gdb/

[thirdparty/binutils-gdb.git] / gdb / inferior.c

/* Multi-process control for GDB, the GNU debugger.

   Copyright (C) 2008-2012 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"
#include "exec.h"
#include "inferior.h"
#include "target.h"
#include "command.h"
#include "completer.h"
#include "gdbcmd.h"
#include "gdbthread.h"
#include "ui-out.h"
#include "observer.h"
#include "gdbthread.h"
#include "gdbcore.h"
#include "symfile.h"
#include "environ.h"
#include "cli/cli-utils.h"
#include "continuations.h"
#include "arch-utils.h"
#include "target-descriptions.h"

void _initialize_inferiors (void);

/* Keep a registry of per-inferior data-pointers required by other GDB
   modules.  */

DEFINE_REGISTRY (inferior, REGISTRY_ACCESS_FIELD)

struct inferior *inferior_list = NULL;
static int highest_inferior_num;

/* Print notices on inferior events (attach, detach, etc.), set with
   `set print inferior-events'.  */
static int print_inferior_events = 0;

/* The Current Inferior.  */
static struct inferior *current_inferior_ = NULL;

struct inferior*
current_inferior (void)
{
  return current_inferior_;
}

void
set_current_inferior (struct inferior *inf)
{
  /* There's always an inferior.  */
  gdb_assert (inf != NULL);

  current_inferior_ = inf;
}

/* A cleanups callback, helper for save_current_program_space
   below.  */

static void
restore_inferior (void *arg)
{
  struct inferior *saved_inferior = arg;

  set_current_inferior (saved_inferior);
}

/* Save the current program space so that it may be restored by a later
   call to do_cleanups.  Returns the struct cleanup pointer needed for
   later doing the cleanup.  */

struct cleanup *
save_current_inferior (void)
{
  struct cleanup *old_chain = make_cleanup (restore_inferior,
					    current_inferior_);

  return old_chain;
}

static void
free_inferior (struct inferior *inf)
{
  discard_all_inferior_continuations (inf);
  inferior_free_data (inf);
  xfree (inf->args);
  xfree (inf->terminal);
  free_environ (inf->environment);
  target_desc_info_free (inf->tdesc_info);
  xfree (inf->private);
  xfree (inf);
}

void
init_inferior_list (void)
{
  struct inferior *inf, *infnext;

  highest_inferior_num = 0;
  if (!inferior_list)
    return;

  for (inf = inferior_list; inf; inf = infnext)
    {
      infnext = inf->next;
      free_inferior (inf);
    }

  inferior_list = NULL;
}

struct inferior *
add_inferior_silent (int pid)
{
  struct inferior *inf;

  inf = xmalloc (sizeof (*inf));
  memset (inf, 0, sizeof (*inf));
  inf->pid = pid;

  inf->control.stop_soon = NO_STOP_QUIETLY;

  inf->num = ++highest_inferior_num;
  inf->next = inferior_list;
  inferior_list = inf;

  inf->environment = make_environ ();
  init_environ (inf->environment);

  inferior_alloc_data (inf);

  observer_notify_inferior_added (inf);

  if (pid != 0)
    inferior_appeared (inf, pid);

  return inf;
}

struct inferior *
add_inferior (int pid)
{
  struct inferior *inf = add_inferior_silent (pid);

  if (print_inferior_events)
    printf_unfiltered (_("[New inferior %d]\n"), pid);

  return inf;
}

struct delete_thread_of_inferior_arg
{
  int pid;
  int silent;
};

static int
delete_thread_of_inferior (struct thread_info *tp, void *data)
{
  struct delete_thread_of_inferior_arg *arg = data;

  if (ptid_get_pid (tp->ptid) == arg->pid)
    {
      if (arg->silent)
	delete_thread_silent (tp->ptid);
      else
	delete_thread (tp->ptid);
    }

  return 0;
}

/* If SILENT then be quiet -- don't announce a inferior death, or the
   exit of its threads.  */

void
delete_inferior_1 (struct inferior *todel, int silent)
{
  struct inferior *inf, *infprev;
  struct delete_thread_of_inferior_arg arg;

  infprev = NULL;

  for (inf = inferior_list; inf; infprev = inf, inf = inf->next)
    if (inf == todel)
      break;

  if (!inf)
    return;

  arg.pid = inf->pid;
  arg.silent = silent;

  iterate_over_threads (delete_thread_of_inferior, &arg);

  if (infprev)
    infprev->next = inf->next;
  else
    inferior_list = inf->next;

  observer_notify_inferior_removed (inf);

  free_inferior (inf);
}

void
delete_inferior (int pid)
{
  struct inferior *inf = find_inferior_pid (pid);

  delete_inferior_1 (inf, 0);

  if (print_inferior_events)
    printf_unfiltered (_("[Inferior %d exited]\n"), pid);
}

void
delete_inferior_silent (int pid)
{
  struct inferior *inf = find_inferior_pid (pid);

  delete_inferior_1 (inf, 1);
}


/* If SILENT then be quiet -- don't announce a inferior exit, or the
   exit of its threads.  */

static void
exit_inferior_1 (struct inferior *inftoex, int silent)
{
  struct inferior *inf;
  struct delete_thread_of_inferior_arg arg;

  for (inf = inferior_list; inf; inf = inf->next)
    if (inf == inftoex)
      break;

  if (!inf)
    return;

  arg.pid = inf->pid;
  arg.silent = silent;

  iterate_over_threads (delete_thread_of_inferior, &arg);

  /* Notify the observers before removing the inferior from the list,
     so that the observers have a chance to look it up.  */
  observer_notify_inferior_exit (inf);

  inf->pid = 0;
  inf->fake_pid_p = 0;
  if (inf->vfork_parent != NULL)
    {
      inf->vfork_parent->vfork_child = NULL;
      inf->vfork_parent = NULL;
    }
  if (inf->vfork_child != NULL)
    {
      inf->vfork_child->vfork_parent = NULL;
      inf->vfork_child = NULL;
    }

  inf->has_exit_code = 0;
  inf->exit_code = 0;
  inf->pending_detach = 0;
}

void
exit_inferior (int pid)
{
  struct inferior *inf = find_inferior_pid (pid);

  exit_inferior_1 (inf, 0);

  if (print_inferior_events)
    printf_unfiltered (_("[Inferior %d exited]\n"), pid);
}

void
exit_inferior_silent (int pid)
{
  struct inferior *inf = find_inferior_pid (pid);

  exit_inferior_1 (inf, 1);
}

void
exit_inferior_num_silent (int num)
{
  struct inferior *inf = find_inferior_id (num);

  exit_inferior_1 (inf, 1);
}

void
detach_inferior (int pid)
{
  struct inferior *inf = find_inferior_pid (pid);

  exit_inferior_1 (inf, 1);

  if (print_inferior_events)
    printf_unfiltered (_("[Inferior %d detached]\n"), pid);
}

void
inferior_appeared (struct inferior *inf, int pid)
{
  inf->pid = pid;

  observer_notify_inferior_appeared (inf);
}

void
discard_all_inferiors (void)
{
  struct inferior *inf;

  for (inf = inferior_list; inf; inf = inf->next)
    {
      if (inf->pid != 0)
	exit_inferior_silent (inf->pid);
    }
}

struct inferior *
find_inferior_id (int num)
{
  struct inferior *inf;

  for (inf = inferior_list; inf; inf = inf->next)
    if (inf->num == num)
      return inf;

  return NULL;
}

struct inferior *
find_inferior_pid (int pid)
{
  struct inferior *inf;

  /* Looking for inferior pid == 0 is always wrong, and indicative of
     a bug somewhere else.  There may be more than one with pid == 0,
     for instance.  */
  gdb_assert (pid != 0);

  for (inf = inferior_list; inf; inf = inf->next)
    if (inf->pid == pid)
      return inf;

  return NULL;
}

/* Find an inferior bound to PSPACE.  */

struct inferior *
find_inferior_for_program_space (struct program_space *pspace)
{
  struct inferior *inf;

  for (inf = inferior_list; inf != NULL; inf = inf->next)
    {
      if (inf->pspace == pspace)
	return inf;
    }

  return NULL;
}

struct inferior *
iterate_over_inferiors (int (*callback) (struct inferior *, void *),
			void *data)
{
  struct inferior *inf, *infnext;

  for (inf = inferior_list; inf; inf = infnext)
    {
      infnext = inf->next;
      if ((*callback) (inf, data))
	return inf;
    }

  return NULL;
}

int
valid_gdb_inferior_id (int num)
{
  struct inferior *inf;

  for (inf = inferior_list; inf; inf = inf->next)
    if (inf->num == num)
      return 1;

  return 0;
}

int
pid_to_gdb_inferior_id (int pid)
{
  struct inferior *inf;

  for (inf = inferior_list; inf; inf = inf->next)
    if (inf->pid == pid)
      return inf->num;

  return 0;
}

int
gdb_inferior_id_to_pid (int num)
{
  struct inferior *inferior = find_inferior_id (num);
  if (inferior)
    return inferior->pid;
  else
    return -1;
}

int
in_inferior_list (int pid)
{
  struct inferior *inf;

  for (inf = inferior_list; inf; inf = inf->next)
    if (inf->pid == pid)
      return 1;

  return 0;
}

int
have_inferiors (void)
{
  struct inferior *inf;

  for (inf = inferior_list; inf; inf = inf->next)
    if (inf->pid != 0)
      return 1;

  return 0;
}

int
have_live_inferiors (void)
{
  struct inferior *inf;

  for (inf = inferior_list; inf; inf = inf->next)
    if (inf->pid != 0)
      {
	struct thread_info *tp;
	
	tp = any_thread_of_process (inf->pid);
	if (tp && target_has_execution_1 (tp->ptid))
	  break;
      }

  return inf != NULL;
}

/* Prune away automatically added program spaces that aren't required
   anymore.  */

void
prune_inferiors (void)
{
  struct inferior *ss, **ss_link;
  struct inferior *current = current_inferior ();

  ss = inferior_list;
  ss_link = &inferior_list;
  while (ss)
    {
      if (ss == current
	  || !ss->removable
	  || ss->pid != 0)
	{
	  ss_link = &ss->next;
	  ss = *ss_link;
	  continue;
	}

      *ss_link = ss->next;
      delete_inferior_1 (ss, 1);
      ss = *ss_link;
    }

  prune_program_spaces ();
}

/* Simply returns the count of inferiors.  */

int
number_of_inferiors (void)
{
  struct inferior *inf;
  int count = 0;

  for (inf = inferior_list; inf != NULL; inf = inf->next)
    count++;

  return count;
}

/* Converts an inferior process id to a string.  Like
   target_pid_to_str, but special cases the null process.  */

static char *
inferior_pid_to_str (int pid)
{
  if (pid != 0)
    return target_pid_to_str (pid_to_ptid (pid));
  else
    return _("<null>");
}

/* Prints the list of inferiors and their details on UIOUT.  This is a
   version of 'info_inferior_command' suitable for use from MI.

   If REQUESTED_INFERIORS is not NULL, it's a list of GDB ids of the
   inferiors that should be printed.  Otherwise, all inferiors are
   printed.  */

static void
print_inferior (struct ui_out *uiout, char *requested_inferiors)
{
  struct inferior *inf;
  struct cleanup *old_chain;
  int inf_count = 0;

  /* Compute number of inferiors we will print.  */
  for (inf = inferior_list; inf; inf = inf->next)
    {
      if (!number_is_in_list (requested_inferiors, inf->num))
	continue;

      ++inf_count;
    }

  if (inf_count == 0)
    {
      ui_out_message (uiout, 0, "No inferiors.\n");
      return;
    }

  old_chain = make_cleanup_ui_out_table_begin_end (uiout, 4, inf_count,
						   "inferiors");
  ui_out_table_header (uiout, 1, ui_left, "current", "");
  ui_out_table_header (uiout, 4, ui_left, "number", "Num");
  ui_out_table_header (uiout, 17, ui_left, "target-id", "Description");
  ui_out_table_header (uiout, 17, ui_left, "exec", "Executable");

  ui_out_table_body (uiout);
  for (inf = inferior_list; inf; inf = inf->next)
    {
      struct cleanup *chain2;

      if (!number_is_in_list (requested_inferiors, inf->num))
	continue;

      chain2 = make_cleanup_ui_out_tuple_begin_end (uiout, NULL);

      if (inf == current_inferior ())
	ui_out_field_string (uiout, "current", "*");
      else
	ui_out_field_skip (uiout, "current");

      ui_out_field_int (uiout, "number", inf->num);

      ui_out_field_string (uiout, "target-id",
			   inferior_pid_to_str (inf->pid));

      if (inf->pspace->ebfd)
	ui_out_field_string (uiout, "exec",
			     bfd_get_filename (inf->pspace->ebfd));
      else
	ui_out_field_skip (uiout, "exec");

      /* Print extra info that isn't really fit to always present in
	 tabular form.  Currently we print the vfork parent/child
	 relationships, if any.  */
      if (inf->vfork_parent)
	{
	  ui_out_text (uiout, _("\n\tis vfork child of inferior "));
	  ui_out_field_int (uiout, "vfork-parent", inf->vfork_parent->num);
	}
      if (inf->vfork_child)
	{
	  ui_out_text (uiout, _("\n\tis vfork parent of inferior "));
	  ui_out_field_int (uiout, "vfork-child", inf->vfork_child->num);
	}

      ui_out_text (uiout, "\n");
      do_cleanups (chain2);
    }

  do_cleanups (old_chain);
}

static void
detach_inferior_command (char *args, int from_tty)
{
  int num, pid;
  struct thread_info *tp;
  struct get_number_or_range_state state;

  if (!args || !*args)
    error (_("Requires argument (inferior id(s) to detach)"));

  init_number_or_range (&state, args);
  while (!state.finished)
    {
      num = get_number_or_range (&state);

      if (!valid_gdb_inferior_id (num))
	{
	  warning (_("Inferior ID %d not known."), num);
	  continue;
	}

      pid = gdb_inferior_id_to_pid (num);

      tp = any_thread_of_process (pid);
      if (!tp)
	{
	  warning (_("Inferior ID %d has no threads."), num);
	  continue;
	}

      switch_to_thread (tp->ptid);

      detach_command (NULL, from_tty);
    }
}

static void
kill_inferior_command (char *args, int from_tty)
{
  int num, pid;
  struct thread_info *tp;
  struct get_number_or_range_state state;

  if (!args || !*args)
    error (_("Requires argument (inferior id(s) to kill)"));

  init_number_or_range (&state, args);
  while (!state.finished)
    {
      num = get_number_or_range (&state);

      if (!valid_gdb_inferior_id (num))
	{
	  warning (_("Inferior ID %d not known."), num);
	  continue;
	}

      pid = gdb_inferior_id_to_pid (num);

      tp = any_thread_of_process (pid);
      if (!tp)
	{
	  warning (_("Inferior ID %d has no threads."), num);
	  continue;
	}

      switch_to_thread (tp->ptid);

      target_kill ();
    }

  bfd_cache_close_all ();
}

static void
inferior_command (char *args, int from_tty)
{
  struct inferior *inf;
  int num;

  num = parse_and_eval_long (args);

  inf = find_inferior_id (num);
  if (inf == NULL)
    error (_("Inferior ID %d not known."), num);

  printf_filtered (_("[Switching to inferior %d [%s] (%s)]\n"),
		   inf->num,
		   inferior_pid_to_str (inf->pid),
		   (inf->pspace->ebfd
		    ? bfd_get_filename (inf->pspace->ebfd)
		    : _("<noexec>")));

  if (inf->pid != 0)
    {
      if (inf->pid != ptid_get_pid (inferior_ptid))
	{
	  struct thread_info *tp;

	  tp = any_thread_of_process (inf->pid);
	  if (!tp)
	    error (_("Inferior has no threads."));

	  switch_to_thread (tp->ptid);
	}

      printf_filtered (_("[Switching to thread %d (%s)] "),
		       pid_to_thread_id (inferior_ptid),
		       target_pid_to_str (inferior_ptid));
    }
  else
    {
      struct inferior *inf;

      inf = find_inferior_id (num);
      set_current_inferior (inf);
      switch_to_thread (null_ptid);
      set_current_program_space (inf->pspace);
    }

  if (inf->pid != 0 && is_running (inferior_ptid))
    ui_out_text (current_uiout, "(running)\n");
  else if (inf->pid != 0)
    {
      ui_out_text (current_uiout, "\n");
      print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC);
    }
}

/* Print information about currently known inferiors.  */

static void
info_inferiors_command (char *args, int from_tty)
{
  print_inferior (current_uiout, args);
}

/* remove-inferior ID */

static void
remove_inferior_command (char *args, int from_tty)
{
  int num;
  struct inferior *inf;
  struct get_number_or_range_state state;

  if (args == NULL || *args == '\0')
    error (_("Requires an argument (inferior id(s) to remove)"));

  init_number_or_range (&state, args);
  while (!state.finished)
    {
      num = get_number_or_range (&state);
      inf = find_inferior_id (num);

      if (inf == NULL)
	{
	  warning (_("Inferior ID %d not known."), num);
	  continue;
	}

      if (inf == current_inferior ())
	{
	  warning (_("Can not remove current symbol inferior %d."), num);
	  continue;
	}
    
      if (inf->pid != 0)
	{
	  warning (_("Can not remove active inferior %d."), num);
	  continue;
	}

      delete_inferior_1 (inf, 1);
    }
}

struct inferior *
add_inferior_with_spaces (void)
{
  struct address_space *aspace;
  struct program_space *pspace;
  struct inferior *inf;
  struct gdbarch_info info;

  /* If all inferiors share an address space on this system, this
     doesn't really return a new address space; otherwise, it
     really does.  */
  aspace = maybe_new_address_space ();
  pspace = add_program_space (aspace);
  inf = add_inferior (0);
  inf->pspace = pspace;
  inf->aspace = pspace->aspace;

  /* Setup the inferior's initial arch, based on information obtained
     from the global "set ..." options.  */
  gdbarch_info_init (&info);
  inf->gdbarch = gdbarch_find_by_info (info);
  /* The "set ..." options reject invalid settings, so we should
     always have a valid arch by now.  */
  gdb_assert (inf->gdbarch != NULL);

  return inf;
}

/* add-inferior [-copies N] [-exec FILENAME]  */

static void
add_inferior_command (char *args, int from_tty)
{
  int i, copies = 1;
  char *exec = NULL;
  char **argv;
  struct cleanup *old_chain = make_cleanup (null_cleanup, NULL);

  if (args)
    {
      argv = gdb_buildargv (args);
      make_cleanup_freeargv (argv);

      for (; *argv != NULL; argv++)
	{
	  if (**argv == '-')
	    {
	      if (strcmp (*argv, "-copies") == 0)
		{
		  ++argv;
		  if (!*argv)
		    error (_("No argument to -copies"));
		  copies = parse_and_eval_long (*argv);
		}
	      else if (strcmp (*argv, "-exec") == 0)
		{
		  ++argv;
		  if (!*argv)
		    error (_("No argument to -exec"));
		  exec = *argv;
		}
	    }
	  else
	    error (_("Invalid argument"));
	}
    }

  save_current_space_and_thread ();

  for (i = 0; i < copies; ++i)
    {
      struct inferior *inf = add_inferior_with_spaces ();

      printf_filtered (_("Added inferior %d\n"), inf->num);

      if (exec != NULL)
	{
	  /* Switch over temporarily, while reading executable and
	     symbols.q.  */
	  set_current_program_space (inf->pspace);
	  set_current_inferior (inf);
	  switch_to_thread (null_ptid);

	  exec_file_attach (exec, from_tty);
	  symbol_file_add_main (exec, from_tty);
	}
    }

  do_cleanups (old_chain);
}

/* clone-inferior [-copies N] [ID] */

static void
clone_inferior_command (char *args, int from_tty)
{
  int i, copies = 1;
  char **argv;
  struct inferior *orginf = NULL;
  struct cleanup *old_chain = make_cleanup (null_cleanup, NULL);

  if (args)
    {
      argv = gdb_buildargv (args);
      make_cleanup_freeargv (argv);

      for (; *argv != NULL; argv++)
	{
	  if (**argv == '-')
	    {
	      if (strcmp (*argv, "-copies") == 0)
		{
		  ++argv;
		  if (!*argv)
		    error (_("No argument to -copies"));
		  copies = parse_and_eval_long (*argv);

		  if (copies < 0)
		    error (_("Invalid copies number"));
		}
	    }
	  else
	    {
	      if (orginf == NULL)
		{
		  int num;

		  /* The first non-option (-) argument specified the
		     program space ID.  */
		  num = parse_and_eval_long (*argv);
		  orginf = find_inferior_id (num);

		  if (orginf == NULL)
		    error (_("Inferior ID %d not known."), num);
		  continue;
		}
	      else
		error (_("Invalid argument"));
	    }
	}
    }

  /* If no inferior id was specified, then the user wants to clone the
     current inferior.  */
  if (orginf == NULL)
    orginf = current_inferior ();

  save_current_space_and_thread ();

  for (i = 0; i < copies; ++i)
    {
      struct address_space *aspace;
      struct program_space *pspace;
      struct inferior *inf;

      /* If all inferiors share an address space on this system, this
	 doesn't really return a new address space; otherwise, it
	 really does.  */
      aspace = maybe_new_address_space ();
      pspace = add_program_space (aspace);
      inf = add_inferior (0);
      inf->pspace = pspace;
      inf->aspace = pspace->aspace;
      inf->gdbarch = orginf->gdbarch;

      /* If the original inferior had a user specified target
	 description, make the clone use it too.  */
      if (target_desc_info_from_user_p (inf->tdesc_info))
	copy_inferior_target_desc_info (inf, orginf);

      printf_filtered (_("Added inferior %d.\n"), inf->num);

      set_current_inferior (inf);
      switch_to_thread (null_ptid);
      clone_program_space (pspace, orginf->pspace);
    }

  do_cleanups (old_chain);
}

/* Print notices when new inferiors are created and die.  */
static void
show_print_inferior_events (struct ui_file *file, int from_tty,
			   struct cmd_list_element *c, const char *value)
{
  fprintf_filtered (file, _("Printing of inferior events is %s.\n"), value);
}

\f

void
initialize_inferiors (void)
{
  struct cmd_list_element *c = NULL;

  /* There's always one inferior.  Note that this function isn't an
     automatic _initialize_foo function, since other _initialize_foo
     routines may need to install their per-inferior data keys.  We
     can only allocate an inferior when all those modules have done
     that.  Do this after initialize_progspace, due to the
     current_program_space reference.  */
  current_inferior_ = add_inferior (0);
  current_inferior_->pspace = current_program_space;
  current_inferior_->aspace = current_program_space->aspace;
  /* The architecture will be initialized shortly, by
     initialize_current_architecture.  */

  add_info ("inferiors", info_inferiors_command, 
	    _("IDs of specified inferiors (all inferiors if no argument)."));

  c = add_com ("add-inferior", no_class, add_inferior_command, _("\
Add a new inferior.\n\
Usage: add-inferior [-copies <N>] [-exec <FILENAME>]\n\
N is the optional number of inferiors to add, default is 1.\n\
FILENAME is the file name of the executable to use\n\
as main program."));
  set_cmd_completer (c, filename_completer);

  add_com ("remove-inferiors", no_class, remove_inferior_command, _("\
Remove inferior ID (or list of IDs).\n\
Usage: remove-inferiors ID..."));

  add_com ("clone-inferior", no_class, clone_inferior_command, _("\
Clone inferior ID.\n\
Usage: clone-inferior [-copies <N>] [ID]\n\
Add N copies of inferior ID.  The new inferior has the same\n\
executable loaded as the copied inferior.  If -copies is not specified,\n\
adds 1 copy.  If ID is not specified, it is the current inferior\n\
that is cloned."));

  add_cmd ("inferiors", class_run, detach_inferior_command, _("\
Detach from inferior ID (or list of IDS)."),
	   &detachlist);

  add_cmd ("inferiors", class_run, kill_inferior_command, _("\
Kill inferior ID (or list of IDs)."),
	   &killlist);

  add_cmd ("inferior", class_run, inferior_command, _("\
Use this command to switch between inferiors.\n\
The new inferior ID must be currently known."),
	   &cmdlist);

  add_setshow_boolean_cmd ("inferior-events", no_class,
         &print_inferior_events, _("\
Set printing of inferior events (e.g., inferior start and exit)."), _("\
Show printing of inferior events (e.g., inferior start and exit)."), NULL,
         NULL,
         show_print_inferior_events,
         &setprintlist, &showprintlist);

}