gdb/inferior.c

   1 /* Multi-process control for GDB, the GNU debugger.
   2
   3    Copyright (C) 2008-2020 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   delete_exited_threads ();
 251   if (!any_thread_p ())
 252     init_thread_list ();
 253
 254   inf->pid = pid;
 255   inf->has_exit_code = 0;
 256   inf->exit_code = 0;
 257
 258   gdb::observers::inferior_appeared.notify (inf);
 259 }
 260
 261 void
 262 discard_all_inferiors (void)
 263 {
 264   for (inferior *inf : all_non_exited_inferiors ())
 265     exit_inferior_silent (inf);
 266 }
 267
 268 struct inferior *
 269 find_inferior_id (int num)
 270 {
 271   for (inferior *inf : all_inferiors ())
 272     if (inf->num == num)
 273       return inf;
 274
 275   return NULL;
 276 }
 277
 278 struct inferior *
 279 find_inferior_pid (int pid)
 280 {
 281   /* Looking for inferior pid == 0 is always wrong, and indicative of
 282      a bug somewhere else.  There may be more than one with pid == 0,
 283      for instance.  */
 284   gdb_assert (pid != 0);
 285
 286   for (inferior *inf : all_inferiors ())
 287     if (inf->pid == pid)
 288       return inf;
 289
 290   return NULL;
 291 }
 292
 293 /* See inferior.h */
 294
 295 struct inferior *
 296 find_inferior_ptid (ptid_t ptid)
 297 {
 298   return find_inferior_pid (ptid.pid ());
 299 }
 300
 301 /* See inferior.h.  */
 302
 303 struct inferior *
 304 find_inferior_for_program_space (struct program_space *pspace)
 305 {
 306   struct inferior *cur_inf = current_inferior ();
 307
 308   if (cur_inf->pspace == pspace)
 309     return cur_inf;
 310
 311   for (inferior *inf : all_inferiors ())
 312     if (inf->pspace == pspace)
 313       return inf;
 314
 315   return NULL;
 316 }
 317
 318 struct inferior *
 319 iterate_over_inferiors (int (*callback) (struct inferior *, void *),
 320                         void *data)
 321 {
 322   for (inferior *inf : all_inferiors_safe ())
 323     if ((*callback) (inf, data))
 324       return inf;
 325
 326   return NULL;
 327 }
 328
 329 int
 330 have_inferiors (void)
 331 {
 332   for (inferior *inf ATTRIBUTE_UNUSED : all_non_exited_inferiors ())
 333     return 1;
 334
 335   return 0;
 336 }
 337
 338 /* Return the number of live inferiors.  We account for the case
 339    where an inferior might have a non-zero pid but no threads, as
 340    in the middle of a 'mourn' operation.  */
 341
 342 int
 343 number_of_live_inferiors (void)
 344 {
 345   int num_inf = 0;
 346
 347   for (inferior *inf : all_non_exited_inferiors ())
 348     if (inf->has_execution ())
 349       for (thread_info *tp ATTRIBUTE_UNUSED : inf->non_exited_threads ())
 350         {
 351           /* Found a live thread in this inferior, go to the next
 352              inferior.  */
 353           ++num_inf;
 354           break;
 355         }
 356
 357   return num_inf;
 358 }
 359
 360 /* Return true if there is at least one live inferior.  */
 361
 362 int
 363 have_live_inferiors (void)
 364 {
 365   return number_of_live_inferiors () > 0;
 366 }
 367
 368 /* Prune away any unused inferiors, and then prune away no longer used
 369    program spaces.  */
 370
 371 void
 372 prune_inferiors (void)
 373 {
 374   inferior *ss;
 375
 376   ss = inferior_list;
 377   while (ss)
 378     {
 379       if (!ss->deletable ()
 380           || !ss->removable
 381           || ss->pid != 0)
 382         {
 383           ss = ss->next;
 384           continue;
 385         }
 386
 387       inferior *ss_next = ss->next;
 388       delete_inferior (ss);
 389       ss = ss_next;
 390     }
 391 }
 392
 393 /* Simply returns the count of inferiors.  */
 394
 395 int
 396 number_of_inferiors (void)
 397 {
 398   auto rng = all_inferiors ();
 399   return std::distance (rng.begin (), rng.end ());
 400 }
 401
 402 /* Converts an inferior process id to a string.  Like
 403    target_pid_to_str, but special cases the null process.  */
 404
 405 static std::string
 406 inferior_pid_to_str (int pid)
 407 {
 408   if (pid != 0)
 409     return target_pid_to_str (ptid_t (pid));
 410   else
 411     return _("<null>");
 412 }
 413
 414 /* See inferior.h.  */
 415
 416 void
 417 print_selected_inferior (struct ui_out *uiout)
 418 {
 419   struct inferior *inf = current_inferior ();
 420   const char *filename = inf->pspace->pspace_exec_filename;
 421
 422   if (filename == NULL)
 423     filename = _("<noexec>");
 424
 425   uiout->message (_("[Switching to inferior %d [%s] (%s)]\n"),
 426                   inf->num, inferior_pid_to_str (inf->pid).c_str (), filename);
 427 }
 428
 429 /* Prints the list of inferiors and their details on UIOUT.  This is a
 430    version of 'info_inferior_command' suitable for use from MI.
 431
 432    If REQUESTED_INFERIORS is not NULL, it's a list of GDB ids of the
 433    inferiors that should be printed.  Otherwise, all inferiors are
 434    printed.  */
 435
 436 static void
 437 print_inferior (struct ui_out *uiout, const char *requested_inferiors)
 438 {
 439   int inf_count = 0;
 440
 441   /* Compute number of inferiors we will print.  */
 442   for (inferior *inf : all_inferiors ())
 443     {
 444       if (!number_is_in_list (requested_inferiors, inf->num))
 445         continue;
 446
 447       ++inf_count;
 448     }
 449
 450   if (inf_count == 0)
 451     {
 452       uiout->message ("No inferiors.\n");
 453       return;
 454     }
 455
 456   ui_out_emit_table table_emitter (uiout, 4, inf_count, "inferiors");
 457   uiout->table_header (1, ui_left, "current", "");
 458   uiout->table_header (4, ui_left, "number", "Num");
 459   uiout->table_header (17, ui_left, "target-id", "Description");
 460   uiout->table_header (17, ui_left, "exec", "Executable");
 461
 462   uiout->table_body ();
 463   for (inferior *inf : all_inferiors ())
 464     {
 465       if (!number_is_in_list (requested_inferiors, inf->num))
 466         continue;
 467
 468       ui_out_emit_tuple tuple_emitter (uiout, NULL);
 469
 470       if (inf == current_inferior ())
 471         uiout->field_string ("current", "*");
 472       else
 473         uiout->field_skip ("current");
 474
 475       uiout->field_signed ("number", inf->num);
 476
 477       uiout->field_string ("target-id", inferior_pid_to_str (inf->pid));
 478
 479       if (inf->pspace->pspace_exec_filename != NULL)
 480         uiout->field_string ("exec", inf->pspace->pspace_exec_filename);
 481       else
 482         uiout->field_skip ("exec");
 483
 484       /* Print extra info that isn't really fit to always present in
 485          tabular form.  Currently we print the vfork parent/child
 486          relationships, if any.  */
 487       if (inf->vfork_parent)
 488         {
 489           uiout->text (_("\n\tis vfork child of inferior "));
 490           uiout->field_signed ("vfork-parent", inf->vfork_parent->num);
 491         }
 492       if (inf->vfork_child)
 493         {
 494           uiout->text (_("\n\tis vfork parent of inferior "));
 495           uiout->field_signed ("vfork-child", inf->vfork_child->num);
 496         }
 497
 498       uiout->text ("\n");
 499     }
 500 }
 501
 502 static void
 503 detach_inferior_command (const char *args, int from_tty)
 504 {
 505   if (!args || !*args)
 506     error (_("Requires argument (inferior id(s) to detach)"));
 507
 508   number_or_range_parser parser (args);
 509   while (!parser.finished ())
 510     {
 511       int num = parser.get_number ();
 512
 513       inferior *inf = find_inferior_id (num);
 514       if (inf == NULL)
 515         {
 516           warning (_("Inferior ID %d not known."), num);
 517           continue;
 518         }
 519
 520       if (inf->pid == 0)
 521         {
 522           warning (_("Inferior ID %d is not running."), num);
 523           continue;
 524         }
 525
 526       thread_info *tp = any_thread_of_inferior (inf);
 527       if (tp == NULL)
 528         {
 529           warning (_("Inferior ID %d has no threads."), num);
 530           continue;
 531         }
 532
 533       switch_to_thread (tp);
 534
 535       detach_command (NULL, from_tty);
 536     }
 537 }
 538
 539 static void
 540 kill_inferior_command (const char *args, int from_tty)
 541 {
 542   if (!args || !*args)
 543     error (_("Requires argument (inferior id(s) to kill)"));
 544
 545   number_or_range_parser parser (args);
 546   while (!parser.finished ())
 547     {
 548       int num = parser.get_number ();
 549
 550       inferior *inf = find_inferior_id (num);
 551       if (inf == NULL)
 552         {
 553           warning (_("Inferior ID %d not known."), num);
 554           continue;
 555         }
 556
 557       if (inf->pid == 0)
 558         {
 559           warning (_("Inferior ID %d is not running."), num);
 560           continue;
 561         }
 562
 563       thread_info *tp = any_thread_of_inferior (inf);
 564       if (tp == NULL)
 565         {
 566           warning (_("Inferior ID %d has no threads."), num);
 567           continue;
 568         }
 569
 570       switch_to_thread (tp);
 571
 572       target_kill ();
 573     }
 574
 575   bfd_cache_close_all ();
 576 }
 577
 578 /* See inferior.h.  */
 579
 580 void
 581 switch_to_inferior_no_thread (inferior *inf)
 582 {
 583   set_current_inferior (inf);
 584   switch_to_no_thread ();
 585   set_current_program_space (inf->pspace);
 586 }
 587
 588 static void
 589 inferior_command (const char *args, int from_tty)
 590 {
 591   struct inferior *inf;
 592   int num;
 593
 594   num = parse_and_eval_long (args);
 595
 596   inf = find_inferior_id (num);
 597   if (inf == NULL)
 598     error (_("Inferior ID %d not known."), num);
 599
 600   if (inf->pid != 0)
 601     {
 602       if (inf != current_inferior ())
 603         {
 604           thread_info *tp = any_thread_of_inferior (inf);
 605           if (tp == NULL)
 606             error (_("Inferior has no threads."));
 607
 608           switch_to_thread (tp);
 609         }
 610
 611       gdb::observers::user_selected_context_changed.notify
 612         (USER_SELECTED_INFERIOR
 613          | USER_SELECTED_THREAD
 614          | USER_SELECTED_FRAME);
 615     }
 616   else
 617     {
 618       switch_to_inferior_no_thread (inf);
 619
 620       gdb::observers::user_selected_context_changed.notify
 621         (USER_SELECTED_INFERIOR);
 622     }
 623 }
 624
 625 /* Print information about currently known inferiors.  */
 626
 627 static void
 628 info_inferiors_command (const char *args, int from_tty)
 629 {
 630   print_inferior (current_uiout, args);
 631 }
 632
 633 /* remove-inferior ID */
 634
 635 static void
 636 remove_inferior_command (const char *args, int from_tty)
 637 {
 638   if (args == NULL || *args == '\0')
 639     error (_("Requires an argument (inferior id(s) to remove)"));
 640
 641   number_or_range_parser parser (args);
 642   while (!parser.finished ())
 643     {
 644       int num = parser.get_number ();
 645       struct inferior *inf = find_inferior_id (num);
 646
 647       if (inf == NULL)
 648         {
 649           warning (_("Inferior ID %d not known."), num);
 650           continue;
 651         }
 652
 653       if (!inf->deletable ())
 654         {
 655           warning (_("Can not remove current inferior %d."), num);
 656           continue;
 657         }
 658
 659       if (inf->pid != 0)
 660         {
 661           warning (_("Can not remove active inferior %d."), num);
 662           continue;
 663         }
 664
 665       delete_inferior (inf);
 666     }
 667 }
 668
 669 struct inferior *
 670 add_inferior_with_spaces (void)
 671 {
 672   struct address_space *aspace;
 673   struct program_space *pspace;
 674   struct inferior *inf;
 675   struct gdbarch_info info;
 676
 677   /* If all inferiors share an address space on this system, this
 678      doesn't really return a new address space; otherwise, it
 679      really does.  */
 680   aspace = maybe_new_address_space ();
 681   pspace = new program_space (aspace);
 682   inf = add_inferior (0);
 683   inf->pspace = pspace;
 684   inf->aspace = pspace->aspace;
 685
 686   /* Setup the inferior's initial arch, based on information obtained
 687      from the global "set ..." options.  */
 688   gdbarch_info_init (&info);
 689   inf->gdbarch = gdbarch_find_by_info (info);
 690   /* The "set ..." options reject invalid settings, so we should
 691      always have a valid arch by now.  */
 692   gdb_assert (inf->gdbarch != NULL);
 693
 694   return inf;
 695 }
 696
 697 /* add-inferior [-copies N] [-exec FILENAME]  */
 698
 699 static void
 700 add_inferior_command (const char *args, int from_tty)
 701 {
 702   int i, copies = 1;
 703   gdb::unique_xmalloc_ptr<char> exec;
 704   symfile_add_flags add_flags = 0;
 705
 706   if (from_tty)
 707     add_flags |= SYMFILE_VERBOSE;
 708
 709   if (args)
 710     {
 711       gdb_argv built_argv (args);
 712
 713       for (char **argv = built_argv.get (); *argv != NULL; argv++)
 714         {
 715           if (**argv == '-')
 716             {
 717               if (strcmp (*argv, "-copies") == 0)
 718                 {
 719                   ++argv;
 720                   if (!*argv)
 721                     error (_("No argument to -copies"));
 722                   copies = parse_and_eval_long (*argv);
 723                 }
 724               else if (strcmp (*argv, "-exec") == 0)
 725                 {
 726                   ++argv;
 727                   if (!*argv)
 728                     error (_("No argument to -exec"));
 729                   exec.reset (tilde_expand (*argv));
 730                 }
 731             }
 732           else
 733             error (_("Invalid argument"));
 734         }
 735     }
 736
 737   scoped_restore_current_pspace_and_thread restore_pspace_thread;
 738
 739   for (i = 0; i < copies; ++i)
 740     {
 741       struct inferior *inf = add_inferior_with_spaces ();
 742
 743       printf_filtered (_("Added inferior %d\n"), inf->num);
 744
 745       if (exec != NULL)
 746         {
 747           /* Switch over temporarily, while reading executable and
 748              symbols.  */
 749           switch_to_inferior_no_thread (inf);
 750           exec_file_attach (exec.get (), from_tty);
 751           symbol_file_add_main (exec.get (), add_flags);
 752         }
 753     }
 754 }
 755
 756 /* clone-inferior [-copies N] [ID] */
 757
 758 static void
 759 clone_inferior_command (const char *args, int from_tty)
 760 {
 761   int i, copies = 1;
 762   struct inferior *orginf = NULL;
 763
 764   if (args)
 765     {
 766       gdb_argv built_argv (args);
 767
 768       char **argv = built_argv.get ();
 769       for (; *argv != NULL; argv++)
 770         {
 771           if (**argv == '-')
 772             {
 773               if (strcmp (*argv, "-copies") == 0)
 774                 {
 775                   ++argv;
 776                   if (!*argv)
 777                     error (_("No argument to -copies"));
 778                   copies = parse_and_eval_long (*argv);
 779
 780                   if (copies < 0)
 781                     error (_("Invalid copies number"));
 782                 }
 783             }
 784           else
 785             {
 786               if (orginf == NULL)
 787                 {
 788                   int num;
 789
 790                   /* The first non-option (-) argument specified the
 791                      program space ID.  */
 792                   num = parse_and_eval_long (*argv);
 793                   orginf = find_inferior_id (num);
 794
 795                   if (orginf == NULL)
 796                     error (_("Inferior ID %d not known."), num);
 797                   continue;
 798                 }
 799               else
 800                 error (_("Invalid argument"));
 801             }
 802         }
 803     }
 804
 805   /* If no inferior id was specified, then the user wants to clone the
 806      current inferior.  */
 807   if (orginf == NULL)
 808     orginf = current_inferior ();
 809
 810   scoped_restore_current_pspace_and_thread restore_pspace_thread;
 811
 812   for (i = 0; i < copies; ++i)
 813     {
 814       struct address_space *aspace;
 815       struct program_space *pspace;
 816       struct inferior *inf;
 817
 818       /* If all inferiors share an address space on this system, this
 819          doesn't really return a new address space; otherwise, it
 820          really does.  */
 821       aspace = maybe_new_address_space ();
 822       pspace = new program_space (aspace);
 823       inf = add_inferior (0);
 824       inf->pspace = pspace;
 825       inf->aspace = pspace->aspace;
 826       inf->gdbarch = orginf->gdbarch;
 827
 828       /* If the original inferior had a user specified target
 829          description, make the clone use it too.  */
 830       if (target_desc_info_from_user_p (inf->tdesc_info))
 831         copy_inferior_target_desc_info (inf, orginf);
 832
 833       printf_filtered (_("Added inferior %d.\n"), inf->num);
 834
 835       set_current_inferior (inf);
 836       switch_to_no_thread ();
 837       clone_program_space (pspace, orginf->pspace);
 838     }
 839 }
 840
 841 /* Print notices when new inferiors are created and die.  */
 842 static void
 843 show_print_inferior_events (struct ui_file *file, int from_tty,
 844                            struct cmd_list_element *c, const char *value)
 845 {
 846   fprintf_filtered (file, _("Printing of inferior events is %s.\n"), value);
 847 }
 848
 849 /* Return a new value for the selected inferior's id.  */
 850
 851 static struct value *
 852 inferior_id_make_value (struct gdbarch *gdbarch, struct internalvar *var,
 853                         void *ignore)
 854 {
 855   struct inferior *inf = current_inferior ();
 856
 857   return value_from_longest (builtin_type (gdbarch)->builtin_int, inf->num);
 858 }
 859
 860 /* Implementation of `$_inferior' variable.  */
 861
 862 static const struct internalvar_funcs inferior_funcs =
 863 {
 864   inferior_id_make_value,
 865   NULL,
 866   NULL
 867 };
 868
 869 \f
 870
 871 void
 872 initialize_inferiors (void)
 873 {
 874   struct cmd_list_element *c = NULL;
 875
 876   /* There's always one inferior.  Note that this function isn't an
 877      automatic _initialize_foo function, since other _initialize_foo
 878      routines may need to install their per-inferior data keys.  We
 879      can only allocate an inferior when all those modules have done
 880      that.  Do this after initialize_progspace, due to the
 881      current_program_space reference.  */
 882   current_inferior_ = add_inferior_silent (0);
 883   current_inferior_->incref ();
 884   current_inferior_->pspace = current_program_space;
 885   current_inferior_->aspace = current_program_space->aspace;
 886   /* The architecture will be initialized shortly, by
 887      initialize_current_architecture.  */
 888
 889   add_info ("inferiors", info_inferiors_command,
 890             _("Print a list of inferiors being managed.\n\
 891 Usage: info inferiors [ID]...\n\
 892 If IDs are specified, the list is limited to just those inferiors.\n\
 893 By default all inferiors are displayed."));
 894
 895   c = add_com ("add-inferior", no_class, add_inferior_command, _("\
 896 Add a new inferior.\n\
 897 Usage: add-inferior [-copies N] [-exec FILENAME]\n\
 898 N is the optional number of inferiors to add, default is 1.\n\
 899 FILENAME is the file name of the executable to use\n\
 900 as main program."));
 901   set_cmd_completer (c, filename_completer);
 902
 903   add_com ("remove-inferiors", no_class, remove_inferior_command, _("\
 904 Remove inferior ID (or list of IDs).\n\
 905 Usage: remove-inferiors ID..."));
 906
 907   add_com ("clone-inferior", no_class, clone_inferior_command, _("\
 908 Clone inferior ID.\n\
 909 Usage: clone-inferior [-copies N] [ID]\n\
 910 Add N copies of inferior ID.  The new inferior has the same\n\
 911 executable loaded as the copied inferior.  If -copies is not specified,\n\
 912 adds 1 copy.  If ID is not specified, it is the current inferior\n\
 913 that is cloned."));
 914
 915   add_cmd ("inferiors", class_run, detach_inferior_command, _("\
 916 Detach from inferior ID (or list of IDS).\n\
 917 Usage; detach inferiors ID..."),
 918            &detachlist);
 919
 920   add_cmd ("inferiors", class_run, kill_inferior_command, _("\
 921 Kill inferior ID (or list of IDs).\n\
 922 Usage: kill inferiors ID..."),
 923            &killlist);
 924
 925   add_cmd ("inferior", class_run, inferior_command, _("\
 926 Use this command to switch between inferiors.\n\
 927 Usage: inferior ID\n\
 928 The new inferior ID must be currently known."),
 929            &cmdlist);
 930
 931   add_setshow_boolean_cmd ("inferior-events", no_class,
 932          &print_inferior_events, _("\
 933 Set printing of inferior events (such as inferior start and exit)."), _("\
 934 Show printing of inferior events (such as inferior start and exit)."), NULL,
 935          NULL,
 936          show_print_inferior_events,
 937          &setprintlist, &showprintlist);
 938
 939   create_internalvar_type_lazy ("_inferior", &inferior_funcs, NULL);
 940 }