gdb/inferior.c

   1 /* Multi-process control for GDB, the GNU debugger.
   2
   3    Copyright (C) 2008-2018 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "exec.h"
  22 #include "inferior.h"
  23 #include "target.h"
  24 #include "command.h"
  25 #include "completer.h"
  26 #include "gdbcmd.h"
  27 #include "gdbthread.h"
  28 #include "ui-out.h"
  29 #include "observable.h"
  30 #include "gdbcore.h"
  31 #include "symfile.h"
  32 #include "environ.h"
  33 #include "cli/cli-utils.h"
  34 #include "continuations.h"
  35 #include "arch-utils.h"
  36 #include "target-descriptions.h"
  37 #include "readline/tilde.h"
  38 #include "progspace-and-thread.h"
  39
  40 /* Keep a registry of per-inferior data-pointers required by other GDB
  41    modules.  */
  42
  43 DEFINE_REGISTRY (inferior, REGISTRY_ACCESS_FIELD)
  44
  45 struct inferior *inferior_list = NULL;
  46 static int highest_inferior_num;
  47
  48 /* See inferior.h.  */
  49 int print_inferior_events = 1;
  50
  51 /* The Current Inferior.  This is a strong reference.  I.e., whenever
  52    an inferior is the current inferior, its refcount is
  53    incremented.  */
  54 static struct inferior *current_inferior_ = NULL;
  55
  56 struct inferior*
  57 current_inferior (void)
  58 {
  59   return current_inferior_;
  60 }
  61
  62 void
  63 set_current_inferior (struct inferior *inf)
  64 {
  65   /* There's always an inferior.  */
  66   gdb_assert (inf != NULL);
  67
  68   inf->incref ();
  69   current_inferior_->decref ();
  70   current_inferior_ = inf;
  71 }
  72
  73 private_inferior::~private_inferior () = default;
  74
  75 inferior::~inferior ()
  76 {
  77   inferior *inf = this;
  78
  79   discard_all_inferior_continuations (inf);
  80   inferior_free_data (inf);
  81   xfree (inf->args);
  82   xfree (inf->terminal);
  83   target_desc_info_free (inf->tdesc_info);
  84 }
  85
  86 inferior::inferior (int pid_)
  87   : num (++highest_inferior_num),
  88     pid (pid_),
  89     environment (gdb_environ::from_host_environ ()),
  90     registry_data ()
  91 {
  92   inferior_alloc_data (this);
  93 }
  94
  95 struct inferior *
  96 add_inferior_silent (int pid)
  97 {
  98   inferior *inf = new inferior (pid);
  99
 100   if (inferior_list == NULL)
 101     inferior_list = inf;
 102   else
 103     {
 104       inferior *last;
 105
 106       for (last = inferior_list; last->next != NULL; last = last->next)
 107         ;
 108       last->next = inf;
 109     }
 110
 111   gdb::observers::inferior_added.notify (inf);
 112
 113   if (pid != 0)
 114     inferior_appeared (inf, pid);
 115
 116   return inf;
 117 }
 118
 119 struct inferior *
 120 add_inferior (int pid)
 121 {
 122   struct inferior *inf = add_inferior_silent (pid);
 123
 124   if (print_inferior_events)
 125     {
 126       if (pid != 0)
 127         printf_unfiltered (_("[New inferior %d (%s)]\n"),
 128                            inf->num,
 129                            target_pid_to_str (ptid_t (pid)));
 130       else
 131         printf_unfiltered (_("[New inferior %d]\n"), inf->num);
 132     }
 133
 134   return inf;
 135 }
 136
 137 struct delete_thread_of_inferior_arg
 138 {
 139   int pid;
 140   int silent;
 141 };
 142
 143 static int
 144 delete_thread_of_inferior (struct thread_info *tp, void *data)
 145 {
 146   struct delete_thread_of_inferior_arg *arg
 147     = (struct delete_thread_of_inferior_arg *) data;
 148
 149   if (tp->ptid.pid () == arg->pid)
 150     {
 151       if (arg->silent)
 152         delete_thread_silent (tp);
 153       else
 154         delete_thread (tp);
 155     }
 156
 157   return 0;
 158 }
 159
 160 void
 161 delete_inferior (struct inferior *todel)
 162 {
 163   struct inferior *inf, *infprev;
 164   struct delete_thread_of_inferior_arg arg;
 165
 166   infprev = NULL;
 167
 168   for (inf = inferior_list; inf; infprev = inf, inf = inf->next)
 169     if (inf == todel)
 170       break;
 171
 172   if (!inf)
 173     return;
 174
 175   arg.pid = inf->pid;
 176   arg.silent = 1;
 177
 178   iterate_over_threads (delete_thread_of_inferior, &arg);
 179
 180   if (infprev)
 181     infprev->next = inf->next;
 182   else
 183     inferior_list = inf->next;
 184
 185   gdb::observers::inferior_removed.notify (inf);
 186
 187   /* If this program space is rendered useless, remove it. */
 188   if (program_space_empty_p (inf->pspace))
 189     delete_program_space (inf->pspace);
 190
 191   delete inf;
 192 }
 193
 194 /* If SILENT then be quiet -- don't announce a inferior exit, or the
 195    exit of its threads.  */
 196
 197 static void
 198 exit_inferior_1 (struct inferior *inftoex, int silent)
 199 {
 200   struct inferior *inf;
 201   struct delete_thread_of_inferior_arg arg;
 202
 203   for (inf = inferior_list; inf; inf = inf->next)
 204     if (inf == inftoex)
 205       break;
 206
 207   if (!inf)
 208     return;
 209
 210   arg.pid = inf->pid;
 211   arg.silent = silent;
 212
 213   iterate_over_threads (delete_thread_of_inferior, &arg);
 214
 215   gdb::observers::inferior_exit.notify (inf);
 216
 217   inf->pid = 0;
 218   inf->fake_pid_p = 0;
 219   inf->priv = NULL;
 220
 221   if (inf->vfork_parent != NULL)
 222     {
 223       inf->vfork_parent->vfork_child = NULL;
 224       inf->vfork_parent = NULL;
 225     }
 226   if (inf->vfork_child != NULL)
 227     {
 228       inf->vfork_child->vfork_parent = NULL;
 229       inf->vfork_child = NULL;
 230     }
 231
 232   inf->pending_detach = 0;
 233   /* Reset it.  */
 234   inf->control = inferior_control_state (NO_STOP_QUIETLY);
 235 }
 236
 237 void
 238 exit_inferior (inferior *inf)
 239 {
 240   exit_inferior_1 (inf, 0);
 241 }
 242
 243 void
 244 exit_inferior_silent (int pid)
 245 {
 246   struct inferior *inf = find_inferior_pid (pid);
 247
 248   exit_inferior_1 (inf, 1);
 249 }
 250
 251 void
 252 exit_inferior_silent (inferior *inf)
 253 {
 254   exit_inferior_1 (inf, 1);
 255 }
 256
 257 /* See inferior.h.  */
 258
 259 void
 260 detach_inferior (inferior *inf)
 261 {
 262   /* Save the pid, since exit_inferior_1 will reset it.  */
 263   int pid = inf->pid;
 264
 265   exit_inferior_1 (inf, 0);
 266
 267   if (print_inferior_events)
 268     printf_unfiltered (_("[Inferior %d (%s) detached]\n"),
 269                        inf->num,
 270                        target_pid_to_str (ptid_t (pid)));
 271 }
 272
 273 void
 274 inferior_appeared (struct inferior *inf, int pid)
 275 {
 276   inf->pid = pid;
 277   inf->has_exit_code = 0;
 278   inf->exit_code = 0;
 279
 280   gdb::observers::inferior_appeared.notify (inf);
 281 }
 282
 283 void
 284 discard_all_inferiors (void)
 285 {
 286   struct inferior *inf;
 287
 288   for (inf = inferior_list; inf; inf = inf->next)
 289     {
 290       if (inf->pid != 0)
 291         exit_inferior_silent (inf);
 292     }
 293 }
 294
 295 struct inferior *
 296 find_inferior_id (int num)
 297 {
 298   struct inferior *inf;
 299
 300   for (inf = inferior_list; inf; inf = inf->next)
 301     if (inf->num == num)
 302       return inf;
 303
 304   return NULL;
 305 }
 306
 307 struct inferior *
 308 find_inferior_pid (int pid)
 309 {
 310   struct inferior *inf;
 311
 312   /* Looking for inferior pid == 0 is always wrong, and indicative of
 313      a bug somewhere else.  There may be more than one with pid == 0,
 314      for instance.  */
 315   gdb_assert (pid != 0);
 316
 317   for (inf = inferior_list; inf; inf = inf->next)
 318     if (inf->pid == pid)
 319       return inf;
 320
 321   return NULL;
 322 }
 323
 324 /* See inferior.h */
 325
 326 struct inferior *
 327 find_inferior_ptid (ptid_t ptid)
 328 {
 329   return find_inferior_pid (ptid.pid ());
 330 }
 331
 332 /* See inferior.h.  */
 333
 334 struct inferior *
 335 find_inferior_for_program_space (struct program_space *pspace)
 336 {
 337   struct inferior *inf = current_inferior ();
 338
 339   if (inf->pspace == pspace)
 340     return inf;
 341
 342   for (inf = inferior_list; inf != NULL; inf = inf->next)
 343     {
 344       if (inf->pspace == pspace)
 345         return inf;
 346     }
 347
 348   return NULL;
 349 }
 350
 351 struct inferior *
 352 iterate_over_inferiors (int (*callback) (struct inferior *, void *),
 353                         void *data)
 354 {
 355   struct inferior *inf, *infnext;
 356
 357   for (inf = inferior_list; inf; inf = infnext)
 358     {
 359       infnext = inf->next;
 360       if ((*callback) (inf, data))
 361         return inf;
 362     }
 363
 364   return NULL;
 365 }
 366
 367 int
 368 have_inferiors (void)
 369 {
 370   struct inferior *inf;
 371
 372   for (inf = inferior_list; inf; inf = inf->next)
 373     if (inf->pid != 0)
 374       return 1;
 375
 376   return 0;
 377 }
 378
 379 /* Return the number of live inferiors.  We account for the case
 380    where an inferior might have a non-zero pid but no threads, as
 381    in the middle of a 'mourn' operation.  */
 382
 383 int
 384 number_of_live_inferiors (void)
 385 {
 386   struct inferior *inf;
 387   int num_inf = 0;
 388
 389   for (inf = inferior_list; inf; inf = inf->next)
 390     if (inf->pid != 0)
 391       {
 392         struct thread_info *tp;
 393
 394         ALL_NON_EXITED_THREADS (tp)
 395          if (tp && tp->ptid.pid () == inf->pid)
 396            if (target_has_execution_1 (tp->ptid))
 397              {
 398                /* Found a live thread in this inferior, go to the next
 399                   inferior.  */
 400                ++num_inf;
 401                break;
 402              }
 403       }
 404
 405   return num_inf;
 406 }
 407
 408 /* Return true if there is at least one live inferior.  */
 409
 410 int
 411 have_live_inferiors (void)
 412 {
 413   return number_of_live_inferiors () > 0;
 414 }
 415
 416 /* Prune away any unused inferiors, and then prune away no longer used
 417    program spaces.  */
 418
 419 void
 420 prune_inferiors (void)
 421 {
 422   struct inferior *ss, **ss_link;
 423
 424   ss = inferior_list;
 425   ss_link = &inferior_list;
 426   while (ss)
 427     {
 428       if (!ss->deletable ()
 429           || !ss->removable
 430           || ss->pid != 0)
 431         {
 432           ss_link = &ss->next;
 433           ss = *ss_link;
 434           continue;
 435         }
 436
 437       *ss_link = ss->next;
 438       delete_inferior (ss);
 439       ss = *ss_link;
 440     }
 441 }
 442
 443 /* Simply returns the count of inferiors.  */
 444
 445 int
 446 number_of_inferiors (void)
 447 {
 448   struct inferior *inf;
 449   int count = 0;
 450
 451   for (inf = inferior_list; inf != NULL; inf = inf->next)
 452     count++;
 453
 454   return count;
 455 }
 456
 457 /* Converts an inferior process id to a string.  Like
 458    target_pid_to_str, but special cases the null process.  */
 459
 460 static const char *
 461 inferior_pid_to_str (int pid)
 462 {
 463   if (pid != 0)
 464     return target_pid_to_str (ptid_t (pid));
 465   else
 466     return _("<null>");
 467 }
 468
 469 /* See inferior.h.  */
 470
 471 void
 472 print_selected_inferior (struct ui_out *uiout)
 473 {
 474   struct inferior *inf = current_inferior ();
 475   const char *filename = inf->pspace->pspace_exec_filename;
 476
 477   if (filename == NULL)
 478     filename = _("<noexec>");
 479
 480   uiout->message (_("[Switching to inferior %d [%s] (%s)]\n"),
 481                   inf->num, inferior_pid_to_str (inf->pid), filename);
 482 }
 483
 484 /* Prints the list of inferiors and their details on UIOUT.  This is a
 485    version of 'info_inferior_command' suitable for use from MI.
 486
 487    If REQUESTED_INFERIORS is not NULL, it's a list of GDB ids of the
 488    inferiors that should be printed.  Otherwise, all inferiors are
 489    printed.  */
 490
 491 static void
 492 print_inferior (struct ui_out *uiout, const char *requested_inferiors)
 493 {
 494   struct inferior *inf;
 495   int inf_count = 0;
 496
 497   /* Compute number of inferiors we will print.  */
 498   for (inf = inferior_list; inf; inf = inf->next)
 499     {
 500       if (!number_is_in_list (requested_inferiors, inf->num))
 501         continue;
 502
 503       ++inf_count;
 504     }
 505
 506   if (inf_count == 0)
 507     {
 508       uiout->message ("No inferiors.\n");
 509       return;
 510     }
 511
 512   ui_out_emit_table table_emitter (uiout, 4, inf_count, "inferiors");
 513   uiout->table_header (1, ui_left, "current", "");
 514   uiout->table_header (4, ui_left, "number", "Num");
 515   uiout->table_header (17, ui_left, "target-id", "Description");
 516   uiout->table_header (17, ui_left, "exec", "Executable");
 517
 518   uiout->table_body ();
 519   for (inf = inferior_list; inf; inf = inf->next)
 520     {
 521       if (!number_is_in_list (requested_inferiors, inf->num))
 522         continue;
 523
 524       ui_out_emit_tuple tuple_emitter (uiout, NULL);
 525
 526       if (inf == current_inferior ())
 527         uiout->field_string ("current", "*");
 528       else
 529         uiout->field_skip ("current");
 530
 531       uiout->field_int ("number", inf->num);
 532
 533       uiout->field_string ("target-id", inferior_pid_to_str (inf->pid));
 534
 535       if (inf->pspace->pspace_exec_filename != NULL)
 536         uiout->field_string ("exec", inf->pspace->pspace_exec_filename);
 537       else
 538         uiout->field_skip ("exec");
 539
 540       /* Print extra info that isn't really fit to always present in
 541          tabular form.  Currently we print the vfork parent/child
 542          relationships, if any.  */
 543       if (inf->vfork_parent)
 544         {
 545           uiout->text (_("\n\tis vfork child of inferior "));
 546           uiout->field_int ("vfork-parent", inf->vfork_parent->num);
 547         }
 548       if (inf->vfork_child)
 549         {
 550           uiout->text (_("\n\tis vfork parent of inferior "));
 551           uiout->field_int ("vfork-child", inf->vfork_child->num);
 552         }
 553
 554       uiout->text ("\n");
 555     }
 556 }
 557
 558 static void
 559 detach_inferior_command (const char *args, int from_tty)
 560 {
 561   if (!args || !*args)
 562     error (_("Requires argument (inferior id(s) to detach)"));
 563
 564   number_or_range_parser parser (args);
 565   while (!parser.finished ())
 566     {
 567       int num = parser.get_number ();
 568
 569       inferior *inf = find_inferior_id (num);
 570       if (inf == NULL)
 571         {
 572           warning (_("Inferior ID %d not known."), num);
 573           continue;
 574         }
 575
 576       if (inf->pid == 0)
 577         {
 578           warning (_("Inferior ID %d is not running."), num);
 579           continue;
 580         }
 581
 582       thread_info *tp = any_thread_of_inferior (inf);
 583       if (tp == NULL)
 584         {
 585           warning (_("Inferior ID %d has no threads."), num);
 586           continue;
 587         }
 588
 589       switch_to_thread (tp);
 590
 591       detach_command (NULL, from_tty);
 592     }
 593 }
 594
 595 static void
 596 kill_inferior_command (const char *args, int from_tty)
 597 {
 598   if (!args || !*args)
 599     error (_("Requires argument (inferior id(s) to kill)"));
 600
 601   number_or_range_parser parser (args);
 602   while (!parser.finished ())
 603     {
 604       int num = parser.get_number ();
 605
 606       inferior *inf = find_inferior_id (num);
 607       if (inf == NULL)
 608         {
 609           warning (_("Inferior ID %d not known."), num);
 610           continue;
 611         }
 612
 613       if (inf->pid == 0)
 614         {
 615           warning (_("Inferior ID %d is not running."), num);
 616           continue;
 617         }
 618
 619       thread_info *tp = any_thread_of_inferior (inf);
 620       if (tp == NULL)
 621         {
 622           warning (_("Inferior ID %d has no threads."), num);
 623           continue;
 624         }
 625
 626       switch_to_thread (tp);
 627
 628       target_kill ();
 629     }
 630
 631   bfd_cache_close_all ();
 632 }
 633
 634 static void
 635 inferior_command (const char *args, int from_tty)
 636 {
 637   struct inferior *inf;
 638   int num;
 639
 640   num = parse_and_eval_long (args);
 641
 642   inf = find_inferior_id (num);
 643   if (inf == NULL)
 644     error (_("Inferior ID %d not known."), num);
 645
 646   if (inf->pid != 0)
 647     {
 648       if (inf != current_inferior ())
 649         {
 650           thread_info *tp = any_thread_of_inferior (inf);
 651           if (tp == NULL)
 652             error (_("Inferior has no threads."));
 653
 654           switch_to_thread (tp);
 655         }
 656
 657       gdb::observers::user_selected_context_changed.notify
 658         (USER_SELECTED_INFERIOR
 659          | USER_SELECTED_THREAD
 660          | USER_SELECTED_FRAME);
 661     }
 662   else
 663     {
 664       set_current_inferior (inf);
 665       switch_to_no_thread ();
 666       set_current_program_space (inf->pspace);
 667
 668       gdb::observers::user_selected_context_changed.notify
 669         (USER_SELECTED_INFERIOR);
 670     }
 671 }
 672
 673 /* Print information about currently known inferiors.  */
 674
 675 static void
 676 info_inferiors_command (const char *args, int from_tty)
 677 {
 678   print_inferior (current_uiout, args);
 679 }
 680
 681 /* remove-inferior ID */
 682
 683 static void
 684 remove_inferior_command (const char *args, int from_tty)
 685 {
 686   if (args == NULL || *args == '\0')
 687     error (_("Requires an argument (inferior id(s) to remove)"));
 688
 689   number_or_range_parser parser (args);
 690   while (!parser.finished ())
 691     {
 692       int num = parser.get_number ();
 693       struct inferior *inf = find_inferior_id (num);
 694
 695       if (inf == NULL)
 696         {
 697           warning (_("Inferior ID %d not known."), num);
 698           continue;
 699         }
 700
 701       if (!inf->deletable ())
 702         {
 703           warning (_("Can not remove current inferior %d."), num);
 704           continue;
 705         }
 706
 707       if (inf->pid != 0)
 708         {
 709           warning (_("Can not remove active inferior %d."), num);
 710           continue;
 711         }
 712
 713       delete_inferior (inf);
 714     }
 715 }
 716
 717 struct inferior *
 718 add_inferior_with_spaces (void)
 719 {
 720   struct address_space *aspace;
 721   struct program_space *pspace;
 722   struct inferior *inf;
 723   struct gdbarch_info info;
 724
 725   /* If all inferiors share an address space on this system, this
 726      doesn't really return a new address space; otherwise, it
 727      really does.  */
 728   aspace = maybe_new_address_space ();
 729   pspace = new program_space (aspace);
 730   inf = add_inferior (0);
 731   inf->pspace = pspace;
 732   inf->aspace = pspace->aspace;
 733
 734   /* Setup the inferior's initial arch, based on information obtained
 735      from the global "set ..." options.  */
 736   gdbarch_info_init (&info);
 737   inf->gdbarch = gdbarch_find_by_info (info);
 738   /* The "set ..." options reject invalid settings, so we should
 739      always have a valid arch by now.  */
 740   gdb_assert (inf->gdbarch != NULL);
 741
 742   return inf;
 743 }
 744
 745 /* add-inferior [-copies N] [-exec FILENAME]  */
 746
 747 static void
 748 add_inferior_command (const char *args, int from_tty)
 749 {
 750   int i, copies = 1;
 751   gdb::unique_xmalloc_ptr<char> exec;
 752   symfile_add_flags add_flags = 0;
 753
 754   if (from_tty)
 755     add_flags |= SYMFILE_VERBOSE;
 756
 757   if (args)
 758     {
 759       gdb_argv built_argv (args);
 760
 761       for (char **argv = built_argv.get (); *argv != NULL; argv++)
 762         {
 763           if (**argv == '-')
 764             {
 765               if (strcmp (*argv, "-copies") == 0)
 766                 {
 767                   ++argv;
 768                   if (!*argv)
 769                     error (_("No argument to -copies"));
 770                   copies = parse_and_eval_long (*argv);
 771                 }
 772               else if (strcmp (*argv, "-exec") == 0)
 773                 {
 774                   ++argv;
 775                   if (!*argv)
 776                     error (_("No argument to -exec"));
 777                   exec.reset (tilde_expand (*argv));
 778                 }
 779             }
 780           else
 781             error (_("Invalid argument"));
 782         }
 783     }
 784
 785   scoped_restore_current_pspace_and_thread restore_pspace_thread;
 786
 787   for (i = 0; i < copies; ++i)
 788     {
 789       struct inferior *inf = add_inferior_with_spaces ();
 790
 791       printf_filtered (_("Added inferior %d\n"), inf->num);
 792
 793       if (exec != NULL)
 794         {
 795           /* Switch over temporarily, while reading executable and
 796              symbols.q.  */
 797           set_current_program_space (inf->pspace);
 798           set_current_inferior (inf);
 799           switch_to_no_thread ();
 800
 801           exec_file_attach (exec.get (), from_tty);
 802           symbol_file_add_main (exec.get (), add_flags);
 803         }
 804     }
 805 }
 806
 807 /* clone-inferior [-copies N] [ID] */
 808
 809 static void
 810 clone_inferior_command (const char *args, int from_tty)
 811 {
 812   int i, copies = 1;
 813   struct inferior *orginf = NULL;
 814
 815   if (args)
 816     {
 817       gdb_argv built_argv (args);
 818
 819       char **argv = built_argv.get ();
 820       for (; *argv != NULL; argv++)
 821         {
 822           if (**argv == '-')
 823             {
 824               if (strcmp (*argv, "-copies") == 0)
 825                 {
 826                   ++argv;
 827                   if (!*argv)
 828                     error (_("No argument to -copies"));
 829                   copies = parse_and_eval_long (*argv);
 830
 831                   if (copies < 0)
 832                     error (_("Invalid copies number"));
 833                 }
 834             }
 835           else
 836             {
 837               if (orginf == NULL)
 838                 {
 839                   int num;
 840
 841                   /* The first non-option (-) argument specified the
 842                      program space ID.  */
 843                   num = parse_and_eval_long (*argv);
 844                   orginf = find_inferior_id (num);
 845
 846                   if (orginf == NULL)
 847                     error (_("Inferior ID %d not known."), num);
 848                   continue;
 849                 }
 850               else
 851                 error (_("Invalid argument"));
 852             }
 853         }
 854     }
 855
 856   /* If no inferior id was specified, then the user wants to clone the
 857      current inferior.  */
 858   if (orginf == NULL)
 859     orginf = current_inferior ();
 860
 861   scoped_restore_current_pspace_and_thread restore_pspace_thread;
 862
 863   for (i = 0; i < copies; ++i)
 864     {
 865       struct address_space *aspace;
 866       struct program_space *pspace;
 867       struct inferior *inf;
 868
 869       /* If all inferiors share an address space on this system, this
 870          doesn't really return a new address space; otherwise, it
 871          really does.  */
 872       aspace = maybe_new_address_space ();
 873       pspace = new program_space (aspace);
 874       inf = add_inferior (0);
 875       inf->pspace = pspace;
 876       inf->aspace = pspace->aspace;
 877       inf->gdbarch = orginf->gdbarch;
 878
 879       /* If the original inferior had a user specified target
 880          description, make the clone use it too.  */
 881       if (target_desc_info_from_user_p (inf->tdesc_info))
 882         copy_inferior_target_desc_info (inf, orginf);
 883
 884       printf_filtered (_("Added inferior %d.\n"), inf->num);
 885
 886       set_current_inferior (inf);
 887       switch_to_no_thread ();
 888       clone_program_space (pspace, orginf->pspace);
 889     }
 890 }
 891
 892 /* Print notices when new inferiors are created and die.  */
 893 static void
 894 show_print_inferior_events (struct ui_file *file, int from_tty,
 895                            struct cmd_list_element *c, const char *value)
 896 {
 897   fprintf_filtered (file, _("Printing of inferior events is %s.\n"), value);
 898 }
 899
 900 /* Return a new value for the selected inferior's id.  */
 901
 902 static struct value *
 903 inferior_id_make_value (struct gdbarch *gdbarch, struct internalvar *var,
 904                         void *ignore)
 905 {
 906   struct inferior *inf = current_inferior ();
 907
 908   return value_from_longest (builtin_type (gdbarch)->builtin_int, inf->num);
 909 }
 910
 911 /* Implementation of `$_inferior' variable.  */
 912
 913 static const struct internalvar_funcs inferior_funcs =
 914 {
 915   inferior_id_make_value,
 916   NULL,
 917   NULL
 918 };
 919
 920 \f
 921
 922 void
 923 initialize_inferiors (void)
 924 {
 925   struct cmd_list_element *c = NULL;
 926
 927   /* There's always one inferior.  Note that this function isn't an
 928      automatic _initialize_foo function, since other _initialize_foo
 929      routines may need to install their per-inferior data keys.  We
 930      can only allocate an inferior when all those modules have done
 931      that.  Do this after initialize_progspace, due to the
 932      current_program_space reference.  */
 933   current_inferior_ = add_inferior_silent (0);
 934   current_inferior_->incref ();
 935   current_inferior_->pspace = current_program_space;
 936   current_inferior_->aspace = current_program_space->aspace;
 937   /* The architecture will be initialized shortly, by
 938      initialize_current_architecture.  */
 939
 940   add_info ("inferiors", info_inferiors_command,
 941             _("Print a list of inferiors being managed.\n\
 942 Usage: info inferiors [ID]...\n\
 943 If IDs are specified, the list is limited to just those inferiors.\n\
 944 By default all inferiors are displayed."));
 945
 946   c = add_com ("add-inferior", no_class, add_inferior_command, _("\
 947 Add a new inferior.\n\
 948 Usage: add-inferior [-copies N] [-exec FILENAME]\n\
 949 N is the optional number of inferiors to add, default is 1.\n\
 950 FILENAME is the file name of the executable to use\n\
 951 as main program."));
 952   set_cmd_completer (c, filename_completer);
 953
 954   add_com ("remove-inferiors", no_class, remove_inferior_command, _("\
 955 Remove inferior ID (or list of IDs).\n\
 956 Usage: remove-inferiors ID..."));
 957
 958   add_com ("clone-inferior", no_class, clone_inferior_command, _("\
 959 Clone inferior ID.\n\
 960 Usage: clone-inferior [-copies N] [ID]\n\
 961 Add N copies of inferior ID.  The new inferior has the same\n\
 962 executable loaded as the copied inferior.  If -copies is not specified,\n\
 963 adds 1 copy.  If ID is not specified, it is the current inferior\n\
 964 that is cloned."));
 965
 966   add_cmd ("inferiors", class_run, detach_inferior_command, _("\
 967 Detach from inferior ID (or list of IDS).\n\
 968 Usage; detach inferiors ID..."),
 969            &detachlist);
 970
 971   add_cmd ("inferiors", class_run, kill_inferior_command, _("\
 972 Kill inferior ID (or list of IDs).\n\
 973 Usage: kill inferiors ID..."),
 974            &killlist);
 975
 976   add_cmd ("inferior", class_run, inferior_command, _("\
 977 Use this command to switch between inferiors.\n\
 978 Usage: inferior ID\n\
 979 The new inferior ID must be currently known."),
 980            &cmdlist);
 981
 982   add_setshow_boolean_cmd ("inferior-events", no_class,
 983          &print_inferior_events, _("\
 984 Set printing of inferior events (e.g., inferior start and exit)."), _("\
 985 Show printing of inferior events (e.g., inferior start and exit)."), NULL,
 986          NULL,
 987          show_print_inferior_events,
 988          &setprintlist, &showprintlist);
 989
 990   create_internalvar_type_lazy ("_inferior", &inferior_funcs, NULL);
 991 }