svc/startd/utmpx.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Copyright (c) 2013, Joyent, Inc. All rights reserved.
 */

/*
 * utmpx.c - utmpx utility routines
 *
 * Since svc.startd(1M) places utmpx records for its launched instances, it must
 * also mark them as dead once completed.
 */

#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <errno.h>
#include <pthread.h>
#include <sac.h>
#include <string.h>
#include <strings.h>
#include <time.h>
#include <unistd.h>
#include <utmpx.h>
#include <fcntl.h>

#include "startd.h"

static const char rlevels[] = { 'S', '0', '1', '2', '3', '4', '5', '6', 0 };
static int n_prev[] = { 0, 0, 0, 0, 0, 0, 0, 0 };

static pthread_mutex_t utmpx_lock;
static int utmpx_truncated = 0;

#define USEC_PER_MSEC   1000

int
utmpx_mark_init(pid_t pid, char *prefix)
{
    struct utmpx ut, *oldu;
    int tmplen;
    int ret;

    while (st->st_initial && !utmpx_truncated)
        (void) usleep(200 * USEC_PER_MSEC);

    /*
     * Clean out any preexisting records for this PID, as they must be
     * inaccurate.
     */
    utmpx_mark_dead(pid, 0, B_TRUE);

    /*
     * Construct a new record with the appropriate prefix.
     */
    (void) memset(&ut, 0, sizeof (ut));
    (void) strncpy(ut.ut_user, ".startd", sizeof (ut.ut_user));
    ut.ut_pid = pid;

    ut.ut_id[0] = ut.ut_id[1] = ut.ut_id[2] = ut.ut_id[3] = (char)SC_WILDC;

    for (ret = 0; ret < strlen(prefix); ret++)
        ut.ut_id[ret] = prefix[ret];

    ut.ut_type = INIT_PROCESS;
    (void) time(&ut.ut_tv.tv_sec);

    for (;;) {
        MUTEX_LOCK(&utmpx_lock);
        setutxent();

        if ((oldu = getutxid(&ut)) != NULL) {
            /*
             * Copy in the old "line" and "host" fields.
             */
            bcopy(oldu->ut_line, ut.ut_line, sizeof (ut.ut_line));
            bcopy(oldu->ut_host, ut.ut_host, sizeof (ut.ut_host));
            ut.ut_syslen = (tmplen = strlen(ut.ut_host)) ?
                min(tmplen + 1, sizeof (ut.ut_host)) : 0;
        }

        if (makeutx(&ut) != NULL)
            break;

        if (errno != EROFS)
            log_framework(LOG_WARNING,
                "makeutx failed, retrying: %s\n", strerror(errno));

        MUTEX_UNLOCK(&utmpx_lock);

        (void) sleep(1);
    }

    updwtmpx(WTMPX_FILE, &ut);

    endutxent();
    MUTEX_UNLOCK(&utmpx_lock);

    return (ret);
}

void
utmpx_mark_dead(pid_t pid, int status, boolean_t blocking)
{
    struct utmpx *up;
    int logged = 0;

    for (;;) {
        int found = 0;

        MUTEX_LOCK(&utmpx_lock);
        setutxent();

        while (up = getutxent()) {
            if (up->ut_pid == pid) {
                found = 1;

                if (up->ut_type == DEAD_PROCESS) {
                    /*
                     * Cleaned up elsewhere.
                     */
                    endutxent();
                    MUTEX_UNLOCK(&utmpx_lock);
                    return;
                }

                up->ut_type = DEAD_PROCESS;
                up->ut_exit.e_termination = WTERMSIG(status);
                up->ut_exit.e_exit = WEXITSTATUS(status);
                (void) time(&up->ut_tv.tv_sec);

                if (pututxline(up) != NULL) {
                    /*
                     * Now attempt to add to the end of the
                     * wtmp and wtmpx files.  Do not create
                     * if they don't already exist.
                     */
                    updwtmpx(WTMPX_FILE, up);
                    endutxent();
                    MUTEX_UNLOCK(&utmpx_lock);

                    return;
                }
            }
        }

        endutxent();
        MUTEX_UNLOCK(&utmpx_lock);

        if (!found || !blocking)
            return;

        if (!logged) {
            log_framework(LOG_INFO, "retrying utmpx_dead on PID "
                "%ld\n", pid);
            logged++;
        }

        (void) sleep(1);
    }
}

static void
utmpx_check()
{
    struct stat sb;

    if (stat(_UTMPX_FILE, &sb) == 0 &&
        sb.st_mode != (S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH))
        (void) chmod(_UTMPX_FILE, S_IRUSR | S_IWUSR | S_IRGRP |
            S_IROTH);

    if (stat(_WTMPX_FILE, &sb) == 0 &&
        sb.st_mode != (S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH))
        (void) chmod(_WTMPX_FILE, S_IRUSR | S_IWUSR | S_IRGRP |
            S_IROTH);
}

/*
 * Retrieve the runlevel utmpx entry if there is one; used to recover
 * state when svc.startd is restarted.
 */
char
utmpx_get_runlevel(void)
{
    struct utmpx *up;
    char rl = '\0';

    MUTEX_LOCK(&utmpx_lock);
    setutxent();

    while (up = getutxent()) {
        if (up->ut_type == RUN_LVL &&
            sscanf(up->ut_line, RUNLVL_MSG, &rl) == 1)
            break;
    }
    endutxent();
    MUTEX_UNLOCK(&utmpx_lock);

    return (rl);
}

void
utmpx_set_runlevel(char runlevel, char oldrl, boolean_t do_bump)
{
    struct utmpx u;
    struct utmpx *oup;
    size_t tmplen;
    int i;

    if (runlevel == 's')
        runlevel = 'S';
    if (oldrl == 's')
        oldrl = 'S';

    bzero(&u, sizeof (struct utmpx));

    u.ut_id[0] = u.ut_id[1] = u.ut_id[2] = u.ut_id[3] = '\0';
    u.ut_pid = 0;
    u.ut_type = RUN_LVL;

    (void) time(&u.ut_tv.tv_sec);

    MUTEX_LOCK(&utmpx_lock);
    setutxent();

    if ((oup = getutxid(&u)) != NULL) {
        bcopy(oup->ut_host, u.ut_host, sizeof (u.ut_host));
        bcopy(oup->ut_line, u.ut_line, sizeof (u.ut_line));
        bcopy(oup->ut_user, u.ut_user, sizeof (u.ut_user));

        tmplen = strlen(u.ut_host);
        if (tmplen)
            u.ut_syslen = min(tmplen + 1, sizeof (u.ut_host));
        else
            u.ut_syslen =  0;
    }

    if (oldrl != '\0')
        u.ut_exit.e_exit = oldrl;
    else if (oup != NULL)
        u.ut_exit.e_exit = oup->ut_exit.e_termination;
    else
        u.ut_exit.e_exit = '0';

    u.ut_exit.e_termination = runlevel;

    for (i = 0; rlevels[i] != '\0'; ++i) {
        if (rlevels[i] == runlevel)
            break;
    }

    u.ut_pid = n_prev[i];

    if (do_bump) {
        for (i = 0; rlevels[i] != '\0'; ++i) {
            if (rlevels[i] == u.ut_exit.e_exit)
                break;
        }

        ++n_prev[i];
    }

    (void) sprintf(u.ut_line, RUNLVL_MSG, runlevel);

    if (pututxline(&u) == NULL) {
        endutxent();
        MUTEX_UNLOCK(&utmpx_lock);

        return;
    }

    updwtmpx(WTMPX_FILE, &u);

    endutxent();
    MUTEX_UNLOCK(&utmpx_lock);

    utmpx_check();
}

static void
utmpx_write_entry(short type, const char *msg, time_t tstamp)
{
    struct utmpx u;
    struct utmpx *oup;
    size_t tmplen;

    bzero(&u, sizeof (struct utmpx));

    u.ut_id[0] = u.ut_id[1] = u.ut_id[2] = u.ut_id[3] = '\0';
    u.ut_pid = 0;

    u.ut_exit.e_termination = WTERMSIG(0);
    u.ut_exit.e_exit = WEXITSTATUS(0);
    u.ut_type = type;
    u.ut_tv.tv_sec = tstamp;

    MUTEX_LOCK(&utmpx_lock);
    setutxent();

    if ((oup = getutxid(&u)) != NULL) {
        bcopy(oup->ut_user, u.ut_user, sizeof (u.ut_user));
        bcopy(oup->ut_line, u.ut_line, sizeof (u.ut_line));
        bcopy(oup->ut_host, u.ut_host, sizeof (u.ut_host));

        tmplen = strlen(u.ut_host);
        if (tmplen)
            u.ut_syslen = min(tmplen + 1, sizeof (u.ut_host));
        else
            u.ut_syslen =  0;
    }

    (void) sprintf(u.ut_line, "%.12s", msg);

    if (pututxline(&u) == NULL) {
        endutxent();
        MUTEX_UNLOCK(&utmpx_lock);

        return;
    }

    updwtmpx(WTMPX_FILE, &u);

    endutxent();
    MUTEX_UNLOCK(&utmpx_lock);

    utmpx_check();
}

void
utmpx_write_boottime(void)
{
    time_t tstamp;
    struct stat stbuf;

    /*
     * The DOWN_TIME record tracks when the OS became unavailable
     * during the previous boot.  We stat(2) WTMPX and check its
     * attributes to determine when (and how) the OS became
     * unavailable.  If the file is empty, skip writing a DOWN_TIME
     * record.  Otherwise, check the access and modify times and
     * use whichever is latest as the time that the OS became
     * unavailable.  If st_atime is latest, the instance crashed or
     * the machine lost power.  If st_mtime is latest, the shutdown
     * was controlled.
     */
    if (stat(WTMPX_FILE, &stbuf) == 0 && stbuf.st_size != 0) {
        tstamp = (stbuf.st_atime >= stbuf.st_mtime) ?
            stbuf.st_atime : stbuf.st_mtime;
        utmpx_write_entry(DOWN_TIME, DOWN_MSG, tstamp);
    }

    /*
     * The boot time (or start time, for a non-global zone) is retrieved in
     * log_init().
     */
    tstamp = st->st_start_time.tv_sec;

    utmpx_write_entry(BOOT_TIME, BOOT_MSG, tstamp);
}

/*
 * void utmpx_clear_old(void)
 *   At boot and only at boot, truncate the utmpx file.
 *
 */
void
utmpx_clear_old(void)
{
    int fd;
    mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;

    if (!st->st_initial || utmpx_truncated)
        return;

    MUTEX_LOCK(&utmpx_lock);

    if ((fd = open(_UTMPX_FILE,
        O_WRONLY | O_CREAT | O_TRUNC, mode)) != -1) {
        (void) fchmod(fd, mode); /* force mode regardless of umask() */
        (void) fchown(fd, 0, 2); /* force owner to root/bin */
        (void) close(fd);
    } else {
        log_framework(LOG_NOTICE, "Unable to create %s: %s\n",
            _UTMPX_FILE, strerror(errno));
    }

    utmpx_truncated = 1;

    MUTEX_UNLOCK(&utmpx_lock);
}

void
utmpx_init()
{
    (void) pthread_mutex_init(&utmpx_lock, &mutex_attrs);
}

void
utmpx_prefork()
{
    /*
     * The libc utmpx routines are entirely MT-unsafe; we must assure
     * that no other thread is in these routines when we fork lest we
     * leave the child with inconsistent library state.
     */
    MUTEX_LOCK(&utmpx_lock);
}

void
utmpx_postfork()
{
    MUTEX_UNLOCK(&utmpx_lock);
}