From cfe5e3905201349e9cf3f95d52ff4bd100bde37d Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 14 Apr 2024 21:10:49 +0200 Subject: Adding upstream version 2.39.3. Signed-off-by: Daniel Baumann --- term-utils/write.c | 356 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 356 insertions(+) create mode 100644 term-utils/write.c (limited to 'term-utils/write.c') diff --git a/term-utils/write.c b/term-utils/write.c new file mode 100644 index 0000000..a5a2128 --- /dev/null +++ b/term-utils/write.c @@ -0,0 +1,356 @@ +/* + * 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 enabling daemons + * to use write. + * - ANSIed it since I was working on it anyway. + * 1999-02-22 Arkadiusz Miśkiewicz + * - added Native Language Support + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "c.h" +#include "carefulputc.h" +#include "closestream.h" +#include "nls.h" +#include "strutils.h" +#include "ttyutils.h" +#include "xalloc.h" + +static volatile sig_atomic_t signal_received = 0; + +struct write_control { + uid_t src_uid; + const char *src_login; + const char *src_tty_path; + const char *src_tty_name; + const char *dst_login; + char *dst_tty_path; + const char *dst_tty_name; +}; + +static void __attribute__((__noreturn__)) usage(void) +{ + FILE *out = stdout; + fputs(USAGE_HEADER, out); + fprintf(out, + _(" %s [options] []\n"), + program_invocation_short_name); + + fputs(USAGE_SEPARATOR, out); + fputs(_("Send a message to another user.\n"), out); + + fputs(USAGE_OPTIONS, out); + printf(USAGE_HELP_OPTIONS(16)); + printf(USAGE_MAN_TAIL("write(1)")); + exit(EXIT_SUCCESS); +} + +/* + * check_tty - check that a terminal exists, and get the message bit + * and the access time + */ +static int check_tty(const char *tty, int *tty_writeable, time_t *tty_atime, int showerror) +{ + struct stat s; + + if (stat(tty, &s) < 0) { + if (showerror) + warn("%s", tty); + return 1; + } + if (getuid() == 0) /* root can always write */ + *tty_writeable = 1; + else { + if (getegid() != s.st_gid) { + warnx(_("effective gid does not match group of %s"), tty); + return 1; + } + *tty_writeable = s.st_mode & S_IWGRP; + } + if (tty_atime) + *tty_atime = s.st_atime; + return 0; +} + +/* + * check_utmp - checks that the given user is actually logged in on + * the given tty + */ +static int check_utmp(const struct write_control *ctl) +{ + struct utmpx *u; + int res = 1; + + utmpxname(_PATH_UTMP); + setutxent(); + + while ((u = getutxent())) { + if (strncmp(ctl->dst_login, u->ut_user, sizeof(u->ut_user)) == 0 && + strncmp(ctl->dst_tty_name, u->ut_line, sizeof(u->ut_line)) == 0) { + res = 0; + break; + } + } + + endutxent(); + 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. + */ +static void search_utmp(struct write_control *ctl) +{ + struct utmpx *u; + time_t best_atime = 0, tty_atime; + int num_ttys = 0, valid_ttys = 0, tty_writeable = 0, user_is_me = 0; + char path[sizeof(u->ut_line) + 6]; + + utmpxname(_PATH_UTMP); + setutxent(); + + while ((u = getutxent())) { + if (strncmp(ctl->dst_login, u->ut_user, sizeof(u->ut_user)) != 0) + continue; + num_ttys++; + snprintf(path, sizeof(path), "/dev/%s", u->ut_line); + if (check_tty(path, &tty_writeable, &tty_atime, 0)) + /* bad term? skip */ + continue; + if (ctl->src_uid && !tty_writeable) + /* skip ttys with msgs off */ + continue; + if (memcmp(u->ut_line, ctl->src_tty_name, strlen(ctl->src_tty_name) + 1) == 0) { + user_is_me = 1; + /* don't write to yourself */ + continue; + } + if (u->ut_type != USER_PROCESS) + /* it's not a valid entry */ + continue; + valid_ttys++; + if (best_atime < tty_atime) { + best_atime = tty_atime; + free(ctl->dst_tty_path); + ctl->dst_tty_path = xstrdup(path); + ctl->dst_tty_name = ctl->dst_tty_path + 5; + } + } + + endutxent(); + if (num_ttys == 0) + errx(EXIT_FAILURE, _("%s is not logged in"), ctl->dst_login); + if (valid_ttys == 0) { + if (user_is_me) { + /* ok, so write to yourself! */ + if (!ctl->src_tty_path) + errx(EXIT_FAILURE, _("can't find your tty's name")); + ctl->dst_tty_path = xstrdup(ctl->src_tty_path); + ctl->dst_tty_name = ctl->dst_tty_path + 5; + return; + } + errx(EXIT_FAILURE, _("%s has messages disabled"), ctl->dst_login); + } + if (1 < valid_ttys) + warnx(_("%s is logged in more than once; writing to %s"), + ctl->dst_login, ctl->dst_tty_name); +} + +/* + * signal_handler - cause write loop to exit + */ +static void signal_handler(int signo) +{ + signal_received = signo; +} + +/* + * do_write - actually make the connection + */ +static void do_write(const struct write_control *ctl) +{ + char *login, *pwuid; + struct passwd *pwd; + time_t now; + struct tm *tm; + char *host, *line = NULL; + size_t linelen = 0; + struct sigaction sigact; + + /* Determine our login name(s) before the we reopen() stdout */ + if ((pwd = getpwuid(ctl->src_uid)) != NULL) + pwuid = pwd->pw_name; + else + pwuid = "???"; + if ((login = getlogin()) == NULL) + login = pwuid; + + if ((freopen(ctl->dst_tty_path, "w", stdout)) == NULL) + err(EXIT_FAILURE, "%s", ctl->dst_tty_path); + + sigact.sa_handler = signal_handler; + sigemptyset(&sigact.sa_mask); + sigact.sa_flags = 0; + sigaction(SIGINT, &sigact, NULL); + sigaction(SIGHUP, &sigact, NULL); + + host = xgethostname(); + if (!host) + host = xstrdup("???"); + + now = time((time_t *)NULL); + tm = localtime(&now); + /* print greeting */ + printf("\r\n\a\a\a"); + if (strcmp(login, pwuid) != 0) + printf(_("Message from %s@%s (as %s) on %s at %02d:%02d ..."), + login, host, pwuid, ctl->src_tty_name, + tm->tm_hour, tm->tm_min); + else + printf(_("Message from %s@%s on %s at %02d:%02d ..."), + login, host, ctl->src_tty_name, + tm->tm_hour, tm->tm_min); + free(host); + printf("\r\n"); + + while (getline(&line, &linelen, stdin) >= 0) { + if (signal_received) + break; + + if (fputs_careful(line, stdout, '^', true, 0) == EOF) + err(EXIT_FAILURE, _("carefulputc failed")); + } + free(line); + printf("EOF\r\n"); +} + +int main(int argc, char **argv) +{ + int tty_writeable = 0, c; + struct write_control ctl = { 0 }; + + static const struct option longopts[] = { + {"version", no_argument, NULL, 'V'}, + {"help", no_argument, NULL, 'h'}, + {NULL, 0, NULL, 0} + }; + + setlocale(LC_ALL, ""); + bindtextdomain(PACKAGE, LOCALEDIR); + textdomain(PACKAGE); + close_stdout_atexit(); + + while ((c = getopt_long(argc, argv, "Vh", longopts, NULL)) != -1) + switch (c) { + case 'V': + print_version(EXIT_SUCCESS); + case 'h': + usage(); + default: + errtryhelp(EXIT_FAILURE); + } + + if (get_terminal_name(&ctl.src_tty_path, &ctl.src_tty_name, NULL) == 0) { + /* check that sender has write enabled */ + if (check_tty(ctl.src_tty_path, &tty_writeable, NULL, 1)) + exit(EXIT_FAILURE); + if (!tty_writeable) + errx(EXIT_FAILURE, + _("you have write permission turned off")); + tty_writeable = 0; + } else + ctl.src_tty_name = ""; + + ctl.src_uid = getuid(); + + /* check args */ + switch (argc) { + case 2: + ctl.dst_login = argv[1]; + search_utmp(&ctl); + do_write(&ctl); + break; + case 3: + ctl.dst_login = argv[1]; + if (!strncmp(argv[2], "/dev/", 5)) + ctl.dst_tty_path = xstrdup(argv[2]); + else + xasprintf(&ctl.dst_tty_path, "/dev/%s", argv[2]); + ctl.dst_tty_name = ctl.dst_tty_path + 5; + if (check_utmp(&ctl)) + errx(EXIT_FAILURE, + _("%s is not logged in on %s"), + ctl.dst_login, ctl.dst_tty_name); + if (check_tty(ctl.dst_tty_path, &tty_writeable, NULL, 1)) + exit(EXIT_FAILURE); + if (ctl.src_uid && !tty_writeable) + errx(EXIT_FAILURE, + _("%s has messages disabled on %s"), + ctl.dst_login, ctl.dst_tty_name); + do_write(&ctl); + break; + default: + errtryhelp(EXIT_FAILURE); + } + free(ctl.dst_tty_path); + return EXIT_SUCCESS; +} -- cgit v1.2.3