From 6dbe3af945a63f025561abb83275cee9ff06c57b Mon Sep 17 00:00:00 2001 From: Karel Zak Date: Thu, 7 Dec 2006 00:25:32 +0100 Subject: Imported from util-linux-2.2 tarball. --- misc-utils/write.c | 347 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 347 insertions(+) create mode 100644 misc-utils/write.c (limited to 'misc-utils/write.c') diff --git a/misc-utils/write.c b/misc-utils/write.c new file mode 100644 index 000000000..f2fe4a086 --- /dev/null +++ b/misc-utils/write.c @@ -0,0 +1,347 @@ +/* + * Copyright (c) 1989 The Regents of the University of California. + * All rights reserved. + * + * This code is derived from software contributed to Berkeley by + * Jef Poskanzer and Craig Leres of the Lawrence Berkeley Laboratory. + * + * 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. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 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. + * + * Modified for Linux, Mon Mar 8 18:16:24 1993, faith@cs.unc.edu + * Wed Jun 22 21:41:56 1994, faith@cs.unc.edu: + * Added fix from Mike Grupenhoff (kashmir@umiacs.umd.edu) + * + */ + +#ifndef lint +char copyright[] = +"@(#) Copyright (c) 1989 The Regents of the University of California.\n\ + All rights reserved.\n"; +#endif /* not lint */ + +#ifndef lint +static char sccsid[] = "@(#)write.c 4.22 (Berkeley) 6/1/90"; +#endif /* not lint */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#ifdef __linux__ +#include +#endif + +extern int errno; + +main(argc, argv) + int argc; + char **argv; +{ + register char *cp; + time_t atime; + uid_t myuid; + int msgsok, myttyfd; + char tty[MAXPATHLEN], *mytty, *ttyname(); + void done(); + + /* check that sender has write enabled */ + if (isatty(fileno(stdin))) + myttyfd = fileno(stdin); + else if (isatty(fileno(stdout))) + myttyfd = fileno(stdout); + else if (isatty(fileno(stderr))) + myttyfd = fileno(stderr); + else { + (void)fprintf(stderr, "write: can't find your tty\n"); + exit(1); + } + if (!(mytty = ttyname(myttyfd))) { + (void)fprintf(stderr, "write: can't find your tty's name\n"); + exit(1); + } + if (cp = rindex(mytty, '/')) + mytty = cp + 1; + if (term_chk(mytty, &msgsok, &atime, 1)) + exit(1); + if (!msgsok) { + (void)fprintf(stderr, + "write: you have write permission turned off.\n"); + exit(1); + } + + myuid = getuid(); + + /* check args */ + switch (argc) { + case 2: + search_utmp(argv[1], tty, mytty, myuid); + do_write(tty, mytty, myuid); + break; + case 3: + if (!strncmp(argv[2], "/dev/", 5)) + argv[2] += 5; + if (utmp_chk(argv[1], argv[2])) { + (void)fprintf(stderr, + "write: %s is not logged in on %s.\n", + argv[1], argv[2]); + exit(1); + } + if (term_chk(argv[2], &msgsok, &atime, 1)) + exit(1); + if (myuid && !msgsok) { + (void)fprintf(stderr, + "write: %s has messages disabled on %s\n", + argv[1], argv[2]); + exit(1); + } + do_write(argv[2], mytty, myuid); + break; + default: + (void)fprintf(stderr, "usage: write user [tty]\n"); + exit(1); + } + done(); + /* NOTREACHED */ +} + +/* + * utmp_chk - checks that the given user is actually logged in on + * the given tty + */ +utmp_chk(user, tty) + char *user, *tty; +{ + struct utmp u; + int ufd; + + if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0) + return(0); /* ignore error, shouldn't happen anyway */ + + while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u)) + if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0 && + strncmp(tty, u.ut_line, sizeof(u.ut_line)) == 0) { + (void)close(ufd); + return(0); + } + + (void)close(ufd); + return(1); +} + +/* + * search_utmp - search utmp for the "best" terminal to write to + * + * Ignores terminals with messages disabled, and of the rest, returns + * the one with the most recent access time. Returns as value the number + * of the user's terminals with messages enabled, or -1 if the user is + * not logged in at all. + * + * Special case for writing to yourself - ignore the terminal you're + * writing from, unless that's the only terminal with messages enabled. + */ +search_utmp(user, tty, mytty, myuid) + char *user, *tty, *mytty; + uid_t myuid; +{ + struct utmp u; + time_t bestatime, atime; + int ufd, nloggedttys, nttys, msgsok, user_is_me; +#ifdef __linux__ + char atty[sizeof(u.ut_line) + 1]; +#else + char atty[UT_LINESIZE + 1]; +#endif + + if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0) { + perror("utmp"); + exit(1); + } + + nloggedttys = nttys = 0; + bestatime = 0; + user_is_me = 0; + while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u)) + if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0) { + ++nloggedttys; +#ifdef __linux__ + (void)strncpy(atty, u.ut_line, sizeof(u.ut_line)); + atty[sizeof(u.ut_line)] = '\0'; +#else + (void)strncpy(atty, u.ut_line, UT_LINESIZE); + atty[UT_LINESIZE] = '\0'; +#endif + if (term_chk(atty, &msgsok, &atime, 0)) + continue; /* bad term? skip */ + if (myuid && !msgsok) + continue; /* skip ttys with msgs off */ + if (strcmp(atty, mytty) == 0) { + user_is_me = 1; + continue; /* don't write to yourself */ + } +#ifdef __linux__ + if (u.ut_type != USER_PROCESS) + continue; /* it's not a valid entry */ +#endif + ++nttys; + if (atime > bestatime) { + bestatime = atime; + (void)strcpy(tty, atty); + } + } + + (void)close(ufd); + if (nloggedttys == 0) { + (void)fprintf(stderr, "write: %s is not logged in\n", user); + exit(1); + } + if (nttys == 0) { + if (user_is_me) { /* ok, so write to yourself! */ + (void)strcpy(tty, mytty); + return; + } + (void)fprintf(stderr, + "write: %s has messages disabled\n", user); + exit(1); + } else if (nttys > 1) { + (void)fprintf(stderr, + "write: %s is logged in more than once; writing to %s\n", + user, tty); + } +} + +/* + * term_chk - check that a terminal exists, and get the message bit + * and the access time + */ +term_chk(tty, msgsokP, atimeP, showerror) + char *tty; + int *msgsokP, showerror; + time_t *atimeP; +{ + struct stat s; + char path[MAXPATHLEN]; + + (void)sprintf(path, "/dev/%s", tty); + if (stat(path, &s) < 0) { + if (showerror) + (void)fprintf(stderr, + "write: %s: %s\n", path, strerror(errno)); + return(1); + } + *msgsokP = (s.st_mode & (S_IWRITE >> 3)) != 0; /* group write bit */ + *atimeP = s.st_atime; + return(0); +} + +/* + * do_write - actually make the connection + */ +do_write(tty, mytty, myuid) + char *tty, *mytty; + uid_t myuid; +{ + register char *login, *nows; + register struct passwd *pwd; + time_t now, time(); + char *getlogin(), path[MAXPATHLEN], host[MAXHOSTNAMELEN], line[512]; + void done(); + + /* Determine our login name before the we reopen() stdout */ + if ((login = getlogin()) == NULL) + if (pwd = getpwuid(myuid)) + login = pwd->pw_name; + else + login = "???"; + + (void)sprintf(path, "/dev/%s", tty); + if ((freopen(path, "w", stdout)) == NULL) { + (void)fprintf(stderr, "write: %s: %s\n", path, strerror(errno)); + exit(1); + } + + (void)signal(SIGINT, done); + (void)signal(SIGHUP, done); + + /* print greeting */ + if (gethostname(host, sizeof(host)) < 0) + (void)strcpy(host, "???"); + now = time((time_t *)NULL); + nows = ctime(&now); + nows[16] = '\0'; + (void)printf("\r\n\007\007\007Message from %s@%s on %s at %s ...\r\n", + login, host, mytty, nows + 11); + + while (fgets(line, sizeof(line), stdin) != NULL) + wr_fputs(line); +} + +/* + * done - cleanup and exit + */ +void +done() +{ + (void)printf("EOF\r\n"); + exit(0); +} + +/* + * wr_fputs - like fputs(), but makes control characters visible and + * turns \n into \r\n + */ +wr_fputs(s) + register char *s; +{ + register char c; + +#define PUTC(c) if (putchar(c) == EOF) goto err; + + for (; *s != '\0'; ++s) { + c = toascii(*s); + if (c == '\n') { + PUTC('\r'); + PUTC('\n'); + } else if (!isprint(c) && !isspace(c) && c != '\007') { + PUTC('^'); + PUTC(c^0x40); /* DEL to ?, others to alpha */ + } else + PUTC(c); + } + return; + +err: (void)fprintf(stderr, "write: %s\n", strerror(errno)); + exit(1); +#undef PUTC +} -- cgit v1.2.3-55-g7522