Imported from util-linux-2.2 tarball.

1 files changed, 347 insertions, 0 deletions

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 <sys/param.h>
+#include <sys/signal.h>
+#include <sys/stat.h>
+#include <sys/file.h>
+#include <sys/time.h>
+#include <utmp.h>
+#include <ctype.h>
+#include <pwd.h>
+#include <stdio.h>
+#include <string.h>
+#ifdef __linux__
+#include <paths.h>
+#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
+}