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