sysvinit/src/dowall.c
Jesse Smith 584df5efaf Added patch from William Shipley which allows shutdown time to be specified
in the format +hh:mm. This is in addition to the existing formats such as
hh:mm, +m, and "now".

Cleared up compiler warning in dowall which can happen if the
output message is longer than the size limit on the snprintf()
buffer. This is not a bug, a the trucation works, but using a larger
buffer avoids the warning on systems with long user/host names.
2020-06-20 13:41:18 -03:00

261 lines
5.9 KiB
C

/*
* dowall.c Write to all users on the system.
*
* Author: Miquel van Smoorenburg, miquels@cistron.nl
*
* Version: @(#)dowall.c 2.85-5 02-Jul-2003 miquels@cistron.nl
*
* This file is part of the sysvinit suite,
* Copyright (C) 1991-2003 Miquel van Smoorenburg.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <stdio.h>
#include <utmp.h>
#include <pwd.h>
#include <fcntl.h>
#include <signal.h>
#include <setjmp.h>
#include <paths.h>
#ifndef _PATH_DEV
# define _PATH_DEV "/dev/"
#endif
#ifndef HOST_NAME_MAX
# define HOST_NAME_MAX 255
#endif
static sigjmp_buf jbuf;
/*
* Alarm handler
*/
/*ARGSUSED*/
# ifdef __GNUC__
static void handler(int arg __attribute__((unused)))
# else
static void handler(int arg)
# endif
{
siglongjmp(jbuf, 1);
}
/*
* Print a text, escape all characters not in Latin-1.
*/
static void feputs(const char *line, FILE *fp)
{
unsigned char *p;
for (p = (unsigned char *)line; *p; p++) {
if (strchr("\t\r\n", *p) ||
(*p >= 32 && *p <= 127) || (*p >= 160)) {
fputc(*p, fp);
} else {
fprintf(fp, "^%c", (*p & 0x1f) + 'A' - 1);
}
}
fflush(fp);
}
static void getuidtty(char **userp, char **ttyp)
{
struct passwd *pwd;
uid_t uid;
char *tty;
static char uidbuf[32];
static char ttynm[UT_LINESIZE + 4];
static int init = 0;
if (!init) {
uid = getuid();
if ((pwd = getpwuid(uid)) != NULL) {
uidbuf[0] = 0;
strncat(uidbuf, pwd->pw_name, sizeof(uidbuf) - 1);
} else {
/* Using variable number of data parameters in one
function makes the Clang compiler cry. -- Jesse
sprintf(uidbuf, uid ? "uid %d" : "root", (int)uid);
*/
if (uid)
sprintf(uidbuf, "uid %d", (int) uid);
else
sprintf(uidbuf, "root");
}
if ((tty = ttyname(0)) != NULL) {
const size_t plen = strlen(_PATH_DEV);
if (strncmp(tty, _PATH_DEV, plen) == 0) {
tty += plen;
if (tty[0] == '/')
tty++;
}
snprintf(ttynm, sizeof(ttynm), "(%.*s) ",
UT_LINESIZE, tty);
} else
ttynm[0] = 0;
init++;
}
*userp = uidbuf;
*ttyp = ttynm;
}
/*
* Check whether given filename looks like tty device.
*/
static int file_isatty(const char *fname)
{
struct stat st;
int major;
if (stat(fname, &st) < 0)
return 0;
if (st.st_nlink != 1 || !S_ISCHR(st.st_mode))
return 0;
/*
* It would be an impossible task to list all major/minors
* of tty devices here, so we just exclude the obvious
* majors of which just opening has side-effects:
* printers and tapes.
*/
major = major(st.st_dev);
if (major == 1 || major == 2 || major == 6 || major == 9 ||
major == 12 || major == 16 || major == 21 || major == 27 ||
major == 37 || major == 96 || major == 97 || major == 206 ||
major == 230) return 0;
return 1;
}
/*
* Wall function.
*/
void wall(const char *text, int remote)
{
FILE *tp;
struct sigaction sa;
struct utmp *utmp;
time_t t;
char term[UT_LINESIZE+ strlen(_PATH_DEV) + 1];
char line[256];
char hostname[HOST_NAME_MAX+1];
char *date, *p;
char *user, *tty;
int fd, flags;
/*
* Make sure tp and fd aren't in a register. Some versions
* of gcc clobber those after longjmp (or so I understand).
*/
(void) &tp;
(void) &fd;
getuidtty(&user, &tty);
/* Get and report current hostname, to make it easier to find
out which machine is being shut down. */
if (0 != gethostname(hostname, sizeof(hostname))) {
strncpy(hostname, "[unknown]", sizeof(hostname)-1);
}
/* If hostname is truncated, it is unspecified if the string
is null terminated or not. Make sure we know it is null
terminated. */
hostname[sizeof(hostname)-1] = 0;
/* Get the time */
time(&t);
date = ctime(&t);
for(p = date; *p && *p != '\n'; p++)
;
*p = 0;
if (remote) {
snprintf(line, sizeof(line),
"\r\nRemote broadcast message (%s):\r\n\r\n",
date);
} else {
snprintf(line, sizeof(line),
"\r\nBroadcast message from %s@%s %s(%s):\r\n\r\n",
user, hostname, tty, date);
}
/*
* Fork to avoid us hanging in a write()
*/
if (fork() != 0)
return;
memset(&sa, 0, sizeof(sa));
sa.sa_handler = handler;
sa.sa_flags = 0;
sigemptyset(&sa.sa_mask);
sigaction(SIGALRM, &sa, NULL);
setutent();
while ((utmp = getutent()) != NULL) {
if(utmp->ut_type != USER_PROCESS ||
utmp->ut_user[0] == 0) continue;
if (strncmp(utmp->ut_line, _PATH_DEV, strlen(_PATH_DEV)) == 0) {
term[0] = 0;
strncat(term, utmp->ut_line, sizeof(term)-1);
} else
snprintf(term, sizeof(term), _PATH_DEV "%.*s",
UT_LINESIZE, utmp->ut_line);
if (strstr(term, "/../")) continue;
fd = -1;
tp = NULL;
/*
* Open it non-delay
*/
if (sigsetjmp(jbuf, 1) == 0) {
alarm(2);
flags = O_WRONLY|O_NDELAY|O_NOCTTY;
if (file_isatty(term) &&
(fd = open(term, flags)) >= 0) {
if (isatty(fd) &&
(tp = fdopen(fd, "w")) != NULL) {
fputs(line, tp);
feputs(text, tp);
fflush(tp);
}
}
}
alarm(0);
if (fd >= 0) close(fd);
if (tp != NULL) fclose(tp);
}
endutent();
exit(0);
}