/*      $OpenBSD: hotplugd.c,v 1.19 2023/03/08 04:43:13 guenther Exp $  */
/*
 * Copyright (c) 2004 Alexander Yurchenko <grange@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*
 * Devices hot plugging daemon.
 */

#include <sys/types.h>
#include <sys/device.h>
#include <sys/hotplug.h>
#include <sys/wait.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <libgen.h>
#include <limits.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>

#define _PATH_DEV_HOTPLUG               "/dev/hotplug"
#define _PATH_ETC_HOTPLUG               "/etc/hotplug"
#define _PATH_ETC_HOTPLUG_ATTACH        _PATH_ETC_HOTPLUG "/attach"
#define _PATH_ETC_HOTPLUG_DETACH        _PATH_ETC_HOTPLUG "/detach"
#define _LOG_TAG                        "hotplugd"
#define _LOG_FACILITY                   LOG_DAEMON
#define _LOG_OPT                        (LOG_NDELAY | LOG_PID)

volatile sig_atomic_t quit = 0;
char *device = _PATH_DEV_HOTPLUG;
int devfd = -1;

void exec_script(const char *, int, char *);

void sigchild(int);
void sigquit(int);
__dead void usage(void);

int
main(int argc, char *argv[])
{
        int ch;
        struct sigaction sact;
        struct hotplug_event he;

        while ((ch = getopt(argc, argv, "d:")) != -1)
                switch (ch) {
                case 'd':
                        device = optarg;
                        break;
                default:
                        usage();
                        /* NOTREACHED */
                }

        argc -= optind;
        argv += optind;
        if (argc > 0)
                usage();

        if (unveil(device, "r") == -1)
                err(1, "unveil %s", device);
        if (unveil(_PATH_ETC_HOTPLUG_ATTACH, "rx") == -1)
                err(1, "unveil %s", _PATH_ETC_HOTPLUG_ATTACH);
        if (unveil(_PATH_ETC_HOTPLUG_DETACH, "rx") == -1)
                err(1, "unveil %s", _PATH_ETC_HOTPLUG_DETACH);
        if (pledge("stdio rpath proc exec", NULL) == -1)
                err(1, "pledge");

        if ((devfd = open(device, O_RDONLY | O_CLOEXEC)) == -1)
                err(1, "%s", device);

        bzero(&sact, sizeof(sact));
        sigemptyset(&sact.sa_mask);
        sact.sa_flags = 0;
        sact.sa_handler = sigquit;
        sigaction(SIGINT, &sact, NULL);
        sigaction(SIGQUIT, &sact, NULL);
        sigaction(SIGTERM, &sact, NULL);
        sact.sa_handler = SIG_IGN;
        sigaction(SIGHUP, &sact, NULL);
        sact.sa_handler = sigchild;
        sact.sa_flags = SA_NOCLDSTOP;
        sigaction(SIGCHLD, &sact, NULL);

        openlog(_LOG_TAG, _LOG_OPT, _LOG_FACILITY);
        if (daemon(0, 0) == -1)
                err(1, "daemon");

        syslog(LOG_INFO, "started");

        while (!quit) {
                if (read(devfd, &he, sizeof(he)) == -1) {
                        if (errno == EINTR)
                                /* ignore */
                                continue;
                        syslog(LOG_ERR, "read: %m");
                        exit(1);
                }

                switch (he.he_type) {
                case HOTPLUG_DEVAT:
                        syslog(LOG_INFO, "%s attached, class %d",
                            he.he_devname, he.he_devclass);
                        exec_script(_PATH_ETC_HOTPLUG_ATTACH, he.he_devclass,
                            he.he_devname);
                        break;
                case HOTPLUG_DEVDT:
                        syslog(LOG_INFO, "%s detached, class %d",
                            he.he_devname, he.he_devclass);
                        exec_script(_PATH_ETC_HOTPLUG_DETACH, he.he_devclass,
                            he.he_devname);
                        break;
                default:
                        syslog(LOG_NOTICE, "unknown event (0x%x)", he.he_type);
                }
        }

        syslog(LOG_INFO, "terminated");

        closelog();
        close(devfd);

        return (0);
}

void
exec_script(const char *file, int class, char *name)
{
        char strclass[8];
        pid_t pid;

        snprintf(strclass, sizeof(strclass), "%d", class);

        if (access(file, X_OK | R_OK) == -1) {
                if (errno != ENOENT)
                        syslog(LOG_ERR, "%s: %m", file);
                return;
        }

        if ((pid = fork()) == -1) {
                syslog(LOG_ERR, "fork: %m");
                return;
        }
        if (pid == 0) {
                /* child process */
                char filebuf[PATH_MAX];

                strlcpy(filebuf, file, sizeof(filebuf));
                execl(file, basename(filebuf), strclass, name, (char *)NULL);
                syslog(LOG_ERR, "execl %s: %m", file);
                _exit(1);
                /* NOTREACHED */
        }
}

void
sigchild(int signum)
{
        struct syslog_data sdata = SYSLOG_DATA_INIT;
        int saved_errno, status;
        pid_t pid;

        saved_errno = errno;

        sdata.log_tag = _LOG_TAG;
        sdata.log_fac = _LOG_FACILITY;
        sdata.log_stat = _LOG_OPT;

        while ((pid = waitpid(WAIT_ANY, &status, WNOHANG)) != 0) {
                if (pid == -1) {
                        if (errno == EINTR)
                                continue;
                        if (errno != ECHILD)
                                syslog_r(LOG_ERR, &sdata, "waitpid: %m");
                        break;
                }

                if (WIFEXITED(status)) {
                        if (WEXITSTATUS(status) != 0) {
                                syslog_r(LOG_NOTICE, &sdata,
                                    "child exit status: %d",
                                    WEXITSTATUS(status));
                        }
                } else {
                        syslog_r(LOG_NOTICE, &sdata,
                            "child is terminated abnormally");
                }
        }

        errno = saved_errno;
}

void
sigquit(int signum)
{
        quit = 1;
}

__dead void
usage(void)
{
        extern char *__progname;

        fprintf(stderr, "usage: %s [-d device]\n", __progname);
        exit(1);
}