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4ea1f83d | 1 | /* Copyright (C) 1995,1996,1997,1998, 1999 Free Software Foundation, Inc. |
0f2d19dd JB |
2 | * |
3 | * This program is free software; you can redistribute it and/or modify | |
4 | * it under the terms of the GNU General Public License as published by | |
5 | * the Free Software Foundation; either version 2, or (at your option) | |
6 | * any later version. | |
7 | * | |
8 | * This program is distributed in the hope that it will be useful, | |
9 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
11 | * GNU General Public License for more details. | |
12 | * | |
13 | * You should have received a copy of the GNU General Public License | |
14 | * along with this software; see the file COPYING. If not, write to | |
82892bed JB |
15 | * the Free Software Foundation, Inc., 59 Temple Place, Suite 330, |
16 | * Boston, MA 02111-1307 USA | |
0f2d19dd JB |
17 | * |
18 | * As a special exception, the Free Software Foundation gives permission | |
19 | * for additional uses of the text contained in its release of GUILE. | |
20 | * | |
21 | * The exception is that, if you link the GUILE library with other files | |
22 | * to produce an executable, this does not by itself cause the | |
23 | * resulting executable to be covered by the GNU General Public License. | |
24 | * Your use of that executable is in no way restricted on account of | |
25 | * linking the GUILE library code into it. | |
26 | * | |
27 | * This exception does not however invalidate any other reasons why | |
28 | * the executable file might be covered by the GNU General Public License. | |
29 | * | |
30 | * This exception applies only to the code released by the | |
31 | * Free Software Foundation under the name GUILE. If you copy | |
32 | * code from other Free Software Foundation releases into a copy of | |
33 | * GUILE, as the General Public License permits, the exception does | |
34 | * not apply to the code that you add in this way. To avoid misleading | |
35 | * anyone as to the status of such modified files, you must delete | |
36 | * this exception notice from them. | |
37 | * | |
38 | * If you write modifications of your own for GUILE, it is your choice | |
39 | * whether to permit this exception to apply to your modifications. | |
82892bed | 40 | * If you do not wish that, delete this exception notice. */ |
1bbd0b84 GB |
41 | |
42 | /* Software engineering face-lift by Greg J. Badros, 11-Dec-1999, | |
43 | gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */ | |
44 | ||
0f2d19dd JB |
45 | \f |
46 | ||
47 | #include <stdio.h> | |
48 | #include "_scm.h" | |
20e6290e | 49 | #include "stackchk.h" |
d564d753 MD |
50 | #include "dynwind.h" |
51 | #include "eval.h" | |
52 | #include "genio.h" | |
53 | #include "smob.h" | |
54 | #include "pairs.h" | |
55 | #include "throw.h" | |
d9dfcf80 | 56 | #include "fluids.h" |
0f2d19dd | 57 | |
20e6290e | 58 | #include "root.h" |
0f2d19dd JB |
59 | \f |
60 | ||
e71575d9 MV |
61 | /* Define this if you want to try out the stack allocation of cwdr's |
62 | jumpbuf. It works for me but I'm still worried that the dynwinds | |
63 | might be able to make a mess. */ | |
64 | ||
65 | #undef USE_STACKJMPBUF | |
66 | ||
0f2d19dd | 67 | SCM scm_sys_protects[SCM_NUM_PROTECTS]; |
d564d753 MD |
68 | |
69 | long scm_tc16_root; | |
70 | ||
71 | #ifndef USE_THREADS | |
72 | struct scm_root_state *scm_root; | |
73 | #endif | |
0f2d19dd JB |
74 | |
75 | \f | |
76 | ||
d564d753 | 77 | static SCM |
1bbd0b84 | 78 | mark_root (SCM root) |
d564d753 MD |
79 | { |
80 | scm_root_state *s = SCM_ROOT_STATE (root); | |
dc53f026 | 81 | |
d564d753 MD |
82 | scm_gc_mark (s->rootcont); |
83 | scm_gc_mark (s->dynwinds); | |
84 | scm_gc_mark (s->continuation_stack); | |
85 | scm_gc_mark (s->continuation_stack_ptr); | |
86 | scm_gc_mark (s->progargs); | |
87 | scm_gc_mark (s->exitval); | |
88 | scm_gc_mark (s->cur_inp); | |
89 | scm_gc_mark (s->cur_outp); | |
90 | scm_gc_mark (s->cur_errp); | |
91 | scm_gc_mark (s->def_inp); | |
92 | scm_gc_mark (s->def_outp); | |
93 | scm_gc_mark (s->def_errp); | |
903073d5 | 94 | /* No need to gc mark def_loadp */ |
d9dfcf80 | 95 | scm_gc_mark (s->fluids); |
dc19d1d2 | 96 | scm_gc_mark (s->top_level_lookup_closure_var); |
d564d753 MD |
97 | scm_gc_mark (s->system_transformer); |
98 | return SCM_ROOT_STATE (root) -> parent; | |
99 | } | |
0f2d19dd | 100 | |
d564d753 | 101 | |
d564d753 | 102 | static int |
1bbd0b84 | 103 | print_root (SCM exp,SCM port,scm_print_state *pstate) |
d564d753 | 104 | { |
b7f3516f | 105 | scm_puts ("#<root ", port); |
d564d753 | 106 | scm_intprint(SCM_SEQ (SCM_ROOT_STATE (exp) -> rootcont), 16, port); |
b7f3516f | 107 | scm_putc('>', port); |
d564d753 MD |
108 | return 1; |
109 | } | |
110 | ||
d564d753 MD |
111 | |
112 | \f | |
113 | ||
114 | SCM | |
1bbd0b84 | 115 | scm_make_root (SCM parent) |
d564d753 MD |
116 | { |
117 | SCM root; | |
118 | scm_root_state *root_state; | |
119 | ||
120 | root_state = (scm_root_state *) scm_must_malloc (sizeof (scm_root_state), | |
121 | "scm_make_root"); | |
0c95b57d | 122 | if (SCM_ROOTP (parent)) |
d564d753 MD |
123 | { |
124 | memcpy (root_state, SCM_ROOT_STATE (parent), sizeof (scm_root_state)); | |
d9dfcf80 | 125 | scm_copy_fluids (root_state); |
d564d753 MD |
126 | root_state->parent = parent; |
127 | } | |
128 | else | |
129 | { | |
130 | root_state->parent = SCM_BOOL_F; | |
4ea1f83d JB |
131 | |
132 | /* Initialize everything right now, in case a GC happens early. */ | |
133 | root_state->rootcont | |
134 | = root_state->dynwinds | |
135 | = root_state->continuation_stack | |
136 | = root_state->continuation_stack_ptr | |
137 | = root_state->progargs | |
138 | = root_state->exitval | |
139 | = root_state->cur_inp | |
140 | = root_state->cur_outp | |
141 | = root_state->cur_errp | |
142 | = root_state->def_inp | |
143 | = root_state->def_outp | |
144 | = root_state->def_errp | |
145 | = root_state->cur_loadp | |
146 | = root_state->fluids | |
147 | = root_state->system_transformer | |
148 | = root_state->top_level_lookup_closure_var | |
149 | = root_state->handle | |
150 | = root_state->parent | |
151 | = SCM_BOOL_F; | |
d564d753 | 152 | } |
d564d753 | 153 | SCM_REDEFER_INTS; |
23a62151 | 154 | SCM_NEWSMOB (root, scm_tc16_root, root_state); |
d564d753 MD |
155 | root_state->handle = root; |
156 | SCM_REALLOW_INTS; | |
157 | return root; | |
158 | } | |
159 | ||
1cc91f1b | 160 | /* {call-with-dynamic-root} |
d564d753 MD |
161 | * |
162 | * Suspending the current thread to evaluate a thunk on the | |
163 | * same C stack but under a new root. | |
164 | * | |
1cc91f1b | 165 | * Calls to call-with-dynamic-root return exactly once (unless |
e71575d9 | 166 | * the process is somehow exitted). */ |
d564d753 | 167 | |
650fa1ab JB |
168 | /* Some questions about cwdr: |
169 | ||
170 | Couldn't the body just be a closure? Do we really need to pass | |
171 | args through to it? | |
172 | ||
173 | The semantics are a lot like catch's; in fact, we call | |
174 | scm_internal_catch to take care of that part of things. Wouldn't | |
175 | it be cleaner to say that uncaught throws just disappear into the | |
176 | ether (or print a message to stderr), and let the caller use catch | |
177 | themselves if they want to? | |
178 | ||
179 | -JimB */ | |
180 | ||
d564d753 MD |
181 | #if 0 |
182 | SCM scm_exitval; /* INUM with return value */ | |
183 | #endif | |
184 | static int n_dynamic_roots = 0; | |
185 | ||
650fa1ab | 186 | |
e71575d9 MV |
187 | /* cwdr fills out both of these structures, and then passes a pointer |
188 | to them through scm_internal_catch to the cwdr_body and | |
189 | cwdr_handler functions, to tell them how to behave and to get | |
190 | information back from them. | |
650fa1ab JB |
191 | |
192 | A cwdr is a lot like a catch, except there is no tag (all | |
193 | exceptions are caught), and the body procedure takes the arguments | |
e71575d9 MV |
194 | passed to cwdr as A1 and ARGS. The handler is also special since |
195 | it is not directly run from scm_internal_catch. It is executed | |
196 | outside the new dynamic root. */ | |
650fa1ab JB |
197 | |
198 | struct cwdr_body_data { | |
650fa1ab JB |
199 | /* Arguments to pass to the cwdr body function. */ |
200 | SCM a1, args; | |
201 | ||
202 | /* Scheme procedure to use as body of cwdr. */ | |
203 | SCM body_proc; | |
e71575d9 MV |
204 | }; |
205 | ||
206 | struct cwdr_handler_data { | |
207 | /* Do we need to run the handler? */ | |
208 | int run_handler; | |
f032b8a8 | 209 | |
e71575d9 MV |
210 | /* The tag and args to pass it. */ |
211 | SCM tag, args; | |
650fa1ab JB |
212 | }; |
213 | ||
214 | ||
215 | /* Invoke the body of a cwdr, assuming that the throw handler has | |
216 | already been set up. DATA points to a struct set up by cwdr that | |
816a6f06 JB |
217 | says what proc to call, and what args to apply it to. |
218 | ||
219 | With a little thought, we could replace this with scm_body_thunk, | |
220 | but I don't want to mess with that at the moment. */ | |
650fa1ab | 221 | static SCM |
39752bec | 222 | cwdr_body (void *data) |
650fa1ab JB |
223 | { |
224 | struct cwdr_body_data *c = (struct cwdr_body_data *) data; | |
225 | ||
226 | return scm_apply (c->body_proc, c->a1, c->args); | |
227 | } | |
228 | ||
e71575d9 MV |
229 | /* Record the fact that the body of the cwdr has thrown. Record |
230 | enough information to invoke the handler later when the dynamic | |
231 | root has been deestablished. */ | |
650fa1ab | 232 | |
f032b8a8 | 233 | static SCM |
e71575d9 | 234 | cwdr_handler (void *data, SCM tag, SCM args) |
f032b8a8 | 235 | { |
e71575d9 | 236 | struct cwdr_handler_data *c = (struct cwdr_handler_data *) data; |
f032b8a8 | 237 | |
e71575d9 MV |
238 | c->run_handler = 1; |
239 | c->tag = tag; | |
240 | c->args = args; | |
241 | return SCM_UNSPECIFIED; | |
f032b8a8 | 242 | } |
d564d753 MD |
243 | |
244 | /* This is the basic code for new root creation. | |
245 | * | |
246 | * WARNING! The order of actions in this routine is in many ways | |
247 | * critical. E. g., it is essential that an error doesn't leave Guile | |
650fa1ab | 248 | * in a messed up state. */ |
d564d753 | 249 | |
e71575d9 MV |
250 | SCM |
251 | scm_internal_cwdr (scm_catch_body_t body, void *body_data, | |
252 | scm_catch_handler_t handler, void *handler_data, | |
253 | SCM_STACKITEM *stack_start) | |
d564d753 | 254 | { |
e71575d9 MV |
255 | #ifdef USE_STACKJMPBUF |
256 | scm_contregs static_jmpbuf; | |
257 | #endif | |
d564d753 | 258 | int old_ints_disabled = scm_ints_disabled; |
8938d022 | 259 | SCM old_rootcont, old_winds; |
e71575d9 | 260 | struct cwdr_handler_data my_handler_data; |
d564d753 MD |
261 | SCM answer; |
262 | ||
e71575d9 | 263 | /* Create a fresh root continuation. */ |
d564d753 MD |
264 | { |
265 | SCM new_rootcont; | |
266 | SCM_NEWCELL (new_rootcont); | |
267 | SCM_REDEFER_INTS; | |
e71575d9 MV |
268 | #ifdef USE_STACKJMPBUF |
269 | SCM_SETJMPBUF (new_rootcont, &static_jmpbuf); | |
270 | #else | |
d564d753 | 271 | SCM_SETJMPBUF (new_rootcont, |
0db18cf4 | 272 | scm_must_malloc ((long) sizeof (scm_contregs), |
d564d753 | 273 | "inferior root continuation")); |
e71575d9 | 274 | #endif |
a6c64c3c | 275 | SCM_SETCAR (new_rootcont, scm_tc7_contin); |
d564d753 MD |
276 | SCM_DYNENV (new_rootcont) = SCM_EOL; |
277 | SCM_BASE (new_rootcont) = stack_start; | |
8938d022 | 278 | SCM_SEQ (new_rootcont) = ++n_dynamic_roots; |
d564d753 MD |
279 | #ifdef DEBUG_EXTENSIONS |
280 | SCM_DFRAME (new_rootcont) = 0; | |
281 | #endif | |
8938d022 MD |
282 | old_rootcont = scm_rootcont; |
283 | scm_rootcont = new_rootcont; | |
d564d753 MD |
284 | SCM_REALLOW_INTS; |
285 | } | |
286 | ||
8938d022 MD |
287 | /* Exit caller's dynamic state. |
288 | */ | |
289 | old_winds = scm_dynwinds; | |
290 | scm_dowinds (SCM_EOL, scm_ilength (scm_dynwinds)); | |
d564d753 | 291 | #ifdef DEBUG_EXTENSIONS |
308277cb | 292 | SCM_DFRAME (old_rootcont) = scm_last_debug_frame; |
8938d022 | 293 | scm_last_debug_frame = 0; |
d564d753 | 294 | #endif |
650fa1ab | 295 | |
e71575d9 MV |
296 | { |
297 | my_handler_data.run_handler = 0; | |
816a6f06 | 298 | answer = scm_internal_catch (SCM_BOOL_T, |
e71575d9 MV |
299 | body, body_data, |
300 | cwdr_handler, &my_handler_data); | |
650fa1ab | 301 | } |
e71575d9 | 302 | |
d564d753 MD |
303 | scm_dowinds (old_winds, - scm_ilength (old_winds)); |
304 | SCM_REDEFER_INTS; | |
e71575d9 MV |
305 | #ifdef USE_STACKCJMPBUF |
306 | SCM_SETJMPBUF (scm_rootcont, NULL); | |
307 | #endif | |
d564d753 | 308 | #ifdef DEBUG_EXTENSIONS |
308277cb | 309 | scm_last_debug_frame = SCM_DFRAME (old_rootcont); |
d564d753 | 310 | #endif |
308277cb | 311 | scm_rootcont = old_rootcont; |
d564d753 MD |
312 | SCM_REALLOW_INTS; |
313 | scm_ints_disabled = old_ints_disabled; | |
e71575d9 MV |
314 | |
315 | /* Now run the real handler iff the body did a throw. */ | |
316 | if (my_handler_data.run_handler) | |
317 | return handler (handler_data, my_handler_data.tag, my_handler_data.args); | |
318 | else | |
319 | return answer; | |
d564d753 MD |
320 | } |
321 | ||
e71575d9 MV |
322 | /* The original CWDR for invoking Scheme code with a Scheme handler. */ |
323 | ||
324 | static SCM | |
325 | cwdr (SCM proc, SCM a1, SCM args, SCM handler, SCM_STACKITEM *stack_start) | |
326 | { | |
327 | struct cwdr_body_data c; | |
328 | ||
329 | c.a1 = a1; | |
330 | c.args = args; | |
331 | c.body_proc = proc; | |
332 | ||
333 | return scm_internal_cwdr (cwdr_body, &c, | |
334 | scm_handle_by_proc, &handler, | |
335 | stack_start); | |
336 | } | |
d564d753 | 337 | |
a1ec6916 | 338 | SCM_DEFINE(scm_call_with_dynamic_root, "call-with-dynamic-root", 2, 0, 0, |
1bbd0b84 | 339 | (SCM thunk, SCM handler), |
4079f87e GB |
340 | "Evaluate @var{(thunk)} in a new dynamic context, returning its value. |
341 | ||
342 | If an error occurs during evaluation, apply @var{handler} to the | |
343 | arguments to the throw, just as @code{throw} would. If this happens, | |
344 | @var{handler} is called outside the scope of the new root -- it is | |
345 | called in the same dynamic context in which | |
346 | @code{call-with-dynamic-root} was evaluated. | |
347 | ||
348 | If @var{thunk} captures a continuation, the continuation is rooted at | |
349 | the call to @var{thunk}. In particular, the call to | |
350 | @code{call-with-dynamic-root} is not captured. Therefore, | |
351 | @code{call-with-dynamic-root} always returns at most one time. | |
352 | ||
353 | Before calling @var{thunk}, the dynamic-wind chain is un-wound back to | |
354 | the root and a new chain started for @var{thunk}. Therefore, this call | |
355 | may not do what you expect: | |
356 | ||
357 | @example | |
358 | ;; Almost certainly a bug: | |
359 | (with-output-to-port | |
360 | some-port | |
361 | ||
362 | (lambda () | |
363 | (call-with-dynamic-root | |
364 | (lambda () | |
365 | (display 'fnord) | |
366 | (newline)) | |
367 | (lambda (errcode) errcode)))) | |
368 | @end example | |
369 | ||
370 | The problem is, on what port will @samp{fnord\n} be displayed? You | |
371 | might expect that because of the @code{with-output-to-port} that | |
372 | it will be displayed on the port bound to @code{some-port}. But it | |
373 | probably won't -- before evaluating the thunk, dynamic winds are | |
374 | unwound, including those created by @code{with-output-to-port}. | |
375 | So, the standard output port will have been re-set to its default value | |
376 | before @code{display} is evaluated. | |
377 | ||
378 | (This function was added to Guile mostly to help calls to functions in C | |
379 | libraries that can not tolerate non-local exits or calls that return | |
380 | multiple times. If such functions call back to the interpreter, it should | |
381 | be under a new dynamic root.)") | |
1bbd0b84 | 382 | #define FUNC_NAME s_scm_call_with_dynamic_root |
d564d753 MD |
383 | { |
384 | SCM_STACKITEM stack_place; | |
8938d022 | 385 | return cwdr (thunk, SCM_EOL, SCM_EOL, handler, &stack_place); |
d564d753 | 386 | } |
1bbd0b84 | 387 | #undef FUNC_NAME |
d564d753 | 388 | |
a1ec6916 | 389 | SCM_DEFINE(scm_dynamic_root, "dynamic-root", 0, 0, 0, |
1bbd0b84 | 390 | (), |
4079f87e GB |
391 | "Return an object representing the current dynamic root. |
392 | ||
393 | These objects are only useful for comparison using @code{eq?}. | |
394 | They are currently represented as numbers, but your code should | |
395 | in no way depend on this.") | |
1bbd0b84 | 396 | #define FUNC_NAME s_scm_dynamic_root |
d564d753 MD |
397 | { |
398 | return scm_ulong2num (SCM_SEQ (scm_root->rootcont)); | |
399 | } | |
1bbd0b84 | 400 | #undef FUNC_NAME |
d564d753 | 401 | |
d564d753 | 402 | SCM |
1bbd0b84 | 403 | scm_apply_with_dynamic_root (SCM proc, SCM a1, SCM args, SCM handler) |
d564d753 MD |
404 | { |
405 | SCM_STACKITEM stack_place; | |
8938d022 | 406 | return cwdr (proc, a1, args, handler, &stack_place); |
d564d753 | 407 | } |
0f2d19dd JB |
408 | |
409 | \f | |
410 | ||
411 | /* Call thunk(closure) underneath a top-level error handler. | |
412 | * If an error occurs, pass the exitval through err_filter and return it. | |
413 | * If no error occurs, return the value of thunk. | |
414 | */ | |
415 | ||
416 | ||
417 | #ifdef _UNICOS | |
418 | typedef int setjmp_type; | |
419 | #else | |
420 | typedef long setjmp_type; | |
421 | #endif | |
422 | ||
423 | ||
1cc91f1b | 424 | |
0f2d19dd | 425 | SCM |
1bbd0b84 | 426 | scm_call_catching_errors (SCM (*thunk)(), SCM (*err_filter)(), void *closure) |
0f2d19dd JB |
427 | { |
428 | SCM answer; | |
429 | setjmp_type i; | |
faa6b3df | 430 | #ifdef DEBUG_EXTENSIONS |
8938d022 | 431 | SCM_DFRAME (scm_rootcont) = scm_last_debug_frame; |
faa6b3df | 432 | #endif |
0f2d19dd | 433 | i = setjmp (SCM_JMPBUF (scm_rootcont)); |
faa6b3df | 434 | scm_stack_checking_enabled_p = SCM_STACK_CHECKING_P; |
0f2d19dd JB |
435 | if (!i) |
436 | { | |
437 | scm_gc_heap_lock = 0; | |
438 | answer = thunk (closure); | |
439 | } | |
440 | else | |
441 | { | |
442 | scm_gc_heap_lock = 1; | |
443 | answer = err_filter (scm_exitval, closure); | |
444 | } | |
445 | return answer; | |
446 | } | |
447 | ||
d564d753 MD |
448 | void |
449 | scm_init_root () | |
450 | { | |
23a62151 MD |
451 | scm_tc16_root = scm_make_smob_type_mfpe ("root", sizeof (struct scm_root_state), |
452 | mark_root, NULL, print_root, NULL); | |
453 | ||
d564d753 MD |
454 | #include "root.x" |
455 | } |