gdb/continuations.c

   1 /* Continuations for GDB, the GNU debugger.
   2
   3    Copyright (C) 1986-2013 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 "gdbthread.h"
  22 #include "inferior.h"
  23 #include "continuations.h"
  24
  25 struct continuation
  26 {
  27   struct continuation *next;
  28   continuation_ftype *function;
  29   continuation_free_arg_ftype *free_arg;
  30   void *arg;
  31 };
  32
  33 /* Add a new continuation to the continuation chain.  Args are
  34    FUNCTION to run the continuation up with, and ARG to pass to
  35    it.  */
  36
  37 static void
  38 make_continuation (struct continuation **pmy_chain,
  39                    continuation_ftype *function,
  40                    void *arg,  void (*free_arg) (void *))
  41 {
  42   struct continuation *new = XNEW (struct continuation);
  43
  44   new->next = *pmy_chain;
  45   new->function = function;
  46   new->free_arg = free_arg;
  47   new->arg = arg;
  48   *pmy_chain = new;
  49 }
  50
  51 static void
  52 do_my_continuations_1 (struct continuation **pmy_chain, int err)
  53 {
  54   struct continuation *ptr;
  55
  56   while ((ptr = *pmy_chain) != NULL)
  57     {
  58       *pmy_chain = ptr->next;   /* Do this first in case of recursion.  */
  59       (*ptr->function) (ptr->arg, err);
  60       if (ptr->free_arg)
  61         (*ptr->free_arg) (ptr->arg);
  62       xfree (ptr);
  63     }
  64 }
  65
  66 static void
  67 do_my_continuations (struct continuation **list, int err)
  68 {
  69   struct continuation *continuations;
  70
  71   if (*list == NULL)
  72     return;
  73
  74   /* Copy the list header into another pointer, and set the global
  75      list header to null, so that the global list can change as a side
  76      effect of invoking the continuations and the processing of the
  77      preexisting continuations will not be affected.  */
  78
  79   continuations = *list;
  80   *list = NULL;
  81
  82   /* Work now on the list we have set aside.  */
  83   do_my_continuations_1 (&continuations, err);
  84 }
  85
  86 static void
  87 discard_my_continuations_1 (struct continuation **pmy_chain)
  88 {
  89   struct continuation *ptr;
  90
  91   while ((ptr = *pmy_chain) != NULL)
  92     {
  93       *pmy_chain = ptr->next;
  94       if (ptr->free_arg)
  95         (*ptr->free_arg) (ptr->arg);
  96       xfree (ptr);
  97     }
  98 }
  99
 100 static void
 101 discard_my_continuations (struct continuation **list)
 102 {
 103   struct continuation *continuation_ptr = *list;
 104
 105   discard_my_continuations_1 (list);
 106   *list = NULL;
 107 }
 108
 109 /* Add a continuation to the continuation list of INFERIOR.  The new
 110    continuation will be added at the front.  */
 111
 112 void
 113 add_inferior_continuation (continuation_ftype *hook, void *args,
 114                            continuation_free_arg_ftype *free_arg)
 115 {
 116   struct inferior *inf = current_inferior ();
 117
 118   make_continuation (&inf->continuations, hook, args, free_arg);
 119 }
 120
 121 /* Do all continuations of the current inferior.  */
 122
 123 void
 124 do_all_inferior_continuations (int err)
 125 {
 126   struct inferior *inf = current_inferior ();
 127   do_my_continuations (&inf->continuations, err);
 128 }
 129
 130 /* Get rid of all the inferior-wide continuations of INF.  */
 131
 132 void
 133 discard_all_inferior_continuations (struct inferior *inf)
 134 {
 135   discard_my_continuations (&inf->continuations);
 136 }
 137
 138 /* Add a continuation to the continuation list of THREAD.  The new
 139    continuation will be added at the front.  */
 140
 141 void
 142 add_continuation (struct thread_info *thread,
 143                   continuation_ftype *hook, void *args,
 144                   continuation_free_arg_ftype *free_arg)
 145 {
 146   make_continuation (&thread->continuations, hook, args, free_arg);
 147 }
 148
 149 static void
 150 restore_thread_cleanup (void *arg)
 151 {
 152   ptid_t *ptid_p = arg;
 153
 154   switch_to_thread (*ptid_p);
 155 }
 156
 157 /* Walk down the continuation list of PTID, and execute all the
 158    continuations.  There is a problem though.  In some cases new
 159    continuations may be added while we are in the middle of this loop.
 160    If this happens they will be added in the front, and done before we
 161    have a chance of exhausting those that were already there.  We need
 162    to then save the beginning of the list in a pointer and do the
 163    continuations from there on, instead of using the global beginning
 164    of list as our iteration pointer.  */
 165
 166 static void
 167 do_all_continuations_ptid (ptid_t ptid,
 168                            struct continuation **continuations_p,
 169                            int err)
 170 {
 171   struct cleanup *old_chain;
 172   ptid_t current_thread;
 173
 174   if (*continuations_p == NULL)
 175     return;
 176
 177   current_thread = inferior_ptid;
 178
 179   /* Restore selected thread on exit.  Don't try to restore the frame
 180      as well, because:
 181
 182      - When running continuations, the selected frame is always #0.
 183
 184      - The continuations may trigger symbol file loads, which may
 185      change the frame layout (frame ids change), which would trigger
 186      a warning if we used make_cleanup_restore_current_thread.  */
 187
 188   old_chain = make_cleanup (restore_thread_cleanup, &current_thread);
 189
 190   /* Let the continuation see this thread as selected.  */
 191   switch_to_thread (ptid);
 192
 193   do_my_continuations (continuations_p, err);
 194
 195   do_cleanups (old_chain);
 196 }
 197
 198 /* Callback for iterate over threads.  */
 199
 200 static int
 201 do_all_continuations_thread_callback (struct thread_info *thread, void *data)
 202 {
 203   int err = * (int *) data;
 204   do_all_continuations_ptid (thread->ptid, &thread->continuations, err);
 205   return 0;
 206 }
 207
 208 /* Do all continuations of thread THREAD.  */
 209
 210 void
 211 do_all_continuations_thread (struct thread_info *thread, int err)
 212 {
 213   do_all_continuations_thread_callback (thread, &err);
 214 }
 215
 216 /* Do all continuations of all threads.  */
 217
 218 void
 219 do_all_continuations (int err)
 220 {
 221   iterate_over_threads (do_all_continuations_thread_callback, &err);
 222 }
 223
 224 /* Callback for iterate over threads.  */
 225
 226 static int
 227 discard_all_continuations_thread_callback (struct thread_info *thread,
 228                                            void *data)
 229 {
 230   discard_my_continuations (&thread->continuations);
 231   return 0;
 232 }
 233
 234 /* Get rid of all the continuations of THREAD.  */
 235
 236 void
 237 discard_all_continuations_thread (struct thread_info *thread)
 238 {
 239   discard_all_continuations_thread_callback (thread, NULL);
 240 }
 241
 242 /* Get rid of all the continuations of all threads.  */
 243
 244 void
 245 discard_all_continuations (void)
 246 {
 247   iterate_over_threads (discard_all_continuations_thread_callback, NULL);
 248 }
 249
 250
 251 /* Add a continuation to the intermediate continuation list of THREAD.
 252    The new continuation will be added at the front.  */
 253
 254 void
 255 add_intermediate_continuation (struct thread_info *thread,
 256                                continuation_ftype *hook,
 257                                void *args,
 258                                continuation_free_arg_ftype *free_arg)
 259 {
 260   make_continuation (&thread->intermediate_continuations, hook,
 261                      args, free_arg);
 262 }
 263
 264 /* Walk down the cmd_continuation list, and execute all the
 265    continuations.  There is a problem though.  In some cases new
 266    continuations may be added while we are in the middle of this
 267    loop.  If this happens they will be added in the front, and done
 268    before we have a chance of exhausting those that were already
 269    there.  We need to then save the beginning of the list in a pointer
 270    and do the continuations from there on, instead of using the
 271    global beginning of list as our iteration pointer.  */
 272
 273 static int
 274 do_all_intermediate_continuations_thread_callback (struct thread_info *thread,
 275                                                    void *data)
 276 {
 277   int err = * (int *) data;
 278
 279   do_all_continuations_ptid (thread->ptid,
 280                              &thread->intermediate_continuations, err);
 281   return 0;
 282 }
 283
 284 /* Do all intermediate continuations of thread THREAD.  */
 285
 286 void
 287 do_all_intermediate_continuations_thread (struct thread_info *thread, int err)
 288 {
 289   do_all_intermediate_continuations_thread_callback (thread, &err);
 290 }
 291
 292 /* Do all intermediate continuations of all threads.  */
 293
 294 void
 295 do_all_intermediate_continuations (int err)
 296 {
 297   iterate_over_threads (do_all_intermediate_continuations_thread_callback,
 298                         &err);
 299 }
 300
 301 /* Callback for iterate over threads.  */
 302
 303 static int
 304 discard_all_intermediate_continuations_thread_callback (struct thread_info *thread,
 305                                                         void *data)
 306 {
 307   discard_my_continuations (&thread->intermediate_continuations);
 308   return 0;
 309 }
 310
 311 /* Get rid of all the intermediate continuations of THREAD.  */
 312
 313 void
 314 discard_all_intermediate_continuations_thread (struct thread_info *thread)
 315 {
 316   discard_all_intermediate_continuations_thread_callback (thread, NULL);
 317 }
 318
 319 /* Get rid of all the intermediate continuations of all threads.  */
 320
 321 void
 322 discard_all_intermediate_continuations (void)
 323 {
 324   iterate_over_threads (discard_all_intermediate_continuations_thread_callback,
 325                         NULL);
 326 }