systemd/src/utmp-wtmp.c

	utmp-wtmp.c revision 169c1bda807d183a362b47efe0b5b56e9320e430
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering/***
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering  This file is part of systemd.
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering  Copyright 2010 Lennart Poettering
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering  systemd is free software; you can redistribute it and/or modify it
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering  under the terms of the GNU General Public License as published by
822cd601357f6f45d0176ae38fe9f86077462f06Lennart Poettering  the Free Software Foundation; either version 2 of the License, or
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering  (at your option) any later version.
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering  systemd is distributed in the hope that it will be useful, but
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering  WITHOUT ANY WARRANTY; without even the implied warranty of
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering  General Public License for more details.
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering  You should have received a copy of the GNU General Public License
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering  along with systemd; If not, see <http://www.gnu.org/licenses/>.
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering***/
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering#include <utmpx.h>
770b5ce4fc31a336a41e81381c229da725ef0cfaLennart Poettering#include <errno.h>
#include <assert.h>
#include <string.h>
#include <sys/utsname.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/poll.h>

#include "macro.h"
#include "utmp-wtmp.h"

int utmp_get_runlevel(int *runlevel, int *previous) {
        struct utmpx lookup, *found;
        int r;
        const char *e;

        assert(runlevel);

        /* If these values are set in the environment this takes
         * precedence. Presumably, sysvinit does this to work around a
         * race condition that would otherwise exist where we'd always
         * go to disk and hence might read runlevel data that might be
         * very new and does not apply to the current script being
         * executed. */

        if ((e = getenv("RUNLEVEL")) && e[0] > 0) {
                *runlevel = e[0];

                if (previous) {
                        /* $PREVLEVEL seems to be an Upstart thing */

                        if ((e = getenv("PREVLEVEL")) && e[0] > 0)
                                *previous = e[0];
                        else
                                *previous = 0;
                }

                return 0;
        }

        if (utmpxname(_PATH_UTMPX) < 0)
                return -errno;

        setutxent();

        zero(lookup);
        lookup.ut_type = RUN_LVL;

        if (!(found = getutxid(&lookup)))
                r = -errno;
        else {
                int a, b;

                a = found->ut_pid & 0xFF;
                b = (found->ut_pid >> 8) & 0xFF;

                if (a < 0 || b < 0)
                        r = -EIO;
                else {
                        *runlevel = a;

                        if (previous)
                                *previous = b;
                        r = 0;
                }
        }

        endutxent();

        return r;
}

static void init_timestamp(struct utmpx *store, usec_t t) {
        assert(store);

        zero(*store);

        if (t <= 0)
                t = now(CLOCK_REALTIME);

        store->ut_tv.tv_sec = t / USEC_PER_SEC;
        store->ut_tv.tv_usec = t % USEC_PER_SEC;
}

static void init_entry(struct utmpx *store, usec_t t) {
        struct utsname uts;

        assert(store);

        init_timestamp(store, t);

        zero(uts);

        if (uname(&uts) >= 0)
                strncpy(store->ut_host, uts.release, sizeof(store->ut_host));

        strncpy(store->ut_line, "~", sizeof(store->ut_line));  /* or ~~ ? */
        strncpy(store->ut_id, "~~", sizeof(store->ut_id));
}

static int write_entry_utmp(const struct utmpx *store) {
        int r;

        assert(store);

        /* utmp is similar to wtmp, but there is only one entry for
         * each entry type resp. user; i.e. basically a key/value
         * table. */

        if (utmpxname(_PATH_UTMPX) < 0)
                return -errno;

        setutxent();

        if (!pututxline(store))
                r = -errno;
        else
                r = 0;

        endutxent();

        return r;
}

static int write_entry_wtmp(const struct utmpx *store) {
        assert(store);

        /* wtmp is a simple append-only file where each entry is
        simply appended to * the end; i.e. basically a log. */

        errno = 0;
        updwtmpx(_PATH_WTMPX, store);
        return -errno;
}

static int write_entry_both(const struct utmpx *store) {
        int r, s;

        r = write_entry_utmp(store);
        s = write_entry_wtmp(store);

        if (r >= 0)
                r = s;

        /* If utmp/wtmp have been disabled, that's a good thing, hence
         * ignore the errors */
        if (r == -ENOENT)
                r = 0;

        return r;
}

int utmp_put_shutdown(usec_t t) {
        struct utmpx store;

        init_entry(&store, t);

        store.ut_type = RUN_LVL;
        strncpy(store.ut_user, "shutdown", sizeof(store.ut_user));

        return write_entry_both(&store);
}

int utmp_put_reboot(usec_t t) {
        struct utmpx store;

        init_entry(&store, t);

        store.ut_type = BOOT_TIME;
        strncpy(store.ut_user, "reboot", sizeof(store.ut_user));

        return write_entry_both(&store);
}

static const char *sanitize_id(const char *id) {
        size_t l;

        assert(id);
        l = strlen(id);

        if (l <= sizeof(((struct utmpx*) NULL)->ut_id))
                return id;

        return id + l - sizeof(((struct utmpx*) NULL)->ut_id);
}

int utmp_put_init_process(usec_t t, const char *id, pid_t pid, pid_t sid, const char *line) {
        struct utmpx store;

        assert(id);

        init_timestamp(&store, t);

        store.ut_type = INIT_PROCESS;
        store.ut_pid = pid;
        store.ut_session = sid;

        strncpy(store.ut_id, sanitize_id(id), sizeof(store.ut_id));

        if (line)
                strncpy(store.ut_line, file_name_from_path(line), sizeof(store.ut_line));

        return write_entry_both(&store);
}

int utmp_put_dead_process(const char *id, pid_t pid, int code, int status) {
        struct utmpx lookup, store, *found;

        assert(id);

        setutxent();

        zero(lookup);
        lookup.ut_type = INIT_PROCESS; /* looks for DEAD_PROCESS, LOGIN_PROCESS, USER_PROCESS, too */
        strncpy(lookup.ut_id, sanitize_id(id), sizeof(lookup.ut_id));

        if (!(found = getutxid(&lookup)))
                return 0;

        if (found->ut_pid != pid)
                return 0;

        zero(store);

        memcpy(&store, &lookup, sizeof(store));
        store.ut_type = DEAD_PROCESS;
        store.ut_exit.e_termination = code;
        store.ut_exit.e_exit = status;

        zero(store.ut_user);
        zero(store.ut_host);
        zero(store.ut_tv);

        return write_entry_both(&store);
}


int utmp_put_runlevel(usec_t t, int runlevel, int previous) {
        struct utmpx store;
        int r;

        assert(runlevel > 0);

        if (previous <= 0) {
                /* Find the old runlevel automatically */

                if ((r = utmp_get_runlevel(&previous, NULL)) < 0) {
                        if (r != -ESRCH)
                                return r;

                        previous = 0;
                }
        }

        if (previous == runlevel)
                return 0;

        init_entry(&store, t);

        store.ut_type = RUN_LVL;
        store.ut_pid = (runlevel & 0xFF) | ((previous & 0xFF) << 8);
        strncpy(store.ut_user, "runlevel", sizeof(store.ut_user));

        return write_entry_both(&store);
}

#define TIMEOUT_MSEC 50

static int write_to_terminal(const char *tty, const char *message) {
        int fd, r;
        const char *p;
        size_t left;
        usec_t end;

        assert(tty);
        assert(message);

        if ((fd = open(tty, O_WRONLY|O_NDELAY|O_NOCTTY|O_CLOEXEC)) < 0)
                return -errno;

        if (!isatty(fd)) {
                r = -errno;
                goto finish;
        }

        p = message;
        left = strlen(message);

        end = now(CLOCK_MONOTONIC) + TIMEOUT_MSEC*USEC_PER_MSEC;

        while (left > 0) {
                ssize_t n;
                struct pollfd pollfd;
                usec_t t;
                int k;

                t = now(CLOCK_MONOTONIC);

                if (t >= end) {
                        r = -ETIME;
                        goto finish;
                }

                zero(pollfd);
                pollfd.fd = fd;
                pollfd.events = POLLOUT;

                if ((k = poll(&pollfd, 1, (end - t) / USEC_PER_MSEC)) < 0)
                        return -errno;

                if (k <= 0) {
                        r = -ETIME;
                        goto finish;
                }

                if ((n = write(fd, p, left)) < 0) {

                        if (errno == EAGAIN)
                                continue;

                        r = -errno;
                        goto finish;
                }

                assert((size_t) n <= left);

                p += n;
                left -= n;
        }

        r = 0;

finish:
        close_nointr_nofail(fd);

        return r;
}

int utmp_wall(const char *message) {
        struct utmpx *u;
        char date[FORMAT_TIMESTAMP_MAX];
        char *text = NULL, *hn = NULL, *un = NULL, *tty = NULL;
        int r;

        if (!(hn = gethostname_malloc()) ||
            !(un = getlogname_malloc())) {
                r = -ENOMEM;
                goto finish;
        }

        getttyname_malloc(&tty);

        if (asprintf(&text,
                     "\a\r\n"
                     "Broadcast message from %s@%s%s%s (%s):\r\n\r\n"
                     "%s\r\n\r\n",
                     un, hn,
                     tty ? " on " : "", strempty(tty),
                     format_timestamp(date, sizeof(date), now(CLOCK_REALTIME)),
                     message) < 0) {
                r = -ENOMEM;
                goto finish;
        }

        setutxent();

        r = 0;

        while ((u = getutxent())) {
                int q;
                const char *path;
                char *buf = NULL;

                if (u->ut_type != USER_PROCESS || u->ut_user[0] == 0)
                        continue;

                if (path_startswith(u->ut_line, "/dev/"))
                        path = u->ut_line;
                else {
                        if (asprintf(&buf, "/dev/%s", u->ut_line) < 0) {
                                r = -ENOMEM;
                                goto finish;
                        }

                        path = buf;
                }

                if ((q = write_to_terminal(path, text)) < 0)
                        r = q;

                free(buf);
        }

finish:
        free(hn);
        free(un);
        free(tty);
        free(text);

        return r;
}