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authorCameron Katri <me@cameronkatri.com>2021-05-09 14:20:58 -0400
committerCameron Katri <me@cameronkatri.com>2021-05-09 14:20:58 -0400
commit5fd83771641d15c418f747bd343ba6738d3875f7 (patch)
tree5abf0f78f680d9837dbd93d4d4c3933bb7509599 /basic_cmds/write
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Diffstat (limited to 'basic_cmds/write')
-rw-r--r--basic_cmds/write/write.1106
-rw-r--r--basic_cmds/write/write.c332
2 files changed, 438 insertions, 0 deletions
diff --git a/basic_cmds/write/write.1 b/basic_cmds/write/write.1
new file mode 100644
index 0000000..c7c2df1
--- /dev/null
+++ b/basic_cmds/write/write.1
@@ -0,0 +1,106 @@
+.\" 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.
+.\"
+.\" @(#)write.1 8.1 (Berkeley) 6/6/93
+.\" $FreeBSD: src/usr.bin/write/write.1,v 1.10 2002/04/20 12:18:12 charnier Exp $
+.\"
+.Dd June 6, 1993
+.Dt WRITE 1
+.Os
+.Sh NAME
+.Nm write
+.Nd send a message to another user
+.Sh SYNOPSIS
+.Nm
+.Ar user
+.Op Ar ttyname
+.Sh DESCRIPTION
+The
+.Nm
+utility allows you to communicate with other users, by copying lines from
+your terminal to theirs.
+.Pp
+When you run the
+.Nm
+command, the user you are writing to gets a message of the form:
+.Pp
+.Dl Message from yourname@yourhost on yourtty at hh:mm ...
+.Pp
+Any further lines you enter will be copied to the specified user's
+terminal.
+If the other user wants to reply, they must run
+.Nm
+as well.
+.Pp
+When you are done, type an end-of-file or interrupt character.
+The other user will see the message
+.Ql EOF
+indicating that the
+conversation is over.
+.Pp
+You can prevent people (other than the super-user) from writing to you
+with the
+.Xr mesg 1
+command.
+.Pp
+If the user you want to write to is logged in on more than one terminal,
+you can specify which terminal to write to by specifying the terminal
+name as the second operand to the
+.Nm
+command.
+Alternatively, you can let
+.Nm
+select one of the terminals \- it will pick the one with the shortest
+idle time.
+This is so that if the user is logged in at work and also dialed up from
+home, the message will go to the right place.
+.Pp
+The traditional protocol for writing to someone is that the string
+.Ql \-o ,
+either at the end of a line or on a line by itself, means that it's the
+other person's turn to talk.
+The string
+.Ql oo
+means that the person believes the conversation to be
+over.
+.Sh SEE ALSO
+.Xr mesg 1 ,
+.Xr talk 1 ,
+.Xr wall 1 ,
+.Xr who 1
+.Sh HISTORY
+A
+.Nm
+command appeared in
+.At v1 .
diff --git a/basic_cmds/write/write.c b/basic_cmds/write/write.c
new file mode 100644
index 0000000..e3f2255
--- /dev/null
+++ b/basic_cmds/write/write.c
@@ -0,0 +1,332 @@
+/*
+ * 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 <sys/cdefs.h>
+#ifndef lint
+__unused static const char copyright[] =
+"@(#) Copyright (c) 1989, 1993\n\
+ The Regents of the University of California. All rights reserved.\n";
+#endif
+
+#if 0
+#ifndef lint
+static char sccsid[] = "@(#)write.c 8.1 (Berkeley) 6/6/93";
+#endif
+#endif
+
+__RCSID("$FreeBSD: src/usr.bin/write/write.c,v 1.17 2002/09/04 23:29:09 dwmalone Exp $");
+
+#include <sys/param.h>
+#include <sys/signal.h>
+#include <sys/stat.h>
+#include <sys/file.h>
+#include <sys/time.h>
+#include <ctype.h>
+#include <err.h>
+#include <locale.h>
+#include <paths.h>
+#include <pwd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <utmpx.h>
+
+void done(int);
+void do_write(char *, char *, uid_t);
+static void usage(void);
+int term_chk(char *, int *, time_t *, int);
+void wr_fputs(unsigned char *s);
+void search_utmp(char *, char *, char *, uid_t);
+int utmp_chk(char *, char *);
+
+int
+main(int argc, char **argv)
+{
+ char *cp;
+ time_t atime;
+ uid_t myuid;
+ int msgsok, myttyfd;
+ char tty[MAXPATHLEN], *mytty;
+
+ (void)setlocale(LC_CTYPE, "");
+
+ while (getopt(argc, argv, "") != -1)
+ usage();
+ argc -= optind;
+ argv += optind;
+
+ /* 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)
+ mytty = "tty??";
+ else
+ {
+ if (!(mytty = ttyname(myttyfd)))
+ errx(1, "can't find your tty's name");
+ if ((cp = rindex(mytty, '/')))
+ mytty = cp + 1;
+ if (term_chk(mytty, &msgsok, &atime, 1))
+ exit(1);
+ if (!msgsok)
+ errx(1, "you have write permission turned off");
+ }
+ myuid = getuid();
+
+ /* check args */
+ switch (argc) {
+ case 1:
+ search_utmp(argv[0], tty, mytty, myuid);
+ do_write(tty, mytty, myuid);
+ break;
+ case 2:
+ if (!strncmp(argv[1], _PATH_DEV, strlen(_PATH_DEV)))
+ argv[1] += strlen(_PATH_DEV);
+ if (utmp_chk(argv[0], argv[1]))
+ errx(1, "%s is not logged in on %s", argv[0], argv[1]);
+ if (term_chk(argv[1], &msgsok, &atime, 1))
+ exit(1);
+ if (myuid && !msgsok)
+ errx(1, "%s has messages disabled on %s", argv[0], argv[1]);
+ do_write(argv[1], mytty, myuid);
+ break;
+ default:
+ usage();
+ }
+ done(0);
+ return (0);
+}
+
+static void
+usage(void)
+{
+ (void)fprintf(stderr, "usage: write user [tty]\n");
+ exit(1);
+}
+
+/*
+ * utmp_chk - checks that the given user is actually logged in on
+ * the given tty
+ */
+int
+utmp_chk(char *user, char *tty)
+{
+ struct utmpx *u;
+
+ setutxent();
+ while((u = getutxent()) != NULL)
+ if(strncmp(u->ut_line, tty, sizeof(u->ut_line)) == 0) {
+ if(u->ut_type == USER_PROCESS &&
+ strncmp(u->ut_user, user, sizeof(u->ut_user)) == 0) {
+ endutxent();
+ return 0;
+ }
+ break;
+ }
+ endutxent();
+ 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.
+ */
+void
+search_utmp(char *user, char *tty, char *mytty, uid_t myuid)
+{
+ struct utmpx ux, *u;
+ time_t bestatime, atime;
+ int nloggedttys, nttys, msgsok, user_is_me;
+ char atty[sizeof(ux.ut_line) + 1];
+
+ nloggedttys = nttys = 0;
+ bestatime = 0;
+ user_is_me = 0;
+ setutxent();
+ while ((u = getutxent()) != NULL) {
+ if (u->ut_type != USER_PROCESS)
+ continue;
+ if (strncmp(user, u->ut_user, sizeof(u->ut_user)) == 0) {
+ ++nloggedttys;
+ (void)strlcpy(atty, u->ut_line, sizeof(atty));
+ 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);
+ }
+ }
+ }
+
+ endutxent();
+ if (nloggedttys == 0)
+ errx(1, "%s is not logged in", user);
+ if (nttys == 0) {
+ if (user_is_me) { /* ok, so write to yourself! */
+ (void)strcpy(tty, mytty);
+ return;
+ }
+ errx(1, "%s has messages disabled", user);
+ } else if (nttys > 1) {
+ warnx("%s is logged in more than once; writing to %s", 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), "%s%s", _PATH_DEV, tty);
+ if (stat(path, &s) < 0) {
+ if (showerror)
+ warn("%s", path);
+ 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)
+{
+ const char *login;
+ char *nows;
+ struct passwd *pwd;
+ time_t now;
+ char path[MAXPATHLEN], host[MAXHOSTNAMELEN], line[512];
+
+ /* Determine our login name before the we reopen() stdout */
+ if ((login = getlogin()) == NULL) {
+ if ((pwd = getpwuid(myuid)))
+ login = pwd->pw_name;
+ else
+ login = "???";
+ }
+
+ (void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty);
+ if ((freopen(path, "w", stdout)) == NULL)
+ err(1, "%s", path);
+
+ (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((unsigned char *)line);
+}
+
+/*
+ * done - cleanup and exit
+ */
+void
+done(int n)
+{
+ (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(unsigned char *s)
+{
+
+#define PUTC(c) if (putchar(c) == EOF) err(1, NULL);
+
+ for (; *s != '\0'; ++s) {
+ if (*s == '\n') {
+ PUTC('\r');
+ } else if (((*s & 0x80) && *s < 0xA0) ||
+ /* disable upper controls */
+ (!isprint(*s) && !isspace(*s) &&
+ *s != '\a' && *s != '\b')
+ ) {
+ if (*s & 0x80) {
+ *s &= ~0x80;
+ PUTC('M');
+ PUTC('-');
+ }
+ if (iscntrl(*s)) {
+ *s ^= 0x40;
+ PUTC('^');
+ }
+ }
+ PUTC(*s);
+ }
+ return;
+#undef PUTC
+}