Commit | Line | Data |
---|---|---|
2b829bbb | 1 | /* Copyright (C) 1995,1996,1998,2000,2001,2004, 2006 Free Software Foundation, Inc. |
0f2d19dd | 2 | * |
73be1d9e MV |
3 | * This library is free software; you can redistribute it and/or |
4 | * modify it under the terms of the GNU Lesser General Public | |
5 | * License as published by the Free Software Foundation; either | |
6 | * version 2.1 of the License, or (at your option) any later version. | |
0f2d19dd | 7 | * |
73be1d9e MV |
8 | * This library 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 GNU | |
11 | * Lesser General Public License for more details. | |
0f2d19dd | 12 | * |
73be1d9e MV |
13 | * You should have received a copy of the GNU Lesser General Public |
14 | * License along with this library; if not, write to the Free Software | |
92205699 | 15 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
73be1d9e | 16 | */ |
1bbd0b84 | 17 | |
1bbd0b84 | 18 | |
0f2d19dd JB |
19 | \f |
20 | ||
bbd43f03 RB |
21 | #include "libguile/_scm.h" |
22 | ||
13070bd3 | 23 | #include <string.h> |
8b7f0bb3 | 24 | #include <stdio.h> |
13070bd3 | 25 | |
8b7f0bb3 | 26 | #include "libguile/async.h" |
d0f6ceb8 | 27 | #include "libguile/debug.h" |
a0599745 MD |
28 | #include "libguile/root.h" |
29 | #include "libguile/stackchk.h" | |
5f144b10 GH |
30 | #include "libguile/smob.h" |
31 | #include "libguile/ports.h" | |
32 | #include "libguile/dynwind.h" | |
ce212434 | 33 | #include "libguile/values.h" |
9de87eea | 34 | #include "libguile/eval.h" |
5f144b10 | 35 | |
db4b4ca6 | 36 | #include "libguile/validate.h" |
a0599745 | 37 | #include "libguile/continuations.h" |
01c8a3dd | 38 | |
0f2d19dd JB |
39 | \f |
40 | ||
41 | /* {Continuations} | |
42 | */ | |
43 | ||
92c2555f | 44 | scm_t_bits scm_tc16_continuation; |
0f2d19dd | 45 | |
e841c3e0 KN |
46 | static SCM |
47 | continuation_mark (SCM obj) | |
5f144b10 | 48 | { |
92c2555f | 49 | scm_t_contregs *continuation = SCM_CONTREGS (obj); |
01c8a3dd | 50 | |
9de87eea | 51 | scm_gc_mark (continuation->root); |
5f144b10 GH |
52 | scm_gc_mark (continuation->throw_value); |
53 | scm_mark_locations (continuation->stack, continuation->num_stack_items); | |
193297d8 RB |
54 | #ifdef __ia64__ |
55 | if (continuation->backing_store) | |
56 | scm_mark_locations (continuation->backing_store, | |
57 | continuation->backing_store_size / | |
58 | sizeof (SCM_STACKITEM)); | |
59 | #endif /* __ia64__ */ | |
5f144b10 GH |
60 | return continuation->dynenv; |
61 | } | |
01c8a3dd | 62 | |
1be6b49c | 63 | static size_t |
e841c3e0 | 64 | continuation_free (SCM obj) |
5f144b10 | 65 | { |
92c2555f | 66 | scm_t_contregs *continuation = SCM_CONTREGS (obj); |
9de87eea | 67 | /* stack array size is 1 if num_stack_items is 0. */ |
1be6b49c | 68 | size_t extra_items = (continuation->num_stack_items > 0) |
5f144b10 GH |
69 | ? (continuation->num_stack_items - 1) |
70 | : 0; | |
92c2555f | 71 | size_t bytes_free = sizeof (scm_t_contregs) |
5f144b10 | 72 | + extra_items * sizeof (SCM_STACKITEM); |
193297d8 RB |
73 | |
74 | #ifdef __ia64__ | |
4c9419ac MV |
75 | scm_gc_free (continuation->backing_store, continuation->backing_store_size, |
76 | "continuation backing store"); | |
193297d8 | 77 | #endif /* __ia64__ */ |
4c9419ac MV |
78 | scm_gc_free (continuation, bytes_free, "continuation"); |
79 | return 0; | |
5f144b10 | 80 | } |
01c8a3dd | 81 | |
e841c3e0 | 82 | static int |
e81d98ec | 83 | continuation_print (SCM obj, SCM port, scm_print_state *state SCM_UNUSED) |
5f144b10 | 84 | { |
92c2555f | 85 | scm_t_contregs *continuation = SCM_CONTREGS (obj); |
5f144b10 GH |
86 | |
87 | scm_puts ("#<continuation ", port); | |
88 | scm_intprint (continuation->num_stack_items, 10, port); | |
89 | scm_puts (" @ ", port); | |
0345e278 | 90 | scm_uintprint (SCM_CELL_WORD_1 (obj), 16, port); |
5f144b10 GH |
91 | scm_putc ('>', port); |
92 | return 1; | |
93 | } | |
1cc91f1b | 94 | |
193297d8 | 95 | #ifdef __ia64__ |
87855fa2 MV |
96 | /* Extern declaration of getcontext()/setcontext() in order to redefine |
97 | getcontext() since on ia64-linux the second return value indicates whether | |
98 | it returned from getcontext() itself or by running setcontext(). */ | |
193297d8 RB |
99 | struct rv |
100 | { | |
101 | long retval; | |
102 | long first_return; | |
103 | }; | |
08e5f840 RB |
104 | |
105 | #ifdef __GNUC__ | |
106 | __attribute__ ((returns_twice)) | |
107 | #endif /* __GNUC__ */ | |
78b6566e | 108 | extern struct rv ia64_getcontext (ucontext_t *) __asm__ ("getcontext"); |
193297d8 RB |
109 | #endif /* __ia64__ */ |
110 | ||
5f144b10 GH |
111 | /* this may return more than once: the first time with the escape |
112 | procedure, then subsequently with the value to be passed to the | |
113 | continuation. */ | |
114 | #define FUNC_NAME "scm_make_continuation" | |
0f2d19dd | 115 | SCM |
5f144b10 | 116 | scm_make_continuation (int *first) |
0f2d19dd | 117 | { |
9de87eea MV |
118 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; |
119 | SCM cont; | |
92c2555f | 120 | scm_t_contregs *continuation; |
c014a02e | 121 | long stack_size; |
01c8a3dd | 122 | SCM_STACKITEM * src; |
193297d8 RB |
123 | #ifdef __ia64__ |
124 | struct rv rv; | |
87855fa2 | 125 | #endif /* __ia64__ */ |
0f2d19dd | 126 | |
0f2d19dd | 127 | SCM_FLUSH_REGISTER_WINDOWS; |
9de87eea | 128 | stack_size = scm_stack_size (thread->continuation_base); |
4c9419ac MV |
129 | continuation = scm_gc_malloc (sizeof (scm_t_contregs) |
130 | + (stack_size - 1) * sizeof (SCM_STACKITEM), | |
131 | "continuation"); | |
5f144b10 | 132 | continuation->num_stack_items = stack_size; |
9de87eea | 133 | continuation->dynenv = scm_i_dynwinds (); |
5f144b10 | 134 | continuation->throw_value = SCM_EOL; |
9de87eea MV |
135 | continuation->root = thread->continuation_root; |
136 | continuation->dframe = scm_i_last_debug_frame (); | |
137 | src = thread->continuation_base; | |
5f144b10 | 138 | SCM_NEWSMOB (cont, scm_tc16_continuation, continuation); |
01c8a3dd | 139 | |
4ccb2cd2 | 140 | #if ! SCM_STACK_GROWS_UP |
5f144b10 GH |
141 | src -= stack_size; |
142 | #endif | |
5c5c27dc | 143 | continuation->offset = continuation->stack - src; |
5f144b10 GH |
144 | memcpy (continuation->stack, src, sizeof (SCM_STACKITEM) * stack_size); |
145 | ||
193297d8 | 146 | #ifdef __ia64__ |
78b6566e | 147 | rv = ia64_getcontext (&continuation->ctx); |
193297d8 RB |
148 | if (rv.first_return) |
149 | { | |
150 | continuation->backing_store_size = | |
151 | continuation->ctx.uc_mcontext.sc_ar_bsp - | |
87855fa2 | 152 | (unsigned long) __libc_ia64_register_backing_store_base; |
193297d8 RB |
153 | continuation->backing_store = NULL; |
154 | continuation->backing_store = | |
4c9419ac MV |
155 | scm_gc_malloc (continuation->backing_store_size, |
156 | "continuation backing store"); | |
193297d8 RB |
157 | memcpy (continuation->backing_store, |
158 | (void *) __libc_ia64_register_backing_store_base, | |
159 | continuation->backing_store_size); | |
160 | *first = 1; | |
161 | return cont; | |
162 | } | |
163 | else | |
164 | { | |
3c468478 | 165 | SCM ret = continuation->throw_value; |
193297d8 | 166 | *first = 0; |
3c468478 MV |
167 | continuation->throw_value = SCM_BOOL_F; |
168 | return ret; | |
193297d8 RB |
169 | } |
170 | #else /* !__ia64__ */ | |
5f144b10 GH |
171 | if (setjmp (continuation->jmpbuf)) |
172 | { | |
3c468478 | 173 | SCM ret = continuation->throw_value; |
5f144b10 | 174 | *first = 0; |
3c468478 MV |
175 | continuation->throw_value = SCM_BOOL_F; |
176 | return ret; | |
5f144b10 GH |
177 | } |
178 | else | |
179 | { | |
180 | *first = 1; | |
181 | return cont; | |
182 | } | |
193297d8 | 183 | #endif /* !__ia64__ */ |
0f2d19dd | 184 | } |
5f144b10 | 185 | #undef FUNC_NAME |
0f2d19dd | 186 | |
d3c6aef9 MV |
187 | |
188 | /* Invoking a continuation proceeds as follows: | |
189 | * | |
190 | * - the stack is made large enough for the called continuation | |
191 | * - the old windchain is unwound down to the branching point | |
192 | * - the continuation stack is copied into place | |
193 | * - the windchain is rewound up to the continuation's context | |
194 | * - the continuation is invoked via longjmp (or setcontext) | |
195 | * | |
196 | * This order is important so that unwind and rewind handlers are run | |
197 | * with their correct stack. | |
198 | */ | |
199 | ||
5f144b10 | 200 | static void scm_dynthrow (SCM, SCM); |
01c8a3dd DH |
201 | |
202 | /* Grow the stack by a fixed amount to provide space to copy in the | |
203 | * continuation. Possibly this function has to be called several times | |
204 | * recursively before enough space is available. Make sure the compiler does | |
205 | * not optimize the growth array away by storing it's address into a global | |
206 | * variable. | |
207 | */ | |
208 | ||
92c2555f | 209 | scm_t_bits scm_i_dummy; |
1cc91f1b | 210 | |
0f2d19dd | 211 | static void |
01c8a3dd DH |
212 | grow_stack (SCM cont, SCM val) |
213 | { | |
92c2555f | 214 | scm_t_bits growth[100]; |
01c8a3dd | 215 | |
92c2555f | 216 | scm_i_dummy = (scm_t_bits) growth; |
01c8a3dd | 217 | scm_dynthrow (cont, val); |
0f2d19dd | 218 | } |
0f2d19dd | 219 | |
1cc91f1b | 220 | |
01c8a3dd DH |
221 | /* Copy the continuation stack into the current stack. Calling functions from |
222 | * within this function is safe, since only stack frames below this function's | |
223 | * own frame are overwritten. Thus, memcpy can be used for best performance. | |
224 | */ | |
d3c6aef9 MV |
225 | |
226 | typedef struct { | |
227 | scm_t_contregs *continuation; | |
228 | SCM_STACKITEM *dst; | |
229 | } copy_stack_data; | |
230 | ||
01c8a3dd | 231 | static void |
d3c6aef9 MV |
232 | copy_stack (void *data) |
233 | { | |
234 | copy_stack_data *d = (copy_stack_data *)data; | |
235 | memcpy (d->dst, d->continuation->stack, | |
236 | sizeof (SCM_STACKITEM) * d->continuation->num_stack_items); | |
237 | } | |
238 | ||
239 | static void | |
240 | copy_stack_and_call (scm_t_contregs *continuation, SCM val, | |
5f144b10 | 241 | SCM_STACKITEM * dst) |
0f2d19dd | 242 | { |
d3c6aef9 MV |
243 | long delta; |
244 | copy_stack_data data; | |
245 | ||
9de87eea | 246 | delta = scm_ilength (scm_i_dynwinds ()) - scm_ilength (continuation->dynenv); |
d3c6aef9 MV |
247 | data.continuation = continuation; |
248 | data.dst = dst; | |
14578fa4 | 249 | scm_i_dowinds (continuation->dynenv, delta, copy_stack, &data); |
01c8a3dd | 250 | |
9de87eea | 251 | scm_i_set_last_debug_frame (continuation->dframe); |
01c8a3dd | 252 | |
5f144b10 | 253 | continuation->throw_value = val; |
193297d8 RB |
254 | #ifdef __ia64__ |
255 | memcpy ((void *) __libc_ia64_register_backing_store_base, | |
256 | continuation->backing_store, | |
257 | continuation->backing_store_size); | |
258 | setcontext (&continuation->ctx); | |
259 | #else | |
5f144b10 | 260 | longjmp (continuation->jmpbuf, 1); |
193297d8 | 261 | #endif |
01c8a3dd DH |
262 | } |
263 | ||
01c8a3dd DH |
264 | /* Call grow_stack until the stack space is large enough, then, as the current |
265 | * stack frame might get overwritten, let copy_stack_and_call perform the | |
266 | * actual copying and continuation calling. | |
267 | */ | |
268 | static void | |
269 | scm_dynthrow (SCM cont, SCM val) | |
270 | { | |
9de87eea | 271 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; |
92c2555f | 272 | scm_t_contregs *continuation = SCM_CONTREGS (cont); |
9de87eea | 273 | SCM_STACKITEM *dst = thread->continuation_base; |
01c8a3dd DH |
274 | SCM_STACKITEM stack_top_element; |
275 | ||
8b7f0bb3 MV |
276 | if (scm_i_critical_section_level) |
277 | { | |
278 | fprintf (stderr, "continuation invoked from within critical section.\n"); | |
279 | abort (); | |
280 | } | |
281 | ||
4ccb2cd2 | 282 | #if SCM_STACK_GROWS_UP |
5afcf08b | 283 | if (dst + continuation->num_stack_items >= &stack_top_element) |
01c8a3dd | 284 | grow_stack (cont, val); |
0f2d19dd | 285 | #else |
5f144b10 | 286 | dst -= continuation->num_stack_items; |
c8a1bdc4 | 287 | if (dst <= &stack_top_element) |
01c8a3dd | 288 | grow_stack (cont, val); |
0f2d19dd | 289 | #endif /* def SCM_STACK_GROWS_UP */ |
01c8a3dd | 290 | |
5f144b10 GH |
291 | SCM_FLUSH_REGISTER_WINDOWS; |
292 | copy_stack_and_call (continuation, val, dst); | |
0f2d19dd JB |
293 | } |
294 | ||
db4b4ca6 DH |
295 | |
296 | static SCM | |
297 | continuation_apply (SCM cont, SCM args) | |
5f144b10 | 298 | #define FUNC_NAME "continuation_apply" |
0f2d19dd | 299 | { |
9de87eea | 300 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; |
92c2555f | 301 | scm_t_contregs *continuation = SCM_CONTREGS (cont); |
5f144b10 | 302 | |
9de87eea | 303 | if (continuation->root != thread->continuation_root) |
5f144b10 | 304 | { |
9de87eea MV |
305 | SCM_MISC_ERROR |
306 | ("invoking continuation would cross continuation barrier: ~A", | |
307 | scm_list_1 (cont)); | |
5f144b10 | 308 | } |
0f2d19dd | 309 | |
ce212434 | 310 | scm_dynthrow (cont, scm_values (args)); |
0f2d19dd JB |
311 | return SCM_UNSPECIFIED; /* not reached */ |
312 | } | |
5f144b10 | 313 | #undef FUNC_NAME |
0f2d19dd | 314 | |
9de87eea MV |
315 | SCM |
316 | scm_i_with_continuation_barrier (scm_t_catch_body body, | |
317 | void *body_data, | |
318 | scm_t_catch_handler handler, | |
43e01b1e NJ |
319 | void *handler_data, |
320 | scm_t_catch_handler pre_unwind_handler, | |
321 | void *pre_unwind_handler_data) | |
9de87eea MV |
322 | { |
323 | SCM_STACKITEM stack_item; | |
324 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; | |
325 | SCM old_controot; | |
326 | SCM_STACKITEM *old_contbase; | |
327 | scm_t_debug_frame *old_lastframe; | |
328 | SCM result; | |
329 | ||
330 | /* Establish a fresh continuation root. | |
331 | */ | |
332 | old_controot = thread->continuation_root; | |
333 | old_contbase = thread->continuation_base; | |
334 | old_lastframe = thread->last_debug_frame; | |
335 | thread->continuation_root = scm_cons (thread->handle, old_controot); | |
336 | thread->continuation_base = &stack_item; | |
337 | thread->last_debug_frame = NULL; | |
338 | ||
339 | /* Call FUNC inside a catch all. This is now guaranteed to return | |
340 | directly and exactly once. | |
341 | */ | |
43e01b1e NJ |
342 | result = scm_c_catch (SCM_BOOL_T, |
343 | body, body_data, | |
344 | handler, handler_data, | |
345 | pre_unwind_handler, pre_unwind_handler_data); | |
9de87eea MV |
346 | |
347 | /* Return to old continuation root. | |
348 | */ | |
349 | thread->last_debug_frame = old_lastframe; | |
350 | thread->continuation_base = old_contbase; | |
351 | thread->continuation_root = old_controot; | |
352 | ||
353 | return result; | |
354 | } | |
355 | ||
356 | struct c_data { | |
357 | void *(*func) (void *); | |
358 | void *data; | |
359 | void *result; | |
360 | }; | |
361 | ||
362 | static SCM | |
363 | c_body (void *d) | |
364 | { | |
365 | struct c_data *data = (struct c_data *)d; | |
366 | data->result = data->func (data->data); | |
367 | return SCM_UNSPECIFIED; | |
368 | } | |
369 | ||
370 | static SCM | |
371 | c_handler (void *d, SCM tag, SCM args) | |
372 | { | |
373 | struct c_data *data = (struct c_data *)d; | |
9de87eea MV |
374 | data->result = NULL; |
375 | return SCM_UNSPECIFIED; | |
376 | } | |
377 | ||
378 | void * | |
379 | scm_c_with_continuation_barrier (void *(*func) (void *), void *data) | |
380 | { | |
381 | struct c_data c_data; | |
382 | c_data.func = func; | |
383 | c_data.data = data; | |
384 | scm_i_with_continuation_barrier (c_body, &c_data, | |
43e01b1e NJ |
385 | c_handler, &c_data, |
386 | scm_handle_by_message_noexit, NULL); | |
9de87eea MV |
387 | return c_data.result; |
388 | } | |
389 | ||
390 | struct scm_data { | |
391 | SCM proc; | |
392 | }; | |
393 | ||
394 | static SCM | |
395 | scm_body (void *d) | |
396 | { | |
397 | struct scm_data *data = (struct scm_data *)d; | |
398 | return scm_call_0 (data->proc); | |
399 | } | |
400 | ||
401 | static SCM | |
402 | scm_handler (void *d, SCM tag, SCM args) | |
403 | { | |
9de87eea MV |
404 | return SCM_BOOL_F; |
405 | } | |
406 | ||
407 | SCM_DEFINE (scm_with_continuation_barrier, "with-continuation-barrier", 1,0,0, | |
408 | (SCM proc), | |
69d2000d MV |
409 | "Call @var{proc} and return its result. Do not allow the invocation of\n" |
410 | "continuations that would leave or enter the dynamic extent of the call\n" | |
411 | "to @code{with-continuation-barrier}. Such an attempt causes an error\n" | |
412 | "to be signaled.\n" | |
413 | "\n" | |
414 | "Throws (such as errors) that are not caught from within @var{proc} are\n" | |
415 | "caught by @code{with-continuation-barrier}. In that case, a short\n" | |
416 | "message is printed to the current error port and @code{#f} is returned.\n" | |
417 | "\n" | |
418 | "Thus, @code{with-continuation-barrier} returns exactly once.\n") | |
9de87eea MV |
419 | #define FUNC_NAME s_scm_with_continuation_barrier |
420 | { | |
421 | struct scm_data scm_data; | |
422 | scm_data.proc = proc; | |
423 | return scm_i_with_continuation_barrier (scm_body, &scm_data, | |
43e01b1e NJ |
424 | scm_handler, &scm_data, |
425 | scm_handle_by_message_noexit, NULL); | |
9de87eea MV |
426 | } |
427 | #undef FUNC_NAME | |
db4b4ca6 | 428 | |
0f2d19dd JB |
429 | void |
430 | scm_init_continuations () | |
0f2d19dd | 431 | { |
5f144b10 GH |
432 | scm_tc16_continuation = scm_make_smob_type ("continuation", 0); |
433 | scm_set_smob_mark (scm_tc16_continuation, continuation_mark); | |
434 | scm_set_smob_free (scm_tc16_continuation, continuation_free); | |
435 | scm_set_smob_print (scm_tc16_continuation, continuation_print); | |
436 | scm_set_smob_apply (scm_tc16_continuation, continuation_apply, 0, 0, 1); | |
a0599745 | 437 | #include "libguile/continuations.x" |
0f2d19dd JB |
438 | } |
439 | ||
89e00824 ML |
440 | /* |
441 | Local Variables: | |
442 | c-file-style: "gnu" | |
443 | End: | |
444 | */ |