1 /* Low level interface to ptrace, for GDB when running under Unix.
2 Copyright (C) 1986-2017 Free Software Foundation, Inc.
4 This file is part of GDB.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>. */
26 #include "gdbthread.h"
30 #include "gdb_select.h"
37 #include "job-control.h"
39 #ifdef HAVE_SYS_IOCTL_H
40 #include <sys/ioctl.h>
47 static void pass_signal (int);
49 static void child_terminal_ours_1 (int);
51 /* Record terminal status separately for debugger and inferior. */
53 static struct serial
*stdin_serial
;
55 /* Terminal related info we need to keep track of. Each inferior
56 holds an instance of this structure --- we save it whenever the
57 corresponding inferior stops, and restore it to the foreground
58 inferior when it resumes. */
61 /* The name of the tty (from the `tty' command) that we gave to the
62 inferior when it was started. */
65 /* TTY state. We save it whenever the inferior stops, and restore
66 it when it resumes. */
67 serial_ttystate ttystate
;
70 /* Process group. Saved and restored just like ttystate. */
74 /* fcntl flags. Saved and restored just like ttystate. */
78 /* Our own tty state, which we restore every time we need to deal with
79 the terminal. This is set once, when GDB first starts, and then
80 whenever we enter/leave TUI mode (gdb_save_tty_state). The
81 settings of flags which readline saves and restores are
83 static struct terminal_info our_terminal_info
;
85 /* Snapshot of the initial tty state taken during initialization of
86 GDB, before readline/ncurses have had a chance to change it. This
87 is used as the initial tty state given to each new spawned
88 inferior. Unlike our_terminal_info, this is only ever set
90 static serial_ttystate initial_gdb_ttystate
;
92 static struct terminal_info
*get_inflow_inferior_data (struct inferior
*);
96 /* Return the process group of the current inferior. */
99 inferior_process_group (void)
101 return get_inflow_inferior_data (current_inferior ())->process_group
;
105 /* While the inferior is running, we want SIGINT and SIGQUIT to go to the
106 inferior only. If we have job control, that takes care of it. If not,
107 we save our handlers in these two variables and set SIGINT and SIGQUIT
110 static sighandler_t sigint_ours
;
111 static sighandler_t sigquit_ours
;
113 /* The name of the tty (from the `tty' command) that we're giving to
114 the inferior when starting it up. This is only (and should only
115 be) used as a transient global by new_tty_prefork,
116 create_tty_session, new_tty and new_tty_postfork, all called from
117 fork_inferior, while forking a new child. */
118 static const char *inferior_thisrun_terminal
;
120 /* Nonzero if our terminal settings are in effect. Zero if the
121 inferior's settings are in effect. Ignored if !gdb_has_a_terminal
124 int terminal_is_ours
;
126 /* See terminal.h. */
129 set_initial_gdb_ttystate (void)
131 /* Note we can't do any of this in _initialize_inflow because at
132 that point stdin_serial has not been created yet. */
134 initial_gdb_ttystate
= serial_get_tty_state (stdin_serial
);
136 if (initial_gdb_ttystate
!= NULL
)
138 our_terminal_info
.ttystate
139 = serial_copy_tty_state (stdin_serial
, initial_gdb_ttystate
);
141 our_terminal_info
.tflags
= fcntl (0, F_GETFL
, 0);
143 #ifdef HAVE_TERMIOS_H
144 our_terminal_info
.process_group
= tcgetpgrp (0);
149 /* Does GDB have a terminal (on stdin)? */
152 gdb_has_a_terminal (void)
154 return initial_gdb_ttystate
!= NULL
;
157 /* Macro for printing errors from ioctl operations */
159 #define OOPSY(what) \
161 fprintf_unfiltered(gdb_stderr, "[%s failed in terminal_inferior: %s]\n", \
162 what, safe_strerror (errno))
164 /* Initialize the terminal settings we record for the inferior,
165 before we actually run the inferior. */
168 child_terminal_init (struct target_ops
*self
)
170 struct inferior
*inf
= current_inferior ();
171 struct terminal_info
*tinfo
= get_inflow_inferior_data (inf
);
173 #ifdef HAVE_TERMIOS_H
174 /* Store the process group even without a terminal as it is used not
175 only to reset the tty foreground process group, but also to
176 interrupt the inferior. A child we spawn should be a process
177 group leader (PGID==PID) at this point, though that may not be
178 true if we're attaching to an existing process. */
179 tinfo
->process_group
= inf
->pid
;
182 if (gdb_has_a_terminal ())
184 xfree (tinfo
->ttystate
);
185 tinfo
->ttystate
= serial_copy_tty_state (stdin_serial
,
186 initial_gdb_ttystate
);
188 /* Make sure that next time we call terminal_inferior (which will be
189 before the program runs, as it needs to be), we install the new
191 terminal_is_ours
= 1;
195 /* Save the terminal settings again. This is necessary for the TUI
196 when it switches to TUI or non-TUI mode; curses changes the terminal
197 and gdb must be able to restore it correctly. */
200 gdb_save_tty_state (void)
202 if (gdb_has_a_terminal ())
204 xfree (our_terminal_info
.ttystate
);
205 our_terminal_info
.ttystate
= serial_get_tty_state (stdin_serial
);
209 /* Put the inferior's terminal settings into effect.
210 This is preparation for starting or resuming the inferior.
212 N.B. Targets that want to use this with async support must build that
213 support on top of this (e.g., the caller still needs to remove stdin
214 from the event loop). E.g., see linux_nat_terminal_inferior. */
217 child_terminal_inferior (struct target_ops
*self
)
219 struct inferior
*inf
;
220 struct terminal_info
*tinfo
;
222 if (!terminal_is_ours
)
225 inf
= current_inferior ();
226 tinfo
= get_inflow_inferior_data (inf
);
228 if (gdb_has_a_terminal ()
229 && tinfo
->ttystate
!= NULL
230 && tinfo
->run_terminal
== NULL
)
235 result
= fcntl (0, F_SETFL
, tinfo
->tflags
);
236 OOPSY ("fcntl F_SETFL");
239 result
= serial_set_tty_state (stdin_serial
, tinfo
->ttystate
);
240 OOPSY ("setting tty state");
244 sigint_ours
= signal (SIGINT
, SIG_IGN
);
246 sigquit_ours
= signal (SIGQUIT
, SIG_IGN
);
250 /* If attach_flag is set, we don't know whether we are sharing a
251 terminal with the inferior or not. (attaching a process
252 without a terminal is one case where we do not; attaching a
253 process which we ran from the same shell as GDB via `&' is
254 one case where we do, I think (but perhaps this is not
255 `sharing' in the sense that we need to save and restore tty
256 state)). I don't know if there is any way to tell whether we
257 are sharing a terminal. So what we do is to go through all
258 the saving and restoring of the tty state, but ignore errors
259 setting the process group, which will happen if we are not
260 sharing a terminal). */
264 #ifdef HAVE_TERMIOS_H
265 result
= tcsetpgrp (0, tinfo
->process_group
);
266 if (!inf
->attach_flag
)
271 terminal_is_ours
= 0;
274 /* Put some of our terminal settings into effect,
275 enough to get proper results from our output,
276 but do not change into or out of RAW mode
277 so that no input is discarded.
279 After doing this, either terminal_ours or terminal_inferior
280 should be called to get back to a normal state of affairs.
282 N.B. The implementation is (currently) no different than
283 child_terminal_ours. See child_terminal_ours_1. */
286 child_terminal_ours_for_output (struct target_ops
*self
)
288 child_terminal_ours_1 (1);
291 /* Put our terminal settings into effect.
292 First record the inferior's terminal settings
293 so they can be restored properly later.
295 N.B. Targets that want to use this with async support must build that
296 support on top of this (e.g., the caller still needs to add stdin to the
297 event loop). E.g., see linux_nat_terminal_ours. */
300 child_terminal_ours (struct target_ops
*self
)
302 child_terminal_ours_1 (0);
305 /* output_only is not used, and should not be used unless we introduce
306 separate terminal_is_ours and terminal_is_ours_for_output
310 child_terminal_ours_1 (int output_only
)
312 struct inferior
*inf
;
313 struct terminal_info
*tinfo
;
315 if (terminal_is_ours
)
318 terminal_is_ours
= 1;
320 /* Checking inferior->run_terminal is necessary so that
321 if GDB is running in the background, it won't block trying
322 to do the ioctl()'s below. Checking gdb_has_a_terminal
323 avoids attempting all the ioctl's when running in batch. */
325 inf
= current_inferior ();
326 tinfo
= get_inflow_inferior_data (inf
);
328 if (tinfo
->run_terminal
!= NULL
|| gdb_has_a_terminal () == 0)
333 /* Ignore this signal since it will happen when we try to set the
335 sighandler_t osigttou
= NULL
;
337 int result ATTRIBUTE_UNUSED
;
341 osigttou
= signal (SIGTTOU
, SIG_IGN
);
344 xfree (tinfo
->ttystate
);
345 tinfo
->ttystate
= serial_get_tty_state (stdin_serial
);
347 #ifdef HAVE_TERMIOS_H
348 if (!inf
->attach_flag
)
349 /* If tcsetpgrp failed in terminal_inferior, this would give us
350 our process group instead of the inferior's. See
351 terminal_inferior for details. */
352 tinfo
->process_group
= tcgetpgrp (0);
355 /* Set tty state to our_ttystate. */
356 serial_set_tty_state (stdin_serial
, our_terminal_info
.ttystate
);
360 #ifdef HAVE_TERMIOS_H
361 result
= tcsetpgrp (0, our_terminal_info
.process_group
);
363 /* This fails on Ultrix with EINVAL if you run the testsuite
364 in the background with nohup, and then log out. GDB never
365 used to check for an error here, so perhaps there are other
366 such situations as well. */
368 fprintf_unfiltered (gdb_stderr
,
369 "[tcsetpgrp failed in child_terminal_ours: %s]\n",
370 safe_strerror (errno
));
377 signal (SIGTTOU
, osigttou
);
382 signal (SIGINT
, sigint_ours
);
384 signal (SIGQUIT
, sigquit_ours
);
389 tinfo
->tflags
= fcntl (0, F_GETFL
, 0);
390 result
= fcntl (0, F_SETFL
, our_terminal_info
.tflags
);
395 /* Per-inferior data key. */
396 static const struct inferior_data
*inflow_inferior_data
;
399 inflow_inferior_data_cleanup (struct inferior
*inf
, void *arg
)
401 struct terminal_info
*info
= (struct terminal_info
*) arg
;
403 xfree (info
->run_terminal
);
404 xfree (info
->ttystate
);
408 /* Get the current svr4 data. If none is found yet, add it now. This
409 function always returns a valid object. */
411 static struct terminal_info
*
412 get_inflow_inferior_data (struct inferior
*inf
)
414 struct terminal_info
*info
;
416 info
= (struct terminal_info
*) inferior_data (inf
, inflow_inferior_data
);
419 info
= XCNEW (struct terminal_info
);
420 set_inferior_data (inf
, inflow_inferior_data
, info
);
426 /* This is a "inferior_exit" observer. Releases the TERMINAL_INFO member
427 of the inferior structure. This field is private to inflow.c, and
428 its type is opaque to the rest of GDB. PID is the target pid of
429 the inferior that is about to be removed from the inferior
433 inflow_inferior_exit (struct inferior
*inf
)
435 struct terminal_info
*info
;
437 info
= (struct terminal_info
*) inferior_data (inf
, inflow_inferior_data
);
440 xfree (info
->run_terminal
);
441 xfree (info
->ttystate
);
443 set_inferior_data (inf
, inflow_inferior_data
, NULL
);
448 copy_terminal_info (struct inferior
*to
, struct inferior
*from
)
450 struct terminal_info
*tinfo_to
, *tinfo_from
;
452 tinfo_to
= get_inflow_inferior_data (to
);
453 tinfo_from
= get_inflow_inferior_data (from
);
455 xfree (tinfo_to
->run_terminal
);
456 xfree (tinfo_to
->ttystate
);
458 *tinfo_to
= *tinfo_from
;
460 if (tinfo_from
->run_terminal
)
461 tinfo_to
->run_terminal
462 = xstrdup (tinfo_from
->run_terminal
);
464 if (tinfo_from
->ttystate
)
466 = serial_copy_tty_state (stdin_serial
, tinfo_from
->ttystate
);
470 info_terminal_command (const char *arg
, int from_tty
)
472 target_terminal::info (arg
, from_tty
);
476 child_terminal_info (struct target_ops
*self
, const char *args
, int from_tty
)
478 struct inferior
*inf
;
479 struct terminal_info
*tinfo
;
481 if (!gdb_has_a_terminal ())
483 printf_filtered (_("This GDB does not control a terminal.\n"));
487 if (ptid_equal (inferior_ptid
, null_ptid
))
490 inf
= current_inferior ();
491 tinfo
= get_inflow_inferior_data (inf
);
493 printf_filtered (_("Inferior's terminal status "
494 "(currently saved by GDB):\n"));
496 /* First the fcntl flags. */
500 flags
= tinfo
->tflags
;
502 printf_filtered ("File descriptor flags = ");
505 #define O_ACCMODE (O_RDONLY | O_WRONLY | O_RDWR)
507 /* (O_ACCMODE) parens are to avoid Ultrix header file bug. */
508 switch (flags
& (O_ACCMODE
))
511 printf_filtered ("O_RDONLY");
514 printf_filtered ("O_WRONLY");
517 printf_filtered ("O_RDWR");
520 flags
&= ~(O_ACCMODE
);
523 if (flags
& O_NONBLOCK
)
524 printf_filtered (" | O_NONBLOCK");
525 flags
&= ~O_NONBLOCK
;
528 #if defined (O_NDELAY)
529 /* If O_NDELAY and O_NONBLOCK are defined to the same thing, we will
530 print it as O_NONBLOCK, which is good cause that is what POSIX
531 has, and the flag will already be cleared by the time we get here. */
532 if (flags
& O_NDELAY
)
533 printf_filtered (" | O_NDELAY");
537 if (flags
& O_APPEND
)
538 printf_filtered (" | O_APPEND");
541 #if defined (O_BINARY)
542 if (flags
& O_BINARY
)
543 printf_filtered (" | O_BINARY");
548 printf_filtered (" | 0x%x", flags
);
549 printf_filtered ("\n");
552 #ifdef HAVE_TERMIOS_H
553 printf_filtered ("Process group = %d\n", (int) tinfo
->process_group
);
556 serial_print_tty_state (stdin_serial
, tinfo
->ttystate
, gdb_stdout
);
559 /* NEW_TTY_PREFORK is called before forking a new child process,
560 so we can record the state of ttys in the child to be formed.
561 TTYNAME is null if we are to share the terminal with gdb;
562 or points to a string containing the name of the desired tty.
564 NEW_TTY is called in new child processes under Unix, which will
565 become debugger target processes. This actually switches to
566 the terminal specified in the NEW_TTY_PREFORK call. */
569 new_tty_prefork (const char *ttyname
)
571 /* Save the name for later, for determining whether we and the child
572 are sharing a tty. */
573 inferior_thisrun_terminal
= ttyname
;
576 #if !defined(__GO32__) && !defined(_WIN32)
577 /* If RESULT, assumed to be the return value from a system call, is
578 negative, print the error message indicated by errno and exit.
579 MSG should identify the operation that failed. */
581 check_syscall (const char *msg
, int result
)
585 print_sys_errmsg (msg
, errno
);
596 if (inferior_thisrun_terminal
== 0)
598 #if !defined(__GO32__) && !defined(_WIN32)
600 /* Disconnect the child process from our controlling terminal. On some
601 systems (SVR4 for example), this may cause a SIGTTOU, so temporarily
603 tty
= open ("/dev/tty", O_RDWR
);
606 sighandler_t osigttou
;
608 osigttou
= signal (SIGTTOU
, SIG_IGN
);
609 ioctl (tty
, TIOCNOTTY
, 0);
611 signal (SIGTTOU
, osigttou
);
615 /* Now open the specified new terminal. */
616 tty
= open (inferior_thisrun_terminal
, O_RDWR
| O_NOCTTY
);
617 check_syscall (inferior_thisrun_terminal
, tty
);
619 /* Avoid use of dup2; doesn't exist on all systems. */
623 check_syscall ("dup'ing tty into fd 0", dup (tty
));
628 check_syscall ("dup'ing tty into fd 1", dup (tty
));
633 check_syscall ("dup'ing tty into fd 2", dup (tty
));
637 /* Make tty our new controlling terminal. */
638 if (ioctl (tty
, TIOCSCTTY
, 0) == -1)
639 /* Mention GDB in warning because it will appear in the inferior's
640 terminal instead of GDB's. */
641 warning (_("GDB: Failed to set controlling terminal: %s"),
642 safe_strerror (errno
));
647 #endif /* !go32 && !win32 */
650 /* NEW_TTY_POSTFORK is called after forking a new child process, and
651 adding it to the inferior table, to store the TTYNAME being used by
652 the child, or null if it sharing the terminal with gdb. */
655 new_tty_postfork (void)
657 /* Save the name for later, for determining whether we and the child
658 are sharing a tty. */
660 if (inferior_thisrun_terminal
)
662 struct inferior
*inf
= current_inferior ();
663 struct terminal_info
*tinfo
= get_inflow_inferior_data (inf
);
665 tinfo
->run_terminal
= xstrdup (inferior_thisrun_terminal
);
668 inferior_thisrun_terminal
= NULL
;
672 /* Call set_sigint_trap when you need to pass a signal on to an attached
673 process when handling SIGINT. */
676 pass_signal (int signo
)
679 kill (ptid_get_pid (inferior_ptid
), SIGINT
);
683 static sighandler_t osig
;
687 set_sigint_trap (void)
689 struct inferior
*inf
= current_inferior ();
690 struct terminal_info
*tinfo
= get_inflow_inferior_data (inf
);
692 if (inf
->attach_flag
|| tinfo
->run_terminal
)
694 osig
= signal (SIGINT
, pass_signal
);
702 clear_sigint_trap (void)
706 signal (SIGINT
, osig
);
712 /* Create a new session if the inferior will run in a different tty.
713 A session is UNIX's way of grouping processes that share a controlling
714 terminal, so a new one is needed if the inferior terminal will be
715 different from GDB's.
717 Returns the session id of the new session, 0 if no session was created
718 or -1 if an error occurred. */
720 create_tty_session (void)
725 if (!job_control
|| inferior_thisrun_terminal
== 0)
730 warning (_("Failed to create new terminal session: setsid: %s"),
731 safe_strerror (errno
));
736 #endif /* HAVE_SETSID */
739 /* Get all the current tty settings (including whether we have a
740 tty at all!). We can't do this in _initialize_inflow because
741 serial_fdopen() won't work until the serial_ops_list is
742 initialized, but we don't want to do it lazily either, so
743 that we can guarantee stdin_serial is opened if there is
746 initialize_stdin_serial (void)
748 stdin_serial
= serial_fdopen (0);
752 _initialize_inflow (void)
754 add_info ("terminal", info_terminal_command
,
755 _("Print inferior's saved terminal status."));
757 terminal_is_ours
= 1;
759 /* OK, figure out whether we have job control. */
762 observer_attach_inferior_exit (inflow_inferior_exit
);
765 = register_inferior_data_with_cleanup (NULL
, inflow_inferior_data_cleanup
);