text: /*	$OpenBSD: wall.c,v 1.25 2009/10/27 23:59:49 deraadt Exp $	*/
  /*	$NetBSD: wall.c,v 1.6 1994/11/17 07:17:58 jtc 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.
   */
  
  /*
   * 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 <paths.h>
  #include <pwd.h>
  #include <grp.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
  #include <utmp.h>
  #include <vis.h>
  #include <err.h>
  
  struct wallgroup {
  	gid_t	gid;
  	char	*name;
  	char	**mem;
  	struct wallgroup *next;
  } *grouplist;
  
  void	makemsg(char *);
  void	addgroup(struct group *, char *);
  char   *ttymsg(struct iovec *, int, char *, int);
  __dead	void usage(void);
  
  int nobanner;
  int mbufsize;
  char *mbuf;
  
  /* ARGSUSED */
  int
  main(int argc, char **argv)
  {
  	FILE *fp;
  	int ch, ingroup;
  	struct iovec iov;
  	struct utmp utmp;
  	char *p, **mem;
  	char line[sizeof(utmp.ut_line) + 1];
  	char username[sizeof(utmp.ut_name) + 1];
  	struct passwd *pw;
  	struct group *grp;
  	struct wallgroup *g;
  
  	while ((ch = getopt(argc, argv, "ng:")) != -1)
  		switch (ch) {
  		case 'n':
  			/* undoc option for shutdown: suppress banner */
  			pw = getpwnam("nobody");
  			if (geteuid() == 0 || (pw && getuid() == pw->pw_uid))
  				nobanner = 1;
  			break;
  		case 'g':
  			if ((grp = getgrnam(optarg)) == NULL)
  				errx(1, "unknown group `%s'", optarg);
  			addgroup(grp, optarg);
  			break;
  		default:
  			usage();
  		}
  	argc -= optind;
  	argv += optind;
  	if (argc > 1)
  		usage();
  
  	makemsg(*argv);
  
  	if (!(fp = fopen(_PATH_UTMP, "r")))
  		err(1, "cannot read %s", _PATH_UTMP);
  	iov.iov_base = mbuf;
  	iov.iov_len = mbufsize;
  	/* NOSTRICT */
  	while (fread(&utmp, sizeof(utmp), 1, fp) == 1) {
  		if (!utmp.ut_name[0])
  			continue;
  		if (grouplist) {
  			ingroup = 0;
  			strncpy(username, utmp.ut_name, sizeof(utmp.ut_name));
  			username[sizeof(utmp.ut_name)] = '\0';
  			pw = getpwnam(username);
  			if (!pw)
  				continue;
  			for (g = grouplist; g && ingroup == 0; g = g->next) {
  				if (g->gid == pw->pw_gid)
  					ingroup = 1;
  				for (mem = g->mem; *mem && ingroup == 0; mem++)
  					if (strcmp(username, *mem) == 0)
  						ingroup = 1;
  			}
  			if (ingroup == 0)
  				continue;
  		}
  		strncpy(line, utmp.ut_line, sizeof(utmp.ut_line));
  		line[sizeof(utmp.ut_line)] = '\0';
  		if ((p = ttymsg(&iov, 1, line, 60*5)) != NULL)
  			warnx("%s", p);
  	}
  	exit(0);
  }
  
  void
  makemsg(char *fname)
  {
  	int ch, cnt;
  	struct tm *lt;
  	struct passwd *pw;
  	struct stat sbuf;
  	time_t now;
  	FILE *fp;
  	int fd;
  	char *p, *whom, hostname[MAXHOSTNAMELEN], lbuf[100], tmpname[MAXPATHLEN];
  	char tmpbuf[5];
  	char *ttynam;
  
  	snprintf(tmpname, sizeof(tmpname), "%s/wall.XXXXXXXXXX", _PATH_TMP);
  	if ((fd = mkstemp(tmpname)) >= 0) {
  		(void)unlink(tmpname);
  		fp = fdopen(fd, "r+");
  	}
  	if (fd == -1 || fp == NULL)
  		err(1, "can't open temporary file");
  
  	if (!nobanner) {
  		if (!(whom = getlogin()))
  			whom = (pw = getpwuid(getuid())) ? pw->pw_name : "???";
  		(void)gethostname(hostname, sizeof(hostname));
  		(void)time(&now);
  		lt = localtime(&now);
  		if ((ttynam = ttyname(STDERR_FILENO)) == NULL)
  			ttynam = "(not a tty)";
  
  		/*
  		 * 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);
  		(void)snprintf(lbuf, sizeof lbuf,
  		    "        (%s) at %d:%02d ...", ttynam,
  		    lt->tm_hour, lt->tm_min);
  		(void)fprintf(fp, "%-79.79s\r\n", lbuf);
  	}
  	(void)fprintf(fp, "%79s\r\n", " ");
  
  	if (fname) {
  		gid_t egid = getegid();
  
  		setegid(getgid());
  		if (freopen(fname, "r", stdin) == NULL)
  			err(1, "can't read %s", fname);
  		setegid(egid);
  	}
  	while (fgets(lbuf, sizeof(lbuf), stdin))
  		for (cnt = 0, p = lbuf; (ch = *p) != '\0'; ++p, ++cnt) {
  			vis(tmpbuf, ch, VIS_SAFE|VIS_NOSLASH, p[1]);
  			if (cnt == 79+1-strlen(tmpbuf) || ch == '\n') {
  				for (; cnt < 79+1-strlen(tmpbuf); ++cnt)
  					putc(' ', fp);
  				putc('\r', fp);
  				putc('\n', fp);
  				cnt = -1;
  			}
  			if (ch != '\n') {
  				int xx;
  
  				for (xx = 0; tmpbuf[xx]; xx++)
  					putc(tmpbuf[xx], fp);
  			}
  		}
  	(void)fprintf(fp, "%79s\r\n", " ");
  	rewind(fp);
  
  	if (fstat(fd, &sbuf))
  		err(1, "can't stat temporary file");
  	mbufsize = sbuf.st_size;
  	mbuf = malloc((u_int)mbufsize);
  	if (mbuf == NULL)
  		err(1, NULL);
  	if (fread(mbuf, sizeof(*mbuf), mbufsize, fp) != mbufsize)
  		err(1, "can't read temporary file");
  	(void)close(fd);
  }
  
  void
  addgroup(struct group *grp, char *name)
  {
  	int i;
  	struct wallgroup *g;
  
  	for (i = 0; grp->gr_mem[i]; i++)
  		;
  
  	g = (struct wallgroup *)malloc(sizeof *g);
  	if (g == NULL)
  		err(1, NULL);
  	g->gid = grp->gr_gid;
  	g->name = name;
  	g->mem = (char **)calloc(i + 1, sizeof(char *));
  	if (g->mem == NULL)
  		err(1, NULL);
  	for (i = 0; grp->gr_mem[i] != NULL; i++) {
  		g->mem[i] = strdup(grp->gr_mem[i]);
  		if (g->mem[i] == NULL)
  			err(1, NULL);
  	}
  	g->mem[i] = NULL;
  	g->next = grouplist;
  	grouplist = g;
  }
  
  void
  usage(void)
  {
  	extern char *__progname;
  
  	(void)fprintf(stderr, "usage: %s [-g group] [file]\n", __progname);
  	exit(1);
  }
  