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
 225   /* Jump to the containing catch_errors() call, communicating REASON
 226      to that call via setjmp's return value.  Note that REASON can't
 227      be zero, by definition in defs.h. */
 228   exceptions_state_mc (CATCH_THROWING);
 229   *current_catcher->exception = exception;
 230   EXCEPTIONS_SIGLONGJMP (current_catcher->buf, exception.reason);
 231 }
 232
 233 static char *last_message;
 234
 235 NORETURN void
 236 deprecated_throw_reason (enum return_reason reason)
 237 {
 238   struct gdb_exception exception;
 239   memset (&exception, 0, sizeof exception);
 240
 241   exception.reason = reason;
 242   switch (reason)
 243     {
 244     case RETURN_QUIT:
 245       break;
 246     case RETURN_ERROR:
 247       exception.error = GENERIC_ERROR;
 248       break;
 249     default:
 250       internal_error (__FILE__, __LINE__, _("bad switch"));
 251     }
 252
 253   throw_exception (exception);
 254 }
 255
 256 static void
 257 print_flush (void)
 258 {
 259   struct serial *gdb_stdout_serial;
 260
 261   if (deprecated_error_begin_hook)
 262     deprecated_error_begin_hook ();
 263   target_terminal_ours ();
 264
 265   /* We want all output to appear now, before we print the error.  We
 266      have 3 levels of buffering we have to flush (it's possible that
 267      some of these should be changed to flush the lower-level ones
 268      too):  */
 269
 270   /* 1.  The _filtered buffer.  */
 271   wrap_here ("");
 272
 273   /* 2.  The stdio buffer.  */
 274   gdb_flush (gdb_stdout);
 275   gdb_flush (gdb_stderr);
 276
 277   /* 3.  The system-level buffer.  */
 278   gdb_stdout_serial = serial_fdopen (1);
 279   if (gdb_stdout_serial)
 280     {
 281       serial_drain_output (gdb_stdout_serial);
 282       serial_un_fdopen (gdb_stdout_serial);
 283     }
 284
 285   annotate_error_begin ();
 286 }
 287
 288 static void
 289 print_exception (struct ui_file *file, struct gdb_exception e)
 290 {
 291   /* KLUGE: cagney/2005-01-13: Write the string out one line at a time
 292      as that way the MI's behavior is preserved.  */
 293   const char *start;
 294   const char *end;
 295   for (start = e.message; start != NULL; start = end)
 296     {
 297       end = strchr (start, '\n');
 298       if (end == NULL)
 299         fputs_filtered (start, file);
 300       else
 301         {
 302           end++;
 303           ui_file_write (file, start, end - start);
 304         }
 305     }
 306   fprintf_filtered (file, "\n");
 307
 308   /* Now append the annotation.  */
 309   switch (e.reason)
 310     {
 311     case RETURN_QUIT:
 312       annotate_quit ();
 313       break;
 314     case RETURN_ERROR:
 315       /* Assume that these are all errors.  */
 316       annotate_error ();
 317       break;
 318     default:
 319       internal_error (__FILE__, __LINE__, _("Bad switch."));
 320     }
 321 }
 322
 323 void
 324 exception_print (struct ui_file *file, struct gdb_exception e)
 325 {
 326   if (e.reason < 0 && e.message != NULL)
 327     {
 328       print_flush ();
 329       print_exception (file, e);
 330     }
 331 }
 332
 333 void
 334 exception_fprintf (struct ui_file *file, struct gdb_exception e,
 335                    const char *prefix, ...)
 336 {
 337   if (e.reason < 0 && e.message != NULL)
 338     {
 339       va_list args;
 340
 341       print_flush ();
 342
 343       /* Print the prefix.  */
 344       va_start (args, prefix);
 345       vfprintf_filtered (file, prefix, args);
 346       va_end (args);
 347
 348       print_exception (file, e);
 349     }
 350 }
 351
 352 void
 353 print_any_exception (struct ui_file *file, const char *prefix,
 354                      struct gdb_exception e)
 355 {
 356   if (e.reason < 0 && e.message != NULL)
 357     {
 358       target_terminal_ours ();
 359       wrap_here ("");           /* Force out any buffered output */
 360       gdb_flush (gdb_stdout);
 361       annotate_error_begin ();
 362
 363       /* Print the prefix.  */
 364       if (prefix != NULL && prefix[0] != '\0')
 365         fputs_filtered (prefix, file);
 366       print_exception (file, e);
 367     }
 368 }
 369
 370 NORETURN static void ATTR_NORETURN ATTR_FORMAT (printf, 3, 0)
 371 throw_it (enum return_reason reason, enum errors error, const char *fmt,
 372           va_list ap)
 373 {
 374   struct gdb_exception e;
 375   char *new_message;
 376
 377   /* Save the message.  Create the new message before deleting the
 378      old, the new message may include the old message text.  */
 379   new_message = xstrvprintf (fmt, ap);
 380   xfree (last_message);
 381   last_message = new_message;
 382
 383   /* Create the exception.  */
 384   e.reason = reason;
 385   e.error = error;
 386   e.message = last_message;
 387
 388   /* Throw the exception.  */
 389   throw_exception (e);
 390 }
 391
 392 NORETURN void
 393 throw_verror (enum errors error, const char *fmt, va_list ap)
 394 {
 395   throw_it (RETURN_ERROR, error, fmt, ap);
 396 }
 397
 398 NORETURN void
 399 throw_vfatal (const char *fmt, va_list ap)
 400 {
 401   throw_it (RETURN_QUIT, GDB_NO_ERROR, fmt, ap);
 402 }
 403
 404 NORETURN void
 405 throw_error (enum errors error, const char *fmt, ...)
 406 {
 407   va_list args;
 408   va_start (args, fmt);
 409   throw_it (RETURN_ERROR, error, fmt, args);
 410   va_end (args);
 411 }
 412
 413 /* Call FUNC() with args FUNC_UIOUT and FUNC_ARGS, catching any
 414    errors.  Set FUNC_CAUGHT to an ``enum return_reason'' if the
 415    function is aborted (using throw_exception() or zero if the
 416    function returns normally.  Set FUNC_VAL to the value returned by
 417    the function or 0 if the function was aborted.
 418
 419    Must not be called with immediate_quit in effect (bad things might
 420    happen, say we got a signal in the middle of a memcpy to quit_return).
 421    This is an OK restriction; with very few exceptions immediate_quit can
 422    be replaced by judicious use of QUIT.
 423
 424    MASK specifies what to catch; it is normally set to
 425    RETURN_MASK_ALL, if for no other reason than that the code which
 426    calls catch_errors might not be set up to deal with a quit which
 427    isn't caught.  But if the code can deal with it, it generally
 428    should be RETURN_MASK_ERROR, unless for some reason it is more
 429    useful to abort only the portion of the operation inside the
 430    catch_errors.  Note that quit should return to the command line
 431    fairly quickly, even if some further processing is being done.  */
 432
 433 /* MAYBE: cagney/1999-11-05: catch_errors() in conjunction with
 434    error() et.al. could maintain a set of flags that indicate the the
 435    current state of each of the longjmp buffers.  This would give the
 436    longjmp code the chance to detect a longjmp botch (before it gets
 437    to longjmperror()).  Prior to 1999-11-05 this wasn't possible as
 438    code also randomly used a SET_TOP_LEVEL macro that directly
 439    initialize the longjmp buffers. */
 440
 441 /* MAYBE: cagney/1999-11-05: Should the catch_errors and cleanups code
 442    be consolidated into a single file instead of being distributed
 443    between utils.c and top.c? */
 444
 445 int
 446 catch_exceptions (struct ui_out *uiout,
 447                   catch_exceptions_ftype *func,
 448                   void *func_args,
 449                   return_mask mask)
 450 {
 451   return catch_exceptions_with_msg (uiout, func, func_args, NULL, mask);
 452 }
 453
 454 struct gdb_exception
 455 catch_exception (struct ui_out *uiout,
 456                  catch_exception_ftype *func,
 457                  void *func_args,
 458                  return_mask mask)
 459 {
 460   volatile struct gdb_exception exception;
 461   TRY_CATCH (exception, mask)
 462     {
 463       (*func) (uiout, func_args);
 464     }
 465   return exception;
 466 }
 467
 468 int
 469 catch_exceptions_with_msg (struct ui_out *uiout,
 470                            catch_exceptions_ftype *func,
 471                            void *func_args,
 472                            char **gdberrmsg,
 473                            return_mask mask)
 474 {
 475   volatile struct gdb_exception exception;
 476   volatile int val = 0;
 477   TRY_CATCH (exception, mask)
 478     {
 479       val = (*func) (uiout, func_args);
 480     }
 481   print_any_exception (gdb_stderr, NULL, exception);
 482   gdb_assert (val >= 0);
 483   gdb_assert (exception.reason <= 0);
 484   if (exception.reason < 0)
 485     {
 486       /* If caller wants a copy of the low-level error message, make
 487          one.  This is used in the case of a silent error whereby the
 488          caller may optionally want to issue the message.  */
 489       if (gdberrmsg != NULL)
 490         {
 491           if (exception.message != NULL)
 492             *gdberrmsg = xstrdup (exception.message);
 493           else
 494             *gdberrmsg = NULL;
 495         }
 496       return exception.reason;
 497     }
 498   return val;
 499 }
 500
 501 int
 502 catch_errors (catch_errors_ftype *func, void *func_args, char *errstring,
 503               return_mask mask)
 504 {
 505   volatile int val = 0;
 506   volatile struct gdb_exception exception;
 507   TRY_CATCH (exception, mask)
 508     {
 509       val = func (func_args);
 510     }
 511   print_any_exception (gdb_stderr, errstring, exception);
 512   if (exception.reason != 0)
 513     return 0;
 514   return val;
 515 }
 516
 517 int
 518 catch_command_errors (catch_command_errors_ftype * command,
 519                       char *arg, int from_tty, return_mask mask)
 520 {
 521   volatile struct gdb_exception e;
 522   TRY_CATCH (e, mask)
 523     {
 524       command (arg, from_tty);
 525     }
 526   print_any_exception (gdb_stderr, NULL, e);
 527   if (e.reason < 0)
 528     return 0;
 529   return 1;
 530 }