgoyal/kitty · warning

Call to read() from read_signals() failed with error: %s

Error message

Call to read() from read_signals() failed with error: %s

What it means

The signalfd read in read_signals failed with an error other than EINTR/EAGAIN, so the signal-processing pass stops for this iteration; signals may be processed on a later loop iteration.

Source

Thrown at kitty/loop-utils.c:149

            if (errno == EINTR) continue;
            if (!in_signal_handler) log_error("Failed to write to %s wakeup fd with error: %s", loop_name, strerror(errno));
        }
        break;
    }
}


void
read_signals(int fd, handle_signal_func callback, void *data) {
#ifdef HAS_SIGNAL_FD
    static struct signalfd_siginfo fdsi[32];
    siginfo_t si;
    while (true) {
        ssize_t s = read(fd, &fdsi, sizeof(fdsi));
        if (s < 0) {
            if (errno == EINTR) continue;
            if (errno == EAGAIN) break;
            log_error("Call to read() from read_signals() failed with error: %s", strerror(errno));
            break;
        }
        if (s == 0) break;
        size_t num_signals = s / sizeof(struct signalfd_siginfo);
        if (num_signals == 0 || num_signals * sizeof(struct signalfd_siginfo) != (size_t)s) {
            log_error("Incomplete signal read from signalfd");
            break;
        }
        for (size_t i = 0; i < num_signals; i++) {
            si.si_signo = fdsi[i].ssi_signo;
            si.si_code = fdsi[i].ssi_code;
            si.si_pid = fdsi[i].ssi_pid;
            si.si_uid = fdsi[i].ssi_uid;
            si.si_addr = (void *)(uintptr_t)fdsi[i].ssi_addr;
            si.si_status = fdsi[i].ssi_status;
            si.si_value.sival_int = fdsi[i].ssi_int;
            if (!callback(&si, data)) break;
        }

View on GitHub (pinned to 6d5d0c4406)

Solutions

1. Ignore if it appears only at exit
2. Upgrade kitty
3. Report upstream with a reproduction if it happens during normal operation

When it happens

Trigger: read() on the signalfd fd failing with EBADF/EINVAL etc. - typically the fd was closed concurrently during shutdown.

Common situations: Benign shutdown races between the io loop thread and the main thread on Linux.

Related errors

• Incomplete signal read from signalfd
• This must be run as kitten choose-files
• Pipe to kitten was broken while sending data to it
• Failed to find cwd of process with pid: {pid}
• Failed to write to %s wakeup fd with error: %s

AI-assisted analysis of kovidgoyal/kitty@6d5d0c4406 (2026-08-27). Data as JSON: /api/errors/a7187fef9db35cb4. Report an issue: GitHub.