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 Free Software
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 that exception handler. */
73 volatile struct exception
*exception
;
74 /* Saved/current state. */
76 char *saved_error_pre_print
;
77 char *saved_quit_pre_print
;
78 struct ui_out
*saved_uiout
;
79 struct cleanup
*saved_cleanup_chain
;
84 /* Where to go for throw_exception(). */
85 static struct catcher
*current_catcher
;
88 catcher_init (struct ui_out
*func_uiout
,
90 volatile struct exception
*exception
,
93 struct catcher
*new_catcher
= XZALLOC (struct catcher
);
95 /* Start with no exception, save it's address. */
96 exception
->reason
= 0;
97 exception
->error
= NO_ERROR
;
98 exception
->message
= NULL
;
99 new_catcher
->exception
= exception
;
101 new_catcher
->mask
= mask
;
103 /* Override error/quit messages during FUNC. */
104 new_catcher
->saved_error_pre_print
= error_pre_print
;
105 new_catcher
->saved_quit_pre_print
= quit_pre_print
;
106 if (mask
& RETURN_MASK_ERROR
)
107 error_pre_print
= errstring
;
108 if (mask
& RETURN_MASK_QUIT
)
109 quit_pre_print
= errstring
;
111 /* Override the global ``struct ui_out'' builder. */
112 new_catcher
->saved_uiout
= uiout
;
115 /* Prevent error/quit during FUNC from calling cleanups established
117 new_catcher
->saved_cleanup_chain
= save_cleanups ();
119 /* Push this new catcher on the top. */
120 new_catcher
->prev
= current_catcher
;
121 current_catcher
= new_catcher
;
122 new_catcher
->state
= CATCHER_CREATED
;
124 return &new_catcher
->buf
;
130 struct catcher
*old_catcher
= current_catcher
;
131 current_catcher
= old_catcher
->prev
;
133 /* Restore the cleanup chain, the error/quit messages, and the uiout
134 builder, to their original states. */
136 restore_cleanups (old_catcher
->saved_cleanup_chain
);
138 uiout
= old_catcher
->saved_uiout
;
140 quit_pre_print
= old_catcher
->saved_quit_pre_print
;
141 error_pre_print
= old_catcher
->saved_error_pre_print
;
146 /* Catcher state machine. Returns non-zero if the m/c should be run
147 again, zero if it should abort. */
150 catcher_state_machine (enum catcher_action action
)
152 switch (current_catcher
->state
)
154 case CATCHER_CREATED
:
158 /* Allow the code to run the catcher. */
159 current_catcher
->state
= CATCHER_RUNNING
;
162 internal_error (__FILE__
, __LINE__
, "bad state");
164 case CATCHER_RUNNING
:
168 /* No error/quit has occured. Just clean up. */
172 current_catcher
->state
= CATCHER_RUNNING_1
;
175 current_catcher
->state
= CATCHER_ABORTING
;
176 /* See also throw_exception. */
179 internal_error (__FILE__
, __LINE__
, "bad switch");
181 case CATCHER_RUNNING_1
:
185 /* The did a "break" from the inner while loop. */
189 current_catcher
->state
= CATCHER_RUNNING
;
192 current_catcher
->state
= CATCHER_ABORTING
;
193 /* See also throw_exception. */
196 internal_error (__FILE__
, __LINE__
, "bad switch");
198 case CATCHER_ABORTING
:
203 struct exception exception
= *current_catcher
->exception
;
204 if (current_catcher
->mask
& RETURN_MASK (exception
.reason
))
206 /* Exit normally if this catcher can handle this
207 exception. The caller analyses the func return
212 /* The caller didn't request that the event be caught,
213 relay the event to the next containing
216 throw_exception (exception
);
219 internal_error (__FILE__
, __LINE__
, "bad state");
222 internal_error (__FILE__
, __LINE__
, "bad switch");
226 /* Return EXCEPTION to the nearest containing catch_errors(). */
229 throw_exception (struct exception exception
)
234 /* Perhaps it would be cleaner to do this via the cleanup chain (not sure
235 I can think of a reason why that is vital, though). */
236 bpstat_clear_actions (stop_bpstat
); /* Clear queued breakpoint commands */
238 disable_current_display ();
239 do_cleanups (ALL_CLEANUPS
);
240 if (target_can_async_p () && !target_executing
)
241 do_exec_cleanups (ALL_CLEANUPS
);
243 do_exec_error_cleanups (ALL_CLEANUPS
);
245 if (annotation_level
> 1)
246 switch (exception
.reason
)
252 /* Assume that these are all errors. */
256 internal_error (__FILE__
, __LINE__
, "Bad switch.");
259 /* Jump to the containing catch_errors() call, communicating REASON
260 to that call via setjmp's return value. Note that REASON can't
261 be zero, by definition in defs.h. */
262 catcher_state_machine (CATCH_THROWING
);
263 *current_catcher
->exception
= exception
;
264 SIGLONGJMP (current_catcher
->buf
, exception
.reason
);
267 static char *last_message
;
270 throw_reason (enum return_reason reason
)
272 struct exception exception
;
273 memset (&exception
, 0, sizeof exception
);
275 exception
.reason
= reason
;
281 exception
.error
= GENERIC_ERROR
;
282 exception
.message
= last_message
;
285 internal_error (__FILE__
, __LINE__
, "bad switch");
288 throw_exception (exception
);
292 do_write (void *data
, const char *buffer
, long length_buffer
)
294 ui_file_write (data
, buffer
, length_buffer
);
299 print_and_throw (enum return_reason reason
, enum errors error
,
300 const char *prefix
, const char *fmt
,
301 va_list ap
) ATTR_NORETURN
;
303 print_and_throw (enum return_reason reason
, enum errors error
,
304 const char *prefix
, const char *fmt
, va_list ap
)
306 /* FIXME: cagney/2005-01-13: While xstrvprintf is simpler it alters
307 GDB's output. Instead of the message being printed
308 line-at-a-time the message comes out all at once. The problem is
309 that the MI testsuite is checks for line-at-a-time messages and
310 changing this behavior means updating the testsuite. */
313 struct ui_file
*tmp_stream
;
316 /* Convert the message into a print stream. */
317 tmp_stream
= mem_fileopen ();
318 make_cleanup_ui_file_delete (tmp_stream
);
319 vfprintf_unfiltered (tmp_stream
, fmt
, ap
);
321 /* Save the message. */
322 xfree (last_message
);
323 last_message
= ui_file_xstrdup (tmp_stream
, &len
);
325 if (deprecated_error_begin_hook
)
326 deprecated_error_begin_hook ();
328 /* Write the message plus any pre_print to gdb_stderr. */
329 target_terminal_ours ();
330 wrap_here (""); /* Force out any buffered output */
331 gdb_flush (gdb_stdout
);
332 annotate_error_begin ();
334 fputs_filtered (error_pre_print
, gdb_stderr
);
335 ui_file_put (tmp_stream
, do_write
, gdb_stderr
);
336 fprintf_filtered (gdb_stderr
, "\n");
338 /* Throw the exception. */
341 e
.message
= last_message
;
346 throw_verror (enum errors error
, const char *fmt
, va_list ap
)
348 print_and_throw (RETURN_ERROR
, error
, error_pre_print
, fmt
, ap
);
352 throw_vfatal (const char *fmt
, va_list ap
)
354 print_and_throw (RETURN_QUIT
, NO_ERROR
, quit_pre_print
, fmt
, ap
);
358 throw_vsilent (const char *fmt
, va_list ap
)
361 e
.reason
= RETURN_ERROR
;
362 e
.error
= GENERIC_ERROR
;
363 xfree (last_message
);
364 last_message
= xstrvprintf (fmt
, ap
);
365 e
.message
= last_message
;
369 /* Call FUNC() with args FUNC_UIOUT and FUNC_ARGS, catching any
370 errors. Set FUNC_CAUGHT to an ``enum return_reason'' if the
371 function is aborted (using throw_exception() or zero if the
372 function returns normally. Set FUNC_VAL to the value returned by
373 the function or 0 if the function was aborted.
375 Must not be called with immediate_quit in effect (bad things might
376 happen, say we got a signal in the middle of a memcpy to quit_return).
377 This is an OK restriction; with very few exceptions immediate_quit can
378 be replaced by judicious use of QUIT.
380 MASK specifies what to catch; it is normally set to
381 RETURN_MASK_ALL, if for no other reason than that the code which
382 calls catch_errors might not be set up to deal with a quit which
383 isn't caught. But if the code can deal with it, it generally
384 should be RETURN_MASK_ERROR, unless for some reason it is more
385 useful to abort only the portion of the operation inside the
386 catch_errors. Note that quit should return to the command line
387 fairly quickly, even if some further processing is being done. */
389 /* MAYBE: cagney/1999-11-05: catch_errors() in conjunction with
390 error() et.al. could maintain a set of flags that indicate the the
391 current state of each of the longjmp buffers. This would give the
392 longjmp code the chance to detect a longjmp botch (before it gets
393 to longjmperror()). Prior to 1999-11-05 this wasn't possible as
394 code also randomly used a SET_TOP_LEVEL macro that directly
395 initialize the longjmp buffers. */
397 /* MAYBE: cagney/1999-11-05: Should the catch_errors and cleanups code
398 be consolidated into a single file instead of being distributed
399 between utils.c and top.c? */
402 catch_exceptions (struct ui_out
*uiout
,
403 catch_exceptions_ftype
*func
,
408 return catch_exceptions_with_msg (uiout
, func
, func_args
, errstring
,
413 catch_exception (struct ui_out
*uiout
,
414 catch_exception_ftype
*func
,
418 volatile struct exception exception
;
420 catch = catcher_init (uiout
, NULL
, &exception
, mask
);
421 for (SIGSETJMP ((*catch));
422 catcher_state_machine (CATCH_ITER
);)
423 (*func
) (uiout
, func_args
);
428 catch_exceptions_with_msg (struct ui_out
*uiout
,
429 catch_exceptions_ftype
*func
,
435 volatile struct exception exception
;
436 volatile int val
= 0;
437 SIGJMP_BUF
*catch = catcher_init (uiout
, errstring
, &exception
, mask
);
438 for (SIGSETJMP ((*catch)); catcher_state_machine (CATCH_ITER
);)
439 val
= (*func
) (uiout
, func_args
);
440 gdb_assert (val
>= 0);
441 gdb_assert (exception
.reason
<= 0);
442 if (exception
.reason
< 0)
444 /* If caller wants a copy of the low-level error message, make
445 one. This is used in the case of a silent error whereby the
446 caller may optionally want to issue the message. */
447 if (gdberrmsg
!= NULL
)
449 if (exception
.message
!= NULL
)
450 *gdberrmsg
= xstrdup (exception
.message
);
454 return exception
.reason
;
460 catch_errors (catch_errors_ftype
*func
, void *func_args
, char *errstring
,
463 volatile int val
= 0;
464 volatile struct exception exception
;
465 SIGJMP_BUF
*catch = catcher_init (uiout
, errstring
, &exception
, mask
);
466 /* This illustrates how it is possible to nest the mechanism and
467 hence catch "break". Of course this doesn't address the need to
468 also catch "return". */
469 for (SIGSETJMP ((*catch)); catcher_state_machine (CATCH_ITER
);)
470 val
= func (func_args
);
471 if (exception
.reason
!= 0)
476 struct captured_command_args
478 catch_command_errors_ftype
*command
;
484 do_captured_command (void *data
)
486 struct captured_command_args
*context
= data
;
487 context
->command (context
->arg
, context
->from_tty
);
488 /* FIXME: cagney/1999-11-07: Technically this do_cleanups() call
489 isn't needed. Instead an assertion check could be made that
490 simply confirmed that the called function correctly cleaned up
491 after itself. Unfortunately, old code (prior to 1999-11-04) in
492 main.c was calling SET_TOP_LEVEL(), calling the command function,
493 and then *always* calling do_cleanups(). For the moment we
494 remain ``bug compatible'' with that old code.. */
495 do_cleanups (ALL_CLEANUPS
);
500 catch_command_errors (catch_command_errors_ftype
* command
,
501 char *arg
, int from_tty
, return_mask mask
)
503 struct captured_command_args args
;
504 args
.command
= command
;
506 args
.from_tty
= from_tty
;
507 return catch_errors (do_captured_command
, &args
, "", mask
);