/usr.bin/wall/ttymsg.c
https://bitbucket.org/freebsd/freebsd-head/ · C · 167 lines · 109 code · 13 blank · 45 comment · 29 complexity · 49aeb156f582aa71540a456bf9b41562 MD5 · raw file
- /*
- * Copyright (c) 1989, 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.
- * 4. 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>
- __FBSDID("$FreeBSD$");
- #ifndef lint
- static const char sccsid[] = "@(#)ttymsg.c 8.2 (Berkeley) 11/16/93";
- #endif
- #include <sys/types.h>
- #include <sys/uio.h>
- #include <dirent.h>
- #include <errno.h>
- #include <fcntl.h>
- #include <paths.h>
- #include <signal.h>
- #include <stdio.h>
- #include <string.h>
- #include <stdlib.h>
- #include <unistd.h>
- #include "ttymsg.h"
- /*
- * Display the contents of a uio structure on a terminal. Used by wall(1),
- * syslogd(8), and talkd(8). Forks and finishes in child if write would block,
- * waiting up to tmout seconds. Returns pointer to error string on unexpected
- * error; string is not newline-terminated. Various "normal" errors are
- * ignored (exclusive-use, lack of permission, etc.).
- */
- const char *
- ttymsg(struct iovec *iov, int iovcnt, const char *line, int tmout)
- {
- struct iovec localiov[7];
- ssize_t left, wret;
- int cnt, fd;
- static char device[MAXNAMLEN] = _PATH_DEV;
- static char errbuf[1024];
- char *p;
- int forked;
- forked = 0;
- if (iovcnt > (int)(sizeof(localiov) / sizeof(localiov[0])))
- return ("too many iov's (change code in wall/ttymsg.c)");
- p = device + sizeof(_PATH_DEV) - 1;
- strlcpy(p, line, sizeof(device));
- if (strncmp(p, "pts/", 4) == 0)
- p += 4;
- if (strchr(p, '/') != NULL) {
- /* A slash is an attempt to break security... */
- (void) snprintf(errbuf, sizeof(errbuf),
- "Too many '/' in \"%s\"", device);
- return (errbuf);
- }
- /*
- * open will fail on slip lines or exclusive-use lines
- * if not running as root; not an error.
- */
- if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) {
- if (errno == EBUSY || errno == EACCES)
- return (NULL);
- (void) snprintf(errbuf, sizeof(errbuf), "%s: %s", device,
- strerror(errno));
- return (errbuf);
- }
- for (cnt = 0, left = 0; cnt < iovcnt; ++cnt)
- left += iov[cnt].iov_len;
- for (;;) {
- wret = writev(fd, iov, iovcnt);
- if (wret >= left)
- break;
- if (wret >= 0) {
- left -= wret;
- if (iov != localiov) {
- bcopy(iov, localiov,
- iovcnt * sizeof(struct iovec));
- iov = localiov;
- }
- for (cnt = 0; (size_t)wret >= iov->iov_len; ++cnt) {
- wret -= iov->iov_len;
- ++iov;
- --iovcnt;
- }
- if (wret) {
- iov->iov_base = (char *)iov->iov_base + wret;
- iov->iov_len -= wret;
- }
- continue;
- }
- if (errno == EWOULDBLOCK) {
- int cpid;
- if (forked) {
- (void) close(fd);
- _exit(1);
- }
- cpid = fork();
- if (cpid < 0) {
- (void) snprintf(errbuf, sizeof(errbuf),
- "fork: %s", strerror(errno));
- (void) close(fd);
- return (errbuf);
- }
- if (cpid) { /* parent */
- (void) close(fd);
- return (NULL);
- }
- forked++;
- /* wait at most tmout seconds */
- (void) signal(SIGALRM, SIG_DFL);
- (void) signal(SIGTERM, SIG_DFL); /* XXX */
- (void) sigsetmask(0);
- (void) alarm((u_int)tmout);
- (void) fcntl(fd, F_SETFL, 0); /* clear O_NONBLOCK */
- continue;
- }
- /*
- * We get ENODEV on a slip line if we're running as root,
- * and EIO if the line just went away.
- */
- if (errno == ENODEV || errno == EIO)
- break;
- (void) close(fd);
- if (forked)
- _exit(1);
- (void) snprintf(errbuf, sizeof(errbuf),
- "%s: %s", device, strerror(errno));
- return (errbuf);
- }
- (void) close(fd);
- if (forked)
- _exit(0);
- return (NULL);
- }