2 * Pseudo-tty backend for pterm.
19 #include <sys/types.h>
22 #include <sys/ioctl.h>
39 /* updwtmpx() needs the name of the wtmp file. Try to find it. */
42 #define WTMPX_FILE _PATH_WTMPX
44 #define WTMPX_FILE "/var/log/wtmpx"
50 #define LASTLOG_FILE _PATH_LASTLOG
52 #define LASTLOG_FILE "/var/log/lastlog"
57 * Set up a default for vaguely sane systems. The idea is that if
58 * OMIT_UTMP is not defined, then at least one of the symbols which
59 * enable particular forms of utmp processing should be, if only so
60 * that a link error can warn you that you should have defined
61 * OMIT_UTMP if you didn't want any. Currently HAVE_PUTUTLINE is
62 * the only such symbol.
65 #if !defined HAVE_PUTUTLINE
66 #define HAVE_PUTUTLINE
70 typedef struct pty_tag *Pty;
73 * The pty_signal_pipe, along with the SIGCHLD handler, must be
74 * process-global rather than session-specific.
76 static int pty_signal_pipe[2] = { -1, -1 }; /* obviously bogus initial val */
80 int master_fd, slave_fd;
82 char name[FILENAME_MAX];
84 int term_width, term_height;
85 int child_dead, finished;
91 * We store our pty backends in a tree sorted by master fd, so that
92 * when we get an uxsel notification we know which backend instance
93 * is the owner of the pty that caused it.
95 static int pty_compare_by_fd(void *av, void *bv)
100 if (a->master_fd < b->master_fd)
102 else if (a->master_fd > b->master_fd)
107 static int pty_find_by_fd(void *av, void *bv)
112 if (a < b->master_fd)
114 else if (a > b->master_fd)
119 static tree234 *ptys_by_fd = NULL;
122 * We also have a tree sorted by child pid, so that when we wait()
123 * in response to the signal we know which backend instance is the
124 * owner of the process that caused the signal.
126 static int pty_compare_by_pid(void *av, void *bv)
131 if (a->child_pid < b->child_pid)
133 else if (a->child_pid > b->child_pid)
138 static int pty_find_by_pid(void *av, void *bv)
143 if (a < b->child_pid)
145 else if (a > b->child_pid)
150 static tree234 *ptys_by_pid = NULL;
153 * If we are using pty_pre_init(), it will need to have already
154 * allocated a pty structure, which we must then return from
155 * pty_init() rather than allocating a new one. Here we store that
156 * structure between allocation and use.
158 * Note that although most of this module is entirely capable of
159 * handling multiple ptys in a single process, pty_pre_init() is
160 * fundamentally _dependent_ on there being at most one pty per
161 * process, so the normal static-data constraints don't apply.
163 * Likewise, since utmp is only used via pty_pre_init, it too must
164 * be single-instance, so we can declare utmp-related variables
167 static Pty single_pty = NULL;
170 static int pty_utmp_helper_pid, pty_utmp_helper_pipe;
171 static int pty_stamped_utmp;
172 static struct utmpx utmp_entry;
176 * pty_argv is a grievous hack to allow a proper argv to be passed
177 * through from the Unix command line. Again, it doesn't really
178 * make sense outside a one-pty-per-process setup.
182 static void pty_close(Pty pty);
183 static void pty_try_write(Pty pty);
186 static void setup_utmp(char *ttyname, char *location)
189 struct lastlog lastlog_entry;
195 pw = getpwuid(getuid());
196 memset(&utmp_entry, 0, sizeof(utmp_entry));
197 utmp_entry.ut_type = USER_PROCESS;
198 utmp_entry.ut_pid = getpid();
199 strncpy(utmp_entry.ut_line, ttyname+5, lenof(utmp_entry.ut_line));
200 strncpy(utmp_entry.ut_id, ttyname+8, lenof(utmp_entry.ut_id));
201 strncpy(utmp_entry.ut_user, pw->pw_name, lenof(utmp_entry.ut_user));
202 strncpy(utmp_entry.ut_host, location, lenof(utmp_entry.ut_host));
204 * Apparently there are some architectures where (struct
205 * utmpx).ut_tv is not essentially struct timeval (e.g. Linux
206 * amd64). Hence the temporary.
208 gettimeofday(&tv, NULL);
209 utmp_entry.ut_tv.tv_sec = tv.tv_sec;
210 utmp_entry.ut_tv.tv_usec = tv.tv_usec;
213 pututxline(&utmp_entry);
216 updwtmpx(WTMPX_FILE, &utmp_entry);
219 memset(&lastlog_entry, 0, sizeof(lastlog_entry));
220 strncpy(lastlog_entry.ll_line, ttyname+5, lenof(lastlog_entry.ll_line));
221 strncpy(lastlog_entry.ll_host, location, lenof(lastlog_entry.ll_host));
222 time(&lastlog_entry.ll_time);
223 if ((lastlog = fopen(LASTLOG_FILE, "r+")) != NULL) {
224 fseek(lastlog, sizeof(lastlog_entry) * getuid(), SEEK_SET);
225 fwrite(&lastlog_entry, 1, sizeof(lastlog_entry), lastlog);
230 pty_stamped_utmp = 1;
234 static void cleanup_utmp(void)
238 if (!pty_stamped_utmp)
241 utmp_entry.ut_type = DEAD_PROCESS;
242 memset(utmp_entry.ut_user, 0, lenof(utmp_entry.ut_user));
243 gettimeofday(&tv, NULL);
244 utmp_entry.ut_tv.tv_sec = tv.tv_sec;
245 utmp_entry.ut_tv.tv_usec = tv.tv_usec;
247 updwtmpx(WTMPX_FILE, &utmp_entry);
249 memset(utmp_entry.ut_line, 0, lenof(utmp_entry.ut_line));
250 utmp_entry.ut_tv.tv_sec = 0;
251 utmp_entry.ut_tv.tv_usec = 0;
254 pututxline(&utmp_entry);
257 pty_stamped_utmp = 0; /* ensure we never double-cleanup */
261 static void sigchld_handler(int signum)
263 write(pty_signal_pipe[1], "x", 1);
267 static void fatal_sig_handler(int signum)
269 putty_signal(signum, SIG_DFL);
276 static int pty_open_slave(Pty pty)
278 if (pty->slave_fd < 0) {
279 pty->slave_fd = open(pty->name, O_RDWR);
280 cloexec(pty->slave_fd);
283 return pty->slave_fd;
286 static void pty_open_master(Pty pty)
289 const char chars1[] = "pqrstuvwxyz";
290 const char chars2[] = "0123456789abcdef";
292 char master_name[20];
295 for (p1 = chars1; *p1; p1++)
296 for (p2 = chars2; *p2; p2++) {
297 sprintf(master_name, "/dev/pty%c%c", *p1, *p2);
298 pty->master_fd = open(master_name, O_RDWR);
299 if (pty->master_fd >= 0) {
300 if (geteuid() == 0 ||
301 access(master_name, R_OK | W_OK) == 0) {
303 * We must also check at this point that we are
304 * able to open the slave side of the pty. We
305 * wouldn't want to allocate the wrong master,
306 * get all the way down to forking, and _then_
307 * find we're unable to open the slave.
309 strcpy(pty->name, master_name);
310 pty->name[5] = 't'; /* /dev/ptyXX -> /dev/ttyXX */
312 cloexec(pty->master_fd);
314 if (pty_open_slave(pty) >= 0 &&
315 access(pty->name, R_OK | W_OK) == 0)
317 if (pty->slave_fd > 0)
318 close(pty->slave_fd);
321 close(pty->master_fd);
325 /* If we get here, we couldn't get a tty at all. */
326 fprintf(stderr, "pterm: unable to open a pseudo-terminal device\n");
331 /* We need to chown/chmod the /dev/ttyXX device. */
332 gp = getgrnam("tty");
333 chown(pty->name, getuid(), gp ? gp->gr_gid : -1);
334 chmod(pty->name, 0600);
336 pty->master_fd = open("/dev/ptmx", O_RDWR);
338 if (pty->master_fd < 0) {
339 perror("/dev/ptmx: open");
343 if (grantpt(pty->master_fd) < 0) {
348 if (unlockpt(pty->master_fd) < 0) {
353 cloexec(pty->master_fd);
355 pty->name[FILENAME_MAX-1] = '\0';
356 strncpy(pty->name, ptsname(pty->master_fd), FILENAME_MAX-1);
361 * Set the pty master into non-blocking mode.
364 ioctl(pty->master_fd, FIONBIO, &i);
368 ptys_by_fd = newtree234(pty_compare_by_fd);
369 add234(ptys_by_fd, pty);
373 * Pre-initialisation. This is here to get around the fact that GTK
374 * doesn't like being run in setuid/setgid programs (probably
375 * sensibly). So before we initialise GTK - and therefore before we
376 * even process the command line - we check to see if we're running
377 * set[ug]id. If so, we open our pty master _now_, chown it as
378 * necessary, and drop privileges. We can always close it again
379 * later. If we're potentially going to be doing utmp as well, we
380 * also fork off a utmp helper process and communicate with it by
381 * means of a pipe; the utmp helper will keep privileges in order
382 * to clean up utmp when we exit (i.e. when its end of our pipe
385 void pty_pre_init(void)
394 pty = single_pty = snew(struct pty_tag);
395 bufchain_init(&pty->output_data);
397 /* set the child signal handler straight away; it needs to be set
398 * before we ever fork. */
399 putty_signal(SIGCHLD, sigchld_handler);
400 pty->master_fd = pty->slave_fd = -1;
402 pty_stamped_utmp = FALSE;
405 if (geteuid() != getuid() || getegid() != getgid()) {
406 pty_open_master(pty);
411 * Fork off the utmp helper.
413 if (pipe(pipefd) < 0) {
414 perror("pterm: pipe");
421 perror("pterm: fork");
423 } else if (pid == 0) {
424 char display[128], buffer[128];
429 * Now sit here until we receive a display name from the
430 * other end of the pipe, and then stamp utmp. Unstamp utmp
431 * again, and exit, when the pipe closes.
437 ret = read(pipefd[0], buffer, lenof(buffer));
441 } else if (!pty_stamped_utmp) {
442 if (dlen < lenof(display))
443 memcpy(display+dlen, buffer,
444 min(ret, lenof(display)-dlen));
445 if (buffer[ret-1] == '\0') {
447 * Now we have a display name. NUL-terminate
448 * it, and stamp utmp.
450 display[lenof(display)-1] = '\0';
452 * Trap as many fatal signals as we can in the
453 * hope of having the best possible chance to
454 * clean up utmp before termination. We are
455 * unfortunately unprotected against SIGKILL,
458 putty_signal(SIGHUP, fatal_sig_handler);
459 putty_signal(SIGINT, fatal_sig_handler);
460 putty_signal(SIGQUIT, fatal_sig_handler);
461 putty_signal(SIGILL, fatal_sig_handler);
462 putty_signal(SIGABRT, fatal_sig_handler);
463 putty_signal(SIGFPE, fatal_sig_handler);
464 putty_signal(SIGPIPE, fatal_sig_handler);
465 putty_signal(SIGALRM, fatal_sig_handler);
466 putty_signal(SIGTERM, fatal_sig_handler);
467 putty_signal(SIGSEGV, fatal_sig_handler);
468 putty_signal(SIGUSR1, fatal_sig_handler);
469 putty_signal(SIGUSR2, fatal_sig_handler);
471 putty_signal(SIGBUS, fatal_sig_handler);
474 putty_signal(SIGPOLL, fatal_sig_handler);
477 putty_signal(SIGPROF, fatal_sig_handler);
480 putty_signal(SIGSYS, fatal_sig_handler);
483 putty_signal(SIGTRAP, fatal_sig_handler);
486 putty_signal(SIGVTALRM, fatal_sig_handler);
489 putty_signal(SIGXCPU, fatal_sig_handler);
492 putty_signal(SIGXFSZ, fatal_sig_handler);
495 putty_signal(SIGIO, fatal_sig_handler);
497 setup_utmp(pty->name, display);
503 pty_utmp_helper_pid = pid;
504 pty_utmp_helper_pipe = pipefd[1];
510 #ifndef HAVE_NO_SETRESUID
511 int gid = getgid(), uid = getuid();
512 int setresgid(gid_t, gid_t, gid_t);
513 int setresuid(uid_t, uid_t, uid_t);
514 setresgid(gid, gid, gid);
515 setresuid(uid, uid, uid);
523 int pty_real_select_result(Pty pty, int event, int status)
527 int finished = FALSE;
531 * We've been called because our child process did
532 * something. `status' tells us what.
534 if ((WIFEXITED(status) || WIFSIGNALED(status))) {
536 * The primary child process died. We could keep
537 * the terminal open for remaining subprocesses to
538 * output to, but conventional wisdom seems to feel
539 * that that's the Wrong Thing for an xterm-alike,
540 * so we bail out now (though we don't necessarily
541 * _close_ the window, depending on the state of
542 * Close On Exit). This would be easy enough to
543 * change or make configurable if necessary.
545 pty->exit_code = status;
546 pty->child_dead = TRUE;
547 del234(ptys_by_pid, pty);
553 ret = read(pty->master_fd, buf, sizeof(buf));
556 * Clean termination condition is that either ret == 0, or ret
557 * < 0 and errno == EIO. Not sure why the latter, but it seems
560 if (ret == 0 || (ret < 0 && errno == EIO)) {
562 * We assume a clean exit if the pty has closed but the
563 * actual child process hasn't. The only way I can
564 * imagine this happening is if it detaches itself from
565 * the pty and goes daemonic - in which case the
566 * expected usage model would precisely _not_ be for
567 * the pterm window to hang around!
570 if (!pty->child_dead)
572 } else if (ret < 0) {
573 perror("read pty master");
575 } else if (ret > 0) {
576 from_backend(pty->frontend, 0, buf, ret);
578 } else if (event == 2) {
580 * Attempt to send data down the pty.
586 if (finished && !pty->finished) {
587 uxsel_del(pty->master_fd);
591 pty->finished = TRUE;
594 * This is a slight layering-violation sort of hack: only
595 * if we're not closing on exit (COE is set to Never, or to
596 * Only On Clean and it wasn't a clean exit) do we output a
597 * `terminated' message.
599 if (pty->cfg.close_on_exit == FORCE_OFF ||
600 (pty->cfg.close_on_exit == AUTO && pty->exit_code != 0)) {
602 if (WIFEXITED(pty->exit_code))
603 sprintf(message, "\r\n[pterm: process terminated with exit"
604 " code %d]\r\n", WEXITSTATUS(pty->exit_code));
605 else if (WIFSIGNALED(pty->exit_code))
606 #ifdef HAVE_NO_STRSIGNAL
607 sprintf(message, "\r\n[pterm: process terminated on signal"
608 " %d]\r\n", WTERMSIG(pty->exit_code));
610 sprintf(message, "\r\n[pterm: process terminated on signal"
611 " %d (%.400s)]\r\n", WTERMSIG(pty->exit_code),
612 strsignal(WTERMSIG(pty->exit_code)));
614 from_backend(pty->frontend, 0, message, strlen(message));
617 notify_remote_exit(pty->frontend);
623 int pty_select_result(int fd, int event)
628 if (fd == pty_signal_pipe[0]) {
634 read(pty_signal_pipe[0], c, 1); /* ignore its value; it'll be `x' */
637 pid = waitpid(-1, &status, WNOHANG);
640 pty = find234(ptys_by_pid, &pid, pty_find_by_pid);
643 ret = ret && pty_real_select_result(pty, -1, status);
646 pty = find234(ptys_by_fd, &fd, pty_find_by_fd);
649 ret = ret && pty_real_select_result(pty, event, 0);
655 static void pty_uxsel_setup(Pty pty)
659 rwx = 1; /* always want to read from pty */
660 if (bufchain_size(&pty->output_data))
661 rwx |= 2; /* might also want to write to it */
662 uxsel_set(pty->master_fd, rwx, pty_select_result);
665 * In principle this only needs calling once for all pty
666 * backend instances, but it's simplest just to call it every
667 * time; uxsel won't mind.
669 uxsel_set(pty_signal_pipe[0], 1, pty_select_result);
673 * Called to set up the pty.
675 * Returns an error message, or NULL on success.
677 * Also places the canonical host name into `realhost'. It must be
678 * freed by the caller.
680 static const char *pty_init(void *frontend, void **backend_handle, Config *cfg,
681 char *host, int port, char **realhost, int nodelay,
686 #ifndef NOT_X_WINDOWS /* for Mac OS X native compilation */
694 pty = snew(struct pty_tag);
695 pty->master_fd = pty->slave_fd = -1;
697 pty_stamped_utmp = FALSE;
701 pty->frontend = frontend;
702 *backend_handle = NULL; /* we can't sensibly use this, sadly */
704 pty->cfg = *cfg; /* structure copy */
705 pty->term_width = cfg->width;
706 pty->term_height = cfg->height;
708 if (pty->master_fd < 0)
709 pty_open_master(pty);
712 * Set the backspace character to be whichever of ^H and ^? is
713 * specified by bksp_is_delete.
716 struct termios attrs;
717 tcgetattr(pty->master_fd, &attrs);
718 attrs.c_cc[VERASE] = cfg->bksp_is_delete ? '\177' : '\010';
719 tcsetattr(pty->master_fd, TCSANOW, &attrs);
724 * Stamp utmp (that is, tell the utmp helper process to do so),
727 if (!cfg->stamp_utmp) {
728 close(pty_utmp_helper_pipe); /* just let the child process die */
729 pty_utmp_helper_pipe = -1;
731 char *location = get_x_display(pty->frontend);
732 int len = strlen(location)+1, pos = 0; /* +1 to include NUL */
734 int ret = write(pty_utmp_helper_pipe, location+pos, len - pos);
736 perror("pterm: writing to utmp helper process");
737 close(pty_utmp_helper_pipe); /* arrgh, just give up */
738 pty_utmp_helper_pipe = -1;
746 #ifndef NOT_X_WINDOWS /* for Mac OS X native compilation */
747 windowid = get_windowid(pty->frontend);
751 * Fork and execute the command.
764 slavefd = pty_open_slave(pty);
766 perror("slave pty: open");
770 close(pty->master_fd);
771 fcntl(slavefd, F_SETFD, 0); /* don't close on exec */
778 ioctl(slavefd, TIOCSCTTY, 1);
781 tcsetpgrp(slavefd, pgrp);
783 close(open(pty->name, O_WRONLY, 0));
786 char *term_env_var = dupprintf("TERM=%s", cfg->termtype);
787 putenv(term_env_var);
788 /* We mustn't free term_env_var, as putenv links it into the
789 * environment in place.
792 #ifndef NOT_X_WINDOWS /* for Mac OS X native compilation */
794 char *windowid_env_var = dupprintf("WINDOWID=%ld", windowid);
795 putenv(windowid_env_var);
796 /* We mustn't free windowid_env_var, as putenv links it into the
797 * environment in place.
802 char *e = cfg->environmt;
803 char *var, *varend, *val, *varval;
806 while (*e && *e != '\t') e++;
813 varval = dupprintf("%.*s=%s", varend-var, var, val);
816 * We must not free varval, since putenv links it
817 * into the environment _in place_. Weird, but
818 * there we go. Memory usage will be rationalised
819 * as soon as we exec anyway.
825 * SIGINT and SIGQUIT may have been set to ignored by our
826 * parent, particularly by things like sh -c 'pterm &' and
827 * some window managers. SIGCHLD, meanwhile, was blocked
828 * during pt_main() startup. Reverse all this for our child
831 putty_signal(SIGINT, SIG_DFL);
832 putty_signal(SIGQUIT, SIG_DFL);
833 block_signal(SIGCHLD, 0);
835 execvp(pty_argv[0], pty_argv);
837 char *shell = getenv("SHELL");
839 if (cfg->login_shell) {
840 char *p = strrchr(shell, '/');
841 shellname = snewn(2+strlen(shell), char);
843 sprintf(shellname, "-%s", p);
846 execl(getenv("SHELL"), shellname, (void *)NULL);
850 * If we're here, exec has gone badly foom.
855 pty->child_pid = pid;
856 pty->child_dead = FALSE;
857 pty->finished = FALSE;
858 if (pty->slave_fd > 0)
859 close(pty->slave_fd);
861 ptys_by_pid = newtree234(pty_compare_by_pid);
862 add234(ptys_by_pid, pty);
865 if (pty_signal_pipe[0] < 0) {
866 if (pipe(pty_signal_pipe) < 0) {
870 cloexec(pty_signal_pipe[0]);
871 cloexec(pty_signal_pipe[1]);
873 pty_uxsel_setup(pty);
875 *backend_handle = pty;
877 *realhost = dupprintf("\0");
882 static void pty_reconfig(void *handle, Config *cfg)
884 Pty pty = (Pty)handle;
886 * We don't have much need to reconfigure this backend, but
887 * unfortunately we do need to pick up the setting of Close On
888 * Exit so we know whether to give a `terminated' message.
890 pty->cfg = *cfg; /* structure copy */
894 * Stub routine (never called in pterm).
896 static void pty_free(void *handle)
898 Pty pty = (Pty)handle;
900 /* Either of these may fail `not found'. That's fine with us. */
901 del234(ptys_by_pid, pty);
902 del234(ptys_by_fd, pty);
907 static void pty_try_write(Pty pty)
912 assert(pty->master_fd >= 0);
914 while (bufchain_size(&pty->output_data) > 0) {
915 bufchain_prefix(&pty->output_data, &data, &len);
916 ret = write(pty->master_fd, data, len);
918 if (ret < 0 && (errno == EWOULDBLOCK)) {
920 * We've sent all we can for the moment.
925 perror("write pty master");
928 bufchain_consume(&pty->output_data, ret);
931 pty_uxsel_setup(pty);
935 * Called to send data down the pty.
937 static int pty_send(void *handle, char *buf, int len)
939 Pty pty = (Pty)handle;
941 if (pty->master_fd < 0)
942 return 0; /* ignore all writes if fd closed */
944 bufchain_add(&pty->output_data, buf, len);
947 return bufchain_size(&pty->output_data);
950 static void pty_close(Pty pty)
952 if (pty->master_fd >= 0) {
953 close(pty->master_fd);
957 if (pty_utmp_helper_pipe >= 0) {
958 close(pty_utmp_helper_pipe); /* this causes utmp to be cleaned up */
959 pty_utmp_helper_pipe = -1;
965 * Called to query the current socket sendability status.
967 static int pty_sendbuffer(void *handle)
969 /* Pty pty = (Pty)handle; */
974 * Called to set the size of the window
976 static void pty_size(void *handle, int width, int height)
978 Pty pty = (Pty)handle;
981 pty->term_width = width;
982 pty->term_height = height;
984 size.ws_row = (unsigned short)pty->term_height;
985 size.ws_col = (unsigned short)pty->term_width;
986 size.ws_xpixel = (unsigned short) pty->term_width *
987 font_dimension(pty->frontend, 0);
988 size.ws_ypixel = (unsigned short) pty->term_height *
989 font_dimension(pty->frontend, 1);
990 ioctl(pty->master_fd, TIOCSWINSZ, (void *)&size);
995 * Send special codes.
997 static void pty_special(void *handle, Telnet_Special code)
999 /* Pty pty = (Pty)handle; */
1005 * Return a list of the special codes that make sense in this
1008 static const struct telnet_special *pty_get_specials(void *handle)
1010 /* Pty pty = (Pty)handle; */
1012 * Hmm. When I get round to having this actually usable, it
1013 * might be quite nice to have the ability to deliver a few
1014 * well chosen signals to the child process - SIGINT, SIGTERM,
1020 static int pty_connected(void *handle)
1022 /* Pty pty = (Pty)handle; */
1026 static int pty_sendok(void *handle)
1028 /* Pty pty = (Pty)handle; */
1032 static void pty_unthrottle(void *handle, int backlog)
1034 /* Pty pty = (Pty)handle; */
1038 static int pty_ldisc(void *handle, int option)
1040 /* Pty pty = (Pty)handle; */
1041 return 0; /* neither editing nor echoing */
1044 static void pty_provide_ldisc(void *handle, void *ldisc)
1046 /* Pty pty = (Pty)handle; */
1047 /* This is a stub. */
1050 static void pty_provide_logctx(void *handle, void *logctx)
1052 /* Pty pty = (Pty)handle; */
1053 /* This is a stub. */
1056 static int pty_exitcode(void *handle)
1058 Pty pty = (Pty)handle;
1060 return -1; /* not dead yet */
1062 return pty->exit_code;
1065 static int pty_cfg_info(void *handle)
1067 /* Pty pty = (Pty)handle; */
1071 Backend pty_backend = {