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
;
88 static void pty_close(void);
90 static void setup_utmp(char *ttyname
, char *location
)
94 struct lastlog lastlog_entry
;
100 pw
= getpwuid(getuid());
101 memset(&utmp_entry
, 0, sizeof(utmp_entry
));
102 utmp_entry
.ut_type
= USER_PROCESS
;
103 utmp_entry
.ut_pid
= getpid();
104 strncpy(utmp_entry
.ut_line
, ttyname
+5, lenof(utmp_entry
.ut_line
));
105 strncpy(utmp_entry
.ut_id
, ttyname
+8, lenof(utmp_entry
.ut_id
));
106 strncpy(utmp_entry
.ut_user
, pw
->pw_name
, lenof(utmp_entry
.ut_user
));
107 strncpy(utmp_entry
.ut_host
, location
, lenof(utmp_entry
.ut_host
));
108 time(&utmp_entry
.ut_time
);
110 #if defined HAVE_PUTUTLINE
113 pututline(&utmp_entry
);
117 if ((wtmp
= fopen(WTMP_FILE
, "a")) != NULL
) {
118 fwrite(&utmp_entry
, 1, sizeof(utmp_entry
), wtmp
);
123 memset(&lastlog_entry
, 0, sizeof(lastlog_entry
));
124 strncpy(lastlog_entry
.ll_line
, ttyname
+5, lenof(lastlog_entry
.ll_line
));
125 strncpy(lastlog_entry
.ll_host
, location
, lenof(lastlog_entry
.ll_host
));
126 time(&lastlog_entry
.ll_time
);
127 if ((lastlog
= fopen(LASTLOG_FILE
, "r+")) != NULL
) {
128 fseek(lastlog
, sizeof(lastlog_entry
) * getuid(), SEEK_SET
);
129 fwrite(&lastlog_entry
, 1, sizeof(lastlog_entry
), lastlog
);
134 pty_stamped_utmp
= 1;
139 static void cleanup_utmp(void)
144 if (!pty_stamped_utmp
)
147 utmp_entry
.ut_type
= DEAD_PROCESS
;
148 memset(utmp_entry
.ut_user
, 0, lenof(utmp_entry
.ut_user
));
149 time(&utmp_entry
.ut_time
);
151 if ((wtmp
= fopen(WTMP_FILE
, "a")) != NULL
) {
152 fwrite(&utmp_entry
, 1, sizeof(utmp_entry
), wtmp
);
156 memset(utmp_entry
.ut_line
, 0, lenof(utmp_entry
.ut_line
));
157 utmp_entry
.ut_time
= 0;
159 #if defined HAVE_PUTUTLINE
162 pututline(&utmp_entry
);
166 pty_stamped_utmp
= 0; /* ensure we never double-cleanup */
170 static void sigchld_handler(int signum
)
172 write(pty_signal_pipe
[1], "x", 1);
175 static void fatal_sig_handler(int signum
)
177 putty_signal(signum
, SIG_DFL
);
183 static void pty_open_master(void)
186 const char chars1
[] = "pqrstuvwxyz";
187 const char chars2
[] = "0123456789abcdef";
189 char master_name
[20];
192 for (p1
= chars1
; *p1
; p1
++)
193 for (p2
= chars2
; *p2
; p2
++) {
194 sprintf(master_name
, "/dev/pty%c%c", *p1
, *p2
);
195 pty_master_fd
= open(master_name
, O_RDWR
);
196 if (pty_master_fd
>= 0) {
197 if (geteuid() == 0 ||
198 access(master_name
, R_OK
| W_OK
) == 0)
200 close(pty_master_fd
);
204 /* If we get here, we couldn't get a tty at all. */
205 fprintf(stderr
, "pterm: unable to open a pseudo-terminal device\n");
209 strcpy(pty_name
, master_name
);
210 pty_name
[5] = 't'; /* /dev/ptyXX -> /dev/ttyXX */
212 /* We need to chown/chmod the /dev/ttyXX device. */
213 gp
= getgrnam("tty");
214 chown(pty_name
, getuid(), gp ? gp
->gr_gid
: -1);
215 chmod(pty_name
, 0600);
217 pty_master_fd
= open("/dev/ptmx", O_RDWR
);
219 if (pty_master_fd
< 0) {
220 perror("/dev/ptmx: open");
224 if (grantpt(pty_master_fd
) < 0) {
229 if (unlockpt(pty_master_fd
) < 0) {
234 pty_name
[FILENAME_MAX
-1] = '\0';
235 strncpy(pty_name
, ptsname(pty_master_fd
), FILENAME_MAX
-1);
240 * Pre-initialisation. This is here to get around the fact that GTK
241 * doesn't like being run in setuid/setgid programs (probably
242 * sensibly). So before we initialise GTK - and therefore before we
243 * even process the command line - we check to see if we're running
244 * set[ug]id. If so, we open our pty master _now_, chown it as
245 * necessary, and drop privileges. We can always close it again
246 * later. If we're potentially going to be doing utmp as well, we
247 * also fork off a utmp helper process and communicate with it by
248 * means of a pipe; the utmp helper will keep privileges in order
249 * to clean up utmp when we exit (i.e. when its end of our pipe
252 void pty_pre_init(void)
257 /* set the child signal handler straight away; it needs to be set
258 * before we ever fork. */
259 putty_signal(SIGCHLD
, sigchld_handler
);
262 if (geteuid() != getuid() || getegid() != getgid()) {
268 * Fork off the utmp helper.
270 if (pipe(pipefd
) < 0) {
271 perror("pterm: pipe");
276 perror("pterm: fork");
278 } else if (pid
== 0) {
279 char display
[128], buffer
[128];
284 * Now sit here until we receive a display name from the
285 * other end of the pipe, and then stamp utmp. Unstamp utmp
286 * again, and exit, when the pipe closes.
292 ret
= read(pipefd
[0], buffer
, lenof(buffer
));
296 } else if (!pty_stamped_utmp
) {
297 if (dlen
< lenof(display
))
298 memcpy(display
+dlen
, buffer
,
299 min(ret
, lenof(display
)-dlen
));
300 if (buffer
[ret
-1] == '\0') {
302 * Now we have a display name. NUL-terminate
303 * it, and stamp utmp.
305 display
[lenof(display
)-1] = '\0';
307 * Trap as many fatal signals as we can in the
308 * hope of having the best possible chance to
309 * clean up utmp before termination. We are
310 * unfortunately unprotected against SIGKILL,
313 putty_signal(SIGHUP
, fatal_sig_handler
);
314 putty_signal(SIGINT
, fatal_sig_handler
);
315 putty_signal(SIGQUIT
, fatal_sig_handler
);
316 putty_signal(SIGILL
, fatal_sig_handler
);
317 putty_signal(SIGABRT
, fatal_sig_handler
);
318 putty_signal(SIGFPE
, fatal_sig_handler
);
319 putty_signal(SIGPIPE
, fatal_sig_handler
);
320 putty_signal(SIGALRM
, fatal_sig_handler
);
321 putty_signal(SIGTERM
, fatal_sig_handler
);
322 putty_signal(SIGSEGV
, fatal_sig_handler
);
323 putty_signal(SIGUSR1
, fatal_sig_handler
);
324 putty_signal(SIGUSR2
, fatal_sig_handler
);
326 putty_signal(SIGBUS
, fatal_sig_handler
);
329 putty_signal(SIGPOLL
, fatal_sig_handler
);
332 putty_signal(SIGPROF
, fatal_sig_handler
);
335 putty_signal(SIGSYS
, fatal_sig_handler
);
338 putty_signal(SIGTRAP
, fatal_sig_handler
);
341 putty_signal(SIGVTALRM
, fatal_sig_handler
);
344 putty_signal(SIGXCPU
, fatal_sig_handler
);
347 putty_signal(SIGXFSZ
, fatal_sig_handler
);
350 putty_signal(SIGIO
, fatal_sig_handler
);
352 setup_utmp(pty_name
, display
);
358 pty_utmp_helper_pid
= pid
;
359 pty_utmp_helper_pipe
= pipefd
[1];
365 int gid
= getgid(), uid
= getuid();
366 #ifndef HAVE_NO_SETRESUID
367 int setresgid(gid_t
, gid_t
, gid_t
);
368 int setresuid(uid_t
, uid_t
, uid_t
);
369 setresgid(gid
, gid
, gid
);
370 setresuid(uid
, uid
, uid
);
378 int pty_select_result(int fd
, int event
)
382 int finished
= FALSE
;
384 if (fd
== pty_master_fd
&& event
== 1) {
386 ret
= read(pty_master_fd
, buf
, sizeof(buf
));
389 * Clean termination condition is that either ret == 0, or ret
390 * < 0 and errno == EIO. Not sure why the latter, but it seems
393 if (ret
== 0 || (ret
< 0 && errno
== EIO
)) {
395 * We assume a clean exit if the pty has closed but the
396 * actual child process hasn't. The only way I can
397 * imagine this happening is if it detaches itself from
398 * the pty and goes daemonic - in which case the
399 * expected usage model would precisely _not_ be for
400 * the pterm window to hang around!
405 } else if (ret
< 0) {
406 perror("read pty master");
408 } else if (ret
> 0) {
409 from_backend(pty_frontend
, 0, buf
, ret
);
411 } else if (fd
== pty_signal_pipe
[0]) {
416 read(pty_signal_pipe
[0], c
, 1); /* ignore its value; it'll be `x' */
419 pid
= waitpid(-1, &status
, WNOHANG
);
420 if (pid
== pty_child_pid
&&
421 (WIFEXITED(status
) || WIFSIGNALED(status
))) {
423 * The primary child process died. We could keep
424 * the terminal open for remaining subprocesses to
425 * output to, but conventional wisdom seems to feel
426 * that that's the Wrong Thing for an xterm-alike,
427 * so we bail out now (though we don't necessarily
428 * _close_ the window, depending on the state of
429 * Close On Exit). This would be easy enough to
430 * change or make configurable if necessary.
432 pty_exit_code
= status
;
433 pty_child_dead
= TRUE
;
439 if (finished
&& !pty_finished
) {
440 uxsel_del(pty_master_fd
);
447 * This is a slight layering-violation sort of hack: only
448 * if we're not closing on exit (COE is set to Never, or to
449 * Only On Clean and it wasn't a clean exit) do we output a
450 * `terminated' message.
452 if (pty_cfg
.close_on_exit
== FORCE_OFF
||
453 (pty_cfg
.close_on_exit
== AUTO
&& pty_exit_code
!= 0)) {
455 if (WIFEXITED(pty_exit_code
))
456 sprintf(message
, "\r\n[pterm: process terminated with exit"
457 " code %d]\r\n", WEXITSTATUS(pty_exit_code
));
458 else if (WIFSIGNALED(pty_exit_code
))
459 #ifdef HAVE_NO_STRSIGNAL
460 sprintf(message
, "\r\n[pterm: process terminated on signal"
461 " %d]\r\n", WTERMSIG(pty_exit_code
));
463 sprintf(message
, "\r\n[pterm: process terminated on signal"
464 " %d (%.400s)]\r\n", WTERMSIG(pty_exit_code
),
465 strsignal(WTERMSIG(pty_exit_code
)));
467 from_backend(pty_frontend
, 0, message
, strlen(message
));
473 static void pty_uxsel_setup(void)
475 uxsel_set(pty_master_fd
, 1, pty_select_result
);
476 uxsel_set(pty_signal_pipe
[0], 1, pty_select_result
);
480 * Called to set up the pty.
482 * Returns an error message, or NULL on success.
484 * Also places the canonical host name into `realhost'. It must be
485 * freed by the caller.
487 static char *pty_init(void *frontend
, void **backend_handle
, Config
*cfg
,
488 char *host
, int port
, char **realhost
, int nodelay
)
494 pty_frontend
= frontend
;
495 *backend_handle
= NULL
; /* we can't sensibly use this, sadly */
497 pty_cfg
= *cfg
; /* structure copy */
498 pty_term_width
= cfg
->width
;
499 pty_term_height
= cfg
->height
;
501 if (pty_master_fd
< 0)
505 * Set the backspace character to be whichever of ^H and ^? is
506 * specified by bksp_is_delete.
509 struct termios attrs
;
510 tcgetattr(pty_master_fd
, &attrs
);
511 attrs
.c_cc
[VERASE
] = cfg
->bksp_is_delete ?
'\177' : '\010';
512 tcsetattr(pty_master_fd
, TCSANOW
, &attrs
);
516 * Stamp utmp (that is, tell the utmp helper process to do so),
519 if (!cfg
->stamp_utmp
)
520 close(pty_utmp_helper_pipe
); /* just let the child process die */
522 char *location
= get_x_display(pty_frontend
);
523 int len
= strlen(location
)+1, pos
= 0; /* +1 to include NUL */
525 int ret
= write(pty_utmp_helper_pipe
, location
+pos
, len
- pos
);
527 perror("pterm: writing to utmp helper process");
528 close(pty_utmp_helper_pipe
); /* arrgh, just give up */
535 windowid
= get_windowid(pty_frontend
);
538 * Fork and execute the command.
552 slavefd
= open(pty_name
, O_RDWR
);
554 perror("slave pty: open");
558 close(pty_master_fd
);
559 fcntl(slavefd
, F_SETFD
, 0); /* don't close on exec */
564 ioctl(slavefd
, TIOCSCTTY
, 1);
566 tcsetpgrp(slavefd
, pgrp
);
568 close(open(pty_name
, O_WRONLY
, 0));
570 /* Close everything _else_, for tidiness. */
571 for (i
= 3; i
< 1024; i
++)
574 char term_env_var
[10 + sizeof(cfg
->termtype
)];
575 sprintf(term_env_var
, "TERM=%s", cfg
->termtype
);
576 putenv(term_env_var
);
579 char windowid_env_var
[40];
580 sprintf(windowid_env_var
, "WINDOWID=%ld", windowid
);
581 putenv(windowid_env_var
);
584 * SIGINT and SIGQUIT may have been set to ignored by our
585 * parent, particularly by things like sh -c 'pterm &' and
586 * some window managers. Reverse this for our child process.
588 putty_signal(SIGINT
, SIG_DFL
);
589 putty_signal(SIGQUIT
, SIG_DFL
);
591 execvp(pty_argv
[0], pty_argv
);
593 char *shell
= getenv("SHELL");
595 if (cfg
->login_shell
) {
596 char *p
= strrchr(shell
, '/');
597 shellname
= snewn(2+strlen(shell
), char);
599 sprintf(shellname
, "-%s", p
);
602 execl(getenv("SHELL"), shellname
, NULL
);
606 * If we're here, exec has gone badly foom.
612 pty_child_dead
= FALSE
;
613 pty_finished
= FALSE
;
616 if (pipe(pty_signal_pipe
) < 0) {
626 * Stub routine (we don't have any need to reconfigure this backend).
628 static void pty_reconfig(void *handle
, Config
*cfg
)
633 * Stub routine (never called in pterm
635 static void pty_free(void *handle
)
641 * Called to send data down the pty.
643 static int pty_send(void *handle
, char *buf
, int len
)
645 if (pty_master_fd
< 0)
646 return 0; /* ignore all writes if fd closed */
649 int ret
= write(pty_master_fd
, buf
, len
);
651 perror("write pty master");
660 static void pty_close(void)
662 if (pty_master_fd
>= 0) {
663 close(pty_master_fd
);
666 close(pty_utmp_helper_pipe
); /* this causes utmp to be cleaned up */
670 * Called to query the current socket sendability status.
672 static int pty_sendbuffer(void *handle
)
678 * Called to set the size of the window
680 static void pty_size(void *handle
, int width
, int height
)
684 pty_term_width
= width
;
685 pty_term_height
= height
;
687 size
.ws_row
= (unsigned short)pty_term_height
;
688 size
.ws_col
= (unsigned short)pty_term_width
;
689 size
.ws_xpixel
= (unsigned short) pty_term_width
*
690 font_dimension(pty_frontend
, 0);
691 size
.ws_ypixel
= (unsigned short) pty_term_height
*
692 font_dimension(pty_frontend
, 1);
693 ioctl(pty_master_fd
, TIOCSWINSZ
, (void *)&size
);
698 * Send special codes.
700 static void pty_special(void *handle
, Telnet_Special code
)
706 static Socket
pty_socket(void *handle
)
708 return NULL
; /* shouldn't ever be needed */
711 static int pty_sendok(void *handle
)
716 static void pty_unthrottle(void *handle
, int backlog
)
721 static int pty_ldisc(void *handle
, int option
)
723 return 0; /* neither editing nor echoing */
726 static void pty_provide_ldisc(void *handle
, void *ldisc
)
728 /* This is a stub. */
731 static void pty_provide_logctx(void *handle
, void *logctx
)
733 /* This is a stub. */
736 static int pty_exitcode(void *handle
)
739 return -1; /* not dead yet */
741 return pty_exit_code
;
744 Backend pty_backend
= {