gdb/inferior.c

   1 /* Multi-process control for GDB, the GNU debugger.
   2
   3    Copyright (C) 2008-2019 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 "gdbsupport/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 bool print_inferior_events = true;
  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)).c_str ());
 130       else
 131         printf_unfiltered (_("[New inferior %d]\n"), inf->num);
 132     }
 133
 134   return inf;
 135 }
 136
 137 void
 138 delete_inferior (struct inferior *todel)
 139 {
 140   struct inferior *inf, *infprev;
 141
 142   infprev = NULL;
 143
 144   for (inf = inferior_list; inf; infprev = inf, inf = inf->next)
 145     if (inf == todel)
 146       break;
 147
 148   if (!inf)
 149     return;
 150
 151   for (thread_info *tp : inf->threads_safe ())
 152     delete_thread_silent (tp);
 153
 154   if (infprev)
 155     infprev->next = inf->next;
 156   else
 157     inferior_list = inf->next;
 158
 159   gdb::observers::inferior_removed.notify (inf);
 160
 161   /* If this program space is rendered useless, remove it. */
 162   if (program_space_empty_p (inf->pspace))
 163     delete_program_space (inf->pspace);
 164
 165   delete inf;
 166 }
 167
 168 /* If SILENT then be quiet -- don't announce a inferior exit, or the
 169    exit of its threads.  */
 170
 171 static void
 172 exit_inferior_1 (struct inferior *inftoex, int silent)
 173 {
 174   struct inferior *inf;
 175
 176   for (inf = inferior_list; inf; inf = inf->next)
 177     if (inf == inftoex)
 178       break;
 179
 180   if (!inf)
 181     return;
 182
 183   for (thread_info *tp : inf->threads_safe ())
 184     {
 185       if (silent)
 186         delete_thread_silent (tp);
 187       else
 188         delete_thread (tp);
 189     }
 190
 191   gdb::observers::inferior_exit.notify (inf);
 192
 193   inf->pid = 0;
 194   inf->fake_pid_p = false;
 195   inf->priv = NULL;
 196
 197   if (inf->vfork_parent != NULL)
 198     {
 199       inf->vfork_parent->vfork_child = NULL;
 200       inf->vfork_parent = NULL;
 201     }
 202   if (inf->vfork_child != NULL)
 203     {
 204       inf->vfork_child->vfork_parent = NULL;
 205       inf->vfork_child = NULL;
 206     }
 207
 208   inf->pending_detach = 0;
 209   /* Reset it.  */
 210   inf->control = inferior_control_state (NO_STOP_QUIETLY);
 211
 212   /* Clear the register cache and the frame cache.  */
 213   registers_changed ();
 214   reinit_frame_cache ();
 215 }
 216
 217 void
 218 exit_inferior (inferior *inf)
 219 {
 220   exit_inferior_1 (inf, 0);
 221 }
 222
 223 void
 224 exit_inferior_silent (inferior *inf)
 225 {
 226   exit_inferior_1 (inf, 1);
 227 }
 228
 229 /* See inferior.h.  */
 230
 231 void
 232 detach_inferior (inferior *inf)
 233 {
 234   /* Save the pid, since exit_inferior_1 will reset it.  */
 235   int pid = inf->pid;
 236
 237   exit_inferior_1 (inf, 0);
 238
 239   if (print_inferior_events)
 240     printf_unfiltered (_("[Inferior %d (%s) detached]\n"),
 241                        inf->num,
 242                        target_pid_to_str (ptid_t (pid)).c_str ());
 243 }
 244
 245 void
 246 inferior_appeared (struct inferior *inf, int pid)
 247 {
 248   /* If this is the first inferior with threads, reset the global
 249      thread id.  */
 250   if (!any_thread_p ())
 251     init_thread_list ();
 252
 253   inf->pid = pid;
 254   inf->has_exit_code = 0;
 255   inf->exit_code = 0;
 256
 257   gdb::observers::inferior_appeared.notify (inf);
 258 }
 259
 260 void
 261 discard_all_inferiors (void)
 262 {
 263   for (inferior *inf : all_non_exited_inferiors ())
 264     exit_inferior_silent (inf);
 265 }
 266
 267 struct inferior *
 268 find_inferior_id (int num)
 269 {
 270   for (inferior *inf : all_inferiors ())
 271     if (inf->num == num)
 272       return inf;
 273
 274   return NULL;
 275 }
 276
 277 struct inferior *
 278 find_inferior_pid (int pid)
 279 {
 280   /* Looking for inferior pid == 0 is always wrong, and indicative of
 281      a bug somewhere else.  There may be more than one with pid == 0,
 282      for instance.  */
 283   gdb_assert (pid != 0);
 284
 285   for (inferior *inf : all_inferiors ())
 286     if (inf->pid == pid)
 287       return inf;
 288
 289   return NULL;
 290 }
 291
 292 /* See inferior.h */
 293
 294 struct inferior *
 295 find_inferior_ptid (ptid_t ptid)
 296 {
 297   return find_inferior_pid (ptid.pid ());
 298 }
 299
 300 /* See inferior.h.  */
 301
 302 struct inferior *
 303 find_inferior_for_program_space (struct program_space *pspace)
 304 {
 305   struct inferior *cur_inf = current_inferior ();
 306
 307   if (cur_inf->pspace == pspace)
 308     return cur_inf;
 309
 310   for (inferior *inf : all_inferiors ())
 311     if (inf->pspace == pspace)
 312       return inf;
 313
 314   return NULL;
 315 }
 316
 317 struct inferior *
 318 iterate_over_inferiors (int (*callback) (struct inferior *, void *),
 319                         void *data)
 320 {
 321   for (inferior *inf : all_inferiors_safe ())
 322     if ((*callback) (inf, data))
 323       return inf;
 324
 325   return NULL;
 326 }
 327
 328 int
 329 have_inferiors (void)
 330 {
 331   for (inferior *inf ATTRIBUTE_UNUSED : all_non_exited_inferiors ())
 332     return 1;
 333
 334   return 0;
 335 }
 336
 337 /* Return the number of live inferiors.  We account for the case
 338    where an inferior might have a non-zero pid but no threads, as
 339    in the middle of a 'mourn' operation.  */
 340
 341 int
 342 number_of_live_inferiors (void)
 343 {
 344   int num_inf = 0;
 345
 346   for (inferior *inf : all_non_exited_inferiors ())
 347     if (target_has_execution_1 (ptid_t (inf->pid)))
 348       for (thread_info *tp ATTRIBUTE_UNUSED : inf->non_exited_threads ())
 349         {
 350           /* Found a live thread in this inferior, go to the next
 351              inferior.  */
 352           ++num_inf;
 353           break;
 354         }
 355
 356   return num_inf;
 357 }
 358
 359 /* Return true if there is at least one live inferior.  */
 360
 361 int
 362 have_live_inferiors (void)
 363 {
 364   return number_of_live_inferiors () > 0;
 365 }
 366
 367 /* Prune away any unused inferiors, and then prune away no longer used
 368    program spaces.  */
 369
 370 void
 371 prune_inferiors (void)
 372 {
 373   inferior *ss;
 374
 375   ss = inferior_list;
 376   while (ss)
 377     {
 378       if (!ss->deletable ()
 379           || !ss->removable
 380           || ss->pid != 0)
 381         {
 382           ss = ss->next;
 383           continue;
 384         }
 385
 386       inferior *ss_next = ss->next;
 387       delete_inferior (ss);
 388       ss = ss_next;
 389     }
 390 }
 391
 392 /* Simply returns the count of inferiors.  */
 393
 394 int
 395 number_of_inferiors (void)
 396 {
 397   auto rng = all_inferiors ();
 398   return std::distance (rng.begin (), rng.end ());
 399 }
 400
 401 /* Converts an inferior process id to a string.  Like
 402    target_pid_to_str, but special cases the null process.  */
 403
 404 static std::string
 405 inferior_pid_to_str (int pid)
 406 {
 407   if (pid != 0)
 408     return target_pid_to_str (ptid_t (pid));
 409   else
 410     return _("<null>");
 411 }
 412
 413 /* See inferior.h.  */
 414
 415 void
 416 print_selected_inferior (struct ui_out *uiout)
 417 {
 418   struct inferior *inf = current_inferior ();
 419   const char *filename = inf->pspace->pspace_exec_filename;
 420
 421   if (filename == NULL)
 422     filename = _("<noexec>");
 423
 424   uiout->message (_("[Switching to inferior %d [%s] (%s)]\n"),
 425                   inf->num, inferior_pid_to_str (inf->pid).c_str (), filename);
 426 }
 427
 428 /* Prints the list of inferiors and their details on UIOUT.  This is a
 429    version of 'info_inferior_command' suitable for use from MI.
 430
 431    If REQUESTED_INFERIORS is not NULL, it's a list of GDB ids of the
 432    inferiors that should be printed.  Otherwise, all inferiors are
 433    printed.  */
 434
 435 static void
 436 print_inferior (struct ui_out *uiout, const char *requested_inferiors)
 437 {
 438   int inf_count = 0;
 439
 440   /* Compute number of inferiors we will print.  */
 441   for (inferior *inf : all_inferiors ())
 442     {
 443       if (!number_is_in_list (requested_inferiors, inf->num))
 444         continue;
 445
 446       ++inf_count;
 447     }
 448
 449   if (inf_count == 0)
 450     {
 451       uiout->message ("No inferiors.\n");
 452       return;
 453     }
 454
 455   ui_out_emit_table table_emitter (uiout, 4, inf_count, "inferiors");
 456   uiout->table_header (1, ui_left, "current", "");
 457   uiout->table_header (4, ui_left, "number", "Num");
 458   uiout->table_header (17, ui_left, "target-id", "Description");
 459   uiout->table_header (17, ui_left, "exec", "Executable");
 460
 461   uiout->table_body ();
 462   for (inferior *inf : all_inferiors ())
 463     {
 464       if (!number_is_in_list (requested_inferiors, inf->num))
 465         continue;
 466
 467       ui_out_emit_tuple tuple_emitter (uiout, NULL);
 468
 469       if (inf == current_inferior ())
 470         uiout->field_string ("current", "*");
 471       else
 472         uiout->field_skip ("current");
 473
 474       uiout->field_signed ("number", inf->num);
 475
 476       uiout->field_string ("target-id", inferior_pid_to_str (inf->pid));
 477
 478       if (inf->pspace->pspace_exec_filename != NULL)
 479         uiout->field_string ("exec", inf->pspace->pspace_exec_filename);
 480       else
 481         uiout->field_skip ("exec");
 482
 483       /* Print extra info that isn't really fit to always present in
 484          tabular form.  Currently we print the vfork parent/child
 485          relationships, if any.  */
 486       if (inf->vfork_parent)
 487         {
 488           uiout->text (_("\n\tis vfork child of inferior "));
 489           uiout->field_signed ("vfork-parent", inf->vfork_parent->num);
 490         }
 491       if (inf->vfork_child)
 492         {
 493           uiout->text (_("\n\tis vfork parent of inferior "));
 494           uiout->field_signed ("vfork-child", inf->vfork_child->num);
 495         }
 496
 497       uiout->text ("\n");
 498     }
 499 }
 500
 501 static void
 502 detach_inferior_command (const char *args, int from_tty)
 503 {
 504   if (!args || !*args)
 505     error (_("Requires argument (inferior id(s) to detach)"));
 506
 507   number_or_range_parser parser (args);
 508   while (!parser.finished ())
 509     {
 510       int num = parser.get_number ();
 511
 512       inferior *inf = find_inferior_id (num);
 513       if (inf == NULL)
 514         {
 515           warning (_("Inferior ID %d not known."), num);
 516           continue;
 517         }
 518
 519       if (inf->pid == 0)
 520         {
 521           warning (_("Inferior ID %d is not running."), num);
 522           continue;
 523         }
 524
 525       thread_info *tp = any_thread_of_inferior (inf);
 526       if (tp == NULL)
 527         {
 528           warning (_("Inferior ID %d has no threads."), num);
 529           continue;
 530         }
 531
 532       switch_to_thread (tp);
 533
 534       detach_command (NULL, from_tty);
 535     }
 536 }
 537
 538 static void
 539 kill_inferior_command (const char *args, int from_tty)
 540 {
 541   if (!args || !*args)
 542     error (_("Requires argument (inferior id(s) to kill)"));
 543
 544   number_or_range_parser parser (args);
 545   while (!parser.finished ())
 546     {
 547       int num = parser.get_number ();
 548
 549       inferior *inf = find_inferior_id (num);
 550       if (inf == NULL)
 551         {
 552           warning (_("Inferior ID %d not known."), num);
 553           continue;
 554         }
 555
 556       if (inf->pid == 0)
 557         {
 558           warning (_("Inferior ID %d is not running."), num);
 559           continue;
 560         }
 561
 562       thread_info *tp = any_thread_of_inferior (inf);
 563       if (tp == NULL)
 564         {
 565           warning (_("Inferior ID %d has no threads."), num);
 566           continue;
 567         }
 568
 569       switch_to_thread (tp);
 570
 571       target_kill ();
 572     }
 573
 574   bfd_cache_close_all ();
 575 }
 576
 577 static void
 578 inferior_command (const char *args, int from_tty)
 579 {
 580   struct inferior *inf;
 581   int num;
 582
 583   num = parse_and_eval_long (args);
 584
 585   inf = find_inferior_id (num);
 586   if (inf == NULL)
 587     error (_("Inferior ID %d not known."), num);
 588
 589   if (inf->pid != 0)
 590     {
 591       if (inf != current_inferior ())
 592         {
 593           thread_info *tp = any_thread_of_inferior (inf);
 594           if (tp == NULL)
 595             error (_("Inferior has no threads."));
 596
 597           switch_to_thread (tp);
 598         }
 599
 600       gdb::observers::user_selected_context_changed.notify
 601         (USER_SELECTED_INFERIOR
 602          | USER_SELECTED_THREAD
 603          | USER_SELECTED_FRAME);
 604     }
 605   else
 606     {
 607       set_current_inferior (inf);
 608       switch_to_no_thread ();
 609       set_current_program_space (inf->pspace);
 610
 611       gdb::observers::user_selected_context_changed.notify
 612         (USER_SELECTED_INFERIOR);
 613     }
 614 }
 615
 616 /* Print information about currently known inferiors.  */
 617
 618 static void
 619 info_inferiors_command (const char *args, int from_tty)
 620 {
 621   print_inferior (current_uiout, args);
 622 }
 623
 624 /* remove-inferior ID */
 625
 626 static void
 627 remove_inferior_command (const char *args, int from_tty)
 628 {
 629   if (args == NULL || *args == '\0')
 630     error (_("Requires an argument (inferior id(s) to remove)"));
 631
 632   number_or_range_parser parser (args);
 633   while (!parser.finished ())
 634     {
 635       int num = parser.get_number ();
 636       struct inferior *inf = find_inferior_id (num);
 637
 638       if (inf == NULL)
 639         {
 640           warning (_("Inferior ID %d not known."), num);
 641           continue;
 642         }
 643
 644       if (!inf->deletable ())
 645         {
 646           warning (_("Can not remove current inferior %d."), num);
 647           continue;
 648         }
 649
 650       if (inf->pid != 0)
 651         {
 652           warning (_("Can not remove active inferior %d."), num);
 653           continue;
 654         }
 655
 656       delete_inferior (inf);
 657     }
 658 }
 659
 660 struct inferior *
 661 add_inferior_with_spaces (void)
 662 {
 663   struct address_space *aspace;
 664   struct program_space *pspace;
 665   struct inferior *inf;
 666   struct gdbarch_info info;
 667
 668   /* If all inferiors share an address space on this system, this
 669      doesn't really return a new address space; otherwise, it
 670      really does.  */
 671   aspace = maybe_new_address_space ();
 672   pspace = new program_space (aspace);
 673   inf = add_inferior (0);
 674   inf->pspace = pspace;
 675   inf->aspace = pspace->aspace;
 676
 677   /* Setup the inferior's initial arch, based on information obtained
 678      from the global "set ..." options.  */
 679   gdbarch_info_init (&info);
 680   inf->gdbarch = gdbarch_find_by_info (info);
 681   /* The "set ..." options reject invalid settings, so we should
 682      always have a valid arch by now.  */
 683   gdb_assert (inf->gdbarch != NULL);
 684
 685   return inf;
 686 }
 687
 688 /* add-inferior [-copies N] [-exec FILENAME]  */
 689
 690 static void
 691 add_inferior_command (const char *args, int from_tty)
 692 {
 693   int i, copies = 1;
 694   gdb::unique_xmalloc_ptr<char> exec;
 695   symfile_add_flags add_flags = 0;
 696
 697   if (from_tty)
 698     add_flags |= SYMFILE_VERBOSE;
 699
 700   if (args)
 701     {
 702       gdb_argv built_argv (args);
 703
 704       for (char **argv = built_argv.get (); *argv != NULL; argv++)
 705         {
 706           if (**argv == '-')
 707             {
 708               if (strcmp (*argv, "-copies") == 0)
 709                 {
 710                   ++argv;
 711                   if (!*argv)
 712                     error (_("No argument to -copies"));
 713                   copies = parse_and_eval_long (*argv);
 714                 }
 715               else if (strcmp (*argv, "-exec") == 0)
 716                 {
 717                   ++argv;
 718                   if (!*argv)
 719                     error (_("No argument to -exec"));
 720                   exec.reset (tilde_expand (*argv));
 721                 }
 722             }
 723           else
 724             error (_("Invalid argument"));
 725         }
 726     }
 727
 728   scoped_restore_current_pspace_and_thread restore_pspace_thread;
 729
 730   for (i = 0; i < copies; ++i)
 731     {
 732       struct inferior *inf = add_inferior_with_spaces ();
 733
 734       printf_filtered (_("Added inferior %d\n"), inf->num);
 735
 736       if (exec != NULL)
 737         {
 738           /* Switch over temporarily, while reading executable and
 739              symbols.q.  */
 740           set_current_program_space (inf->pspace);
 741           set_current_inferior (inf);
 742           switch_to_no_thread ();
 743
 744           exec_file_attach (exec.get (), from_tty);
 745           symbol_file_add_main (exec.get (), add_flags);
 746         }
 747     }
 748 }
 749
 750 /* clone-inferior [-copies N] [ID] */
 751
 752 static void
 753 clone_inferior_command (const char *args, int from_tty)
 754 {
 755   int i, copies = 1;
 756   struct inferior *orginf = NULL;
 757
 758   if (args)
 759     {
 760       gdb_argv built_argv (args);
 761
 762       char **argv = built_argv.get ();
 763       for (; *argv != NULL; argv++)
 764         {
 765           if (**argv == '-')
 766             {
 767               if (strcmp (*argv, "-copies") == 0)
 768                 {
 769                   ++argv;
 770                   if (!*argv)
 771                     error (_("No argument to -copies"));
 772                   copies = parse_and_eval_long (*argv);
 773
 774                   if (copies < 0)
 775                     error (_("Invalid copies number"));
 776                 }
 777             }
 778           else
 779             {
 780               if (orginf == NULL)
 781                 {
 782                   int num;
 783
 784                   /* The first non-option (-) argument specified the
 785                      program space ID.  */
 786                   num = parse_and_eval_long (*argv);
 787                   orginf = find_inferior_id (num);
 788
 789                   if (orginf == NULL)
 790                     error (_("Inferior ID %d not known."), num);
 791                   continue;
 792                 }
 793               else
 794                 error (_("Invalid argument"));
 795             }
 796         }
 797     }
 798
 799   /* If no inferior id was specified, then the user wants to clone the
 800      current inferior.  */
 801   if (orginf == NULL)
 802     orginf = current_inferior ();
 803
 804   scoped_restore_current_pspace_and_thread restore_pspace_thread;
 805
 806   for (i = 0; i < copies; ++i)
 807     {
 808       struct address_space *aspace;
 809       struct program_space *pspace;
 810       struct inferior *inf;
 811
 812       /* If all inferiors share an address space on this system, this
 813          doesn't really return a new address space; otherwise, it
 814          really does.  */
 815       aspace = maybe_new_address_space ();
 816       pspace = new program_space (aspace);
 817       inf = add_inferior (0);
 818       inf->pspace = pspace;
 819       inf->aspace = pspace->aspace;
 820       inf->gdbarch = orginf->gdbarch;
 821
 822       /* If the original inferior had a user specified target
 823          description, make the clone use it too.  */
 824       if (target_desc_info_from_user_p (inf->tdesc_info))
 825         copy_inferior_target_desc_info (inf, orginf);
 826
 827       printf_filtered (_("Added inferior %d.\n"), inf->num);
 828
 829       set_current_inferior (inf);
 830       switch_to_no_thread ();
 831       clone_program_space (pspace, orginf->pspace);
 832     }
 833 }
 834
 835 /* Print notices when new inferiors are created and die.  */
 836 static void
 837 show_print_inferior_events (struct ui_file *file, int from_tty,
 838                            struct cmd_list_element *c, const char *value)
 839 {
 840   fprintf_filtered (file, _("Printing of inferior events is %s.\n"), value);
 841 }
 842
 843 /* Return a new value for the selected inferior's id.  */
 844
 845 static struct value *
 846 inferior_id_make_value (struct gdbarch *gdbarch, struct internalvar *var,
 847                         void *ignore)
 848 {
 849   struct inferior *inf = current_inferior ();
 850
 851   return value_from_longest (builtin_type (gdbarch)->builtin_int, inf->num);
 852 }
 853
 854 /* Implementation of `$_inferior' variable.  */
 855
 856 static const struct internalvar_funcs inferior_funcs =
 857 {
 858   inferior_id_make_value,
 859   NULL,
 860   NULL
 861 };
 862
 863 \f
 864
 865 void
 866 initialize_inferiors (void)
 867 {
 868   struct cmd_list_element *c = NULL;
 869
 870   /* There's always one inferior.  Note that this function isn't an
 871      automatic _initialize_foo function, since other _initialize_foo
 872      routines may need to install their per-inferior data keys.  We
 873      can only allocate an inferior when all those modules have done
 874      that.  Do this after initialize_progspace, due to the
 875      current_program_space reference.  */
 876   current_inferior_ = add_inferior_silent (0);
 877   current_inferior_->incref ();
 878   current_inferior_->pspace = current_program_space;
 879   current_inferior_->aspace = current_program_space->aspace;
 880   /* The architecture will be initialized shortly, by
 881      initialize_current_architecture.  */
 882
 883   add_info ("inferiors", info_inferiors_command,
 884             _("Print a list of inferiors being managed.\n\
 885 Usage: info inferiors [ID]...\n\
 886 If IDs are specified, the list is limited to just those inferiors.\n\
 887 By default all inferiors are displayed."));
 888
 889   c = add_com ("add-inferior", no_class, add_inferior_command, _("\
 890 Add a new inferior.\n\
 891 Usage: add-inferior [-copies N] [-exec FILENAME]\n\
 892 N is the optional number of inferiors to add, default is 1.\n\
 893 FILENAME is the file name of the executable to use\n\
 894 as main program."));
 895   set_cmd_completer (c, filename_completer);
 896
 897   add_com ("remove-inferiors", no_class, remove_inferior_command, _("\
 898 Remove inferior ID (or list of IDs).\n\
 899 Usage: remove-inferiors ID..."));
 900
 901   add_com ("clone-inferior", no_class, clone_inferior_command, _("\
 902 Clone inferior ID.\n\
 903 Usage: clone-inferior [-copies N] [ID]\n\
 904 Add N copies of inferior ID.  The new inferior has the same\n\
 905 executable loaded as the copied inferior.  If -copies is not specified,\n\
 906 adds 1 copy.  If ID is not specified, it is the current inferior\n\
 907 that is cloned."));
 908
 909   add_cmd ("inferiors", class_run, detach_inferior_command, _("\
 910 Detach from inferior ID (or list of IDS).\n\
 911 Usage; detach inferiors ID..."),
 912            &detachlist);
 913
 914   add_cmd ("inferiors", class_run, kill_inferior_command, _("\
 915 Kill inferior ID (or list of IDs).\n\
 916 Usage: kill inferiors ID..."),
 917            &killlist);
 918
 919   add_cmd ("inferior", class_run, inferior_command, _("\
 920 Use this command to switch between inferiors.\n\
 921 Usage: inferior ID\n\
 922 The new inferior ID must be currently known."),
 923            &cmdlist);
 924
 925   add_setshow_boolean_cmd ("inferior-events", no_class,
 926          &print_inferior_events, _("\
 927 Set printing of inferior events (such as inferior start and exit)."), _("\
 928 Show printing of inferior events (such as inferior start and exit)."), NULL,
 929          NULL,
 930          show_print_inferior_events,
 931          &setprintlist, &showprintlist);
 932
 933   create_internalvar_type_lazy ("_inferior", &inferior_funcs, NULL);
 934 }