/* Low level interface to ptrace, for GDB when running under Unix.
- Copyright (C) 1986-2017 Free Software Foundation, Inc.
+ Copyright (C) 1986-2018 Free Software Foundation, Inc.
This file is part of GDB.
static void pass_signal (int);
-static void child_terminal_ours_1 (int);
+static void child_terminal_ours_1 (target_terminal_state);
\f
/* Record terminal status separately for debugger and inferior. */
/* Terminal related info we need to keep track of. Each inferior
holds an instance of this structure --- we save it whenever the
- corresponding inferior stops, and restore it to the foreground
- inferior when it resumes. */
+ corresponding inferior stops, and restore it to the terminal when
+ the inferior is resumed in the foreground. */
struct terminal_info
{
/* The name of the tty (from the `tty' command) that we gave to the
char *run_terminal;
/* TTY state. We save it whenever the inferior stops, and restore
- it when it resumes. */
+ it when it resumes in the foreground. */
serial_ttystate ttystate;
#ifdef HAVE_TERMIOS_H
- /* Process group. Saved and restored just like ttystate. */
+ /* The terminal's foreground process group. Saved whenever the
+ inferior stops. This is the pgrp displayed by "info terminal".
+ Note that this may be not the inferior's actual process group,
+ since each inferior that we spawn has its own process group, and
+ only one can be in the foreground at a time. When the inferior
+ resumes, if we can determine the inferior's actual pgrp, then we
+ make that the foreground pgrp instead of what was saved here.
+ While it's a bit arbitrary which inferior's pgrp ends up in the
+ foreground when we resume several inferiors, this at least makes
+ 'resume inf1+inf2' + 'stop all' + 'resume inf2' end up with
+ inf2's pgrp in the foreground instead of inf1's (which would be
+ problematic since it would be left stopped: Ctrl-C wouldn't work,
+ for example). */
pid_t process_group;
#endif
static struct terminal_info *get_inflow_inferior_data (struct inferior *);
-#ifdef HAVE_TERMIOS_H
-
-/* Return the process group of the current inferior. */
+/* RAII class used to ignore SIGTTOU in a scope. */
-pid_t
-inferior_process_group (void)
+class scoped_ignore_sigttou
{
- return get_inflow_inferior_data (current_inferior ())->process_group;
-}
+public:
+ scoped_ignore_sigttou ()
+ {
+#ifdef SIGTTOU
+ if (job_control)
+ m_osigttou = signal (SIGTTOU, SIG_IGN);
#endif
+ }
+
+ ~scoped_ignore_sigttou ()
+ {
+#ifdef SIGTTOU
+ if (job_control)
+ signal (SIGTTOU, m_osigttou);
+#endif
+ }
+
+ DISABLE_COPY_AND_ASSIGN (scoped_ignore_sigttou);
+
+private:
+#ifdef SIGTTOU
+ sighandler_t m_osigttou = NULL;
+#endif
+};
/* While the inferior is running, we want SIGINT and SIGQUIT to go to the
inferior only. If we have job control, that takes care of it. If not,
fork_inferior, while forking a new child. */
static const char *inferior_thisrun_terminal;
-/* Nonzero if our terminal settings are in effect. Zero if the
- inferior's settings are in effect. Ignored if !gdb_has_a_terminal
- (). */
+/* Track who owns GDB's terminal (is it GDB or some inferior?). While
+ target_terminal::is_ours() etc. tracks the core's intention and is
+ independent of the target backend, this tracks the actual state of
+ GDB's own tty. So for example,
-int terminal_is_ours;
+ (target_terminal::is_inferior () && gdb_tty_state == terminal_is_ours)
+
+ is true when the (native) inferior is not sharing a terminal with
+ GDB (e.g., because we attached to an inferior that is running on a
+ different terminal). */
+static target_terminal_state gdb_tty_state = target_terminal_state::is_ours;
/* See terminal.h. */
void
child_terminal_init (struct target_ops *self)
{
- struct inferior *inf = current_inferior ();
- struct terminal_info *tinfo = get_inflow_inferior_data (inf);
+ if (!gdb_has_a_terminal ())
+ return;
+
+ inferior *inf = current_inferior ();
+ terminal_info *tinfo = get_inflow_inferior_data (inf);
#ifdef HAVE_TERMIOS_H
- /* Store the process group even without a terminal as it is used not
- only to reset the tty foreground process group, but also to
- interrupt the inferior. A child we spawn should be a process
- group leader (PGID==PID) at this point, though that may not be
- true if we're attaching to an existing process. */
+ /* A child we spawn should be a process group leader (PGID==PID) at
+ this point, though that may not be true if we're attaching to an
+ existing process. */
tinfo->process_group = inf->pid;
#endif
- if (gdb_has_a_terminal ())
- {
- xfree (tinfo->ttystate);
- tinfo->ttystate = serial_copy_tty_state (stdin_serial,
- initial_gdb_ttystate);
-
- /* Make sure that next time we call terminal_inferior (which will be
- before the program runs, as it needs to be), we install the new
- process group. */
- terminal_is_ours = 1;
- }
+ xfree (tinfo->ttystate);
+ tinfo->ttystate = serial_copy_tty_state (stdin_serial, initial_gdb_ttystate);
}
/* Save the terminal settings again. This is necessary for the TUI
}
}
-/* Put the inferior's terminal settings into effect.
- This is preparation for starting or resuming the inferior.
+/* Try to determine whether TTY is GDB's input terminal. Returns
+ TRIBOOL_UNKNOWN if we can't tell. */
- N.B. Targets that want to use this with async support must build that
- support on top of this (e.g., the caller still needs to remove stdin
- from the event loop). E.g., see linux_nat_terminal_inferior. */
+static tribool
+is_gdb_terminal (const char *tty)
+{
+ struct stat gdb_tty;
+ struct stat other_tty;
+ int res;
+
+ res = stat (tty, &other_tty);
+ if (res == -1)
+ return TRIBOOL_UNKNOWN;
+
+ res = fstat (STDIN_FILENO, &gdb_tty);
+ if (res == -1)
+ return TRIBOOL_UNKNOWN;
+
+ return ((gdb_tty.st_dev == other_tty.st_dev
+ && gdb_tty.st_ino == other_tty.st_ino)
+ ? TRIBOOL_TRUE
+ : TRIBOOL_FALSE);
+}
+
+/* Helper for sharing_input_terminal. Try to determine whether
+ inferior INF is using the same TTY for input as GDB is. Returns
+ TRIBOOL_UNKNOWN if we can't tell. */
+
+static tribool
+sharing_input_terminal_1 (inferior *inf)
+{
+ /* Using host-dependent code here is fine, because the
+ child_terminal_foo functions are meant to be used by child/native
+ targets. */
+#if defined (__linux__) || defined (__sun__)
+ char buf[100];
+
+ xsnprintf (buf, sizeof (buf), "/proc/%d/fd/0", inf->pid);
+ return is_gdb_terminal (buf);
+#else
+ return TRIBOOL_UNKNOWN;
+#endif
+}
+
+/* Return true if the inferior is using the same TTY for input as GDB
+ is. If this is true, then we save/restore terminal flags/state.
+
+ This is necessary because if inf->attach_flag is set, we don't
+ offhand know whether we are sharing a terminal with the inferior or
+ not. Attaching a process without a terminal is one case where we
+ do not; attaching a process which we ran from the same shell as GDB
+ via `&' is one case where we do.
+
+ If we can't determine, we assume the TTY is being shared. This
+ works OK if you're only debugging one inferior. However, if you're
+ debugging more than one inferior, and e.g., one is spawned by GDB
+ with "run" (sharing terminal with GDB), and another is attached to
+ (and running on a different terminal, as is most common), then it
+ matters, because we can only restore the terminal settings of one
+ of the inferiors, and in that scenario, we want to restore the
+ settings of the "run"'ed inferior.
+
+ Note, this is not the same as determining whether GDB and the
+ inferior are in the same session / connected to the same
+ controlling tty. An inferior (fork child) may call setsid,
+ disconnecting itself from the ctty, while still leaving
+ stdin/stdout/stderr associated with the original terminal. If
+ we're debugging that process, we should also save/restore terminal
+ settings. */
+
+static bool
+sharing_input_terminal (inferior *inf)
+{
+ terminal_info *tinfo = get_inflow_inferior_data (inf);
+
+ tribool res = sharing_input_terminal_1 (inf);
+
+ if (res == TRIBOOL_UNKNOWN)
+ {
+ /* As fallback, if we can't determine by stat'ing the inferior's
+ tty directly (because it's not supported on this host) and
+ the child was spawned, check whether run_terminal is our tty.
+ This isn't ideal, since this is checking the child's
+ controlling terminal, not the input terminal (which may have
+ been redirected), but is still better than nothing. A false
+ positive ("set inferior-tty" points to our terminal, but I/O
+ was redirected) is much more likely than a false negative
+ ("set inferior-tty" points to some other terminal, and then
+ output was redirected to our terminal), and with a false
+ positive we just end up trying to save/restore terminal
+ settings when we didn't need to or we actually can't. */
+ if (tinfo->run_terminal != NULL)
+ res = is_gdb_terminal (tinfo->run_terminal);
+
+ /* If we still can't determine, assume yes. */
+ if (res == TRIBOOL_UNKNOWN)
+ return true;
+ }
+
+ return res == TRIBOOL_TRUE;
+}
+
+/* Put the inferior's terminal settings into effect. This is
+ preparation for starting or resuming the inferior. */
void
child_terminal_inferior (struct target_ops *self)
{
- struct inferior *inf;
- struct terminal_info *tinfo;
-
- if (!terminal_is_ours)
+ /* If we resume more than one inferior in the foreground on GDB's
+ terminal, then the first inferior's terminal settings "win".
+ Note that every child process is put in its own process group, so
+ the first process that ends up resumed ends up determining which
+ process group the kernel forwards Ctrl-C/Ctrl-Z (SIGINT/SIGTTOU)
+ to. */
+ if (gdb_tty_state == target_terminal_state::is_inferior)
return;
- inf = current_inferior ();
- tinfo = get_inflow_inferior_data (inf);
+ inferior *inf = current_inferior ();
+ terminal_info *tinfo = get_inflow_inferior_data (inf);
if (gdb_has_a_terminal ()
&& tinfo->ttystate != NULL
- && tinfo->run_terminal == NULL)
+ && sharing_input_terminal (inf))
{
int result;
+ /* Ignore SIGTTOU since it will happen when we try to set the
+ terminal's state (if gdb_tty_state is currently
+ ours_for_output). */
+ scoped_ignore_sigttou ignore_sigttou;
+
#ifdef F_GETFL
result = fcntl (0, F_SETFL, tinfo->tflags);
OOPSY ("fcntl F_SETFL");
#endif
}
- /* If attach_flag is set, we don't know whether we are sharing a
- terminal with the inferior or not. (attaching a process
- without a terminal is one case where we do not; attaching a
- process which we ran from the same shell as GDB via `&' is
- one case where we do, I think (but perhaps this is not
- `sharing' in the sense that we need to save and restore tty
- state)). I don't know if there is any way to tell whether we
- are sharing a terminal. So what we do is to go through all
- the saving and restoring of the tty state, but ignore errors
- setting the process group, which will happen if we are not
- sharing a terminal). */
-
if (job_control)
{
#ifdef HAVE_TERMIOS_H
+ /* If we can't tell the inferior's actual process group,
+ then restore whatever was the foreground pgrp the last
+ time the inferior was running. See also comments
+ describing terminal_state::process_group. */
+#ifdef HAVE_GETPGID
+ result = tcsetpgrp (0, getpgid (inf->pid));
+#else
result = tcsetpgrp (0, tinfo->process_group);
- if (!inf->attach_flag)
- OOPSY ("tcsetpgrp");
+#endif
+ if (result == -1)
+ {
+#if 0
+ /* This fails if either GDB has no controlling terminal,
+ e.g., running under 'setsid(1)', or if the inferior
+ is not attached to GDB's controlling terminal. E.g.,
+ if it called setsid to create a new session or used
+ the TIOCNOTTY ioctl, or simply if we've attached to a
+ process running on another terminal and we couldn't
+ tell whether it was sharing GDB's terminal (and so
+ assumed yes). */
+ fprintf_unfiltered
+ (gdb_stderr,
+ "[tcsetpgrp failed in child_terminal_inferior: %s]\n",
+ safe_strerror (errno));
+#endif
+ }
#endif
}
+
+ gdb_tty_state = target_terminal_state::is_inferior;
}
- terminal_is_ours = 0;
}
/* Put some of our terminal settings into effect,
void
child_terminal_ours_for_output (struct target_ops *self)
{
- child_terminal_ours_1 (1);
+ child_terminal_ours_1 (target_terminal_state::is_ours_for_output);
}
/* Put our terminal settings into effect.
void
child_terminal_ours (struct target_ops *self)
{
- child_terminal_ours_1 (0);
+ child_terminal_ours_1 (target_terminal_state::is_ours);
}
-/* output_only is not used, and should not be used unless we introduce
- separate terminal_is_ours and terminal_is_ours_for_output
- flags. */
+/* Save the current terminal settings in the inferior's terminal_info
+ cache. */
-static void
-child_terminal_ours_1 (int output_only)
+void
+child_terminal_save_inferior (struct target_ops *self)
{
- struct inferior *inf;
- struct terminal_info *tinfo;
-
- if (terminal_is_ours)
+ /* Avoid attempting all the ioctl's when running in batch. */
+ if (!gdb_has_a_terminal ())
return;
- terminal_is_ours = 1;
+ inferior *inf = current_inferior ();
+ terminal_info *tinfo = get_inflow_inferior_data (inf);
- /* Checking inferior->run_terminal is necessary so that
- if GDB is running in the background, it won't block trying
- to do the ioctl()'s below. Checking gdb_has_a_terminal
- avoids attempting all the ioctl's when running in batch. */
+ /* No need to save/restore if the inferior is not sharing GDB's
+ tty. */
+ if (!sharing_input_terminal (inf))
+ return;
- inf = current_inferior ();
- tinfo = get_inflow_inferior_data (inf);
+ xfree (tinfo->ttystate);
+ tinfo->ttystate = serial_get_tty_state (stdin_serial);
- if (tinfo->run_terminal != NULL || gdb_has_a_terminal () == 0)
- return;
- else
- {
-#ifdef SIGTTOU
- /* Ignore this signal since it will happen when we try to set the
- pgrp. */
- sighandler_t osigttou = NULL;
+#ifdef HAVE_TERMIOS_H
+ tinfo->process_group = tcgetpgrp (0);
#endif
- int result ATTRIBUTE_UNUSED;
-#ifdef SIGTTOU
- if (job_control)
- osigttou = signal (SIGTTOU, SIG_IGN);
+#ifdef F_GETFL
+ tinfo->tflags = fcntl (0, F_GETFL, 0);
#endif
+}
- xfree (tinfo->ttystate);
- tinfo->ttystate = serial_get_tty_state (stdin_serial);
+/* Switch terminal state to DESIRED_STATE, either is_ours, or
+ is_ours_for_output. */
-#ifdef HAVE_TERMIOS_H
- if (!inf->attach_flag)
- /* If tcsetpgrp failed in terminal_inferior, this would give us
- our process group instead of the inferior's. See
- terminal_inferior for details. */
- tinfo->process_group = tcgetpgrp (0);
-#endif
+static void
+child_terminal_ours_1 (target_terminal_state desired_state)
+{
+ gdb_assert (desired_state != target_terminal_state::is_inferior);
+
+ /* Avoid attempting all the ioctl's when running in batch. */
+ if (!gdb_has_a_terminal ())
+ return;
+
+ if (gdb_tty_state != desired_state)
+ {
+ int result ATTRIBUTE_UNUSED;
+
+ /* Ignore SIGTTOU since it will happen when we try to set the
+ terminal's pgrp. */
+ scoped_ignore_sigttou ignore_sigttou;
/* Set tty state to our_ttystate. */
serial_set_tty_state (stdin_serial, our_terminal_info.ttystate);
- if (job_control)
+ /* If we only want output, then leave the inferior's pgrp in the
+ foreground, so that Ctrl-C/Ctrl-Z reach the inferior
+ directly. */
+ if (job_control && desired_state == target_terminal_state::is_ours)
{
#ifdef HAVE_TERMIOS_H
result = tcsetpgrp (0, our_terminal_info.process_group);
#endif /* termios */
}
-#ifdef SIGTTOU
- if (job_control)
- signal (SIGTTOU, osigttou);
-#endif
-
- if (!job_control)
+ if (!job_control && desired_state == target_terminal_state::is_ours)
{
signal (SIGINT, sigint_ours);
#ifdef SIGQUIT
}
#ifdef F_GETFL
- tinfo->tflags = fcntl (0, F_GETFL, 0);
result = fcntl (0, F_SETFL, our_terminal_info.tflags);
#endif
+
+ gdb_tty_state = desired_state;
}
}
+/* Interrupt the inferior. Implementation of target_interrupt for
+ child/native targets. */
+
+void
+child_interrupt (struct target_ops *self)
+{
+ /* Interrupt the first inferior that has a resumed thread. */
+ thread_info *thr;
+ thread_info *resumed = NULL;
+ ALL_NON_EXITED_THREADS (thr)
+ {
+ if (thr->executing)
+ {
+ resumed = thr;
+ break;
+ }
+ if (thr->suspend.waitstatus_pending_p)
+ resumed = thr;
+ }
+
+ if (resumed != NULL)
+ {
+ /* Note that unlike pressing Ctrl-C on the controlling terminal,
+ here we only interrupt one process, not the whole process
+ group. This is because interrupting a process group (with
+ either Ctrl-C or with kill(3) with negative PID) sends a
+ SIGINT to each process in the process group, and we may not
+ be debugging all processes in the process group. */
+#ifndef _WIN32
+ kill (resumed->inf->pid, SIGINT);
+#endif
+ }
+}
+
+/* Pass a Ctrl-C to the inferior as-if a Ctrl-C was pressed while the
+ inferior was in the foreground. Implementation of
+ target_pass_ctrlc for child/native targets. */
+
+void
+child_pass_ctrlc (struct target_ops *self)
+{
+ gdb_assert (!target_terminal::is_ours ());
+
+#ifdef HAVE_TERMIOS_H
+ if (job_control)
+ {
+ pid_t term_pgrp = tcgetpgrp (0);
+
+ /* If there's any inferior sharing our terminal, pass the SIGINT
+ to the terminal's foreground process group. This acts just
+ like the user typed a ^C on the terminal while the inferior
+ was in the foreground. Note that using a negative process
+ number in kill() is a System V-ism. The proper BSD interface
+ is killpg(). However, all modern BSDs support the System V
+ interface too. */
+
+ if (term_pgrp != -1 && term_pgrp != our_terminal_info.process_group)
+ {
+ kill (-term_pgrp, SIGINT);
+ return;
+ }
+ }
+#endif
+
+ /* Otherwise, pass the Ctrl-C to the first inferior that was resumed
+ in the foreground. */
+ inferior *inf;
+ ALL_INFERIORS (inf)
+ {
+ if (inf->terminal_state != target_terminal_state::is_ours)
+ {
+ gdb_assert (inf->pid != 0);
+
+#ifndef _WIN32
+ kill (inf->pid, SIGINT);
+#endif
+ return;
+ }
+ }
+
+ /* If no inferior was resumed in the foreground, then how did the
+ !is_ours assert above pass? */
+ gdb_assert_not_reached ("no inferior resumed in the fg found");
+}
+
/* Per-inferior data key. */
static const struct inferior_data *inflow_inferior_data;
{
struct terminal_info *info;
+ inf->terminal_state = target_terminal_state::is_ours;
+
info = (struct terminal_info *) inferior_data (inf, inflow_inferior_data);
if (info != NULL)
{
if (tinfo_from->ttystate)
tinfo_to->ttystate
= serial_copy_tty_state (stdin_serial, tinfo_from->ttystate);
+
+ to->terminal_state = from->terminal_state;
}
void
-info_terminal_command (char *arg, int from_tty)
+info_terminal_command (const char *arg, int from_tty)
{
target_terminal::info (arg, from_tty);
}
tty = open ("/dev/tty", O_RDWR);
if (tty > 0)
{
- sighandler_t osigttou;
+ scoped_ignore_sigttou ignore_sigttou;
- osigttou = signal (SIGTTOU, SIG_IGN);
ioctl (tty, TIOCNOTTY, 0);
close (tty);
- signal (SIGTTOU, osigttou);
}
#endif
add_info ("terminal", info_terminal_command,
_("Print inferior's saved terminal status."));
- terminal_is_ours = 1;
-
/* OK, figure out whether we have job control. */
have_job_control ();
projects / deliverable / binutils-gdb.git / blobdiff