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