| /* |
| * Copyright (c) 1989, 1993 |
| * 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) |
| * Mon Jul 1 17:01:39 MET DST 1996, janl@math.uio.no: |
| * - Added fix from David.Chapell@mail.trincoll.edu enabeling daemons |
| * to use write. |
| * - ANSIed it since I was working on it anyway. |
| */ |
| |
| #ifndef lint |
| static char copyright[] = |
| "@(#) Copyright (c) 1989, 1993\n\ |
| The Regents of the University of California. All rights reserved.\n"; |
| #endif /* not lint */ |
| |
| #ifndef lint |
| static char sccsid[] = "@(#)write.c 8.1 (Berkeley) 6/6/93"; |
| #endif /* not lint */ |
| |
| #define _GNU_SOURCE /* for snprintf */ |
| |
| #include <unistd.h> |
| #include <utmp.h> |
| #include <ctype.h> |
| #include <pwd.h> |
| #include <stdio.h> |
| #include <string.h> |
| #include <sys/param.h> |
| #include <sys/signal.h> |
| #include <sys/stat.h> |
| #include <sys/file.h> |
| #include <sys/time.h> |
| #ifdef __linux__ |
| #include <paths.h> |
| #include "pathnames.h" |
| #include <locale.h> |
| #endif |
| |
| void search_utmp(char *, char *, char *, uid_t); |
| void do_write(char *, char *, uid_t); |
| void wr_fputs(char *); |
| int term_chk(char *, int *, time_t *, int); |
| int utmp_chk(char *, char *); |
| |
| extern int errno; |
| |
| void |
| main(int argc, char **argv) |
| { |
| register char *cp; |
| time_t atime; |
| uid_t myuid; |
| int msgsok, myttyfd; |
| char tty[MAXPATHLEN], *mytty, *ttyname(); |
| void done(); |
| |
| #ifdef __linux__ |
| setlocale(LC_CTYPE,""); |
| #endif |
| |
| /* 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 { |
| myttyfd = -1; |
| } |
| if (myttyfd != -1) { |
| if (!(mytty = ttyname(myttyfd))) { |
| (void)fprintf(stderr, "write: can't find your tty's name\n"); |
| exit(1); |
| } |
| if ((cp = rindex(mytty, '/')) != NULL) |
| 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); |
| } |
| |
| } else { |
| mytty = "<no tty>"; |
| } |
| |
| 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 |
| */ |
| int utmp_chk(char *user, char *tty) |
| |
| { |
| struct utmp u; |
| struct utmp *uptr; |
| int res = 1; |
| |
| utmpname(_PATH_UTMP); |
| setutent(); |
| |
| while ((uptr = getutent())) { |
| memcpy(&u, uptr, sizeof(u)); |
| if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0 && |
| strncmp(tty, u.ut_line, sizeof(u.ut_line)) == 0) { |
| res = 0; |
| break; |
| } |
| } |
| |
| endutent(); |
| return(res); |
| } |
| |
| /* |
| * 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. |
| */ |
| void search_utmp(char *user, char *tty, char *mytty, uid_t myuid) |
| |
| { |
| struct utmp u; |
| struct utmp *uptr; |
| time_t bestatime, atime; |
| int nloggedttys, nttys, msgsok, user_is_me; |
| #ifdef __linux__ |
| char atty[sizeof(u.ut_line) + 1]; |
| #else |
| char atty[UT_LINESIZE + 1]; |
| #endif |
| |
| utmpname(_PATH_UTMP); |
| setutent(); |
| |
| nloggedttys = nttys = 0; |
| bestatime = 0; |
| user_is_me = 0; |
| while ((uptr = getutent())) { |
| memcpy(&u, uptr, 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); |
| } |
| } |
| } |
| |
| endutent(); |
| 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 |
| */ |
| int term_chk(char *tty, int *msgsokP, time_t *atimeP, int showerror) |
| |
| { |
| struct stat s; |
| char path[MAXPATHLEN]; |
| |
| (void)snprintf(path, sizeof(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 |
| */ |
| void do_write(char *tty, char *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)) != NULL) |
| login = pwd->pw_name; |
| else |
| login = "???"; |
| |
| (void)snprintf(path, sizeof(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) |
| { |
| (void)printf("EOF\r\n"); |
| exit(0); |
| } |
| |
| /* |
| * wr_fputs - like fputs(), but makes control characters visible and |
| * turns \n into \r\n |
| */ |
| void wr_fputs(char *s) |
| |
| { |
| char c; |
| |
| #define PUTC(c) if (putchar(c) == EOF) goto err; |
| |
| for (; *s != '\0'; ++s) { |
| c = *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 |
| } |