| 1 | /* GDB/Scheme support for safe calls into the Guile interpreter. |
| 2 | |
| 3 | Copyright (C) 2014-2018 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 "guile-internal.h" |
| 26 | #include "common/pathstuff.h" |
| 27 | |
| 28 | /* Struct to marshall args to scscm_safe_call_body. */ |
| 29 | |
| 30 | struct c_data |
| 31 | { |
| 32 | const char *(*func) (void *); |
| 33 | void *data; |
| 34 | /* An error message or NULL for success. */ |
| 35 | const char *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 = (struct with_catch_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 = (struct with_catch_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 = (struct with_catch_data *) 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 | #if HAVE_GUILE_MANUAL_FINALIZATION |
| 160 | scm_run_finalizers (); |
| 161 | #endif |
| 162 | |
| 163 | return NULL; |
| 164 | } |
| 165 | |
| 166 | /* A wrapper around scm_with_guile that prints backtraces and exceptions |
| 167 | according to "set guile print-stack". |
| 168 | The result if NULL if no exception occurred, otherwise it is a statically |
| 169 | allocated error message (caller must *not* free). */ |
| 170 | |
| 171 | const char * |
| 172 | gdbscm_with_guile (const char *(*func) (void *), void *data) |
| 173 | { |
| 174 | struct c_data c_data; |
| 175 | struct with_catch_data catch_data; |
| 176 | |
| 177 | c_data.func = func; |
| 178 | c_data.data = data; |
| 179 | /* Set this now in case an exception is thrown. */ |
| 180 | c_data.result = _("Error while executing Scheme code."); |
| 181 | |
| 182 | catch_data.func = scscm_safe_call_body; |
| 183 | catch_data.data = &c_data; |
| 184 | catch_data.unwind_handler = scscm_nop_unwind_handler; |
| 185 | catch_data.pre_unwind_handler = scscm_printing_pre_unwind_handler; |
| 186 | catch_data.excp_matcher = NULL; |
| 187 | catch_data.stack = SCM_BOOL_F; |
| 188 | catch_data.catch_result = SCM_UNSPECIFIED; |
| 189 | |
| 190 | scm_with_guile (gdbscm_with_catch, &catch_data); |
| 191 | |
| 192 | return c_data.result; |
| 193 | } |
| 194 | |
| 195 | /* Another wrapper of scm_with_guile for use by the safe call/apply routines |
| 196 | in this file, as well as for general purpose calling other functions safely. |
| 197 | For these we want to record the exception, but leave the possible printing |
| 198 | of it to later. */ |
| 199 | |
| 200 | SCM |
| 201 | gdbscm_call_guile (SCM (*func) (void *), void *data, |
| 202 | excp_matcher_func *ok_excps) |
| 203 | { |
| 204 | struct with_catch_data catch_data; |
| 205 | |
| 206 | catch_data.func = func; |
| 207 | catch_data.data = data; |
| 208 | catch_data.unwind_handler = scscm_recording_unwind_handler; |
| 209 | catch_data.pre_unwind_handler = scscm_recording_pre_unwind_handler; |
| 210 | catch_data.excp_matcher = ok_excps; |
| 211 | catch_data.stack = SCM_BOOL_F; |
| 212 | catch_data.catch_result = SCM_UNSPECIFIED; |
| 213 | |
| 214 | #if 0 |
| 215 | scm_c_with_continuation_barrier (gdbscm_with_catch, &catch_data); |
| 216 | #else |
| 217 | scm_with_guile (gdbscm_with_catch, &catch_data); |
| 218 | #endif |
| 219 | |
| 220 | return catch_data.catch_result; |
| 221 | } |
| 222 | \f |
| 223 | /* Utilities to safely call Scheme code, catching all exceptions, and |
| 224 | preventing continuation capture. |
| 225 | The result is the result of calling the function, or if an exception occurs |
| 226 | then the result is a <gdb:exception> smob, which can be tested for with |
| 227 | gdbscm_is_exception. */ |
| 228 | |
| 229 | /* Helper for gdbscm_safe_call_0. */ |
| 230 | |
| 231 | static SCM |
| 232 | scscm_call_0_body (void *argsp) |
| 233 | { |
| 234 | SCM *args = (SCM *) argsp; |
| 235 | |
| 236 | return scm_call_0 (args[0]); |
| 237 | } |
| 238 | |
| 239 | SCM |
| 240 | gdbscm_safe_call_0 (SCM proc, excp_matcher_func *ok_excps) |
| 241 | { |
| 242 | SCM args[] = { proc }; |
| 243 | |
| 244 | return gdbscm_call_guile (scscm_call_0_body, args, ok_excps); |
| 245 | } |
| 246 | |
| 247 | /* Helper for gdbscm_safe_call_1. */ |
| 248 | |
| 249 | static SCM |
| 250 | scscm_call_1_body (void *argsp) |
| 251 | { |
| 252 | SCM *args = (SCM *) argsp; |
| 253 | |
| 254 | return scm_call_1 (args[0], args[1]); |
| 255 | } |
| 256 | |
| 257 | SCM |
| 258 | gdbscm_safe_call_1 (SCM proc, SCM arg0, excp_matcher_func *ok_excps) |
| 259 | { |
| 260 | SCM args[] = { proc, arg0 }; |
| 261 | |
| 262 | return gdbscm_call_guile (scscm_call_1_body, args, ok_excps); |
| 263 | } |
| 264 | |
| 265 | /* Helper for gdbscm_safe_call_2. */ |
| 266 | |
| 267 | static SCM |
| 268 | scscm_call_2_body (void *argsp) |
| 269 | { |
| 270 | SCM *args = (SCM *) argsp; |
| 271 | |
| 272 | return scm_call_2 (args[0], args[1], args[2]); |
| 273 | } |
| 274 | |
| 275 | SCM |
| 276 | gdbscm_safe_call_2 (SCM proc, SCM arg0, SCM arg1, excp_matcher_func *ok_excps) |
| 277 | { |
| 278 | SCM args[] = { proc, arg0, arg1 }; |
| 279 | |
| 280 | return gdbscm_call_guile (scscm_call_2_body, args, ok_excps); |
| 281 | } |
| 282 | |
| 283 | /* Helper for gdbscm_safe_call_3. */ |
| 284 | |
| 285 | static SCM |
| 286 | scscm_call_3_body (void *argsp) |
| 287 | { |
| 288 | SCM *args = (SCM *) argsp; |
| 289 | |
| 290 | return scm_call_3 (args[0], args[1], args[2], args[3]); |
| 291 | } |
| 292 | |
| 293 | SCM |
| 294 | gdbscm_safe_call_3 (SCM proc, SCM arg1, SCM arg2, SCM arg3, |
| 295 | excp_matcher_func *ok_excps) |
| 296 | { |
| 297 | SCM args[] = { proc, arg1, arg2, arg3 }; |
| 298 | |
| 299 | return gdbscm_call_guile (scscm_call_3_body, args, ok_excps); |
| 300 | } |
| 301 | |
| 302 | /* Helper for gdbscm_safe_call_4. */ |
| 303 | |
| 304 | static SCM |
| 305 | scscm_call_4_body (void *argsp) |
| 306 | { |
| 307 | SCM *args = (SCM *) argsp; |
| 308 | |
| 309 | return scm_call_4 (args[0], args[1], args[2], args[3], args[4]); |
| 310 | } |
| 311 | |
| 312 | SCM |
| 313 | gdbscm_safe_call_4 (SCM proc, SCM arg1, SCM arg2, SCM arg3, SCM arg4, |
| 314 | excp_matcher_func *ok_excps) |
| 315 | { |
| 316 | SCM args[] = { proc, arg1, arg2, arg3, arg4 }; |
| 317 | |
| 318 | return gdbscm_call_guile (scscm_call_4_body, args, ok_excps); |
| 319 | } |
| 320 | |
| 321 | /* Helper for gdbscm_safe_apply_1. */ |
| 322 | |
| 323 | static SCM |
| 324 | scscm_apply_1_body (void *argsp) |
| 325 | { |
| 326 | SCM *args = (SCM *) argsp; |
| 327 | |
| 328 | return scm_apply_1 (args[0], args[1], args[2]); |
| 329 | } |
| 330 | |
| 331 | SCM |
| 332 | gdbscm_safe_apply_1 (SCM proc, SCM arg0, SCM rest, excp_matcher_func *ok_excps) |
| 333 | { |
| 334 | SCM args[] = { proc, arg0, rest }; |
| 335 | |
| 336 | return gdbscm_call_guile (scscm_apply_1_body, args, ok_excps); |
| 337 | } |
| 338 | \f |
| 339 | /* Utilities to call Scheme code, not catching exceptions, and |
| 340 | not preventing continuation capture. |
| 341 | The result is the result of calling the function. |
| 342 | If an exception occurs then Guile is left to handle the exception, |
| 343 | unwinding the stack as appropriate. |
| 344 | |
| 345 | USE THESE WITH CARE. |
| 346 | Typically these are called from functions that implement Scheme procedures, |
| 347 | and we don't want to catch the exception; otherwise it will get printed |
| 348 | twice: once when first caught and once if it ends up being rethrown and the |
| 349 | rethrow reaches the top repl, which will confuse the user. |
| 350 | |
| 351 | While these calls just pass the call off to the corresponding Guile |
| 352 | procedure, all such calls are routed through these ones to: |
| 353 | a) provide a place to put hooks or whatnot in if we need to, |
| 354 | b) add "unsafe" to the name to alert the reader. */ |
| 355 | |
| 356 | SCM |
| 357 | gdbscm_unsafe_call_1 (SCM proc, SCM arg0) |
| 358 | { |
| 359 | return scm_call_1 (proc, arg0); |
| 360 | } |
| 361 | \f |
| 362 | /* Utilities for safely evaluating a Scheme expression string. */ |
| 363 | |
| 364 | struct eval_scheme_string_data |
| 365 | { |
| 366 | const char *string; |
| 367 | int display_result; |
| 368 | }; |
| 369 | |
| 370 | /* Wrapper to eval a C string in the Guile interpreter. |
| 371 | This is passed to gdbscm_with_guile. */ |
| 372 | |
| 373 | static const char * |
| 374 | scscm_eval_scheme_string (void *datap) |
| 375 | { |
| 376 | struct eval_scheme_string_data *data |
| 377 | = (struct eval_scheme_string_data *) datap; |
| 378 | SCM result = scm_c_eval_string (data->string); |
| 379 | |
| 380 | if (data->display_result && !scm_is_eq (result, SCM_UNSPECIFIED)) |
| 381 | { |
| 382 | SCM port = scm_current_output_port (); |
| 383 | |
| 384 | scm_write (result, port); |
| 385 | scm_newline (port); |
| 386 | } |
| 387 | |
| 388 | /* If we get here the eval succeeded. */ |
| 389 | return NULL; |
| 390 | } |
| 391 | |
| 392 | /* Evaluate EXPR in the Guile interpreter, catching all exceptions |
| 393 | and preventing continuation capture. |
| 394 | The result is NULL if no exception occurred. Otherwise, the exception is |
| 395 | printed according to "set guile print-stack" and the result is an error |
| 396 | message. */ |
| 397 | |
| 398 | gdb::unique_xmalloc_ptr<char> |
| 399 | gdbscm_safe_eval_string (const char *string, int display_result) |
| 400 | { |
| 401 | struct eval_scheme_string_data data = { string, display_result }; |
| 402 | const char *result; |
| 403 | |
| 404 | result = gdbscm_with_guile (scscm_eval_scheme_string, (void *) &data); |
| 405 | |
| 406 | if (result != NULL) |
| 407 | return gdb::unique_xmalloc_ptr<char> (xstrdup (result)); |
| 408 | return NULL; |
| 409 | } |
| 410 | \f |
| 411 | /* Utilities for safely loading Scheme scripts. */ |
| 412 | |
| 413 | /* Helper function for gdbscm_safe_source_scheme_script. */ |
| 414 | |
| 415 | static const char * |
| 416 | scscm_source_scheme_script (void *data) |
| 417 | { |
| 418 | const char *filename = (const char *) data; |
| 419 | |
| 420 | /* The Guile docs don't specify what the result is. |
| 421 | Maybe it's SCM_UNSPECIFIED, but the docs should specify that. :-) */ |
| 422 | scm_c_primitive_load_path (filename); |
| 423 | |
| 424 | /* If we get here the load succeeded. */ |
| 425 | return NULL; |
| 426 | } |
| 427 | |
| 428 | /* Try to load a script, catching all exceptions, |
| 429 | and preventing continuation capture. |
| 430 | The result is NULL if the load succeeded. Otherwise, the exception is |
| 431 | printed according to "set guile print-stack" and the result is an error |
| 432 | message allocated with malloc, caller must free. */ |
| 433 | |
| 434 | char * |
| 435 | gdbscm_safe_source_script (const char *filename) |
| 436 | { |
| 437 | /* scm_c_primitive_load_path only looks in %load-path for files with |
| 438 | relative paths. An alternative could be to temporarily add "." to |
| 439 | %load-path, but we don't want %load-path to be searched. At least not |
| 440 | by default. This function is invoked by the "source" GDB command which |
| 441 | already has its own path search support. */ |
| 442 | gdb::unique_xmalloc_ptr<char> abs_filename; |
| 443 | const char *result; |
| 444 | |
| 445 | if (!IS_ABSOLUTE_PATH (filename)) |
| 446 | { |
| 447 | abs_filename = gdb_realpath (filename); |
| 448 | filename = abs_filename.get (); |
| 449 | } |
| 450 | |
| 451 | result = gdbscm_with_guile (scscm_source_scheme_script, |
| 452 | (void *) filename); |
| 453 | |
| 454 | if (result != NULL) |
| 455 | return xstrdup (result); |
| 456 | return NULL; |
| 457 | } |
| 458 | \f |
| 459 | /* Utility for entering an interactive Guile repl. */ |
| 460 | |
| 461 | void |
| 462 | gdbscm_enter_repl (void) |
| 463 | { |
| 464 | /* It's unfortunate to have to resort to something like this, but |
| 465 | scm_shell doesn't return. :-( I found this code on guile-user@. */ |
| 466 | gdbscm_safe_call_1 (scm_c_public_ref ("system repl repl", "start-repl"), |
| 467 | scm_from_latin1_symbol ("scheme"), NULL); |
| 468 | } |