gdb/gdbthread.h

   1 /* Multi-process/thread control defs for GDB, the GNU debugger.
   2    Copyright (C) 1987-2018 Free Software Foundation, Inc.
   3    Contributed by Lynx Real-Time Systems, Inc.  Los Gatos, CA.
   4
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #ifndef GDBTHREAD_H
  22 #define GDBTHREAD_H
  23
  24 struct symtab;
  25
  26 #include "breakpoint.h"
  27 #include "frame.h"
  28 #include "ui-out.h"
  29 #include "inferior.h"
  30 #include "btrace.h"
  31 #include "common/vec.h"
  32 #include "target/waitstatus.h"
  33 #include "cli/cli-utils.h"
  34 #include "common/refcounted-object.h"
  35 #include "common-gdbthread.h"
  36
  37 /* Frontend view of the thread state.  Possible extensions: stepping,
  38    finishing, until(ling),...  */
  39 enum thread_state
  40 {
  41   THREAD_STOPPED,
  42   THREAD_RUNNING,
  43   THREAD_EXITED,
  44 };
  45
  46 /* Inferior thread specific part of `struct infcall_control_state'.
  47
  48    Inferior process counterpart is `struct inferior_control_state'.  */
  49
  50 struct thread_control_state
  51 {
  52   /* User/external stepping state.  */
  53
  54   /* Step-resume or longjmp-resume breakpoint.  */
  55   struct breakpoint *step_resume_breakpoint;
  56
  57   /* Exception-resume breakpoint.  */
  58   struct breakpoint *exception_resume_breakpoint;
  59
  60   /* Breakpoints used for software single stepping.  Plural, because
  61      it may have multiple locations.  E.g., if stepping over a
  62      conditional branch instruction we can't decode the condition for,
  63      we'll need to put a breakpoint at the branch destination, and
  64      another at the instruction after the branch.  */
  65   struct breakpoint *single_step_breakpoints;
  66
  67   /* Range to single step within.
  68
  69      If this is nonzero, respond to a single-step signal by continuing
  70      to step if the pc is in this range.
  71
  72      If step_range_start and step_range_end are both 1, it means to
  73      step for a single instruction (FIXME: it might clean up
  74      wait_for_inferior in a minor way if this were changed to the
  75      address of the instruction and that address plus one.  But maybe
  76      not).  */
  77   CORE_ADDR step_range_start;   /* Inclusive */
  78   CORE_ADDR step_range_end;     /* Exclusive */
  79
  80   /* Function the thread was in as of last it started stepping.  */
  81   struct symbol *step_start_function;
  82
  83   /* If GDB issues a target step request, and this is nonzero, the
  84      target should single-step this thread once, and then continue
  85      single-stepping it without GDB core involvement as long as the
  86      thread stops in the step range above.  If this is zero, the
  87      target should ignore the step range, and only issue one single
  88      step.  */
  89   int may_range_step;
  90
  91   /* Stack frame address as of when stepping command was issued.
  92      This is how we know when we step into a subroutine call, and how
  93      to set the frame for the breakpoint used to step out.  */
  94   struct frame_id step_frame_id;
  95
  96   /* Similarly, the frame ID of the underlying stack frame (skipping
  97      any inlined frames).  */
  98   struct frame_id step_stack_frame_id;
  99
 100   /* Nonzero if we are presently stepping over a breakpoint.
 101
 102      If we hit a breakpoint or watchpoint, and then continue, we need
 103      to single step the current thread with breakpoints disabled, to
 104      avoid hitting the same breakpoint or watchpoint again.  And we
 105      should step just a single thread and keep other threads stopped,
 106      so that other threads don't miss breakpoints while they are
 107      removed.
 108
 109      So, this variable simultaneously means that we need to single
 110      step the current thread, keep other threads stopped, and that
 111      breakpoints should be removed while we step.
 112
 113      This variable is set either:
 114      - in proceed, when we resume inferior on user's explicit request
 115      - in keep_going, if handle_inferior_event decides we need to
 116      step over breakpoint.
 117
 118      The variable is cleared in normal_stop.  The proceed calls
 119      wait_for_inferior, which calls handle_inferior_event in a loop,
 120      and until wait_for_inferior exits, this variable is changed only
 121      by keep_going.  */
 122   int trap_expected;
 123
 124   /* Nonzero if the thread is being proceeded for a "finish" command
 125      or a similar situation when return value should be printed.  */
 126   int proceed_to_finish;
 127
 128   /* Nonzero if the thread is being proceeded for an inferior function
 129      call.  */
 130   int in_infcall;
 131
 132   enum step_over_calls_kind step_over_calls;
 133
 134   /* Nonzero if stopped due to a step command.  */
 135   int stop_step;
 136
 137   /* Chain containing status of breakpoint(s) the thread stopped
 138      at.  */
 139   bpstat stop_bpstat;
 140
 141   /* Whether the command that started the thread was a stepping
 142      command.  This is used to decide whether "set scheduler-locking
 143      step" behaves like "on" or "off".  */
 144   int stepping_command;
 145 };
 146
 147 /* Inferior thread specific part of `struct infcall_suspend_state'.  */
 148
 149 struct thread_suspend_state
 150 {
 151   /* Last signal that the inferior received (why it stopped).  When
 152      the thread is resumed, this signal is delivered.  Note: the
 153      target should not check whether the signal is in pass state,
 154      because the signal may have been explicitly passed with the
 155      "signal" command, which overrides "handle nopass".  If the signal
 156      should be suppressed, the core will take care of clearing this
 157      before the target is resumed.  */
 158   enum gdb_signal stop_signal;
 159
 160   /* The reason the thread last stopped, if we need to track it
 161      (breakpoint, watchpoint, etc.)  */
 162   enum target_stop_reason stop_reason;
 163
 164   /* The waitstatus for this thread's last event.  */
 165   struct target_waitstatus waitstatus;
 166   /* If true WAITSTATUS hasn't been handled yet.  */
 167   int waitstatus_pending_p;
 168
 169   /* Record the pc of the thread the last time it stopped.  (This is
 170      not the current thread's PC as that may have changed since the
 171      last stop, e.g., "return" command, or "p $pc = 0xf000").  This is
 172      used in coordination with stop_reason and waitstatus_pending_p:
 173      if the thread's PC is changed since it last stopped, a pending
 174      breakpoint waitstatus is discarded.  */
 175   CORE_ADDR stop_pc;
 176 };
 177
 178 /* Base class for target-specific thread data.  */
 179 struct private_thread_info
 180 {
 181   virtual ~private_thread_info () = 0;
 182 };
 183
 184 /* Threads are intrusively refcounted objects.  Being the
 185    user-selected thread is normally considered an implicit strong
 186    reference and is thus not accounted in the refcount, unlike
 187    inferior objects.  This is necessary, because there's no "current
 188    thread" pointer.  Instead the current thread is inferred from the
 189    inferior_ptid global.  However, when GDB needs to remember the
 190    selected thread to later restore it, GDB bumps the thread object's
 191    refcount, to prevent something deleting the thread object before
 192    reverting back (e.g., due to a "kill" command).  If the thread
 193    meanwhile exits before being re-selected, then the thread object is
 194    left listed in the thread list, but marked with state
 195    THREAD_EXITED.  (See make_cleanup_restore_current_thread and
 196    delete_thread).  All other thread references are considered weak
 197    references.  Placing a thread in the thread list is an implicit
 198    strong reference, and is thus not accounted for in the thread's
 199    refcount.  */
 200
 201 class thread_info : public refcounted_object
 202 {
 203 public:
 204   explicit thread_info (inferior *inf, ptid_t ptid);
 205   ~thread_info ();
 206
 207   bool deletable () const
 208   {
 209     /* If this is the current thread, or there's code out there that
 210        relies on it existing (refcount > 0) we can't delete yet.  */
 211     return (refcount () == 0 && !ptid_equal (ptid, inferior_ptid));
 212   }
 213
 214   /* Mark this thread as running and notify observers.  */
 215   void set_running (bool running);
 216
 217   struct thread_info *next = NULL;
 218   ptid_t ptid;                  /* "Actual process id";
 219                                     In fact, this may be overloaded with
 220                                     kernel thread id, etc.  */
 221
 222   /* Each thread has two GDB IDs.
 223
 224      a) The thread ID (Id).  This consists of the pair of:
 225
 226         - the number of the thread's inferior and,
 227
 228         - the thread's thread number in its inferior, aka, the
 229           per-inferior thread number.  This number is unique in the
 230           inferior but not unique between inferiors.
 231
 232      b) The global ID (GId).  This is a a single integer unique
 233         between all inferiors.
 234
 235      E.g.:
 236
 237       (gdb) info threads -gid
 238         Id    GId   Target Id   Frame
 239       * 1.1   1     Thread A    0x16a09237 in foo () at foo.c:10
 240         1.2   3     Thread B    0x15ebc6ed in bar () at foo.c:20
 241         1.3   5     Thread C    0x15ebc6ed in bar () at foo.c:20
 242         2.1   2     Thread A    0x16a09237 in foo () at foo.c:10
 243         2.2   4     Thread B    0x15ebc6ed in bar () at foo.c:20
 244         2.3   6     Thread C    0x15ebc6ed in bar () at foo.c:20
 245
 246      Above, both inferiors 1 and 2 have threads numbered 1-3, but each
 247      thread has its own unique global ID.  */
 248
 249   /* The thread's global GDB thread number.  This is exposed to MI,
 250      Python/Scheme, visible with "info threads -gid", and is also what
 251      the $_gthread convenience variable is bound to.  */
 252   int global_num;
 253
 254   /* The per-inferior thread number.  This is unique in the inferior
 255      the thread belongs to, but not unique between inferiors.  This is
 256      what the $_thread convenience variable is bound to.  */
 257   int per_inf_num;
 258
 259   /* The inferior this thread belongs to.  */
 260   struct inferior *inf;
 261
 262   /* The name of the thread, as specified by the user.  This is NULL
 263      if the thread does not have a user-given name.  */
 264   char *name = NULL;
 265
 266   /* Non-zero means the thread is executing.  Note: this is different
 267      from saying that there is an active target and we are stopped at
 268      a breakpoint, for instance.  This is a real indicator whether the
 269      thread is off and running.  */
 270   int executing = 0;
 271
 272   /* Non-zero if this thread is resumed from infrun's perspective.
 273      Note that a thread can be marked both as not-executing and
 274      resumed at the same time.  This happens if we try to resume a
 275      thread that has a wait status pending.  We shouldn't let the
 276      thread really run until that wait status has been processed, but
 277      we should not process that wait status if we didn't try to let
 278      the thread run.  */
 279   int resumed = 0;
 280
 281   /* Frontend view of the thread state.  Note that the THREAD_RUNNING/
 282      THREAD_STOPPED states are different from EXECUTING.  When the
 283      thread is stopped internally while handling an internal event,
 284      like a software single-step breakpoint, EXECUTING will be false,
 285      but STATE will still be THREAD_RUNNING.  */
 286   enum thread_state state = THREAD_STOPPED;
 287
 288   /* State of GDB control of inferior thread execution.
 289      See `struct thread_control_state'.  */
 290   thread_control_state control {};
 291
 292   /* State of inferior thread to restore after GDB is done with an inferior
 293      call.  See `struct thread_suspend_state'.  */
 294   thread_suspend_state suspend {};
 295
 296   int current_line = 0;
 297   struct symtab *current_symtab = NULL;
 298
 299   /* Internal stepping state.  */
 300
 301   /* Record the pc of the thread the last time it was resumed.  (It
 302      can't be done on stop as the PC may change since the last stop,
 303      e.g., "return" command, or "p $pc = 0xf000").  This is maintained
 304      by proceed and keep_going, and among other things, it's used in
 305      adjust_pc_after_break to distinguish a hardware single-step
 306      SIGTRAP from a breakpoint SIGTRAP.  */
 307   CORE_ADDR prev_pc = 0;
 308
 309   /* Did we set the thread stepping a breakpoint instruction?  This is
 310      used in conjunction with PREV_PC to decide whether to adjust the
 311      PC.  */
 312   int stepped_breakpoint = 0;
 313
 314   /* Should we step over breakpoint next time keep_going is called?  */
 315   int stepping_over_breakpoint = 0;
 316
 317   /* Should we step over a watchpoint next time keep_going is called?
 318      This is needed on targets with non-continuable, non-steppable
 319      watchpoints.  */
 320   int stepping_over_watchpoint = 0;
 321
 322   /* Set to TRUE if we should finish single-stepping over a breakpoint
 323      after hitting the current step-resume breakpoint.  The context here
 324      is that GDB is to do `next' or `step' while signal arrives.
 325      When stepping over a breakpoint and signal arrives, GDB will attempt
 326      to skip signal handler, so it inserts a step_resume_breakpoint at the
 327      signal return address, and resume inferior.
 328      step_after_step_resume_breakpoint is set to TRUE at this moment in
 329      order to keep GDB in mind that there is still a breakpoint to step over
 330      when GDB gets back SIGTRAP from step_resume_breakpoint.  */
 331   int step_after_step_resume_breakpoint = 0;
 332
 333   /* Pointer to the state machine manager object that handles what is
 334      left to do for the thread's execution command after the target
 335      stops.  Several execution commands use it.  */
 336   struct thread_fsm *thread_fsm = NULL;
 337
 338   /* This is used to remember when a fork or vfork event was caught by
 339      a catchpoint, and thus the event is to be followed at the next
 340      resume of the thread, and not immediately.  */
 341   struct target_waitstatus pending_follow;
 342
 343   /* True if this thread has been explicitly requested to stop.  */
 344   int stop_requested = 0;
 345
 346   /* The initiating frame of a nexting operation, used for deciding
 347      which exceptions to intercept.  If it is null_frame_id no
 348      bp_longjmp or bp_exception but longjmp has been caught just for
 349      bp_longjmp_call_dummy.  */
 350   struct frame_id initiating_frame = null_frame_id;
 351
 352   /* Private data used by the target vector implementation.  */
 353   std::unique_ptr<private_thread_info> priv;
 354
 355   /* Branch trace information for this thread.  */
 356   struct btrace_thread_info btrace {};
 357
 358   /* Flag which indicates that the stack temporaries should be stored while
 359      evaluating expressions.  */
 360   bool stack_temporaries_enabled = false;
 361
 362   /* Values that are stored as temporaries on stack while evaluating
 363      expressions.  */
 364   std::vector<struct value *> stack_temporaries;
 365
 366   /* Step-over chain.  A thread is in the step-over queue if these are
 367      non-NULL.  If only a single thread is in the chain, then these
 368      fields point to self.  */
 369   struct thread_info *step_over_prev = NULL;
 370   struct thread_info *step_over_next = NULL;
 371 };
 372
 373 /* A gdb::ref_ptr pointer to a thread_info.  */
 374
 375 using thread_info_ref
 376   = gdb::ref_ptr<struct thread_info, refcounted_object_ref_policy>;
 377
 378 /* Create an empty thread list, or empty the existing one.  */
 379 extern void init_thread_list (void);
 380
 381 /* Add a thread to the thread list, print a message
 382    that a new thread is found, and return the pointer to
 383    the new thread.  Caller my use this pointer to
 384    initialize the private thread data.  */
 385 extern struct thread_info *add_thread (ptid_t ptid);
 386
 387 /* Same as add_thread, but does not print a message
 388    about new thread.  */
 389 extern struct thread_info *add_thread_silent (ptid_t ptid);
 390
 391 /* Same as add_thread, and sets the private info.  */
 392 extern struct thread_info *add_thread_with_info (ptid_t ptid,
 393                                                  struct private_thread_info *);
 394
 395 /* Delete an existing thread list entry.  */
 396 extern void delete_thread (struct thread_info *thread);
 397
 398 /* Delete an existing thread list entry, and be quiet about it.  Used
 399    after the process this thread having belonged to having already
 400    exited, for example.  */
 401 extern void delete_thread_silent (struct thread_info *thread);
 402
 403 /* Delete a step_resume_breakpoint from the thread database.  */
 404 extern void delete_step_resume_breakpoint (struct thread_info *);
 405
 406 /* Delete an exception_resume_breakpoint from the thread database.  */
 407 extern void delete_exception_resume_breakpoint (struct thread_info *);
 408
 409 /* Delete the single-step breakpoints of thread TP, if any.  */
 410 extern void delete_single_step_breakpoints (struct thread_info *tp);
 411
 412 /* Check if the thread has software single stepping breakpoints
 413    set.  */
 414 extern int thread_has_single_step_breakpoints_set (struct thread_info *tp);
 415
 416 /* Check whether the thread has software single stepping breakpoints
 417    set at PC.  */
 418 extern int thread_has_single_step_breakpoint_here (struct thread_info *tp,
 419                                                    const address_space *aspace,
 420                                                    CORE_ADDR addr);
 421
 422 /* Returns whether to show inferior-qualified thread IDs, or plain
 423    thread numbers.  Inferior-qualified IDs are shown whenever we have
 424    multiple inferiors, or the only inferior left has number > 1.  */
 425 extern int show_inferior_qualified_tids (void);
 426
 427 /* Return a string version of THR's thread ID.  If there are multiple
 428    inferiors, then this prints the inferior-qualifier form, otherwise
 429    it only prints the thread number.  The result is stored in a
 430    circular static buffer, NUMCELLS deep.  */
 431 const char *print_thread_id (struct thread_info *thr);
 432
 433 /* Boolean test for an already-known ptid.  */
 434 extern int in_thread_list (ptid_t ptid);
 435
 436 /* Boolean test for an already-known global thread id (GDB's homegrown
 437    global id, not the system's).  */
 438 extern int valid_global_thread_id (int global_id);
 439
 440 /* Search function to lookup a thread by 'pid'.  */
 441 extern struct thread_info *find_thread_ptid (ptid_t ptid);
 442
 443 /* Find thread by GDB global thread ID.  */
 444 struct thread_info *find_thread_global_id (int global_id);
 445
 446 /* Find thread by thread library specific handle in inferior INF.  */
 447 struct thread_info *find_thread_by_handle (struct value *thread_handle,
 448                                            struct inferior *inf);
 449
 450 /* Finds the first thread of the specified inferior.  */
 451 extern struct thread_info *first_thread_of_inferior (inferior *inf);
 452
 453 /* Returns any thread of inferior INF, giving preference to the
 454    current thread.  */
 455 extern struct thread_info *any_thread_of_inferior (inferior *inf);
 456
 457 /* Returns any non-exited thread of inferior INF, giving preference to
 458    the current thread, and to not executing threads.  */
 459 extern struct thread_info *any_live_thread_of_inferior (inferior *inf);
 460
 461 /* Change the ptid of thread OLD_PTID to NEW_PTID.  */
 462 void thread_change_ptid (ptid_t old_ptid, ptid_t new_ptid);
 463
 464 /* Iterator function to call a user-provided callback function
 465    once for each known thread.  */
 466 typedef int (*thread_callback_func) (struct thread_info *, void *);
 467 extern struct thread_info *iterate_over_threads (thread_callback_func, void *);
 468
 469 /* Traverse all threads.  */
 470 #define ALL_THREADS(T)                          \
 471   for (T = thread_list; T; T = T->next)         \
 472
 473 /* Traverse over all threads, sorted by inferior.  */
 474 #define ALL_THREADS_BY_INFERIOR(inf, tp) \
 475   ALL_INFERIORS (inf) \
 476     ALL_THREADS (tp) \
 477       if (inf == tp->inf)
 478
 479 /* Traverse all threads, except those that have THREAD_EXITED
 480    state.  */
 481
 482 #define ALL_NON_EXITED_THREADS(T)                               \
 483   for (T = thread_list; T; T = T->next) \
 484     if ((T)->state != THREAD_EXITED)
 485
 486 /* Traverse all threads, including those that have THREAD_EXITED
 487    state.  Allows deleting the currently iterated thread.  */
 488 #define ALL_THREADS_SAFE(T, TMP)        \
 489   for ((T) = thread_list;                       \
 490        (T) != NULL ? ((TMP) = (T)->next, 1): 0; \
 491        (T) = (TMP))
 492
 493 extern int thread_count (void);
 494
 495 /* Switch context to thread THR.  Also sets the STOP_PC global.  */
 496 extern void switch_to_thread (struct thread_info *thr);
 497
 498 /* Switch context to no thread selected.  */
 499 extern void switch_to_no_thread ();
 500
 501 /* Switch from one thread to another.  Does not read registers and
 502    sets STOP_PC to -1.  */
 503 extern void switch_to_thread_no_regs (struct thread_info *thread);
 504
 505 /* Marks or clears thread(s) PTID as resumed.  If PTID is
 506    MINUS_ONE_PTID, applies to all threads.  If ptid_is_pid(PTID) is
 507    true, applies to all threads of the process pointed at by PTID.  */
 508 extern void set_resumed (ptid_t ptid, int resumed);
 509
 510 /* Marks thread PTID is running, or stopped.
 511    If PTID is minus_one_ptid, marks all threads.  */
 512 extern void set_running (ptid_t ptid, int running);
 513
 514 /* Marks or clears thread(s) PTID as having been requested to stop.
 515    If PTID is MINUS_ONE_PTID, applies to all threads.  If
 516    ptid_is_pid(PTID) is true, applies to all threads of the process
 517    pointed at by PTID.  If STOP, then the THREAD_STOP_REQUESTED
 518    observer is called with PTID as argument.  */
 519 extern void set_stop_requested (ptid_t ptid, int stop);
 520
 521 /* NOTE: Since the thread state is not a boolean, most times, you do
 522    not want to check it with negation.  If you really want to check if
 523    the thread is stopped,
 524
 525     use (good):
 526
 527      if (is_stopped (ptid))
 528
 529     instead of (bad):
 530
 531      if (!is_running (ptid))
 532
 533    The latter also returns true on exited threads, most likelly not
 534    what you want.  */
 535
 536 /* Reports if in the frontend's perpective, thread PTID is running.  */
 537 extern int is_running (ptid_t ptid);
 538
 539 /* Is this thread listed, but known to have exited?  We keep it listed
 540    (but not visible) until it's safe to delete.  */
 541 extern int is_exited (ptid_t ptid);
 542
 543 /* In the frontend's perpective, is this thread stopped?  */
 544 extern int is_stopped (ptid_t ptid);
 545
 546 /* Marks thread PTID as executing, or not.  If PTID is minus_one_ptid,
 547    marks all threads.
 548
 549    Note that this is different from the running state.  See the
 550    description of state and executing fields of struct
 551    thread_info.  */
 552 extern void set_executing (ptid_t ptid, int executing);
 553
 554 /* True if any (known or unknown) thread is or may be executing.  */
 555 extern int threads_are_executing (void);
 556
 557 /* Merge the executing property of thread PTID over to its thread
 558    state property (frontend running/stopped view).
 559
 560    "not executing" -> "stopped"
 561    "executing"     -> "running"
 562    "exited"        -> "exited"
 563
 564    If PTID is minus_one_ptid, go over all threads.
 565
 566    Notifications are only emitted if the thread state did change.  */
 567 extern void finish_thread_state (ptid_t ptid);
 568
 569 /* Calls finish_thread_state on scope exit, unless release() is called
 570    to disengage.  */
 571 class scoped_finish_thread_state
 572 {
 573 public:
 574   explicit scoped_finish_thread_state (ptid_t ptid)
 575     : m_ptid (ptid)
 576   {}
 577
 578   ~scoped_finish_thread_state ()
 579   {
 580     if (!m_released)
 581       finish_thread_state (m_ptid);
 582   }
 583
 584   /* Disengage.  */
 585   void release ()
 586   {
 587     m_released = true;
 588   }
 589
 590   DISABLE_COPY_AND_ASSIGN (scoped_finish_thread_state);
 591
 592 private:
 593   bool m_released = false;
 594   ptid_t m_ptid;
 595 };
 596
 597 /* Commands with a prefix of `thread'.  */
 598 extern struct cmd_list_element *thread_cmd_list;
 599
 600 extern void thread_command (const char *tidstr, int from_tty);
 601
 602 /* Print notices on thread events (attach, detach, etc.), set with
 603    `set print thread-events'.  */
 604 extern int print_thread_events;
 605
 606 /* Prints the list of threads and their details on UIOUT.  If
 607    REQUESTED_THREADS, a list of GDB ids/ranges, is not NULL, only
 608    print threads whose ID is included in the list.  If PID is not -1,
 609    only print threads from the process PID.  Otherwise, threads from
 610    all attached PIDs are printed.  If both REQUESTED_THREADS is not
 611    NULL and PID is not -1, then the thread is printed if it belongs to
 612    the specified process.  Otherwise, an error is raised.  */
 613 extern void print_thread_info (struct ui_out *uiout, char *requested_threads,
 614                                int pid);
 615
 616 /* Save/restore current inferior/thread/frame.  */
 617
 618 class scoped_restore_current_thread
 619 {
 620 public:
 621   scoped_restore_current_thread ();
 622   ~scoped_restore_current_thread ();
 623
 624   DISABLE_COPY_AND_ASSIGN (scoped_restore_current_thread);
 625
 626 private:
 627   /* Use the "class" keyword here, because of a clash with a "thread_info"
 628      function in the Darwin API.  */
 629   class thread_info *m_thread;
 630   inferior *m_inf;
 631   frame_id m_selected_frame_id;
 632   int m_selected_frame_level;
 633   bool m_was_stopped;
 634 };
 635
 636 /* Returns a pointer into the thread_info corresponding to
 637    INFERIOR_PTID.  INFERIOR_PTID *must* be in the thread list.  */
 638 extern struct thread_info* inferior_thread (void);
 639
 640 extern void update_thread_list (void);
 641
 642 /* Delete any thread the target says is no longer alive.  */
 643
 644 extern void prune_threads (void);
 645
 646 /* Delete threads marked THREAD_EXITED.  Unlike prune_threads, this
 647    does not consult the target about whether the thread is alive right
 648    now.  */
 649 extern void delete_exited_threads (void);
 650
 651 /* Return true if PC is in the stepping range of THREAD.  */
 652
 653 int pc_in_thread_step_range (CORE_ADDR pc, struct thread_info *thread);
 654
 655 /* Enable storing stack temporaries for thread THR and disable and
 656    clear the stack temporaries on destruction.  Holds a strong
 657    reference to THR.  */
 658
 659 class enable_thread_stack_temporaries
 660 {
 661 public:
 662
 663   explicit enable_thread_stack_temporaries (struct thread_info *thr)
 664     : m_thr (thr)
 665   {
 666     gdb_assert (m_thr != NULL);
 667
 668     m_thr->incref ();
 669
 670     m_thr->stack_temporaries_enabled = true;
 671     m_thr->stack_temporaries.clear ();
 672   }
 673
 674   ~enable_thread_stack_temporaries ()
 675   {
 676     m_thr->stack_temporaries_enabled = false;
 677     m_thr->stack_temporaries.clear ();
 678
 679     m_thr->decref ();
 680   }
 681
 682   DISABLE_COPY_AND_ASSIGN (enable_thread_stack_temporaries);
 683
 684 private:
 685
 686   struct thread_info *m_thr;
 687 };
 688
 689 extern bool thread_stack_temporaries_enabled_p (struct thread_info *tp);
 690
 691 extern void push_thread_stack_temporary (struct thread_info *tp, struct value *v);
 692
 693 extern value *get_last_thread_stack_temporary (struct thread_info *tp);
 694
 695 extern bool value_in_thread_stack_temporaries (struct value *,
 696                                                struct thread_info *thr);
 697
 698 /* Add TP to the end of its inferior's pending step-over chain.  */
 699
 700 extern void thread_step_over_chain_enqueue (struct thread_info *tp);
 701
 702 /* Remove TP from its inferior's pending step-over chain.  */
 703
 704 extern void thread_step_over_chain_remove (struct thread_info *tp);
 705
 706 /* Return the next thread in the step-over chain starting at TP.  NULL
 707    if TP is the last entry in the chain.  */
 708
 709 extern struct thread_info *thread_step_over_chain_next (struct thread_info *tp);
 710
 711 /* Return true if TP is in the step-over chain.  */
 712
 713 extern int thread_is_in_step_over_chain (struct thread_info *tp);
 714
 715 /* Cancel any ongoing execution command.  */
 716
 717 extern void thread_cancel_execution_command (struct thread_info *thr);
 718
 719 /* Check whether it makes sense to access a register of the current
 720    thread at this point.  If not, throw an error (e.g., the thread is
 721    executing).  */
 722 extern void validate_registers_access (void);
 723
 724 /* Check whether it makes sense to access a register of THREAD at this point.
 725    Returns true if registers may be accessed; false otherwise.  */
 726 extern bool can_access_registers_thread (struct thread_info *thread);
 727
 728 /* Returns whether to show which thread hit the breakpoint, received a
 729    signal, etc. and ended up causing a user-visible stop.  This is
 730    true iff we ever detected multiple threads.  */
 731 extern int show_thread_that_caused_stop (void);
 732
 733 /* Print the message for a thread or/and frame selected.  */
 734 extern void print_selected_thread_frame (struct ui_out *uiout,
 735                                          user_selected_what selection);
 736
 737 /* Helper for the CLI's "thread" command and for MI's -thread-select.
 738    Selects thread THR.  TIDSTR is the original string the thread ID
 739    was parsed from.  This is used in the error message if THR is not
 740    alive anymore.  */
 741 extern void thread_select (const char *tidstr, class thread_info *thr);
 742
 743 extern struct thread_info *thread_list;
 744
 745 #endif /* GDBTHREAD_H */