1 /* Exception (throw catch) mechanism, for GDB, the GNU debugger.
3 Copyright 1986, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995,
4 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005 Free
5 Software Foundation, Inc.
7 This file is part of GDB.
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 2 of the License, or
12 (at your option) any later version.
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.
19 You should have received a copy of the GNU General Public License
20 along with this program; if not, write to the Free Software
21 Foundation, Inc., 59 Temple Place - Suite 330,
22 Boston, MA 02111-1307, USA. */
25 #include "exceptions.h"
27 #include "breakpoint.h"
32 #include "gdb_assert.h"
33 #include "gdb_string.h"
35 const struct exception exception_none = { 0, NO_ERROR, NULL };
37 /* One should use catch_errors rather than manipulating these
39 #if defined(HAVE_SIGSETJMP)
40 #define SIGJMP_BUF sigjmp_buf
41 #define SIGSETJMP(buf) sigsetjmp((buf), 1)
42 #define SIGLONGJMP(buf,val) siglongjmp((buf), (val))
44 #define SIGJMP_BUF jmp_buf
45 #define SIGSETJMP(buf) setjmp(buf)
46 #define SIGLONGJMP(buf,val) longjmp((buf), (val))
49 /* Possible catcher states. */
51 /* Initial state, a new catcher has just been created. */
53 /* The catch code is running. */
56 /* The catch code threw an exception. */
60 /* Possible catcher actions. */
69 enum catcher_state state;
70 /* Jump buffer pointing back at the exception handler. */
72 /* Status buffer belonging to the exception handler. */
73 volatile struct exception *exception;
74 /* Should the error / quit message be printed? Old code assumes
75 that this file prints the error/quit message when first reported.
76 New code instead directly handles the printing of error/quit
79 /* Saved/current state. */
81 char *saved_error_pre_print;
82 char *saved_quit_pre_print;
83 struct ui_out *saved_uiout;
84 struct cleanup *saved_cleanup_chain;
89 /* Where to go for throw_exception(). */
90 static struct catcher *current_catcher;
93 catcher_init (struct ui_out *func_uiout,
95 volatile struct exception *exception,
99 struct catcher *new_catcher = XZALLOC (struct catcher);
101 /* Start with no exception, save it's address. */
102 exception->reason = 0;
103 exception->error = NO_ERROR;
104 exception->message = NULL;
105 new_catcher->exception = exception;
107 new_catcher->mask = mask;
108 new_catcher->print_message = print_message;
110 /* Override error/quit messages during FUNC. */
111 new_catcher->saved_error_pre_print = error_pre_print;
112 new_catcher->saved_quit_pre_print = quit_pre_print;
113 if (mask & RETURN_MASK_ERROR)
114 error_pre_print = errstring;
115 if (mask & RETURN_MASK_QUIT)
116 quit_pre_print = errstring;
118 /* Override the global ``struct ui_out'' builder. */
119 new_catcher->saved_uiout = uiout;
122 /* Prevent error/quit during FUNC from calling cleanups established
124 new_catcher->saved_cleanup_chain = save_cleanups ();
126 /* Push this new catcher on the top. */
127 new_catcher->prev = current_catcher;
128 current_catcher = new_catcher;
129 new_catcher->state = CATCHER_CREATED;
131 return &new_catcher->buf;
137 struct catcher *old_catcher = current_catcher;
138 current_catcher = old_catcher->prev;
140 /* Restore the cleanup chain, the error/quit messages, and the uiout
141 builder, to their original states. */
143 restore_cleanups (old_catcher->saved_cleanup_chain);
145 uiout = old_catcher->saved_uiout;
147 quit_pre_print = old_catcher->saved_quit_pre_print;
148 error_pre_print = old_catcher->saved_error_pre_print;
153 /* Catcher state machine. Returns non-zero if the m/c should be run
154 again, zero if it should abort. */
157 catcher_state_machine (enum catcher_action action)
159 switch (current_catcher->state)
161 case CATCHER_CREATED:
165 /* Allow the code to run the catcher. */
166 current_catcher->state = CATCHER_RUNNING;
169 internal_error (__FILE__, __LINE__, "bad state");
171 case CATCHER_RUNNING:
175 /* No error/quit has occured. Just clean up. */
179 current_catcher->state = CATCHER_RUNNING_1;
182 current_catcher->state = CATCHER_ABORTING;
183 /* See also throw_exception. */
186 internal_error (__FILE__, __LINE__, "bad switch");
188 case CATCHER_RUNNING_1:
192 /* The did a "break" from the inner while loop. */
196 current_catcher->state = CATCHER_RUNNING;
199 current_catcher->state = CATCHER_ABORTING;
200 /* See also throw_exception. */
203 internal_error (__FILE__, __LINE__, "bad switch");
205 case CATCHER_ABORTING:
210 struct exception exception = *current_catcher->exception;
211 if (current_catcher->mask & RETURN_MASK (exception.reason))
213 /* Exit normally if this catcher can handle this
214 exception. The caller analyses the func return
219 /* The caller didn't request that the event be caught,
220 relay the event to the next containing
223 throw_exception (exception);
226 internal_error (__FILE__, __LINE__, "bad state");
229 internal_error (__FILE__, __LINE__, "bad switch");
233 /* Return EXCEPTION to the nearest containing catch_errors(). */
236 throw_exception (struct exception exception)
241 /* Perhaps it would be cleaner to do this via the cleanup chain (not sure
242 I can think of a reason why that is vital, though). */
243 bpstat_clear_actions (stop_bpstat); /* Clear queued breakpoint commands */
245 disable_current_display ();
246 do_cleanups (ALL_CLEANUPS);
247 if (target_can_async_p () && !target_executing)
248 do_exec_cleanups (ALL_CLEANUPS);
250 do_exec_error_cleanups (ALL_CLEANUPS);
252 /* Jump to the containing catch_errors() call, communicating REASON
253 to that call via setjmp's return value. Note that REASON can't
254 be zero, by definition in defs.h. */
255 catcher_state_machine (CATCH_THROWING);
256 *current_catcher->exception = exception;
257 SIGLONGJMP (current_catcher->buf, exception.reason);
260 static char *last_message;
263 throw_reason (enum return_reason reason)
265 struct exception exception;
266 memset (&exception, 0, sizeof exception);
268 exception.reason = reason;
274 exception.error = GENERIC_ERROR;
277 internal_error (__FILE__, __LINE__, "bad switch");
280 throw_exception (exception);
286 if (deprecated_error_begin_hook)
287 deprecated_error_begin_hook ();
288 target_terminal_ours ();
289 wrap_here (""); /* Force out any buffered output */
290 gdb_flush (gdb_stdout);
291 annotate_error_begin ();
295 print_exception (struct ui_file *file, struct exception e)
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. */
301 for (start = e.message; start != NULL; start = end)
303 end = strchr (start, '\n');
305 fputs_filtered (start, file);
309 ui_file_write (file, start, end - start);
312 fprintf_filtered (file, "\n");
314 /* Now append the annotation. */
321 /* Assume that these are all errors. */
325 internal_error (__FILE__, __LINE__, _("Bad switch."));
330 exception_print (struct ui_file *file, struct exception e)
332 if (e.reason < 0 && e.message != NULL)
335 print_exception (file, e);
340 exception_fprintf (struct ui_file *file, struct exception e,
341 const char *prefix, ...)
343 if (e.reason < 0 && e.message != NULL)
349 /* Print the prefix. */
350 va_start (args, prefix);
351 vfprintf_filtered (file, prefix, args);
354 print_exception (file, e);
359 print_any_exception (struct ui_file *file, const char *prefix,
362 if (e.reason < 0 && e.message != NULL)
364 target_terminal_ours ();
365 wrap_here (""); /* Force out any buffered output */
366 gdb_flush (gdb_stdout);
367 annotate_error_begin ();
369 /* Print the prefix. */
370 if (prefix != NULL && prefix[0] != '\0')
371 fputs_filtered (prefix, file);
372 print_exception (file, e);
377 throw_it (enum return_reason reason, enum errors error, const char *prefix,
378 const char *fmt, va_list ap) ATTR_NORETURN;
380 throw_it (enum return_reason reason, enum errors error, const char *prefix,
381 const char *fmt, va_list ap)
385 /* Save the message. */
386 xfree (last_message);
387 last_message = xstrvprintf (fmt, ap);
389 /* Create the exception. */
392 e.message = last_message;
394 /* Throw the exception. */
399 throw_verror (enum errors error, const char *fmt, va_list ap)
401 throw_it (RETURN_ERROR, error, error_pre_print, fmt, ap);
405 throw_vfatal (const char *fmt, va_list ap)
407 throw_it (RETURN_QUIT, NO_ERROR, quit_pre_print, fmt, ap);
411 throw_error (enum errors error, const char *fmt, ...)
414 va_start (args, fmt);
415 throw_it (RETURN_ERROR, error, error_pre_print, fmt, args);
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.
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.
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. */
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. */
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? */
452 catch_exceptions (struct ui_out *uiout,
453 catch_exceptions_ftype *func,
457 return catch_exceptions_with_msg (uiout, func, func_args, NULL, mask);
461 catch_exception (struct ui_out *uiout,
462 catch_exception_ftype *func,
466 volatile struct exception exception;
468 catch = catcher_init (uiout, NULL, &exception, mask, 0);
469 for (SIGSETJMP ((*catch));
470 catcher_state_machine (CATCH_ITER);)
471 (*func) (uiout, func_args);
476 catch_exceptions_with_msg (struct ui_out *uiout,
477 catch_exceptions_ftype *func,
482 volatile struct exception exception;
483 volatile int val = 0;
484 SIGJMP_BUF *catch = catcher_init (uiout, NULL, &exception, mask, 1);
485 for (SIGSETJMP ((*catch)); catcher_state_machine (CATCH_ITER);)
486 val = (*func) (uiout, func_args);
487 print_any_exception (gdb_stderr, NULL, exception);
488 gdb_assert (val >= 0);
489 gdb_assert (exception.reason <= 0);
490 if (exception.reason < 0)
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)
497 if (exception.message != NULL)
498 *gdberrmsg = xstrdup (exception.message);
502 return exception.reason;
508 catch_errors (catch_errors_ftype *func, void *func_args, char *errstring,
511 volatile int val = 0;
512 volatile struct exception exception;
513 SIGJMP_BUF *catch = catcher_init (uiout, errstring, &exception, mask, 1);
514 /* This illustrates how it is possible to nest the mechanism and
515 hence catch "break". Of course this doesn't address the need to
516 also catch "return". */
517 for (SIGSETJMP ((*catch)); catcher_state_machine (CATCH_ITER);)
518 val = func (func_args);
519 print_any_exception (gdb_stderr, errstring, exception);
520 if (exception.reason != 0)
525 struct captured_command_args
527 catch_command_errors_ftype *command;
533 do_captured_command (void *data)
535 struct captured_command_args *context = data;
536 context->command (context->arg, context->from_tty);
537 /* FIXME: cagney/1999-11-07: Technically this do_cleanups() call
538 isn't needed. Instead an assertion check could be made that
539 simply confirmed that the called function correctly cleaned up
540 after itself. Unfortunately, old code (prior to 1999-11-04) in
541 main.c was calling SET_TOP_LEVEL(), calling the command function,
542 and then *always* calling do_cleanups(). For the moment we
543 remain ``bug compatible'' with that old code.. */
544 do_cleanups (ALL_CLEANUPS);
549 catch_command_errors (catch_command_errors_ftype * command,
550 char *arg, int from_tty, return_mask mask)
552 struct captured_command_args args;
553 args.command = command;
555 args.from_tty = from_tty;
556 return catch_errors (do_captured_command, &args, "", mask);