gdb/exceptions.c

   1 /* Exception (throw catch) mechanism, for GDB, the GNU debugger.
   2
   3    Copyright (C) 1986, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996,
   4    1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
   5    Free Software Foundation, Inc.
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  21
  22 #include "defs.h"
  23 #include "exceptions.h"
  24 #include "breakpoint.h"
  25 #include "target.h"
  26 #include "inferior.h"
  27 #include "annotate.h"
  28 #include "ui-out.h"
  29 #include "gdb_assert.h"
  30 #include "gdb_string.h"
  31 #include "serial.h"
  32
  33 const struct gdb_exception exception_none = { 0, GDB_NO_ERROR, NULL };
  34
  35 /* Possible catcher states.  */
  36 enum catcher_state {
  37   /* Initial state, a new catcher has just been created.  */
  38   CATCHER_CREATED,
  39   /* The catch code is running.  */
  40   CATCHER_RUNNING,
  41   CATCHER_RUNNING_1,
  42   /* The catch code threw an exception.  */
  43   CATCHER_ABORTING
  44 };
  45
  46 /* Possible catcher actions.  */
  47 enum catcher_action {
  48   CATCH_ITER,
  49   CATCH_ITER_1,
  50   CATCH_THROWING
  51 };
  52
  53 struct catcher
  54 {
  55   enum catcher_state state;
  56   /* Jump buffer pointing back at the exception handler.  */
  57   EXCEPTIONS_SIGJMP_BUF buf;
  58   /* Status buffer belonging to the exception handler.  */
  59   volatile struct gdb_exception *exception;
  60   /* Saved/current state.  */
  61   int mask;
  62   struct ui_out *saved_uiout;
  63   struct cleanup *saved_cleanup_chain;
  64   /* Back link.  */
  65   struct catcher *prev;
  66 };
  67
  68 /* Where to go for throw_exception().  */
  69 static struct catcher *current_catcher;
  70
  71 EXCEPTIONS_SIGJMP_BUF *
  72 exceptions_state_mc_init (struct ui_out *func_uiout,
  73                           volatile struct gdb_exception *exception,
  74                           return_mask mask)
  75 {
  76   struct catcher *new_catcher = XZALLOC (struct catcher);
  77
  78   /* Start with no exception, save it's address.  */
  79   exception->reason = 0;
  80   exception->error = GDB_NO_ERROR;
  81   exception->message = NULL;
  82   new_catcher->exception = exception;
  83
  84   new_catcher->mask = mask;
  85
  86   /* Override the global ``struct ui_out'' builder.  */
  87   new_catcher->saved_uiout = uiout;
  88   uiout = func_uiout;
  89
  90   /* Prevent error/quit during FUNC from calling cleanups established
  91      prior to here. */
  92   new_catcher->saved_cleanup_chain = save_cleanups ();
  93
  94   /* Push this new catcher on the top.  */
  95   new_catcher->prev = current_catcher;
  96   current_catcher = new_catcher;
  97   new_catcher->state = CATCHER_CREATED;
  98
  99   return &new_catcher->buf;
 100 }
 101
 102 static void
 103 catcher_pop (void)
 104 {
 105   struct catcher *old_catcher = current_catcher;
 106   current_catcher = old_catcher->prev;
 107
 108   /* Restore the cleanup chain, the error/quit messages, and the uiout
 109      builder, to their original states. */
 110
 111   restore_cleanups (old_catcher->saved_cleanup_chain);
 112
 113   uiout = old_catcher->saved_uiout;
 114
 115   xfree (old_catcher);
 116 }
 117
 118 /* Catcher state machine.  Returns non-zero if the m/c should be run
 119    again, zero if it should abort.  */
 120
 121 static int
 122 exceptions_state_mc (enum catcher_action action)
 123 {
 124   switch (current_catcher->state)
 125     {
 126     case CATCHER_CREATED:
 127       switch (action)
 128         {
 129         case CATCH_ITER:
 130           /* Allow the code to run the catcher.  */
 131           current_catcher->state = CATCHER_RUNNING;
 132           return 1;
 133         default:
 134           internal_error (__FILE__, __LINE__, _("bad state"));
 135         }
 136     case CATCHER_RUNNING:
 137       switch (action)
 138         {
 139         case CATCH_ITER:
 140           /* No error/quit has occured.  Just clean up.  */
 141           catcher_pop ();
 142           return 0;
 143         case CATCH_ITER_1:
 144           current_catcher->state = CATCHER_RUNNING_1;
 145           return 1;
 146         case CATCH_THROWING:
 147           current_catcher->state = CATCHER_ABORTING;
 148           /* See also throw_exception.  */
 149           return 1;
 150         default:
 151           internal_error (__FILE__, __LINE__, _("bad switch"));
 152         }
 153     case CATCHER_RUNNING_1:
 154       switch (action)
 155         {
 156         case CATCH_ITER:
 157           /* The did a "break" from the inner while loop.  */
 158           catcher_pop ();
 159           return 0;
 160         case CATCH_ITER_1:
 161           current_catcher->state = CATCHER_RUNNING;
 162           return 0;
 163         case CATCH_THROWING:
 164           current_catcher->state = CATCHER_ABORTING;
 165           /* See also throw_exception.  */
 166           return 1;
 167         default:
 168           internal_error (__FILE__, __LINE__, _("bad switch"));
 169         }
 170     case CATCHER_ABORTING:
 171       switch (action)
 172         {
 173         case CATCH_ITER:
 174           {
 175             struct gdb_exception exception = *current_catcher->exception;
 176             if (current_catcher->mask & RETURN_MASK (exception.reason))
 177               {
 178                 /* Exit normally if this catcher can handle this
 179                    exception.  The caller analyses the func return
 180                    values.  */
 181                 catcher_pop ();
 182                 return 0;
 183               }
 184             /* The caller didn't request that the event be caught,
 185                relay the event to the next containing
 186                catch_errors(). */
 187             catcher_pop ();
 188             throw_exception (exception);
 189           }
 190         default:
 191           internal_error (__FILE__, __LINE__, _("bad state"));
 192         }
 193     default:
 194       internal_error (__FILE__, __LINE__, _("bad switch"));
 195     }
 196 }
 197
 198 int
 199 exceptions_state_mc_action_iter (void)
 200 {
 201   return exceptions_state_mc (CATCH_ITER);
 202 }
 203
 204 int
 205 exceptions_state_mc_action_iter_1 (void)
 206 {
 207   return exceptions_state_mc (CATCH_ITER_1);
 208 }
 209
 210 /* Return EXCEPTION to the nearest containing catch_errors().  */
 211
 212 NORETURN void
 213 throw_exception (struct gdb_exception exception)
 214 {
 215   quit_flag = 0;
 216   immediate_quit = 0;
 217
 218   /* Perhaps it would be cleaner to do this via the cleanup chain (not sure
 219      I can think of a reason why that is vital, though).  */
 220   bpstat_clear_actions (stop_bpstat);   /* Clear queued breakpoint commands */
 221
 222   disable_current_display ();
 223   do_cleanups (ALL_CLEANUPS);
 224   /* When we implement non-stop mode, this should be redone.  If we get
 225      exception in a command pertaining to one thread, or maybe even not
 226      involving inferior at all, we should not do exec cleanups for all
 227      threads.  */
 228   if (target_can_async_p () && !target_executing)
 229     do_exec_cleanups (ALL_CLEANUPS);
 230
 231   /* Jump to the containing catch_errors() call, communicating REASON
 232      to that call via setjmp's return value.  Note that REASON can't
 233      be zero, by definition in defs.h. */
 234   exceptions_state_mc (CATCH_THROWING);
 235   *current_catcher->exception = exception;
 236   EXCEPTIONS_SIGLONGJMP (current_catcher->buf, exception.reason);
 237 }
 238
 239 static char *last_message;
 240
 241 NORETURN void
 242 deprecated_throw_reason (enum return_reason reason)
 243 {
 244   struct gdb_exception exception;
 245   memset (&exception, 0, sizeof exception);
 246
 247   exception.reason = reason;
 248   switch (reason)
 249     {
 250     case RETURN_QUIT:
 251       break;
 252     case RETURN_ERROR:
 253       exception.error = GENERIC_ERROR;
 254       break;
 255     default:
 256       internal_error (__FILE__, __LINE__, _("bad switch"));
 257     }
 258
 259   throw_exception (exception);
 260 }
 261
 262 static void
 263 print_flush (void)
 264 {
 265   struct serial *gdb_stdout_serial;
 266
 267   if (deprecated_error_begin_hook)
 268     deprecated_error_begin_hook ();
 269   target_terminal_ours ();
 270
 271   /* We want all output to appear now, before we print the error.  We
 272      have 3 levels of buffering we have to flush (it's possible that
 273      some of these should be changed to flush the lower-level ones
 274      too):  */
 275
 276   /* 1.  The _filtered buffer.  */
 277   wrap_here ("");
 278
 279   /* 2.  The stdio buffer.  */
 280   gdb_flush (gdb_stdout);
 281   gdb_flush (gdb_stderr);
 282
 283   /* 3.  The system-level buffer.  */
 284   gdb_stdout_serial = serial_fdopen (1);
 285   if (gdb_stdout_serial)
 286     {
 287       serial_drain_output (gdb_stdout_serial);
 288       serial_un_fdopen (gdb_stdout_serial);
 289     }
 290
 291   annotate_error_begin ();
 292 }
 293
 294 static void
 295 print_exception (struct ui_file *file, struct gdb_exception e)
 296 {
 297   /* KLUGE: cagney/2005-01-13: Write the string out one line at a time
 298      as that way the MI's behavior is preserved.  */
 299   const char *start;
 300   const char *end;
 301   for (start = e.message; start != NULL; start = end)
 302     {
 303       end = strchr (start, '\n');
 304       if (end == NULL)
 305         fputs_filtered (start, file);
 306       else
 307         {
 308           end++;
 309           ui_file_write (file, start, end - start);
 310         }
 311     }
 312   fprintf_filtered (file, "\n");
 313
 314   /* Now append the annotation.  */
 315   switch (e.reason)
 316     {
 317     case RETURN_QUIT:
 318       annotate_quit ();
 319       break;
 320     case RETURN_ERROR:
 321       /* Assume that these are all errors.  */
 322       annotate_error ();
 323       break;
 324     default:
 325       internal_error (__FILE__, __LINE__, _("Bad switch."));
 326     }
 327 }
 328
 329 void
 330 exception_print (struct ui_file *file, struct gdb_exception e)
 331 {
 332   if (e.reason < 0 && e.message != NULL)
 333     {
 334       print_flush ();
 335       print_exception (file, e);
 336     }
 337 }
 338
 339 void
 340 exception_fprintf (struct ui_file *file, struct gdb_exception e,
 341                    const char *prefix, ...)
 342 {
 343   if (e.reason < 0 && e.message != NULL)
 344     {
 345       va_list args;
 346
 347       print_flush ();
 348
 349       /* Print the prefix.  */
 350       va_start (args, prefix);
 351       vfprintf_filtered (file, prefix, args);
 352       va_end (args);
 353
 354       print_exception (file, e);
 355     }
 356 }
 357
 358 void
 359 print_any_exception (struct ui_file *file, const char *prefix,
 360                      struct gdb_exception e)
 361 {
 362   if (e.reason < 0 && e.message != NULL)
 363     {
 364       target_terminal_ours ();
 365       wrap_here ("");           /* Force out any buffered output */
 366       gdb_flush (gdb_stdout);
 367       annotate_error_begin ();
 368
 369       /* Print the prefix.  */
 370       if (prefix != NULL && prefix[0] != '\0')
 371         fputs_filtered (prefix, file);
 372       print_exception (file, e);
 373     }
 374 }
 375
 376 NORETURN static void ATTR_NORETURN ATTR_FORMAT (printf, 3, 0)
 377 throw_it (enum return_reason reason, enum errors error, const char *fmt,
 378           va_list ap)
 379 {
 380   struct gdb_exception e;
 381   char *new_message;
 382
 383   /* Save the message.  Create the new message before deleting the
 384      old, the new message may include the old message text.  */
 385   new_message = xstrvprintf (fmt, ap);
 386   xfree (last_message);
 387   last_message = new_message;
 388
 389   /* Create the exception.  */
 390   e.reason = reason;
 391   e.error = error;
 392   e.message = last_message;
 393
 394   /* Throw the exception.  */
 395   throw_exception (e);
 396 }
 397
 398 NORETURN void
 399 throw_verror (enum errors error, const char *fmt, va_list ap)
 400 {
 401   throw_it (RETURN_ERROR, error, fmt, ap);
 402 }
 403
 404 NORETURN void
 405 throw_vfatal (const char *fmt, va_list ap)
 406 {
 407   throw_it (RETURN_QUIT, GDB_NO_ERROR, fmt, ap);
 408 }
 409
 410 NORETURN void
 411 throw_error (enum errors error, const char *fmt, ...)
 412 {
 413   va_list args;
 414   va_start (args, fmt);
 415   throw_it (RETURN_ERROR, error, fmt, args);
 416   va_end (args);
 417 }
 418
 419 /* Call FUNC() with args FUNC_UIOUT and FUNC_ARGS, catching any
 420    errors.  Set FUNC_CAUGHT to an ``enum return_reason'' if the
 421    function is aborted (using throw_exception() or zero if the
 422    function returns normally.  Set FUNC_VAL to the value returned by
 423    the function or 0 if the function was aborted.
 424
 425    Must not be called with immediate_quit in effect (bad things might
 426    happen, say we got a signal in the middle of a memcpy to quit_return).
 427    This is an OK restriction; with very few exceptions immediate_quit can
 428    be replaced by judicious use of QUIT.
 429
 430    MASK specifies what to catch; it is normally set to
 431    RETURN_MASK_ALL, if for no other reason than that the code which
 432    calls catch_errors might not be set up to deal with a quit which
 433    isn't caught.  But if the code can deal with it, it generally
 434    should be RETURN_MASK_ERROR, unless for some reason it is more
 435    useful to abort only the portion of the operation inside the
 436    catch_errors.  Note that quit should return to the command line
 437    fairly quickly, even if some further processing is being done.  */
 438
 439 /* MAYBE: cagney/1999-11-05: catch_errors() in conjunction with
 440    error() et.al. could maintain a set of flags that indicate the the
 441    current state of each of the longjmp buffers.  This would give the
 442    longjmp code the chance to detect a longjmp botch (before it gets
 443    to longjmperror()).  Prior to 1999-11-05 this wasn't possible as
 444    code also randomly used a SET_TOP_LEVEL macro that directly
 445    initialize the longjmp buffers. */
 446
 447 /* MAYBE: cagney/1999-11-05: Should the catch_errors and cleanups code
 448    be consolidated into a single file instead of being distributed
 449    between utils.c and top.c? */
 450
 451 int
 452 catch_exceptions (struct ui_out *uiout,
 453                   catch_exceptions_ftype *func,
 454                   void *func_args,
 455                   return_mask mask)
 456 {
 457   return catch_exceptions_with_msg (uiout, func, func_args, NULL, mask);
 458 }
 459
 460 struct gdb_exception
 461 catch_exception (struct ui_out *uiout,
 462                  catch_exception_ftype *func,
 463                  void *func_args,
 464                  return_mask mask)
 465 {
 466   volatile struct gdb_exception exception;
 467   TRY_CATCH (exception, mask)
 468     {
 469       (*func) (uiout, func_args);
 470     }
 471   return exception;
 472 }
 473
 474 int
 475 catch_exceptions_with_msg (struct ui_out *uiout,
 476                            catch_exceptions_ftype *func,
 477                            void *func_args,
 478                            char **gdberrmsg,
 479                            return_mask mask)
 480 {
 481   volatile struct gdb_exception exception;
 482   volatile int val = 0;
 483   TRY_CATCH (exception, mask)
 484     {
 485       val = (*func) (uiout, func_args);
 486     }
 487   print_any_exception (gdb_stderr, NULL, exception);
 488   gdb_assert (val >= 0);
 489   gdb_assert (exception.reason <= 0);
 490   if (exception.reason < 0)
 491     {
 492       /* If caller wants a copy of the low-level error message, make
 493          one.  This is used in the case of a silent error whereby the
 494          caller may optionally want to issue the message.  */
 495       if (gdberrmsg != NULL)
 496         {
 497           if (exception.message != NULL)
 498             *gdberrmsg = xstrdup (exception.message);
 499           else
 500             *gdberrmsg = NULL;
 501         }
 502       return exception.reason;
 503     }
 504   return val;
 505 }
 506
 507 int
 508 catch_errors (catch_errors_ftype *func, void *func_args, char *errstring,
 509               return_mask mask)
 510 {
 511   volatile int val = 0;
 512   volatile struct gdb_exception exception;
 513   TRY_CATCH (exception, mask)
 514     {
 515       val = func (func_args);
 516     }
 517   print_any_exception (gdb_stderr, errstring, exception);
 518   if (exception.reason != 0)
 519     return 0;
 520   return val;
 521 }
 522
 523 int
 524 catch_command_errors (catch_command_errors_ftype * command,
 525                       char *arg, int from_tty, return_mask mask)
 526 {
 527   volatile struct gdb_exception e;
 528   TRY_CATCH (e, mask)
 529     {
 530       command (arg, from_tty);
 531     }
 532   print_any_exception (gdb_stderr, NULL, e);
 533   if (e.reason < 0)
 534     return 0;
 535   return 1;
 536 }