-#ifndef lint
-static char *sccsid = "@(#)write.c 4.14 %G%";
-#endif
/*
- * write to another user
+ * 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.
*/
-#include <stdio.h>
-#include <ctype.h>
-#include <sys/types.h>
+#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 */
+
+#include <sys/param.h>
+#include <sys/signal.h>
#include <sys/stat.h>
-#include <signal.h>
-#include <utmp.h>
+#include <sys/file.h>
#include <sys/time.h>
-#include "pathnames.h"
-
-#define NMAX sizeof(ubuf.ut_name)
-#define LMAX sizeof(ubuf.ut_line)
-
-char *strcat();
-char *strcpy();
-struct utmp ubuf;
-int signum[] = {SIGHUP, SIGINT, SIGQUIT, 0};
-char me[NMAX + 1] = "???";
-char *him;
-char *mytty;
-char histty[32];
-char ttybuf[32];
-char *histtya;
-char *ttyname();
-char *rindex();
-int logcnt;
-int eof();
-int timout();
-FILE *tf;
-char *getenv();
+#include <utmp.h>
+#include <ctype.h>
+#include <pwd.h>
+#include <stdio.h>
+#include <string.h>
+
+extern int errno;
main(argc, argv)
int argc;
- char *argv[];
+ char **argv;
{
- struct stat stbuf;
- register i;
- register FILE *uf;
- int c1, c2;
- long clock = time(0);
- int suser = getuid() == 0;
- int nomesg = 0;
- struct tm *localtime();
- struct tm *localclock = localtime( &clock );
-
- if (argc < 2) {
- fprintf(stderr, "Usage: write user [ttyname]\n");
+ 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);
}
- him = argv[1];
- if (argc > 2)
- histtya = argv[2];
- if ((uf = fopen(_PATH_UTMP, "r")) == NULL) {
- fprintf(stderr, "write: can't read %s\n", _PATH_UTMP);
- if (histtya == 0)
- exit(10);
- goto cont;
- }
- mytty = ttyname(2);
- if (mytty == NULL) {
- fprintf(stderr, "write: Can't find your tty\n");
+ if (!(mytty = ttyname(myttyfd))) {
+ (void)fprintf(stderr, "write: can't find your tty's name\n");
exit(1);
}
- if (stat(mytty, &stbuf) < 0) {
- perror("write: Can't stat your tty");
+ 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);
}
- if ((stbuf.st_mode&020) == 0) {
- fprintf(stderr,
- "write: You have write permission turned off\n");
- if (!suser)
+
+ 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);
- }
- mytty = rindex(mytty, '/') + 1;
- if (histtya) {
- strcpy(histty, _PATH_DEV);
- strcat(histty, histtya);
- }
- while (fread((char *)&ubuf, sizeof(ubuf), 1, uf) == 1) {
- if (ubuf.ut_name[0] == '\0')
- continue;
- if (strcmp(ubuf.ut_line, mytty)==0) {
- for (i=0; i<NMAX; i++) {
- c1 = ubuf.ut_name[i];
- if (c1 == ' ')
- c1 = 0;
- me[i] = c1;
- if (c1 == 0)
- break;
- }
}
- if (him[0] == '-' && him[1] == 0)
- goto nomat;
- for (i=0; i<NMAX; i++) {
- c1 = him[i];
- c2 = ubuf.ut_name[i];
- if (c1 == 0)
- if (c2 == 0 || c2 == ' ')
- break;
- if (c1 != c2)
- goto nomat;
- }
- if (histtya && strncmp(histtya, ubuf.ut_line,
- sizeof(ubuf.ut_line)))
- continue;
- logcnt++;
- if (histty[0]==0 || nomesg && histtya == 0) {
- strcpy(ttybuf, _PATH_DEV);
- strcat(ttybuf, ubuf.ut_line);
- if (histty[0]==0)
- strcpy(histty, ttybuf);
- if (access(ttybuf, 0) < 0 || stat(ttybuf, &stbuf) < 0 ||
- (stbuf.st_mode&020) == 0)
- nomesg++;
- else {
- strcpy(histty, ttybuf);
- nomesg = 0;
- }
+ 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);
}
- nomat:
- ;
- }
- fclose(uf);
- if (logcnt==0) {
- fprintf(stderr, "write: %s not logged in%s\n", him,
- histtya ? " on that tty" : "");
- exit(1);
- }
- if (histtya==0 && logcnt > 1) {
- fprintf(stderr,
- "write: %s logged in more than once ... writing to %s\n",
- him, histty+5);
- }
-cont:
- if (access(histty, 0) < 0) {
- fprintf(stderr, "write: No such tty\n");
- exit(1);
- }
- signal(SIGALRM, timout);
- alarm(5);
- if ((tf = fopen(histty, "w")) == NULL) {
- fprintf(stderr, "write: Permission denied\n");
+ do_write(argv[2], mytty, myuid);
+ break;
+ default:
+ (void)fprintf(stderr, "usage: write user [tty]\n");
exit(1);
}
- alarm(0);
- sigs(eof);
- { char hostname[32];
- gethostname(hostname, sizeof (hostname));
- fprintf(tf,
- "\r\nMessage from %s@%s on %s at %d:%02d ...\r\n\007\007\007",
- me, hostname, mytty, localclock->tm_hour, localclock->tm_min);
- fflush(tf);
- }
- for (;;) {
- char buf[BUFSIZ];
- register char *bp;
- i = read(0, buf, sizeof buf);
- if (i <= 0)
- eof();
- if (buf[0] == '!') {
- buf[i] = 0;
- ex(buf);
- continue;
+ 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);
}
- for (bp = buf; --i >= 0; bp++) {
- if (*bp == '\n')
- putc('\r', tf);
-
- if (!isascii(*bp)) {
- putc('M', tf);
- putc('-', tf);
- *bp = toascii(*bp);
- }
- if (isprint(*bp) ||
- *bp == ' ' || *bp == '\t' || *bp == '\n') {
- putc(*bp, tf);
- } else {
- putc('^', tf);
- putc(*bp ^ 0100, tf);
- }
+ (void)close(ufd);
+ return(1);
+}
- if (*bp == '\n')
- fflush(tf);
+/*
+ * 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;
+ char atty[UT_LINESIZE + 1];
+
+ if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0) {
+ perror("utmp");
+ exit(1);
+ }
- if (ferror(tf) || feof(tf)) {
- printf("\n\007Write failed (%s logged out?)\n",
- him);
- 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;
+ (void)strncpy(atty, u.ut_line, UT_LINESIZE);
+ atty[UT_LINESIZE] = '\0';
+ 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 */
+ }
+ ++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);
}
}
-timout()
+/*
+ * 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];
- fprintf(stderr, "write: Timeout opening their tty\n");
- exit(1);
+ (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);
}
-eof()
+/*
+ * 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();
- fprintf(tf, "EOF\r\n");
- exit(0);
+ /* 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);
}
-ex(bp)
- char *bp;
+/*
+ * done - cleanup and exit
+ */
+void
+done()
{
- register i;
-
- sigs(SIG_IGN);
- i = fork();
- if (i < 0) {
- printf("Try again\n");
- goto out;
- }
- if (i == 0) {
- fclose(tf); /* Close his terminal */
- setgid(getgid()); /* Give up effective group privs */
- sigs((int (*)())0);
- execl(getenv("SHELL") ?
- getenv("SHELL") : _PATH_BSHELL, "sh", "-c", bp+1, 0);
- exit(0);
- }
- while (wait((int *)NULL) != i)
- ;
- printf("!\n");
-out:
- sigs(eof);
+ (void)printf("EOF\r\n");
+ exit(0);
}
-sigs(sig)
- int (*sig)();
+/*
+ * wr_fputs - like fputs(), but makes control characters visible and
+ * turns \n into \r\n
+ */
+wr_fputs(s)
+ register char *s;
{
- register i;
+ register char c;
- for (i=0; signum[i]; i++)
- signal(signum[i], sig);
+#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
}