1 /* 2 * Copyright (c) 1989 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 */ 7 8 #ifndef lint 9 static char sccsid[] = "@(#)ttymsg.c 5.6 (Berkeley) 09/07/90"; 10 #endif /* not lint */ 11 12 #include <sys/types.h> 13 #include <sys/uio.h> 14 #include <sys/file.h> 15 #include <sys/signal.h> 16 #include <dirent.h> 17 #include <errno.h> 18 #include <paths.h> 19 #include <stdio.h> 20 21 /* 22 * display the contents of a uio structure on a terminal. Used by 23 * wall(1) and syslogd(8). Forks and finishes in child if write 24 * would block, waiting at most five minutes. 25 * Returns pointer to error string on unexpected error; 26 * string is not newline-terminated. Various "normal" errors 27 * are ignored (exclusive-use, lack of permission, etc.). 28 */ 29 char * 30 ttymsg(iov, iovcnt, line) 31 struct iovec *iov; 32 int iovcnt; 33 char *line; 34 { 35 extern int errno; 36 static char device[MAXNAMLEN] = _PATH_DEV; 37 static char errbuf[1024]; 38 register int cnt, fd, left, wret; 39 char *strcpy(), *strerror(); 40 struct iovec localiov[6]; 41 int forked = 0; 42 43 if (iovcnt > 6) 44 return ("too many iov's (change code in wall/ttymsg.c)"); 45 /* 46 * open will fail on slip lines or exclusive-use lines 47 * if not running as root; not an error. 48 */ 49 (void) strcpy(device + sizeof(_PATH_DEV) - 1, line); 50 if ((fd = open(device, O_WRONLY|O_NONBLOCK, 0)) < 0) { 51 if (errno != EBUSY && errno != EACCES) { 52 (void) sprintf(errbuf, "open %s: %s", device, 53 strerror(errno)); 54 return (errbuf); 55 } else 56 return (NULL); 57 } 58 59 for (cnt = left = 0; cnt < iovcnt; ++cnt) 60 left += iov[cnt].iov_len; 61 62 for (;;) { 63 if ((wret = writev(fd, iov, iovcnt)) < 0) { 64 if (errno == EWOULDBLOCK) { 65 int off = 0; 66 int cpid; 67 68 if (forked) { 69 (void) close(fd); 70 /* return ("already forked"); */ 71 /* "can't happen" */ 72 exit(1); 73 } 74 cpid = fork(); 75 if (cpid < 0) { 76 (void) sprintf(errbuf, "can't fork: %s", 77 strerror(errno)); 78 (void) close(fd); 79 return (errbuf); 80 } 81 if (cpid) { /* parent */ 82 (void) close(fd); 83 return (NULL); 84 } 85 forked++; 86 /* wait at most 5 minutes */ 87 (void) signal(SIGALRM, SIG_DFL); 88 (void) signal(SIGTERM, SIG_DFL); /* XXX */ 89 (void) sigsetmask(0); 90 (void) alarm((u_int)(60 * 5)); 91 (void) fcntl(fd, FNDELAY, &off); 92 continue; 93 } else { 94 /* 95 * we get ENODEV on a slip line if we're 96 * running as root, and EIO if the line 97 * just went away 98 */ 99 if (errno == ENODEV || errno == EIO) 100 break; 101 (void) sprintf(errbuf, "writing %s: %s", 102 device, strerror(errno)); 103 (void) close(fd); 104 return (errbuf); 105 } 106 } 107 if (wret < left) { 108 left -= wret; 109 if (iov != localiov) { 110 bcopy(iov, localiov, 111 iovcnt * sizeof (struct iovec)); 112 iov = localiov; 113 } 114 for (cnt = 0; wret >= iov->iov_len; ++cnt) { 115 wret -= iov->iov_len; 116 ++iov; 117 --iovcnt; 118 } 119 if (wret) { 120 iov->iov_base += wret; 121 iov->iov_len -= wret; 122 } 123 } else 124 break; 125 } 126 if (forked) 127 exit(0); 128 (void) close(fd); 129 return (NULL); 130 } 131