libmail/common/notifyu.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (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 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*  Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*    All Rights Reserved   */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include "libmail.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <utmpx.h>
#include <syslog.h>
#if !defined(__cplusplus) && !defined(c_plusplus)
typedef void (*SIG_PF) (int);
#endif
#include <unistd.h>
#include <signal.h>

static SIG_PF catcher(void);

static SIG_PF catcher(void)
{
    /* do nothing, but allow the write() to break */
    return (0);
}

void
notify(char *user, char *msg, int check_mesg_y, char *etcdir)
{
    /* search the utmp file for this user */
    SIG_PF old;
    unsigned int oldalarm;
    struct utmpx utmpx, *putmpx = &utmpx;

    setutxent();

    /* grab the tty name */
    while ((putmpx = getutxent()) != NULL) {
        if (strncmp(user, utmpx.ut_name,
            sizeof (utmpx.ut_name)) == 0) {
            char tty[sizeof (utmpx.ut_line)+1];
            char dev[MAXFILENAME];
            FILE *port;
            size_t i;
            int fd;

            for (i = 0; i < sizeof (utmpx.ut_line); i++)
                tty[i] = utmpx.ut_line[i];
            tty[i] = '\0';

            /* stick /dev/ in front */
            (void) sprintf(dev, "%s/dev/%s", etcdir, tty);

            /* break out if write() to the tty hangs */
            old = (SIG_PF)signal(SIGALRM, (SIG_PF)catcher);
            oldalarm = alarm(300);

            /* check if device is really a tty */
            if ((fd = open(dev, O_WRONLY|O_NOCTTY)) == -1) {
                (void) fprintf(stderr,
                    "Cannot open %s.\n", dev);
                continue;
            } else {
                if (!isatty(fd)) {
                    (void) fprintf(stderr, "%s in utmpx is "
                        "not a tty\n", tty);
                    openlog("mail", 0, LOG_AUTH);
                    syslog(LOG_CRIT, "%s in utmp is "
                        "not a tty\n", tty);
                    closelog();
                    (void) close(fd);
                    continue;
                }
            }
            (void) close(fd);

            /* write to the tty */
            port = fopen(dev, "w");
            if (port != 0) {
                (void) fprintf(port, "\r\n%s\r\n", msg);
                (void) fclose(port);
            }

            /* clean up our alarm */
            (void) alarm(0);
            (void) signal(SIGALRM, old);
            (void) alarm(oldalarm);
        }
    }
    endutxent();
}