/*      $NetBSD: wall.c,v 1.30 2015/11/21 14:59:51 christos Exp $       */

/*
 * Copyright (c) 1988, 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1988, 1990, 1993\
 The Regents of the University of California.  All rights reserved.");
#endif /* not lint */

#ifndef lint
#if 0
static char sccsid[] = "@(#)wall.c      8.2 (Berkeley) 11/16/93";
#endif
__RCSID("$NetBSD: wall.c,v 1.30 2015/11/21 14:59:51 christos Exp $");
#endif /* not lint */

/*
 * This program is not related to David Wall, whose Stanford Ph.D. thesis
 * is entitled "Mechanisms for Broadcast and Selective Broadcast".
 */

#include <sys/param.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/uio.h>

#include <ctype.h>
#include <err.h>
#include <grp.h>
#include <errno.h>
#include <paths.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <util.h>

#include "utmpentry.h"
#include "term_chk.h"

static void     addgroup(char *);
static void     makemsg(struct iovec *, const char *, int);
__dead static void      usage(void);

static struct wallgroup {
        gid_t   gid;
        char    *name;
        char    **mem;
        struct wallgroup *next;
} *grouplist;

int
main(int argc, char **argv)
{
        int ch;
        struct iovec iov;
        char *p, **mem;
        struct utmpentry *ep;
        gid_t egid;
        struct wallgroup *wg;
        struct passwd *pw;
        int nobanner;

        setprogname(argv[0]);
        egid = getegid();
        if (setegid(getgid()) == -1)
                err(EXIT_FAILURE, "setegid");
        pw = getpwnam("nobody");
        if (pw == NULL)
                errx(EXIT_FAILURE, "Can't find passwd entry for `nobody'");

        (void)check_sender(NULL, getuid(), egid);

        nobanner = 0;
        while ((ch = getopt(argc, argv, "g:n")) != -1)
                switch (ch) {
                case 'n':
                        /* undoc option for shutdown: suppress banner */
                        if (geteuid() == 0 || (pw && getuid() == pw->pw_uid))
                                nobanner = 1;
                        break;
                case 'g':
                        addgroup(optarg);
                        break;
                case '?':
                default:
                        usage();
                }
        argc -= optind;
        argv += optind;
        if (argc > 1)
                usage();

        makemsg(&iov, *argv, nobanner);

        (void)getutentries(NULL, &ep);
        (void)setegid(egid);
        for (; ep; ep = ep->next) {
                if (grouplist) {
                        int ingroup;

                        ingroup = 0;
                        pw = getpwnam(ep->name);
                        if (!pw)
                                continue;
                        for (wg = grouplist; wg && !ingroup; wg = wg->next) {
                                if (wg->gid == pw->pw_gid)
                                        ingroup = 1;
                                for (mem = wg->mem; *mem && !ingroup; mem++)
                                        if (strcmp(ep->name, *mem) == 0)
                                                ingroup = 1;
                        }
                        if (ingroup == 0)
                                continue;
                }

                /* skip [xgk]dm/xserver entries (":0", ":1", etc.) */
                if (ep->line[0] == ':' && isdigit((unsigned char)ep->line[1]))
                        continue;

                if ((p = ttymsg(&iov, 1, ep->line, 60*5)) != NULL)
                        warnx("%s", p);
        }
        return EXIT_SUCCESS;
}

static void
addgroup(char *name)
{
        size_t i;
        struct group *grp;
        struct wallgroup *g;

        grp = getgrnam(name);
        if ((grp = getgrnam(name)) == NULL)
                errx(EXIT_FAILURE, "unknown group `%s'", name);
        for (i = 0; grp->gr_mem[i]; i++)
                continue;

        g = malloc(sizeof(*g));
        if (g == NULL)
                err(EXIT_FAILURE, "malloc");
        g->gid = grp->gr_gid;
        g->name = name;
        g->mem = calloc(i + 1, sizeof(*g->mem));
        if (g->mem == NULL)
                err(EXIT_FAILURE, "calloc");
        for (i = 0; grp->gr_mem[i] != NULL; i++) {
                g->mem[i] = strdup(grp->gr_mem[i]);
                if (g->mem[i] == NULL)
                        err(EXIT_FAILURE, "strdup");
        }
        g->mem[i] = NULL;
        g->next = grouplist;
        grouplist = g;
}

static void
makebanner(FILE *fp)
{
        const char *whom, *tty;
        char hostname[MAXHOSTNAMELEN + 1], lbuf[100];
        time_t now;
        struct tm *lt;
        struct passwd *pw;

        if (!(whom = getlogin()))
                whom = (pw = getpwuid(getuid())) ? pw->pw_name : "???";
        (void)gethostname(hostname, sizeof(hostname));
        hostname[sizeof(hostname) - 1] = '\0';
        (void)time(&now);
        lt = localtime(&now);

        /*
         * all this stuff is to blank out a square for the message;
         * we wrap message lines at column 79, not 80, because some
         * terminals wrap after 79, some do not, and we can't tell.
         * Which means that we may leave a non-blank character
         * in column 80, but that can't be helped.
         */
        (void)fprintf(fp, "\r%79s\r\n", " ");
        (void)snprintf(lbuf, sizeof lbuf,
            "Broadcast Message from %s@%s", whom, hostname);
        (void)fprintf(fp, "%-79.79s\007\007\r\n", lbuf);
        tty = ttyname(STDERR_FILENO);
        if (tty == NULL)
                tty = "??";
        (void)snprintf(lbuf, sizeof lbuf, "        (%s) at %d:%02d %s...", tty,
            lt->tm_hour, lt->tm_min, lt->tm_zone);
        (void)fprintf(fp, "%-79.79s\r\n", lbuf);
}

static void
makemsg(struct iovec *iov, const char *fname, int nobanner)
{
        int ch, cnt;
        struct stat sbuf;
        FILE *fp;
        int fd;
        char *p, tmpname[MAXPATHLEN], lbuf[100];
        size_t mbufsize;
        char *mbuf;

        (void)snprintf(tmpname, sizeof tmpname, "%s/wall.XXXXXX", _PATH_TMP);
        if ((fd = mkstemp(tmpname)) == -1)
                err(EXIT_FAILURE, "can't open temporary file");
        (void)unlink(tmpname);
        if (!(fp = fdopen(fd, "r+")))
                err(EXIT_FAILURE, "can't open temporary file");

        if (!nobanner)
                makebanner(fp);

        (void)fprintf(fp, "%79s\r\n", " ");

        if (fname && !(freopen(fname, "r", stdin)))
                err(EXIT_FAILURE, "can't read %s", fname);

        while (fgets(lbuf, sizeof(lbuf), stdin))
                for (cnt = 0, p = lbuf; (ch = *p) != '\0'; ++p, ++cnt) {
                        if (cnt == 79 || ch == '\n') {
                                for (; cnt < 79; ++cnt)
                                        putc(' ', fp);
                                putc('\r', fp);
                                putc('\n', fp);
                                cnt = -1;
                        }
                        if (ch != '\n')
                                putc(ch, fp);
                }
        (void)fprintf(fp, "%79s\r\n", " ");
        rewind(fp);

        if (fstat(fd, &sbuf) == -1)
                err(EXIT_FAILURE, "can't stat temporary file");
        if ((uint64_t)sbuf.st_size > SIZE_T_MAX)
                errx(EXIT_FAILURE, "file too big");
        mbufsize = (size_t)sbuf.st_size;
        if (!(mbuf = malloc(mbufsize)))
                err(EXIT_FAILURE, "malloc");
        if (fread(mbuf, 1, mbufsize, fp) != mbufsize)
                err(EXIT_FAILURE, "can't read temporary file");
        (void)fclose(fp);
        iov->iov_base = mbuf;
        iov->iov_len = mbufsize;
}

static void
usage(void)
{

        (void)fprintf(stderr, "Usage: %s [-g group] [file]\n", getprogname());
        exit(EXIT_FAILURE);
}