2 * Pseudo-tty backend for pterm.
4 * Unlike the other backends, data for this one is not neatly
5 * encapsulated into a data structure, because it wouldn't make
6 * sense to do so - the utmp stuff has to be done before a backend
7 * is initialised, and starting a second pterm from the same
8 * process would therefore be infeasible because privileges would
9 * already have been dropped. Hence, I haven't bothered to keep the
10 * data dynamically allocated: instead, the backend handle is just
11 * a null pointer and ignored everywhere.
15 #define _XOPEN_SOURCE_EXTENDED
30 #include <sys/types.h>
32 #include <sys/ioctl.h>
45 #define UTMP_FILE "/var/run/utmp"
48 #define WTMP_FILE "/var/log/wtmp"
52 #define LASTLOG_FILE _PATH_LASTLOG
54 #define LASTLOG_FILE "/var/log/lastlog"
59 * Set up a default for vaguely sane systems. The idea is that if
60 * OMIT_UTMP is not defined, then at least one of the symbols which
61 * enable particular forms of utmp processing should be, if only so
62 * that a link error can warn you that you should have defined
63 * OMIT_UTMP if you didn't want any. Currently HAVE_PUTUTLINE is
64 * the only such symbol.
67 #if !defined HAVE_PUTUTLINE
68 #define HAVE_PUTUTLINE
72 static Config pty_cfg
;
73 static int pty_master_fd
;
74 static void *pty_frontend
;
75 static char pty_name
[FILENAME_MAX
];
76 static int pty_signal_pipe
[2];
77 static int pty_stamped_utmp
= 0;
78 static int pty_child_pid
;
79 static int pty_utmp_helper_pid
, pty_utmp_helper_pipe
;
80 static int pty_term_width
, pty_term_height
;
81 static int pty_child_dead
, pty_finished
;
82 static int pty_exit_code
;
84 static struct utmp utmp_entry
;
87 int use_pty_argv
= TRUE
;
89 static void pty_close(void);
91 static void setup_utmp(char *ttyname
, char *location
)
95 struct lastlog lastlog_entry
;
101 pw
= getpwuid(getuid());
102 memset(&utmp_entry
, 0, sizeof(utmp_entry
));
103 utmp_entry
.ut_type
= USER_PROCESS
;
104 utmp_entry
.ut_pid
= getpid();
105 strncpy(utmp_entry
.ut_line
, ttyname
+5, lenof(utmp_entry
.ut_line
));
106 strncpy(utmp_entry
.ut_id
, ttyname
+8, lenof(utmp_entry
.ut_id
));
107 strncpy(utmp_entry
.ut_user
, pw
->pw_name
, lenof(utmp_entry
.ut_user
));
108 strncpy(utmp_entry
.ut_host
, location
, lenof(utmp_entry
.ut_host
));
109 time(&utmp_entry
.ut_time
);
111 #if defined HAVE_PUTUTLINE
114 pututline(&utmp_entry
);
118 if ((wtmp
= fopen(WTMP_FILE
, "a")) != NULL
) {
119 fwrite(&utmp_entry
, 1, sizeof(utmp_entry
), wtmp
);
124 memset(&lastlog_entry
, 0, sizeof(lastlog_entry
));
125 strncpy(lastlog_entry
.ll_line
, ttyname
+5, lenof(lastlog_entry
.ll_line
));
126 strncpy(lastlog_entry
.ll_host
, location
, lenof(lastlog_entry
.ll_host
));
127 time(&lastlog_entry
.ll_time
);
128 if ((lastlog
= fopen(LASTLOG_FILE
, "r+")) != NULL
) {
129 fseek(lastlog
, sizeof(lastlog_entry
) * getuid(), SEEK_SET
);
130 fwrite(&lastlog_entry
, 1, sizeof(lastlog_entry
), lastlog
);
135 pty_stamped_utmp
= 1;
140 static void cleanup_utmp(void)
145 if (!pty_stamped_utmp
)
148 utmp_entry
.ut_type
= DEAD_PROCESS
;
149 memset(utmp_entry
.ut_user
, 0, lenof(utmp_entry
.ut_user
));
150 time(&utmp_entry
.ut_time
);
152 if ((wtmp
= fopen(WTMP_FILE
, "a")) != NULL
) {
153 fwrite(&utmp_entry
, 1, sizeof(utmp_entry
), wtmp
);
157 memset(utmp_entry
.ut_line
, 0, lenof(utmp_entry
.ut_line
));
158 utmp_entry
.ut_time
= 0;
160 #if defined HAVE_PUTUTLINE
163 pututline(&utmp_entry
);
167 pty_stamped_utmp
= 0; /* ensure we never double-cleanup */
171 static void sigchld_handler(int signum
)
173 write(pty_signal_pipe
[1], "x", 1);
176 static void fatal_sig_handler(int signum
)
178 putty_signal(signum
, SIG_DFL
);
184 static void pty_open_master(void)
187 const char chars1
[] = "pqrstuvwxyz";
188 const char chars2
[] = "0123456789abcdef";
190 char master_name
[20];
193 for (p1
= chars1
; *p1
; p1
++)
194 for (p2
= chars2
; *p2
; p2
++) {
195 sprintf(master_name
, "/dev/pty%c%c", *p1
, *p2
);
196 pty_master_fd
= open(master_name
, O_RDWR
);
197 if (pty_master_fd
>= 0) {
198 if (geteuid() == 0 ||
199 access(master_name
, R_OK
| W_OK
) == 0)
201 close(pty_master_fd
);
205 /* If we get here, we couldn't get a tty at all. */
206 fprintf(stderr
, "pterm: unable to open a pseudo-terminal device\n");
210 strcpy(pty_name
, master_name
);
211 pty_name
[5] = 't'; /* /dev/ptyXX -> /dev/ttyXX */
213 /* We need to chown/chmod the /dev/ttyXX device. */
214 gp
= getgrnam("tty");
215 chown(pty_name
, getuid(), gp ? gp
->gr_gid
: -1);
216 chmod(pty_name
, 0600);
218 pty_master_fd
= open("/dev/ptmx", O_RDWR
);
220 if (pty_master_fd
< 0) {
221 perror("/dev/ptmx: open");
225 if (grantpt(pty_master_fd
) < 0) {
230 if (unlockpt(pty_master_fd
) < 0) {
235 pty_name
[FILENAME_MAX
-1] = '\0';
236 strncpy(pty_name
, ptsname(pty_master_fd
), FILENAME_MAX
-1);
241 * Pre-initialisation. This is here to get around the fact that GTK
242 * doesn't like being run in setuid/setgid programs (probably
243 * sensibly). So before we initialise GTK - and therefore before we
244 * even process the command line - we check to see if we're running
245 * set[ug]id. If so, we open our pty master _now_, chown it as
246 * necessary, and drop privileges. We can always close it again
247 * later. If we're potentially going to be doing utmp as well, we
248 * also fork off a utmp helper process and communicate with it by
249 * means of a pipe; the utmp helper will keep privileges in order
250 * to clean up utmp when we exit (i.e. when its end of our pipe
253 void pty_pre_init(void)
258 /* set the child signal handler straight away; it needs to be set
259 * before we ever fork. */
260 putty_signal(SIGCHLD
, sigchld_handler
);
263 if (geteuid() != getuid() || getegid() != getgid()) {
269 * Fork off the utmp helper.
271 if (pipe(pipefd
) < 0) {
272 perror("pterm: pipe");
277 perror("pterm: fork");
279 } else if (pid
== 0) {
280 char display
[128], buffer
[128];
285 * Now sit here until we receive a display name from the
286 * other end of the pipe, and then stamp utmp. Unstamp utmp
287 * again, and exit, when the pipe closes.
293 ret
= read(pipefd
[0], buffer
, lenof(buffer
));
297 } else if (!pty_stamped_utmp
) {
298 if (dlen
< lenof(display
))
299 memcpy(display
+dlen
, buffer
,
300 min(ret
, lenof(display
)-dlen
));
301 if (buffer
[ret
-1] == '\0') {
303 * Now we have a display name. NUL-terminate
304 * it, and stamp utmp.
306 display
[lenof(display
)-1] = '\0';
308 * Trap as many fatal signals as we can in the
309 * hope of having the best possible chance to
310 * clean up utmp before termination. We are
311 * unfortunately unprotected against SIGKILL,
314 putty_signal(SIGHUP
, fatal_sig_handler
);
315 putty_signal(SIGINT
, fatal_sig_handler
);
316 putty_signal(SIGQUIT
, fatal_sig_handler
);
317 putty_signal(SIGILL
, fatal_sig_handler
);
318 putty_signal(SIGABRT
, fatal_sig_handler
);
319 putty_signal(SIGFPE
, fatal_sig_handler
);
320 putty_signal(SIGPIPE
, fatal_sig_handler
);
321 putty_signal(SIGALRM
, fatal_sig_handler
);
322 putty_signal(SIGTERM
, fatal_sig_handler
);
323 putty_signal(SIGSEGV
, fatal_sig_handler
);
324 putty_signal(SIGUSR1
, fatal_sig_handler
);
325 putty_signal(SIGUSR2
, fatal_sig_handler
);
327 putty_signal(SIGBUS
, fatal_sig_handler
);
330 putty_signal(SIGPOLL
, fatal_sig_handler
);
333 putty_signal(SIGPROF
, fatal_sig_handler
);
336 putty_signal(SIGSYS
, fatal_sig_handler
);
339 putty_signal(SIGTRAP
, fatal_sig_handler
);
342 putty_signal(SIGVTALRM
, fatal_sig_handler
);
345 putty_signal(SIGXCPU
, fatal_sig_handler
);
348 putty_signal(SIGXFSZ
, fatal_sig_handler
);
351 putty_signal(SIGIO
, fatal_sig_handler
);
353 setup_utmp(pty_name
, display
);
359 pty_utmp_helper_pid
= pid
;
360 pty_utmp_helper_pipe
= pipefd
[1];
366 int gid
= getgid(), uid
= getuid();
367 #ifndef HAVE_NO_SETRESUID
368 int setresgid(gid_t
, gid_t
, gid_t
);
369 int setresuid(uid_t
, uid_t
, uid_t
);
370 setresgid(gid
, gid
, gid
);
371 setresuid(uid
, uid
, uid
);
379 int pty_select_result(int fd
, int event
)
383 int finished
= FALSE
;
385 if (fd
== pty_master_fd
&& event
== 1) {
387 ret
= read(pty_master_fd
, buf
, sizeof(buf
));
390 * Clean termination condition is that either ret == 0, or ret
391 * < 0 and errno == EIO. Not sure why the latter, but it seems
394 if (ret
== 0 || (ret
< 0 && errno
== EIO
)) {
396 * We assume a clean exit if the pty has closed but the
397 * actual child process hasn't. The only way I can
398 * imagine this happening is if it detaches itself from
399 * the pty and goes daemonic - in which case the
400 * expected usage model would precisely _not_ be for
401 * the pterm window to hang around!
406 } else if (ret
< 0) {
407 perror("read pty master");
409 } else if (ret
> 0) {
410 from_backend(pty_frontend
, 0, buf
, ret
);
412 } else if (fd
== pty_signal_pipe
[0]) {
417 read(pty_signal_pipe
[0], c
, 1); /* ignore its value; it'll be `x' */
420 pid
= waitpid(-1, &status
, WNOHANG
);
421 if (pid
== pty_child_pid
&&
422 (WIFEXITED(status
) || WIFSIGNALED(status
))) {
424 * The primary child process died. We could keep
425 * the terminal open for remaining subprocesses to
426 * output to, but conventional wisdom seems to feel
427 * that that's the Wrong Thing for an xterm-alike,
428 * so we bail out now (though we don't necessarily
429 * _close_ the window, depending on the state of
430 * Close On Exit). This would be easy enough to
431 * change or make configurable if necessary.
433 pty_exit_code
= status
;
434 pty_child_dead
= TRUE
;
440 if (finished
&& !pty_finished
) {
441 uxsel_del(pty_master_fd
);
448 * This is a slight layering-violation sort of hack: only
449 * if we're not closing on exit (COE is set to Never, or to
450 * Only On Clean and it wasn't a clean exit) do we output a
451 * `terminated' message.
453 if (pty_cfg
.close_on_exit
== FORCE_OFF
||
454 (pty_cfg
.close_on_exit
== AUTO
&& pty_exit_code
!= 0)) {
456 if (WIFEXITED(pty_exit_code
))
457 sprintf(message
, "\r\n[pterm: process terminated with exit"
458 " code %d]\r\n", WEXITSTATUS(pty_exit_code
));
459 else if (WIFSIGNALED(pty_exit_code
))
460 #ifdef HAVE_NO_STRSIGNAL
461 sprintf(message
, "\r\n[pterm: process terminated on signal"
462 " %d]\r\n", WTERMSIG(pty_exit_code
));
464 sprintf(message
, "\r\n[pterm: process terminated on signal"
465 " %d (%.400s)]\r\n", WTERMSIG(pty_exit_code
),
466 strsignal(WTERMSIG(pty_exit_code
)));
468 from_backend(pty_frontend
, 0, message
, strlen(message
));
474 static void pty_uxsel_setup(void)
476 uxsel_set(pty_master_fd
, 1, pty_select_result
);
477 uxsel_set(pty_signal_pipe
[0], 1, pty_select_result
);
481 * Called to set up the pty.
483 * Returns an error message, or NULL on success.
485 * Also places the canonical host name into `realhost'. It must be
486 * freed by the caller.
488 static char *pty_init(void *frontend
, void **backend_handle
, Config
*cfg
,
489 char *host
, int port
, char **realhost
, int nodelay
)
495 pty_frontend
= frontend
;
496 *backend_handle
= NULL
; /* we can't sensibly use this, sadly */
498 pty_cfg
= *cfg
; /* structure copy */
499 pty_term_width
= cfg
->width
;
500 pty_term_height
= cfg
->height
;
502 if (pty_master_fd
< 0)
506 * Set the backspace character to be whichever of ^H and ^? is
507 * specified by bksp_is_delete.
510 struct termios attrs
;
511 tcgetattr(pty_master_fd
, &attrs
);
512 attrs
.c_cc
[VERASE
] = cfg
->bksp_is_delete ?
'\177' : '\010';
513 tcsetattr(pty_master_fd
, TCSANOW
, &attrs
);
517 * Stamp utmp (that is, tell the utmp helper process to do so),
520 if (!cfg
->stamp_utmp
)
521 close(pty_utmp_helper_pipe
); /* just let the child process die */
523 char *location
= get_x_display(pty_frontend
);
524 int len
= strlen(location
)+1, pos
= 0; /* +1 to include NUL */
526 int ret
= write(pty_utmp_helper_pipe
, location
+pos
, len
- pos
);
528 perror("pterm: writing to utmp helper process");
529 close(pty_utmp_helper_pipe
); /* arrgh, just give up */
536 windowid
= get_windowid(pty_frontend
);
539 * Fork and execute the command.
553 slavefd
= open(pty_name
, O_RDWR
);
555 perror("slave pty: open");
559 close(pty_master_fd
);
560 fcntl(slavefd
, F_SETFD
, 0); /* don't close on exec */
565 ioctl(slavefd
, TIOCSCTTY
, 1);
567 tcsetpgrp(slavefd
, pgrp
);
569 close(open(pty_name
, O_WRONLY
, 0));
571 /* Close everything _else_, for tidiness. */
572 for (i
= 3; i
< 1024; i
++)
575 char term_env_var
[10 + sizeof(cfg
->termtype
)];
576 sprintf(term_env_var
, "TERM=%s", cfg
->termtype
);
577 putenv(term_env_var
);
580 char windowid_env_var
[40];
581 sprintf(windowid_env_var
, "WINDOWID=%ld", windowid
);
582 putenv(windowid_env_var
);
585 * SIGINT and SIGQUIT may have been set to ignored by our
586 * parent, particularly by things like sh -c 'pterm &' and
587 * some window managers. Reverse this for our child process.
589 putty_signal(SIGINT
, SIG_DFL
);
590 putty_signal(SIGQUIT
, SIG_DFL
);
592 execvp(pty_argv
[0], pty_argv
);
594 char *shell
= getenv("SHELL");
596 if (cfg
->login_shell
) {
597 char *p
= strrchr(shell
, '/');
598 shellname
= snewn(2+strlen(shell
), char);
600 sprintf(shellname
, "-%s", p
);
603 execl(getenv("SHELL"), shellname
, NULL
);
607 * If we're here, exec has gone badly foom.
613 pty_child_dead
= FALSE
;
614 pty_finished
= FALSE
;
617 if (pipe(pty_signal_pipe
) < 0) {
627 * Stub routine (we don't have any need to reconfigure this backend).
629 static void pty_reconfig(void *handle
, Config
*cfg
)
634 * Stub routine (never called in pterm
636 static void pty_free(void *handle
)
642 * Called to send data down the pty.
644 static int pty_send(void *handle
, char *buf
, int len
)
646 if (pty_master_fd
< 0)
647 return 0; /* ignore all writes if fd closed */
650 int ret
= write(pty_master_fd
, buf
, len
);
652 perror("write pty master");
661 static void pty_close(void)
663 if (pty_master_fd
>= 0) {
664 close(pty_master_fd
);
667 close(pty_utmp_helper_pipe
); /* this causes utmp to be cleaned up */
671 * Called to query the current socket sendability status.
673 static int pty_sendbuffer(void *handle
)
679 * Called to set the size of the window
681 static void pty_size(void *handle
, int width
, int height
)
685 pty_term_width
= width
;
686 pty_term_height
= height
;
688 size
.ws_row
= (unsigned short)pty_term_height
;
689 size
.ws_col
= (unsigned short)pty_term_width
;
690 size
.ws_xpixel
= (unsigned short) pty_term_width
*
691 font_dimension(pty_frontend
, 0);
692 size
.ws_ypixel
= (unsigned short) pty_term_height
*
693 font_dimension(pty_frontend
, 1);
694 ioctl(pty_master_fd
, TIOCSWINSZ
, (void *)&size
);
699 * Send special codes.
701 static void pty_special(void *handle
, Telnet_Special code
)
708 * Return a list of the special codes that make sense in this
711 static const struct telnet_special
*pty_get_specials(void *handle
)
714 * Hmm. When I get round to having this actually usable, it
715 * might be quite nice to have the ability to deliver a few
716 * well chosen signals to the child process - SIGINT, SIGTERM,
722 static Socket
pty_socket(void *handle
)
724 return NULL
; /* shouldn't ever be needed */
727 static int pty_sendok(void *handle
)
732 static void pty_unthrottle(void *handle
, int backlog
)
737 static int pty_ldisc(void *handle
, int option
)
739 return 0; /* neither editing nor echoing */
742 static void pty_provide_ldisc(void *handle
, void *ldisc
)
744 /* This is a stub. */
747 static void pty_provide_logctx(void *handle
, void *logctx
)
749 /* This is a stub. */
752 static int pty_exitcode(void *handle
)
755 return -1; /* not dead yet */
757 return pty_exit_code
;
760 Backend pty_backend
= {