gdb/thread.c

   1 /* Multi-process/thread control for GDB, the GNU debugger.
   2
   3    Copyright (C) 1986, 1987, 1988, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
   4    2000, 2001, 2002, 2003, 2004, 2007 Free Software Foundation, Inc.
   5
   6    Contributed by Lynx Real-Time Systems, Inc.  Los Gatos, CA.
   7
   8    This file is part of GDB.
   9
  10    This program is free software; you can redistribute it and/or modify
  11    it under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 2 of the License, or
  13    (at your option) any later version.
  14
  15    This program is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with this program; if not, write to the Free Software
  22    Foundation, Inc., 51 Franklin Street, Fifth Floor,
  23    Boston, MA 02110-1301, USA.  */
  24
  25 #include "defs.h"
  26 #include "symtab.h"
  27 #include "frame.h"
  28 #include "inferior.h"
  29 #include "environ.h"
  30 #include "value.h"
  31 #include "target.h"
  32 #include "gdbthread.h"
  33 #include "exceptions.h"
  34 #include "command.h"
  35 #include "gdbcmd.h"
  36 #include "regcache.h"
  37 #include "gdb.h"
  38 #include "gdb_string.h"
  39
  40 #include <ctype.h>
  41 #include <sys/types.h>
  42 #include <signal.h>
  43 #include "ui-out.h"
  44
  45 /* Definition of struct thread_info exported to gdbthread.h */
  46
  47 /* Prototypes for exported functions. */
  48
  49 void _initialize_thread (void);
  50
  51 /* Prototypes for local functions. */
  52
  53 static struct thread_info *thread_list = NULL;
  54 static int highest_thread_num;
  55
  56 static struct thread_info *find_thread_id (int num);
  57
  58 static void thread_command (char *tidstr, int from_tty);
  59 static void thread_apply_all_command (char *, int);
  60 static int thread_alive (struct thread_info *);
  61 static void info_threads_command (char *, int);
  62 static void thread_apply_command (char *, int);
  63 static void restore_current_thread (ptid_t);
  64 static void switch_to_thread (ptid_t ptid);
  65 static void prune_threads (void);
  66 static struct cleanup *make_cleanup_restore_current_thread (ptid_t,
  67                                                             struct frame_id);
  68
  69 void
  70 delete_step_resume_breakpoint (void *arg)
  71 {
  72   struct breakpoint **breakpointp = (struct breakpoint **) arg;
  73   struct thread_info *tp;
  74
  75   if (*breakpointp != NULL)
  76     {
  77       delete_breakpoint (*breakpointp);
  78       for (tp = thread_list; tp; tp = tp->next)
  79         if (tp->step_resume_breakpoint == *breakpointp)
  80           tp->step_resume_breakpoint = NULL;
  81
  82       *breakpointp = NULL;
  83     }
  84 }
  85
  86 static void
  87 free_thread (struct thread_info *tp)
  88 {
  89   /* NOTE: this will take care of any left-over step_resume breakpoints,
  90      but not any user-specified thread-specific breakpoints. */
  91   if (tp->step_resume_breakpoint)
  92     delete_breakpoint (tp->step_resume_breakpoint);
  93
  94   /* FIXME: do I ever need to call the back-end to give it a
  95      chance at this private data before deleting the thread?  */
  96   if (tp->private)
  97     xfree (tp->private);
  98
  99   xfree (tp);
 100 }
 101
 102 void
 103 init_thread_list (void)
 104 {
 105   struct thread_info *tp, *tpnext;
 106
 107   highest_thread_num = 0;
 108   if (!thread_list)
 109     return;
 110
 111   for (tp = thread_list; tp; tp = tpnext)
 112     {
 113       tpnext = tp->next;
 114       free_thread (tp);
 115     }
 116
 117   thread_list = NULL;
 118 }
 119
 120 /* add_thread now returns a pointer to the new thread_info,
 121    so that back_ends can initialize their private data.  */
 122
 123 struct thread_info *
 124 add_thread (ptid_t ptid)
 125 {
 126   struct thread_info *tp;
 127
 128   tp = (struct thread_info *) xmalloc (sizeof (*tp));
 129   memset (tp, 0, sizeof (*tp));
 130   tp->ptid = ptid;
 131   tp->num = ++highest_thread_num;
 132   tp->next = thread_list;
 133   thread_list = tp;
 134   return tp;
 135 }
 136
 137 void
 138 delete_thread (ptid_t ptid)
 139 {
 140   struct thread_info *tp, *tpprev;
 141
 142   tpprev = NULL;
 143
 144   for (tp = thread_list; tp; tpprev = tp, tp = tp->next)
 145     if (ptid_equal (tp->ptid, ptid))
 146       break;
 147
 148   if (!tp)
 149     return;
 150
 151   if (tpprev)
 152     tpprev->next = tp->next;
 153   else
 154     thread_list = tp->next;
 155
 156   free_thread (tp);
 157 }
 158
 159 static struct thread_info *
 160 find_thread_id (int num)
 161 {
 162   struct thread_info *tp;
 163
 164   for (tp = thread_list; tp; tp = tp->next)
 165     if (tp->num == num)
 166       return tp;
 167
 168   return NULL;
 169 }
 170
 171 /* Find a thread_info by matching PTID.  */
 172 struct thread_info *
 173 find_thread_pid (ptid_t ptid)
 174 {
 175   struct thread_info *tp;
 176
 177   for (tp = thread_list; tp; tp = tp->next)
 178     if (ptid_equal (tp->ptid, ptid))
 179       return tp;
 180
 181   return NULL;
 182 }
 183
 184 /*
 185  * Thread iterator function.
 186  *
 187  * Calls a callback function once for each thread, so long as
 188  * the callback function returns false.  If the callback function
 189  * returns true, the iteration will end and the current thread
 190  * will be returned.  This can be useful for implementing a
 191  * search for a thread with arbitrary attributes, or for applying
 192  * some operation to every thread.
 193  *
 194  * FIXME: some of the existing functionality, such as
 195  * "Thread apply all", might be rewritten using this functionality.
 196  */
 197
 198 struct thread_info *
 199 iterate_over_threads (int (*callback) (struct thread_info *, void *),
 200                       void *data)
 201 {
 202   struct thread_info *tp;
 203
 204   for (tp = thread_list; tp; tp = tp->next)
 205     if ((*callback) (tp, data))
 206       return tp;
 207
 208   return NULL;
 209 }
 210
 211 int
 212 valid_thread_id (int num)
 213 {
 214   struct thread_info *tp;
 215
 216   for (tp = thread_list; tp; tp = tp->next)
 217     if (tp->num == num)
 218       return 1;
 219
 220   return 0;
 221 }
 222
 223 int
 224 pid_to_thread_id (ptid_t ptid)
 225 {
 226   struct thread_info *tp;
 227
 228   for (tp = thread_list; tp; tp = tp->next)
 229     if (ptid_equal (tp->ptid, ptid))
 230       return tp->num;
 231
 232   return 0;
 233 }
 234
 235 ptid_t
 236 thread_id_to_pid (int num)
 237 {
 238   struct thread_info *thread = find_thread_id (num);
 239   if (thread)
 240     return thread->ptid;
 241   else
 242     return pid_to_ptid (-1);
 243 }
 244
 245 int
 246 in_thread_list (ptid_t ptid)
 247 {
 248   struct thread_info *tp;
 249
 250   for (tp = thread_list; tp; tp = tp->next)
 251     if (ptid_equal (tp->ptid, ptid))
 252       return 1;
 253
 254   return 0;                     /* Never heard of 'im */
 255 }
 256
 257 /* Print a list of thread ids currently known, and the total number of
 258    threads. To be used from within catch_errors. */
 259 static int
 260 do_captured_list_thread_ids (struct ui_out *uiout, void *arg)
 261 {
 262   struct thread_info *tp;
 263   int num = 0;
 264   struct cleanup *cleanup_chain;
 265
 266   prune_threads ();
 267   target_find_new_threads ();
 268
 269   cleanup_chain = make_cleanup_ui_out_tuple_begin_end (uiout, "thread-ids");
 270
 271   for (tp = thread_list; tp; tp = tp->next)
 272     {
 273       num++;
 274       ui_out_field_int (uiout, "thread-id", tp->num);
 275     }
 276
 277   do_cleanups (cleanup_chain);
 278   ui_out_field_int (uiout, "number-of-threads", num);
 279   return GDB_RC_OK;
 280 }
 281
 282 /* Official gdblib interface function to get a list of thread ids and
 283    the total number. */
 284 enum gdb_rc
 285 gdb_list_thread_ids (struct ui_out *uiout, char **error_message)
 286 {
 287   return catch_exceptions_with_msg (uiout, do_captured_list_thread_ids, NULL,
 288                                     error_message, RETURN_MASK_ALL);
 289 }
 290
 291 /* Load infrun state for the thread PID.  */
 292
 293 void
 294 load_infrun_state (ptid_t ptid,
 295                    CORE_ADDR *prev_pc,
 296                    int *trap_expected,
 297                    struct breakpoint **step_resume_breakpoint,
 298                    CORE_ADDR *step_range_start,
 299                    CORE_ADDR *step_range_end,
 300                    struct frame_id *step_frame_id,
 301                    int *handling_longjmp,
 302                    int *another_trap,
 303                    int *stepping_through_solib_after_catch,
 304                    bpstat *stepping_through_solib_catchpoints,
 305                    int *current_line,
 306                    struct symtab **current_symtab)
 307 {
 308   struct thread_info *tp;
 309
 310   /* If we can't find the thread, then we're debugging a single threaded
 311      process.  No need to do anything in that case.  */
 312   tp = find_thread_id (pid_to_thread_id (ptid));
 313   if (tp == NULL)
 314     return;
 315
 316   *prev_pc = tp->prev_pc;
 317   *trap_expected = tp->trap_expected;
 318   *step_resume_breakpoint = tp->step_resume_breakpoint;
 319   *step_range_start = tp->step_range_start;
 320   *step_range_end = tp->step_range_end;
 321   *step_frame_id = tp->step_frame_id;
 322   *handling_longjmp = tp->handling_longjmp;
 323   *another_trap = tp->another_trap;
 324   *stepping_through_solib_after_catch =
 325     tp->stepping_through_solib_after_catch;
 326   *stepping_through_solib_catchpoints =
 327     tp->stepping_through_solib_catchpoints;
 328   *current_line = tp->current_line;
 329   *current_symtab = tp->current_symtab;
 330 }
 331
 332 /* Save infrun state for the thread PID.  */
 333
 334 void
 335 save_infrun_state (ptid_t ptid,
 336                    CORE_ADDR prev_pc,
 337                    int trap_expected,
 338                    struct breakpoint *step_resume_breakpoint,
 339                    CORE_ADDR step_range_start,
 340                    CORE_ADDR step_range_end,
 341                    const struct frame_id *step_frame_id,
 342                    int handling_longjmp,
 343                    int another_trap,
 344                    int stepping_through_solib_after_catch,
 345                    bpstat stepping_through_solib_catchpoints,
 346                    int current_line,
 347                    struct symtab *current_symtab)
 348 {
 349   struct thread_info *tp;
 350
 351   /* If we can't find the thread, then we're debugging a single-threaded
 352      process.  Nothing to do in that case.  */
 353   tp = find_thread_id (pid_to_thread_id (ptid));
 354   if (tp == NULL)
 355     return;
 356
 357   tp->prev_pc = prev_pc;
 358   tp->trap_expected = trap_expected;
 359   tp->step_resume_breakpoint = step_resume_breakpoint;
 360   tp->step_range_start = step_range_start;
 361   tp->step_range_end = step_range_end;
 362   tp->step_frame_id = (*step_frame_id);
 363   tp->handling_longjmp = handling_longjmp;
 364   tp->another_trap = another_trap;
 365   tp->stepping_through_solib_after_catch = stepping_through_solib_after_catch;
 366   tp->stepping_through_solib_catchpoints = stepping_through_solib_catchpoints;
 367   tp->current_line = current_line;
 368   tp->current_symtab = current_symtab;
 369 }
 370
 371 /* Return true if TP is an active thread. */
 372 static int
 373 thread_alive (struct thread_info *tp)
 374 {
 375   if (PIDGET (tp->ptid) == -1)
 376     return 0;
 377   if (!target_thread_alive (tp->ptid))
 378     {
 379       tp->ptid = pid_to_ptid (-1);      /* Mark it as dead */
 380       return 0;
 381     }
 382   return 1;
 383 }
 384
 385 static void
 386 prune_threads (void)
 387 {
 388   struct thread_info *tp, *next;
 389
 390   for (tp = thread_list; tp; tp = next)
 391     {
 392       next = tp->next;
 393       if (!thread_alive (tp))
 394         delete_thread (tp->ptid);
 395     }
 396 }
 397
 398 /* Print information about currently known threads
 399
 400  * Note: this has the drawback that it _really_ switches
 401  *       threads, which frees the frame cache.  A no-side
 402  *       effects info-threads command would be nicer.
 403  */
 404
 405 static void
 406 info_threads_command (char *arg, int from_tty)
 407 {
 408   struct thread_info *tp;
 409   ptid_t current_ptid;
 410   struct frame_info *cur_frame;
 411   struct cleanup *old_chain;
 412   struct frame_id saved_frame_id;
 413   char *extra_info;
 414
 415   /* Backup current thread and selected frame.  */
 416   saved_frame_id = get_frame_id (get_selected_frame (NULL));
 417   old_chain = make_cleanup_restore_current_thread (inferior_ptid, saved_frame_id);
 418
 419   prune_threads ();
 420   target_find_new_threads ();
 421   current_ptid = inferior_ptid;
 422   for (tp = thread_list; tp; tp = tp->next)
 423     {
 424       if (ptid_equal (tp->ptid, current_ptid))
 425         printf_filtered ("* ");
 426       else
 427         printf_filtered ("  ");
 428
 429       printf_filtered ("%d %s", tp->num, target_tid_to_str (tp->ptid));
 430
 431       extra_info = target_extra_thread_info (tp);
 432       if (extra_info)
 433         printf_filtered (" (%s)", extra_info);
 434       puts_filtered ("  ");
 435       /* That switch put us at the top of the stack (leaf frame).  */
 436       switch_to_thread (tp->ptid);
 437       print_stack_frame (get_selected_frame (NULL), 0, LOCATION);
 438     }
 439
 440   /* Restores the current thread and the frame selected before
 441      the "info threads" command.  */
 442   do_cleanups (old_chain);
 443
 444   /*  If case we were not able to find the original frame, print the
 445       new selected frame.  */
 446   if (frame_find_by_id (saved_frame_id) == NULL)
 447     {
 448       warning (_("Couldn't restore frame in current thread, at frame 0"));
 449       print_stack_frame (get_selected_frame (NULL), 0, LOCATION);
 450     }
 451 }
 452
 453 /* Switch from one thread to another. */
 454
 455 static void
 456 switch_to_thread (ptid_t ptid)
 457 {
 458   if (ptid_equal (ptid, inferior_ptid))
 459     return;
 460
 461   inferior_ptid = ptid;
 462   reinit_frame_cache ();
 463   registers_changed ();
 464   stop_pc = read_pc ();
 465 }
 466
 467 static void
 468 restore_current_thread (ptid_t ptid)
 469 {
 470   if (!ptid_equal (ptid, inferior_ptid))
 471     {
 472       switch_to_thread (ptid);
 473     }
 474 }
 475
 476 static void
 477 restore_selected_frame (struct frame_id a_frame_id)
 478 {
 479   struct frame_info *selected_frame_info = NULL;
 480
 481   if (frame_id_eq (a_frame_id, null_frame_id))
 482     return;
 483
 484   if ((selected_frame_info = frame_find_by_id (a_frame_id)) != NULL)
 485     {
 486       select_frame (selected_frame_info);
 487     }
 488 }
 489
 490 struct current_thread_cleanup
 491 {
 492   ptid_t inferior_ptid;
 493   struct frame_id selected_frame_id;
 494 };
 495
 496 static void
 497 do_restore_current_thread_cleanup (void *arg)
 498 {
 499   struct current_thread_cleanup *old = arg;
 500   restore_current_thread (old->inferior_ptid);
 501   restore_selected_frame (old->selected_frame_id);
 502   xfree (old);
 503 }
 504
 505 static struct cleanup *
 506 make_cleanup_restore_current_thread (ptid_t inferior_ptid,
 507                                      struct frame_id a_frame_id)
 508 {
 509   struct current_thread_cleanup *old
 510     = xmalloc (sizeof (struct current_thread_cleanup));
 511   old->inferior_ptid = inferior_ptid;
 512   old->selected_frame_id = a_frame_id;
 513   return make_cleanup (do_restore_current_thread_cleanup, old);
 514 }
 515
 516 /* Apply a GDB command to a list of threads.  List syntax is a whitespace
 517    seperated list of numbers, or ranges, or the keyword `all'.  Ranges consist
 518    of two numbers seperated by a hyphen.  Examples:
 519
 520    thread apply 1 2 7 4 backtrace       Apply backtrace cmd to threads 1,2,7,4
 521    thread apply 2-7 9 p foo(1)  Apply p foo(1) cmd to threads 2->7 & 9
 522    thread apply all p x/i $pc   Apply x/i $pc cmd to all threads
 523  */
 524
 525 static void
 526 thread_apply_all_command (char *cmd, int from_tty)
 527 {
 528   struct thread_info *tp;
 529   struct cleanup *old_chain;
 530   struct cleanup *saved_cmd_cleanup_chain;
 531   char *saved_cmd;
 532   struct frame_id saved_frame_id;
 533   ptid_t current_ptid;
 534   int thread_has_changed = 0;
 535
 536   if (cmd == NULL || *cmd == '\000')
 537     error (_("Please specify a command following the thread ID list"));
 538
 539   current_ptid = inferior_ptid;
 540   saved_frame_id = get_frame_id (get_selected_frame (NULL));
 541   old_chain = make_cleanup_restore_current_thread (inferior_ptid, saved_frame_id);
 542
 543   /* It is safe to update the thread list now, before
 544      traversing it for "thread apply all".  MVS */
 545   target_find_new_threads ();
 546
 547   /* Save a copy of the command in case it is clobbered by
 548      execute_command */
 549   saved_cmd = xstrdup (cmd);
 550   saved_cmd_cleanup_chain = make_cleanup (xfree, (void *) saved_cmd);
 551   for (tp = thread_list; tp; tp = tp->next)
 552     if (thread_alive (tp))
 553       {
 554         switch_to_thread (tp->ptid);
 555         printf_filtered (_("\nThread %d (%s):\n"),
 556                          tp->num, target_tid_to_str (inferior_ptid));
 557         execute_command (cmd, from_tty);
 558         strcpy (cmd, saved_cmd);        /* Restore exact command used previously */
 559       }
 560
 561   if (!ptid_equal (current_ptid, inferior_ptid))
 562     thread_has_changed = 1;
 563
 564   do_cleanups (saved_cmd_cleanup_chain);
 565   do_cleanups (old_chain);
 566   /* Print stack frame only if we changed thread.  */
 567   if (thread_has_changed)
 568     print_stack_frame (get_current_frame (), 1, SRC_LINE);
 569
 570 }
 571
 572 static void
 573 thread_apply_command (char *tidlist, int from_tty)
 574 {
 575   char *cmd;
 576   char *p;
 577   struct cleanup *old_chain;
 578   struct cleanup *saved_cmd_cleanup_chain;
 579   char *saved_cmd;
 580   struct frame_id saved_frame_id;
 581   ptid_t current_ptid;
 582   int thread_has_changed = 0;
 583
 584   if (tidlist == NULL || *tidlist == '\000')
 585     error (_("Please specify a thread ID list"));
 586
 587   for (cmd = tidlist; *cmd != '\000' && !isalpha (*cmd); cmd++);
 588
 589   if (*cmd == '\000')
 590     error (_("Please specify a command following the thread ID list"));
 591
 592   current_ptid = inferior_ptid;
 593   saved_frame_id = get_frame_id (get_selected_frame (NULL));
 594   old_chain = make_cleanup_restore_current_thread (inferior_ptid, saved_frame_id);
 595
 596   /* Save a copy of the command in case it is clobbered by
 597      execute_command */
 598   saved_cmd = xstrdup (cmd);
 599   saved_cmd_cleanup_chain = make_cleanup (xfree, (void *) saved_cmd);
 600   while (tidlist < cmd)
 601     {
 602       struct thread_info *tp;
 603       int start, end;
 604
 605       start = strtol (tidlist, &p, 10);
 606       if (p == tidlist)
 607         error (_("Error parsing %s"), tidlist);
 608       tidlist = p;
 609
 610       while (*tidlist == ' ' || *tidlist == '\t')
 611         tidlist++;
 612
 613       if (*tidlist == '-')      /* Got a range of IDs? */
 614         {
 615           tidlist++;            /* Skip the - */
 616           end = strtol (tidlist, &p, 10);
 617           if (p == tidlist)
 618             error (_("Error parsing %s"), tidlist);
 619           tidlist = p;
 620
 621           while (*tidlist == ' ' || *tidlist == '\t')
 622             tidlist++;
 623         }
 624       else
 625         end = start;
 626
 627       for (; start <= end; start++)
 628         {
 629           tp = find_thread_id (start);
 630
 631           if (!tp)
 632             warning (_("Unknown thread %d."), start);
 633           else if (!thread_alive (tp))
 634             warning (_("Thread %d has terminated."), start);
 635           else
 636             {
 637               switch_to_thread (tp->ptid);
 638               printf_filtered (_("\nThread %d (%s):\n"), tp->num,
 639                                target_tid_to_str (inferior_ptid));
 640               execute_command (cmd, from_tty);
 641               strcpy (cmd, saved_cmd);  /* Restore exact command used previously */
 642             }
 643         }
 644     }
 645
 646   if (!ptid_equal (current_ptid, inferior_ptid))
 647     thread_has_changed = 1;
 648
 649   do_cleanups (saved_cmd_cleanup_chain);
 650   do_cleanups (old_chain);
 651   /* Print stack frame only if we changed thread.  */
 652   if (thread_has_changed)
 653     print_stack_frame (get_current_frame (), 1, SRC_LINE);
 654 }
 655
 656 /* Switch to the specified thread.  Will dispatch off to thread_apply_command
 657    if prefix of arg is `apply'.  */
 658
 659 static void
 660 thread_command (char *tidstr, int from_tty)
 661 {
 662   if (!tidstr)
 663     {
 664       /* Don't generate an error, just say which thread is current. */
 665       if (target_has_stack)
 666         printf_filtered (_("[Current thread is %d (%s)]\n"),
 667                          pid_to_thread_id (inferior_ptid),
 668                          target_tid_to_str (inferior_ptid));
 669       else
 670         error (_("No stack."));
 671       return;
 672     }
 673
 674   gdb_thread_select (uiout, tidstr, NULL);
 675 }
 676
 677 static int
 678 do_captured_thread_select (struct ui_out *uiout, void *tidstr)
 679 {
 680   int num;
 681   struct thread_info *tp;
 682
 683   num = value_as_long (parse_and_eval (tidstr));
 684
 685   tp = find_thread_id (num);
 686
 687   if (!tp)
 688     error (_("Thread ID %d not known."), num);
 689
 690   if (!thread_alive (tp))
 691     error (_("Thread ID %d has terminated."), num);
 692
 693   switch_to_thread (tp->ptid);
 694
 695   ui_out_text (uiout, "[Switching to thread ");
 696   ui_out_field_int (uiout, "new-thread-id", pid_to_thread_id (inferior_ptid));
 697   ui_out_text (uiout, " (");
 698   ui_out_text (uiout, target_tid_to_str (inferior_ptid));
 699   ui_out_text (uiout, ")]");
 700
 701   print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC);
 702   return GDB_RC_OK;
 703 }
 704
 705 enum gdb_rc
 706 gdb_thread_select (struct ui_out *uiout, char *tidstr, char **error_message)
 707 {
 708   return catch_exceptions_with_msg (uiout, do_captured_thread_select, tidstr,
 709                                     error_message, RETURN_MASK_ALL);
 710 }
 711
 712 /* Commands with a prefix of `thread'.  */
 713 struct cmd_list_element *thread_cmd_list = NULL;
 714
 715 void
 716 _initialize_thread (void)
 717 {
 718   static struct cmd_list_element *thread_apply_list = NULL;
 719
 720   add_info ("threads", info_threads_command,
 721             _("IDs of currently known threads."));
 722
 723   add_prefix_cmd ("thread", class_run, thread_command, _("\
 724 Use this command to switch between threads.\n\
 725 The new thread ID must be currently known."),
 726                   &thread_cmd_list, "thread ", 1, &cmdlist);
 727
 728   add_prefix_cmd ("apply", class_run, thread_apply_command,
 729                   _("Apply a command to a list of threads."),
 730                   &thread_apply_list, "thread apply ", 1, &thread_cmd_list);
 731
 732   add_cmd ("all", class_run, thread_apply_all_command,
 733            _("Apply a command to all threads."), &thread_apply_list);
 734
 735   if (!xdb_commands)
 736     add_com_alias ("t", "thread", class_run, 1);
 737 }