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ed3ef339 DE |
1 | /* GDB/Scheme support for safe calls into the Guile interpreter. |
2 | ||
61baf725 | 3 | Copyright (C) 2014-2017 Free Software Foundation, Inc. |
ed3ef339 DE |
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 | /* See README file in this directory for implementation notes, coding | |
21 | conventions, et.al. */ | |
22 | ||
23 | #include "defs.h" | |
24 | #include "filenames.h" | |
ed3ef339 DE |
25 | #include "guile-internal.h" |
26 | ||
27 | /* Struct to marshall args to scscm_safe_call_body. */ | |
28 | ||
29 | struct c_data | |
30 | { | |
c5192092 | 31 | const char *(*func) (void *); |
ed3ef339 DE |
32 | void *data; |
33 | /* An error message or NULL for success. */ | |
c5192092 | 34 | const char *result; |
ed3ef339 DE |
35 | }; |
36 | ||
37 | /* Struct to marshall args through gdbscm_with_catch. */ | |
38 | ||
39 | struct with_catch_data | |
40 | { | |
41 | scm_t_catch_body func; | |
42 | void *data; | |
43 | scm_t_catch_handler unwind_handler; | |
44 | scm_t_catch_handler pre_unwind_handler; | |
45 | ||
46 | /* If EXCP_MATCHER is non-NULL, it is an excp_matcher_func function. | |
47 | If the exception is recognized by it, the exception is recorded as is, | |
48 | without wrapping it in gdb:with-stack. */ | |
49 | excp_matcher_func *excp_matcher; | |
50 | ||
51 | SCM stack; | |
52 | SCM catch_result; | |
53 | }; | |
54 | ||
55 | /* The "body" argument to scm_i_with_continuation_barrier. | |
56 | Invoke the user-supplied function. */ | |
57 | ||
58 | static SCM | |
59 | scscm_safe_call_body (void *d) | |
60 | { | |
61 | struct c_data *data = (struct c_data *) d; | |
62 | ||
63 | data->result = data->func (data->data); | |
64 | ||
65 | return SCM_UNSPECIFIED; | |
66 | } | |
67 | ||
68 | /* A "pre-unwind handler" to scm_c_catch that prints the exception | |
69 | according to "set guile print-stack". */ | |
70 | ||
71 | static SCM | |
72 | scscm_printing_pre_unwind_handler (void *data, SCM key, SCM args) | |
73 | { | |
74 | SCM stack = scm_make_stack (SCM_BOOL_T, scm_list_1 (scm_from_int (2))); | |
75 | ||
76 | gdbscm_print_exception_with_stack (SCM_BOOL_F, stack, key, args); | |
77 | ||
78 | return SCM_UNSPECIFIED; | |
79 | } | |
80 | ||
81 | /* A no-op unwind handler. */ | |
82 | ||
83 | static SCM | |
84 | scscm_nop_unwind_handler (void *data, SCM key, SCM args) | |
85 | { | |
86 | return SCM_UNSPECIFIED; | |
87 | } | |
88 | ||
89 | /* The "pre-unwind handler" to scm_c_catch that records the exception | |
90 | for possible later printing. We do this in the pre-unwind handler because | |
91 | we want the stack to include point where the exception occurred. | |
92 | ||
93 | If DATA is non-NULL, it is an excp_matcher_func function. | |
94 | If the exception is recognized by it, the exception is recorded as is, | |
95 | without wrapping it in gdb:with-stack. */ | |
96 | ||
97 | static SCM | |
98 | scscm_recording_pre_unwind_handler (void *datap, SCM key, SCM args) | |
99 | { | |
9a3c8263 | 100 | struct with_catch_data *data = (struct with_catch_data *) datap; |
ed3ef339 DE |
101 | excp_matcher_func *matcher = data->excp_matcher; |
102 | ||
103 | if (matcher != NULL && matcher (key)) | |
104 | return SCM_UNSPECIFIED; | |
105 | ||
106 | /* There's no need to record the whole stack if we're not going to print it. | |
107 | However, convention is to still print the stack frame in which the | |
108 | exception occurred, even if we're not going to print a full backtrace. | |
109 | For now, keep it simple. */ | |
110 | ||
111 | data->stack = scm_make_stack (SCM_BOOL_T, scm_list_1 (scm_from_int (2))); | |
112 | ||
113 | /* IWBN if we could return the <gdb:exception> here and skip the unwind | |
114 | handler, but it doesn't work that way. If we want to return a | |
115 | <gdb:exception> object from the catch it needs to come from the unwind | |
116 | handler. So what we do is save the stack for later use by the unwind | |
117 | handler. */ | |
118 | ||
119 | return SCM_UNSPECIFIED; | |
120 | } | |
121 | ||
122 | /* Part two of the recording unwind handler. | |
123 | Here we take the stack saved from the pre-unwind handler and create | |
124 | the <gdb:exception> object. */ | |
125 | ||
126 | static SCM | |
127 | scscm_recording_unwind_handler (void *datap, SCM key, SCM args) | |
128 | { | |
9a3c8263 | 129 | struct with_catch_data *data = (struct with_catch_data *) datap; |
ed3ef339 DE |
130 | |
131 | /* We need to record the stack in the exception since we're about to | |
132 | throw and lose the location that got the exception. We do this by | |
133 | wrapping the exception + stack in a new exception. */ | |
134 | ||
135 | if (gdbscm_is_true (data->stack)) | |
136 | return gdbscm_make_exception_with_stack (key, args, data->stack); | |
137 | ||
138 | return gdbscm_make_exception (key, args); | |
139 | } | |
140 | ||
141 | /* Ugh. :-( | |
142 | Guile doesn't export scm_i_with_continuation_barrier which is exactly | |
143 | what we need. To cope, have our own wrapper around scm_c_catch and | |
144 | pass this as the "body" argument to scm_c_with_continuation_barrier. | |
145 | Darn darn darn. */ | |
146 | ||
147 | static void * | |
148 | gdbscm_with_catch (void *data) | |
149 | { | |
9a3c8263 | 150 | struct with_catch_data *d = (struct with_catch_data *) data; |
ed3ef339 DE |
151 | |
152 | d->catch_result | |
153 | = scm_c_catch (SCM_BOOL_T, | |
154 | d->func, d->data, | |
155 | d->unwind_handler, d, | |
156 | d->pre_unwind_handler, d); | |
157 | ||
92fab5a6 AW |
158 | #if HAVE_GUILE_MANUAL_FINALIZATION |
159 | scm_run_finalizers (); | |
160 | #endif | |
161 | ||
ed3ef339 DE |
162 | return NULL; |
163 | } | |
164 | ||
165 | /* A wrapper around scm_with_guile that prints backtraces and exceptions | |
166 | according to "set guile print-stack". | |
167 | The result if NULL if no exception occurred, otherwise it is a statically | |
168 | allocated error message (caller must *not* free). */ | |
169 | ||
c5192092 SM |
170 | const char * |
171 | gdbscm_with_guile (const char *(*func) (void *), void *data) | |
ed3ef339 DE |
172 | { |
173 | struct c_data c_data; | |
174 | struct with_catch_data catch_data; | |
175 | ||
176 | c_data.func = func; | |
177 | c_data.data = data; | |
178 | /* Set this now in case an exception is thrown. */ | |
179 | c_data.result = _("Error while executing Scheme code."); | |
180 | ||
181 | catch_data.func = scscm_safe_call_body; | |
182 | catch_data.data = &c_data; | |
183 | catch_data.unwind_handler = scscm_nop_unwind_handler; | |
184 | catch_data.pre_unwind_handler = scscm_printing_pre_unwind_handler; | |
185 | catch_data.excp_matcher = NULL; | |
186 | catch_data.stack = SCM_BOOL_F; | |
187 | catch_data.catch_result = SCM_UNSPECIFIED; | |
188 | ||
189 | scm_with_guile (gdbscm_with_catch, &catch_data); | |
190 | ||
191 | return c_data.result; | |
192 | } | |
193 | ||
194 | /* Another wrapper of scm_with_guile for use by the safe call/apply routines | |
195 | in this file, as well as for general purpose calling other functions safely. | |
196 | For these we want to record the exception, but leave the possible printing | |
197 | of it to later. */ | |
198 | ||
199 | SCM | |
200 | gdbscm_call_guile (SCM (*func) (void *), void *data, | |
201 | excp_matcher_func *ok_excps) | |
202 | { | |
203 | struct with_catch_data catch_data; | |
204 | ||
205 | catch_data.func = func; | |
206 | catch_data.data = data; | |
207 | catch_data.unwind_handler = scscm_recording_unwind_handler; | |
208 | catch_data.pre_unwind_handler = scscm_recording_pre_unwind_handler; | |
209 | catch_data.excp_matcher = ok_excps; | |
210 | catch_data.stack = SCM_BOOL_F; | |
211 | catch_data.catch_result = SCM_UNSPECIFIED; | |
212 | ||
213 | #if 0 | |
214 | scm_c_with_continuation_barrier (gdbscm_with_catch, &catch_data); | |
215 | #else | |
216 | scm_with_guile (gdbscm_with_catch, &catch_data); | |
217 | #endif | |
218 | ||
219 | return catch_data.catch_result; | |
220 | } | |
221 | \f | |
222 | /* Utilities to safely call Scheme code, catching all exceptions, and | |
223 | preventing continuation capture. | |
224 | The result is the result of calling the function, or if an exception occurs | |
225 | then the result is a <gdb:exception> smob, which can be tested for with | |
226 | gdbscm_is_exception. */ | |
227 | ||
228 | /* Helper for gdbscm_safe_call_0. */ | |
229 | ||
230 | static SCM | |
231 | scscm_call_0_body (void *argsp) | |
232 | { | |
9a3c8263 | 233 | SCM *args = (SCM *) argsp; |
ed3ef339 DE |
234 | |
235 | return scm_call_0 (args[0]); | |
236 | } | |
237 | ||
238 | SCM | |
239 | gdbscm_safe_call_0 (SCM proc, excp_matcher_func *ok_excps) | |
240 | { | |
241 | SCM args[] = { proc }; | |
242 | ||
243 | return gdbscm_call_guile (scscm_call_0_body, args, ok_excps); | |
244 | } | |
245 | ||
246 | /* Helper for gdbscm_safe_call_1. */ | |
247 | ||
248 | static SCM | |
249 | scscm_call_1_body (void *argsp) | |
250 | { | |
9a3c8263 | 251 | SCM *args = (SCM *) argsp; |
ed3ef339 DE |
252 | |
253 | return scm_call_1 (args[0], args[1]); | |
254 | } | |
255 | ||
256 | SCM | |
257 | gdbscm_safe_call_1 (SCM proc, SCM arg0, excp_matcher_func *ok_excps) | |
258 | { | |
259 | SCM args[] = { proc, arg0 }; | |
260 | ||
261 | return gdbscm_call_guile (scscm_call_1_body, args, ok_excps); | |
262 | } | |
263 | ||
264 | /* Helper for gdbscm_safe_call_2. */ | |
265 | ||
266 | static SCM | |
267 | scscm_call_2_body (void *argsp) | |
268 | { | |
9a3c8263 | 269 | SCM *args = (SCM *) argsp; |
ed3ef339 DE |
270 | |
271 | return scm_call_2 (args[0], args[1], args[2]); | |
272 | } | |
273 | ||
274 | SCM | |
275 | gdbscm_safe_call_2 (SCM proc, SCM arg0, SCM arg1, excp_matcher_func *ok_excps) | |
276 | { | |
277 | SCM args[] = { proc, arg0, arg1 }; | |
278 | ||
279 | return gdbscm_call_guile (scscm_call_2_body, args, ok_excps); | |
280 | } | |
281 | ||
282 | /* Helper for gdbscm_safe_call_3. */ | |
283 | ||
284 | static SCM | |
285 | scscm_call_3_body (void *argsp) | |
286 | { | |
9a3c8263 | 287 | SCM *args = (SCM *) argsp; |
ed3ef339 DE |
288 | |
289 | return scm_call_3 (args[0], args[1], args[2], args[3]); | |
290 | } | |
291 | ||
292 | SCM | |
293 | gdbscm_safe_call_3 (SCM proc, SCM arg1, SCM arg2, SCM arg3, | |
294 | excp_matcher_func *ok_excps) | |
295 | { | |
296 | SCM args[] = { proc, arg1, arg2, arg3 }; | |
297 | ||
298 | return gdbscm_call_guile (scscm_call_3_body, args, ok_excps); | |
299 | } | |
300 | ||
301 | /* Helper for gdbscm_safe_call_4. */ | |
302 | ||
303 | static SCM | |
304 | scscm_call_4_body (void *argsp) | |
305 | { | |
9a3c8263 | 306 | SCM *args = (SCM *) argsp; |
ed3ef339 DE |
307 | |
308 | return scm_call_4 (args[0], args[1], args[2], args[3], args[4]); | |
309 | } | |
310 | ||
311 | SCM | |
312 | gdbscm_safe_call_4 (SCM proc, SCM arg1, SCM arg2, SCM arg3, SCM arg4, | |
313 | excp_matcher_func *ok_excps) | |
314 | { | |
315 | SCM args[] = { proc, arg1, arg2, arg3, arg4 }; | |
316 | ||
317 | return gdbscm_call_guile (scscm_call_4_body, args, ok_excps); | |
318 | } | |
319 | ||
320 | /* Helper for gdbscm_safe_apply_1. */ | |
321 | ||
322 | static SCM | |
323 | scscm_apply_1_body (void *argsp) | |
324 | { | |
9a3c8263 | 325 | SCM *args = (SCM *) argsp; |
ed3ef339 DE |
326 | |
327 | return scm_apply_1 (args[0], args[1], args[2]); | |
328 | } | |
329 | ||
330 | SCM | |
331 | gdbscm_safe_apply_1 (SCM proc, SCM arg0, SCM rest, excp_matcher_func *ok_excps) | |
332 | { | |
333 | SCM args[] = { proc, arg0, rest }; | |
334 | ||
335 | return gdbscm_call_guile (scscm_apply_1_body, args, ok_excps); | |
336 | } | |
337 | \f | |
338 | /* Utilities to call Scheme code, not catching exceptions, and | |
339 | not preventing continuation capture. | |
340 | The result is the result of calling the function. | |
341 | If an exception occurs then Guile is left to handle the exception, | |
342 | unwinding the stack as appropriate. | |
343 | ||
344 | USE THESE WITH CARE. | |
345 | Typically these are called from functions that implement Scheme procedures, | |
346 | and we don't want to catch the exception; otherwise it will get printed | |
347 | twice: once when first caught and once if it ends up being rethrown and the | |
348 | rethrow reaches the top repl, which will confuse the user. | |
349 | ||
350 | While these calls just pass the call off to the corresponding Guile | |
351 | procedure, all such calls are routed through these ones to: | |
352 | a) provide a place to put hooks or whatnot in if we need to, | |
353 | b) add "unsafe" to the name to alert the reader. */ | |
354 | ||
355 | SCM | |
356 | gdbscm_unsafe_call_1 (SCM proc, SCM arg0) | |
357 | { | |
358 | return scm_call_1 (proc, arg0); | |
359 | } | |
360 | \f | |
361 | /* Utilities for safely evaluating a Scheme expression string. */ | |
362 | ||
363 | struct eval_scheme_string_data | |
364 | { | |
365 | const char *string; | |
366 | int display_result; | |
367 | }; | |
368 | ||
369 | /* Wrapper to eval a C string in the Guile interpreter. | |
b51a69ee | 370 | This is passed to gdbscm_with_guile. */ |
ed3ef339 | 371 | |
c5192092 | 372 | static const char * |
ed3ef339 DE |
373 | scscm_eval_scheme_string (void *datap) |
374 | { | |
9a3c8263 SM |
375 | struct eval_scheme_string_data *data |
376 | = (struct eval_scheme_string_data *) datap; | |
ed3ef339 DE |
377 | SCM result = scm_c_eval_string (data->string); |
378 | ||
379 | if (data->display_result && !scm_is_eq (result, SCM_UNSPECIFIED)) | |
380 | { | |
381 | SCM port = scm_current_output_port (); | |
382 | ||
383 | scm_write (result, port); | |
384 | scm_newline (port); | |
385 | } | |
386 | ||
387 | /* If we get here the eval succeeded. */ | |
388 | return NULL; | |
389 | } | |
390 | ||
391 | /* Evaluate EXPR in the Guile interpreter, catching all exceptions | |
392 | and preventing continuation capture. | |
393 | The result is NULL if no exception occurred. Otherwise, the exception is | |
394 | printed according to "set guile print-stack" and the result is an error | |
395 | message allocated with malloc, caller must free. */ | |
396 | ||
397 | char * | |
398 | gdbscm_safe_eval_string (const char *string, int display_result) | |
399 | { | |
400 | struct eval_scheme_string_data data = { string, display_result }; | |
c5192092 | 401 | const char *result; |
ed3ef339 DE |
402 | |
403 | result = gdbscm_with_guile (scscm_eval_scheme_string, (void *) &data); | |
404 | ||
405 | if (result != NULL) | |
c5192092 | 406 | return xstrdup (result); |
ed3ef339 DE |
407 | return NULL; |
408 | } | |
409 | \f | |
410 | /* Utilities for safely loading Scheme scripts. */ | |
411 | ||
412 | /* Helper function for gdbscm_safe_source_scheme_script. */ | |
413 | ||
c5192092 | 414 | static const char * |
ed3ef339 DE |
415 | scscm_source_scheme_script (void *data) |
416 | { | |
9a3c8263 | 417 | const char *filename = (const char *) data; |
ed3ef339 DE |
418 | |
419 | /* The Guile docs don't specify what the result is. | |
420 | Maybe it's SCM_UNSPECIFIED, but the docs should specify that. :-) */ | |
421 | scm_c_primitive_load_path (filename); | |
422 | ||
423 | /* If we get here the load succeeded. */ | |
424 | return NULL; | |
425 | } | |
426 | ||
427 | /* Try to load a script, catching all exceptions, | |
428 | and preventing continuation capture. | |
429 | The result is NULL if the load succeeded. Otherwise, the exception is | |
430 | printed according to "set guile print-stack" and the result is an error | |
431 | message allocated with malloc, caller must free. */ | |
432 | ||
433 | char * | |
434 | gdbscm_safe_source_script (const char *filename) | |
435 | { | |
436 | /* scm_c_primitive_load_path only looks in %load-path for files with | |
437 | relative paths. An alternative could be to temporarily add "." to | |
438 | %load-path, but we don't want %load-path to be searched. At least not | |
439 | by default. This function is invoked by the "source" GDB command which | |
440 | already has its own path search support. */ | |
14278e1f | 441 | gdb::unique_xmalloc_ptr<char> abs_filename; |
c5192092 | 442 | const char *result; |
ed3ef339 DE |
443 | |
444 | if (!IS_ABSOLUTE_PATH (filename)) | |
445 | { | |
446 | abs_filename = gdb_realpath (filename); | |
14278e1f | 447 | filename = abs_filename.get (); |
ed3ef339 DE |
448 | } |
449 | ||
450 | result = gdbscm_with_guile (scscm_source_scheme_script, | |
451 | (void *) filename); | |
452 | ||
ed3ef339 | 453 | if (result != NULL) |
c5192092 | 454 | return xstrdup (result); |
ed3ef339 DE |
455 | return NULL; |
456 | } | |
457 | \f | |
458 | /* Utility for entering an interactive Guile repl. */ | |
459 | ||
460 | void | |
461 | gdbscm_enter_repl (void) | |
462 | { | |
463 | /* It's unfortunate to have to resort to something like this, but | |
464 | scm_shell doesn't return. :-( I found this code on guile-user@. */ | |
465 | gdbscm_safe_call_1 (scm_c_public_ref ("system repl repl", "start-repl"), | |
466 | scm_from_latin1_symbol ("scheme"), NULL); | |
467 | } |