Commit | Line | Data |
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5556c175 | 1 | /* Copyright (C) 1995,1996,1998,2000,2001,2004, 2006, 2008, 2009, 2010, 2011, 2012 Free Software Foundation, Inc. |
0f2d19dd | 2 | * |
73be1d9e | 3 | * This library is free software; you can redistribute it and/or |
53befeb7 NJ |
4 | * modify it under the terms of the GNU Lesser General Public License |
5 | * as published by the Free Software Foundation; either version 3 of | |
6 | * the License, or (at your option) any later version. | |
0f2d19dd | 7 | * |
53befeb7 NJ |
8 | * This library is distributed in the hope that it will be useful, but |
9 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
73be1d9e MV |
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 | |
53befeb7 NJ |
15 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
16 | * 02110-1301 USA | |
73be1d9e | 17 | */ |
1bbd0b84 | 18 | |
1bbd0b84 | 19 | |
0f2d19dd | 20 | \f |
dbb605f5 LC |
21 | #ifdef HAVE_CONFIG_H |
22 | # include <config.h> | |
23 | #endif | |
0f2d19dd | 24 | |
bbd43f03 RB |
25 | #include "libguile/_scm.h" |
26 | ||
13070bd3 | 27 | #include <string.h> |
8b7f0bb3 | 28 | #include <stdio.h> |
13070bd3 | 29 | |
8b7f0bb3 | 30 | #include "libguile/async.h" |
d0f6ceb8 | 31 | #include "libguile/debug.h" |
a0599745 MD |
32 | #include "libguile/root.h" |
33 | #include "libguile/stackchk.h" | |
5f144b10 GH |
34 | #include "libguile/smob.h" |
35 | #include "libguile/ports.h" | |
36 | #include "libguile/dynwind.h" | |
9de87eea | 37 | #include "libguile/eval.h" |
bfffd258 | 38 | #include "libguile/vm.h" |
1d1cae0e | 39 | #include "libguile/instructions.h" |
5f144b10 | 40 | |
db4b4ca6 | 41 | #include "libguile/validate.h" |
a0599745 | 42 | #include "libguile/continuations.h" |
01c8a3dd | 43 | |
0f2d19dd JB |
44 | \f |
45 | ||
1d1cae0e AW |
46 | static scm_t_bits tc16_continuation; |
47 | #define SCM_CONTREGSP(x) SCM_TYP16_PREDICATE (tc16_continuation, x) | |
48 | ||
49 | #define SCM_CONTREGS(x) ((scm_t_contregs *) SCM_SMOB_DATA_1 (x)) | |
50 | ||
51 | #define SCM_CONTINUATION_LENGTH(x) (SCM_CONTREGS (x)->num_stack_items) | |
52 | #define SCM_SET_CONTINUATION_LENGTH(x, n)\ | |
53 | (SCM_CONTREGS (x)->num_stack_items = (n)) | |
54 | #define SCM_JMPBUF(x) ((SCM_CONTREGS (x))->jmpbuf) | |
55 | #define SCM_DYNENV(x) ((SCM_CONTREGS (x))->dynenv) | |
1d1cae0e AW |
56 | #define SCM_CONTINUATION_ROOT(x) ((SCM_CONTREGS (x))->root) |
57 | #define SCM_DFRAME(x) ((SCM_CONTREGS (x))->dframe) | |
58 | ||
59 | \f | |
60 | ||
997659f8 | 61 | /* scm_i_make_continuation will return a procedure whose objcode contains an |
1d1cae0e AW |
62 | instruction to reinstate the continuation. Here, as in gsubr.c and smob.c, we |
63 | define the form of that trampoline function. | |
0f2d19dd JB |
64 | */ |
65 | ||
1d1cae0e | 66 | #ifdef WORDS_BIGENDIAN |
babfc7b2 AW |
67 | #define OBJCODE_HEADER(main,meta) 0, 0, 0, main, 0, 0, 0, meta+8 |
68 | #define META_HEADER(meta) 0, 0, 0, meta, 0, 0, 0, 0 | |
1d1cae0e | 69 | #else |
babfc7b2 AW |
70 | #define OBJCODE_HEADER(main,meta) main, 0, 0, 0, meta+8, 0, 0, 0 |
71 | #define META_HEADER(meta) meta, 0, 0, 0, 0, 0, 0, 0 | |
1d1cae0e AW |
72 | #endif |
73 | ||
5556c175 | 74 | #define OBJCODE_TAG SCM_MAKE_OBJCODE_TAG (SCM_OBJCODE_TYPE_STATIC, 0) |
1d1cae0e | 75 | |
5556c175 | 76 | #if defined (SCM_ALIGNED) && 0 |
1c05a2a1 | 77 | #define SCM_DECLARE_STATIC_ALIGNED_ARRAY(type, sym) \ |
1d1cae0e | 78 | static const type sym[] |
1c05a2a1 | 79 | #define SCM_STATIC_ALIGNED_ARRAY(alignment, type, sym) \ |
1d1cae0e | 80 | static SCM_ALIGNED (alignment) const type sym[] |
1d1cae0e AW |
81 | #define SCM_STATIC_OBJCODE(sym) \ |
82 | SCM_DECLARE_STATIC_ALIGNED_ARRAY (scm_t_uint8, sym##__bytecode); \ | |
83 | SCM_STATIC_ALIGNED_ARRAY (8, scm_t_cell, sym##__cells) = { \ | |
5556c175 | 84 | { SCM_PACK (OBJCODE_TAG), SCM_PACK (sym##__bytecode) }, \ |
1d1cae0e AW |
85 | { SCM_BOOL_F, SCM_PACK (0) } \ |
86 | }; \ | |
87 | static const SCM sym = SCM_PACK (sym##__cells); \ | |
88 | SCM_STATIC_ALIGNED_ARRAY (8, scm_t_uint8, sym##__bytecode) | |
5556c175 AW |
89 | #else |
90 | #define SCM_STATIC_OBJCODE(sym) \ | |
91 | static SCM sym; \ | |
92 | static scm_t_uint8 *sym##_bytecode; \ | |
93 | SCM_SNARF_INIT(sym##_bytecode = scm_gc_malloc_pointerless (sizeof(sym##_bytecode__unaligned), "partial continuation stub"); \ | |
94 | memcpy (sym##_bytecode, sym##_bytecode__unaligned, sizeof(sym##_bytecode__unaligned));) \ | |
95 | SCM_SNARF_INIT(sym = scm_double_cell (OBJCODE_TAG, \ | |
96 | (scm_t_bits)sym##_bytecode, \ | |
97 | SCM_UNPACK (SCM_BOOL_F), \ | |
98 | 0);) \ | |
99 | static const scm_t_uint8 sym##_bytecode__unaligned[] | |
100 | #endif | |
101 | ||
1d1cae0e | 102 | |
1d1cae0e | 103 | SCM_STATIC_OBJCODE (cont_objcode) = { |
2ac16429 AW |
104 | /* This code is the same as in gsubr.c, except we use continuation_call |
105 | instead of subr_call. */ | |
babfc7b2 | 106 | OBJCODE_HEADER (8, 19), |
1d1cae0e AW |
107 | /* leave args on the stack */ |
108 | /* 0 */ scm_op_object_ref, 0, /* push scm_t_contregs smob */ | |
109 | /* 2 */ scm_op_continuation_call, /* and longjmp (whee) */ | |
110 | /* 3 */ scm_op_nop, /* pad to 8 bytes */ | |
111 | /* 4 */ scm_op_nop, scm_op_nop, scm_op_nop, scm_op_nop, | |
112 | /* 8 */ | |
113 | ||
114 | /* We could put some meta-info to say that this proc is a continuation. Not sure | |
115 | how to do that, though. */ | |
babfc7b2 | 116 | META_HEADER (19), |
1d1cae0e AW |
117 | /* 0 */ scm_op_make_eol, /* bindings */ |
118 | /* 1 */ scm_op_make_eol, /* sources */ | |
119 | /* 2 */ scm_op_make_int8, 0, scm_op_make_int8, 3, /* arity: from ip 0 to ip 3 */ | |
120 | /* 6 */ scm_op_make_int8_0, /* the arity is 0 required args */ | |
121 | /* 7 */ scm_op_make_int8_0, /* 0 optionals */ | |
122 | /* 8 */ scm_op_make_true, /* and a rest arg */ | |
123 | /* 9 */ scm_op_list, 0, 5, /* make a list of those 5 vals */ | |
124 | /* 12 */ scm_op_list, 0, 1, /* and the arities will be a list of that one list */ | |
125 | /* 15 */ scm_op_list, 0, 3, /* pack bindings, sources, and arities into list */ | |
126 | /* 18 */ scm_op_return /* and return */ | |
127 | /* 19 */ | |
128 | }; | |
129 | ||
130 | ||
babfc7b2 AW |
131 | SCM_STATIC_OBJCODE (call_cc_objcode) = { |
132 | /* Before Scheme's call/cc is compiled, eval.c will use this hand-coded | |
133 | call/cc. */ | |
134 | OBJCODE_HEADER (8, 17), | |
135 | /* 0 */ scm_op_assert_nargs_ee, 0, 1, /* assert that nargs==1 */ | |
136 | /* 3 */ scm_op_local_ref, 0, /* push the proc */ | |
137 | /* 5 */ scm_op_tail_call_cc, /* and call/cc */ | |
138 | /* 6 */ scm_op_nop, scm_op_nop, /* pad to 8 bytes */ | |
139 | /* 8 */ | |
140 | ||
141 | META_HEADER (17), | |
142 | /* 0 */ scm_op_make_eol, /* bindings */ | |
143 | /* 1 */ scm_op_make_eol, /* sources */ | |
144 | /* 2 */ scm_op_make_int8, 3, scm_op_make_int8, 6, /* arity: from ip 0 to ip 6 */ | |
145 | /* 6 */ scm_op_make_int8_1, /* the arity is 0 required args */ | |
146 | /* 7 */ scm_op_list, 0, 3, /* make a list of those 5 vals */ | |
147 | /* 10 */ scm_op_list, 0, 1, /* and the arities will be a list of that one list */ | |
148 | /* 13 */ scm_op_list, 0, 3, /* pack bindings, sources, and arities into list */ | |
149 | /* 16 */ scm_op_return /* and return */ | |
150 | /* 17 */ | |
151 | }; | |
152 | ||
153 | ||
1d1cae0e AW |
154 | static SCM |
155 | make_continuation_trampoline (SCM contregs) | |
156 | { | |
157 | SCM ret = scm_make_program (cont_objcode, | |
158 | scm_c_make_vector (1, contregs), | |
159 | SCM_BOOL_F); | |
160 | SCM_SET_CELL_WORD_0 (ret, | |
161 | SCM_CELL_WORD_0 (ret) | SCM_F_PROGRAM_IS_CONTINUATION); | |
162 | ||
163 | return ret; | |
164 | } | |
165 | ||
166 | ||
167 | /* {Continuations} | |
168 | */ | |
0f2d19dd | 169 | |
01c8a3dd | 170 | |
e841c3e0 | 171 | static int |
e81d98ec | 172 | continuation_print (SCM obj, SCM port, scm_print_state *state SCM_UNUSED) |
5f144b10 | 173 | { |
92c2555f | 174 | scm_t_contregs *continuation = SCM_CONTREGS (obj); |
5f144b10 GH |
175 | |
176 | scm_puts ("#<continuation ", port); | |
177 | scm_intprint (continuation->num_stack_items, 10, port); | |
178 | scm_puts (" @ ", port); | |
0236bc68 | 179 | scm_uintprint (SCM_SMOB_DATA_1 (obj), 16, port); |
5f144b10 GH |
180 | scm_putc ('>', port); |
181 | return 1; | |
182 | } | |
1cc91f1b | 183 | |
5f144b10 | 184 | /* this may return more than once: the first time with the escape |
d8873dfe AW |
185 | procedure, then subsequently with SCM_UNDEFINED (the vals already having been |
186 | placed on the VM stack). */ | |
997659f8 | 187 | #define FUNC_NAME "scm_i_make_continuation" |
0f2d19dd | 188 | SCM |
269479e3 | 189 | scm_i_make_continuation (int *first, SCM vm, SCM vm_cont) |
0f2d19dd | 190 | { |
9de87eea MV |
191 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; |
192 | SCM cont; | |
92c2555f | 193 | scm_t_contregs *continuation; |
c014a02e | 194 | long stack_size; |
01c8a3dd | 195 | SCM_STACKITEM * src; |
0f2d19dd | 196 | |
0f2d19dd | 197 | SCM_FLUSH_REGISTER_WINDOWS; |
9de87eea | 198 | stack_size = scm_stack_size (thread->continuation_base); |
4c9419ac MV |
199 | continuation = scm_gc_malloc (sizeof (scm_t_contregs) |
200 | + (stack_size - 1) * sizeof (SCM_STACKITEM), | |
201 | "continuation"); | |
5f144b10 | 202 | continuation->num_stack_items = stack_size; |
9de87eea | 203 | continuation->dynenv = scm_i_dynwinds (); |
9de87eea | 204 | continuation->root = thread->continuation_root; |
9de87eea | 205 | src = thread->continuation_base; |
4ccb2cd2 | 206 | #if ! SCM_STACK_GROWS_UP |
5f144b10 GH |
207 | src -= stack_size; |
208 | #endif | |
5c5c27dc | 209 | continuation->offset = continuation->stack - src; |
5f144b10 | 210 | memcpy (continuation->stack, src, sizeof (SCM_STACKITEM) * stack_size); |
269479e3 AW |
211 | continuation->vm = vm; |
212 | continuation->vm_cont = vm_cont; | |
5f144b10 | 213 | |
1d1cae0e | 214 | SCM_NEWSMOB (cont, tc16_continuation, continuation); |
79824460 | 215 | |
a4dbe1ac | 216 | *first = !SCM_I_SETJMP (continuation->jmpbuf); |
346e4402 | 217 | if (*first) |
193297d8 | 218 | { |
346e4402 | 219 | #ifdef __ia64__ |
9a5fa6e9 | 220 | continuation->backing_store_size = |
346e4402 | 221 | (char *) scm_ia64_ar_bsp(&continuation->jmpbuf.ctx) |
9a5fa6e9 | 222 | - |
346e4402 | 223 | (char *) thread->register_backing_store_base; |
193297d8 RB |
224 | continuation->backing_store = NULL; |
225 | continuation->backing_store = | |
4c9419ac MV |
226 | scm_gc_malloc (continuation->backing_store_size, |
227 | "continuation backing store"); | |
193297d8 | 228 | memcpy (continuation->backing_store, |
346e4402 | 229 | (void *) thread->register_backing_store_base, |
193297d8 | 230 | continuation->backing_store_size); |
346e4402 | 231 | #endif /* __ia64__ */ |
1d1cae0e | 232 | return make_continuation_trampoline (cont); |
193297d8 RB |
233 | } |
234 | else | |
d8873dfe | 235 | return SCM_UNDEFINED; |
0f2d19dd | 236 | } |
5f144b10 | 237 | #undef FUNC_NAME |
0f2d19dd | 238 | |
babfc7b2 AW |
239 | SCM |
240 | scm_i_call_with_current_continuation (SCM proc) | |
241 | { | |
242 | static SCM call_cc = SCM_BOOL_F; | |
243 | ||
244 | if (scm_is_false (call_cc)) | |
245 | call_cc = scm_make_program (call_cc_objcode, SCM_BOOL_F, SCM_BOOL_F); | |
246 | ||
247 | return scm_call_1 (call_cc, proc); | |
248 | } | |
249 | ||
1d1cae0e AW |
250 | SCM |
251 | scm_i_continuation_to_frame (SCM continuation) | |
252 | { | |
253 | SCM contregs; | |
254 | scm_t_contregs *cont; | |
255 | ||
256 | contregs = scm_c_vector_ref (scm_program_objects (continuation), 0); | |
257 | cont = SCM_CONTREGS (contregs); | |
258 | ||
269479e3 | 259 | if (scm_is_true (cont->vm_cont)) |
1d1cae0e | 260 | { |
269479e3 AW |
261 | struct scm_vm_cont *data = SCM_VM_CONT_DATA (cont->vm_cont); |
262 | return scm_c_make_frame (cont->vm_cont, | |
1d1cae0e AW |
263 | data->fp + data->reloc, |
264 | data->sp + data->reloc, | |
d8873dfe | 265 | data->ra, |
1d1cae0e AW |
266 | data->reloc); |
267 | } | |
268 | else | |
269 | return SCM_BOOL_F; | |
270 | } | |
271 | ||
d8873dfe AW |
272 | SCM |
273 | scm_i_contregs_vm (SCM contregs) | |
274 | { | |
275 | return SCM_CONTREGS (contregs)->vm; | |
276 | } | |
277 | ||
278 | SCM | |
279 | scm_i_contregs_vm_cont (SCM contregs) | |
280 | { | |
281 | return SCM_CONTREGS (contregs)->vm_cont; | |
282 | } | |
283 | ||
1d1cae0e AW |
284 | |
285 | /* {Apply} | |
286 | */ | |
d3c6aef9 MV |
287 | |
288 | /* Invoking a continuation proceeds as follows: | |
289 | * | |
290 | * - the stack is made large enough for the called continuation | |
291 | * - the old windchain is unwound down to the branching point | |
292 | * - the continuation stack is copied into place | |
293 | * - the windchain is rewound up to the continuation's context | |
294 | * - the continuation is invoked via longjmp (or setcontext) | |
295 | * | |
296 | * This order is important so that unwind and rewind handlers are run | |
297 | * with their correct stack. | |
298 | */ | |
299 | ||
d8873dfe | 300 | static void scm_dynthrow (SCM); |
01c8a3dd DH |
301 | |
302 | /* Grow the stack by a fixed amount to provide space to copy in the | |
303 | * continuation. Possibly this function has to be called several times | |
304 | * recursively before enough space is available. Make sure the compiler does | |
305 | * not optimize the growth array away by storing it's address into a global | |
306 | * variable. | |
307 | */ | |
308 | ||
8c93b597 | 309 | static scm_t_bits scm_i_dummy; |
1cc91f1b | 310 | |
0f2d19dd | 311 | static void |
d8873dfe | 312 | grow_stack (SCM cont) |
01c8a3dd | 313 | { |
92c2555f | 314 | scm_t_bits growth[100]; |
01c8a3dd | 315 | |
92c2555f | 316 | scm_i_dummy = (scm_t_bits) growth; |
d8873dfe | 317 | scm_dynthrow (cont); |
0f2d19dd | 318 | } |
0f2d19dd | 319 | |
1cc91f1b | 320 | |
01c8a3dd DH |
321 | /* Copy the continuation stack into the current stack. Calling functions from |
322 | * within this function is safe, since only stack frames below this function's | |
323 | * own frame are overwritten. Thus, memcpy can be used for best performance. | |
324 | */ | |
d3c6aef9 MV |
325 | |
326 | typedef struct { | |
327 | scm_t_contregs *continuation; | |
328 | SCM_STACKITEM *dst; | |
329 | } copy_stack_data; | |
330 | ||
01c8a3dd | 331 | static void |
d3c6aef9 MV |
332 | copy_stack (void *data) |
333 | { | |
334 | copy_stack_data *d = (copy_stack_data *)data; | |
335 | memcpy (d->dst, d->continuation->stack, | |
336 | sizeof (SCM_STACKITEM) * d->continuation->num_stack_items); | |
346e4402 NJ |
337 | #ifdef __ia64__ |
338 | SCM_I_CURRENT_THREAD->pending_rbs_continuation = d->continuation; | |
339 | #endif | |
d3c6aef9 MV |
340 | } |
341 | ||
342 | static void | |
d8873dfe | 343 | copy_stack_and_call (scm_t_contregs *continuation, |
5f144b10 | 344 | SCM_STACKITEM * dst) |
0f2d19dd | 345 | { |
d3c6aef9 MV |
346 | long delta; |
347 | copy_stack_data data; | |
348 | ||
9de87eea | 349 | delta = scm_ilength (scm_i_dynwinds ()) - scm_ilength (continuation->dynenv); |
d3c6aef9 MV |
350 | data.continuation = continuation; |
351 | data.dst = dst; | |
14578fa4 | 352 | scm_i_dowinds (continuation->dynenv, delta, copy_stack, &data); |
01c8a3dd | 353 | |
a4dbe1ac | 354 | SCM_I_LONGJMP (continuation->jmpbuf, 1); |
01c8a3dd DH |
355 | } |
356 | ||
346e4402 NJ |
357 | #ifdef __ia64__ |
358 | void | |
a4dbe1ac | 359 | scm_ia64_longjmp (scm_i_jmp_buf *JB, int VAL) |
346e4402 NJ |
360 | { |
361 | scm_i_thread *t = SCM_I_CURRENT_THREAD; | |
362 | ||
363 | if (t->pending_rbs_continuation) | |
364 | { | |
365 | memcpy (t->register_backing_store_base, | |
366 | t->pending_rbs_continuation->backing_store, | |
367 | t->pending_rbs_continuation->backing_store_size); | |
368 | t->pending_rbs_continuation = NULL; | |
369 | } | |
370 | setcontext (&JB->ctx); | |
371 | } | |
372 | #endif | |
373 | ||
01c8a3dd DH |
374 | /* Call grow_stack until the stack space is large enough, then, as the current |
375 | * stack frame might get overwritten, let copy_stack_and_call perform the | |
376 | * actual copying and continuation calling. | |
377 | */ | |
378 | static void | |
d8873dfe | 379 | scm_dynthrow (SCM cont) |
01c8a3dd | 380 | { |
9de87eea | 381 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; |
92c2555f | 382 | scm_t_contregs *continuation = SCM_CONTREGS (cont); |
9de87eea | 383 | SCM_STACKITEM *dst = thread->continuation_base; |
01c8a3dd DH |
384 | SCM_STACKITEM stack_top_element; |
385 | ||
87f30eda | 386 | if (thread->critical_section_level) |
8b7f0bb3 MV |
387 | { |
388 | fprintf (stderr, "continuation invoked from within critical section.\n"); | |
389 | abort (); | |
390 | } | |
391 | ||
4ccb2cd2 | 392 | #if SCM_STACK_GROWS_UP |
5afcf08b | 393 | if (dst + continuation->num_stack_items >= &stack_top_element) |
d8873dfe | 394 | grow_stack (cont); |
0f2d19dd | 395 | #else |
5f144b10 | 396 | dst -= continuation->num_stack_items; |
c8a1bdc4 | 397 | if (dst <= &stack_top_element) |
d8873dfe | 398 | grow_stack (cont); |
0f2d19dd | 399 | #endif /* def SCM_STACK_GROWS_UP */ |
01c8a3dd | 400 | |
5f144b10 | 401 | SCM_FLUSH_REGISTER_WINDOWS; |
d8873dfe | 402 | copy_stack_and_call (continuation, dst); |
0f2d19dd JB |
403 | } |
404 | ||
db4b4ca6 | 405 | |
1d1cae0e | 406 | void |
d8873dfe | 407 | scm_i_check_continuation (SCM cont) |
0f2d19dd | 408 | { |
9de87eea | 409 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; |
92c2555f | 410 | scm_t_contregs *continuation = SCM_CONTREGS (cont); |
5f144b10 | 411 | |
d223c3fc | 412 | if (!scm_is_eq (continuation->root, thread->continuation_root)) |
1d1cae0e AW |
413 | scm_misc_error |
414 | ("%continuation-call", | |
415 | "invoking continuation would cross continuation barrier: ~A", | |
416 | scm_list_1 (cont)); | |
d8873dfe AW |
417 | } |
418 | ||
419 | void | |
420 | scm_i_reinstate_continuation (SCM cont) | |
421 | { | |
422 | scm_dynthrow (cont); | |
0f2d19dd | 423 | } |
0f2d19dd | 424 | |
9de87eea MV |
425 | SCM |
426 | scm_i_with_continuation_barrier (scm_t_catch_body body, | |
427 | void *body_data, | |
428 | scm_t_catch_handler handler, | |
43e01b1e NJ |
429 | void *handler_data, |
430 | scm_t_catch_handler pre_unwind_handler, | |
431 | void *pre_unwind_handler_data) | |
9de87eea MV |
432 | { |
433 | SCM_STACKITEM stack_item; | |
434 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; | |
435 | SCM old_controot; | |
436 | SCM_STACKITEM *old_contbase; | |
9de87eea MV |
437 | SCM result; |
438 | ||
439 | /* Establish a fresh continuation root. | |
440 | */ | |
441 | old_controot = thread->continuation_root; | |
442 | old_contbase = thread->continuation_base; | |
9de87eea MV |
443 | thread->continuation_root = scm_cons (thread->handle, old_controot); |
444 | thread->continuation_base = &stack_item; | |
9de87eea MV |
445 | |
446 | /* Call FUNC inside a catch all. This is now guaranteed to return | |
447 | directly and exactly once. | |
448 | */ | |
43e01b1e NJ |
449 | result = scm_c_catch (SCM_BOOL_T, |
450 | body, body_data, | |
451 | handler, handler_data, | |
452 | pre_unwind_handler, pre_unwind_handler_data); | |
9de87eea MV |
453 | |
454 | /* Return to old continuation root. | |
455 | */ | |
9de87eea MV |
456 | thread->continuation_base = old_contbase; |
457 | thread->continuation_root = old_controot; | |
458 | ||
459 | return result; | |
460 | } | |
461 | ||
e309f3bf AW |
462 | \f |
463 | ||
464 | static int | |
465 | should_print_backtrace (SCM tag, SCM stack) | |
466 | { | |
467 | return SCM_BACKTRACE_P | |
468 | && scm_is_true (stack) | |
469 | && scm_initialized_p | |
470 | /* It's generally not useful to print backtraces for errors reading | |
471 | or expanding code in these fallback catch statements. */ | |
472 | && !scm_is_eq (tag, scm_from_latin1_symbol ("read-error")) | |
473 | && !scm_is_eq (tag, scm_from_latin1_symbol ("syntax-error")); | |
474 | } | |
475 | ||
476 | static void | |
477 | print_exception_and_backtrace (SCM port, SCM tag, SCM args) | |
478 | { | |
479 | SCM stack, frame; | |
480 | ||
481 | /* We get here via a throw to a catch-all. In that case there is the | |
482 | throw frame active, and this catch closure, so narrow by two | |
483 | frames. */ | |
484 | stack = scm_make_stack (SCM_BOOL_T, scm_list_1 (scm_from_int (2))); | |
485 | frame = scm_is_true (stack) ? scm_stack_ref (stack, SCM_INUM0) : SCM_BOOL_F; | |
486 | ||
487 | if (should_print_backtrace (tag, stack)) | |
488 | { | |
489 | scm_puts ("Backtrace:\n", port); | |
490 | scm_display_backtrace_with_highlights (stack, port, | |
491 | SCM_BOOL_F, SCM_BOOL_F, | |
492 | SCM_EOL); | |
493 | scm_newline (port); | |
494 | } | |
495 | ||
496 | scm_print_exception (port, frame, tag, args); | |
497 | } | |
498 | ||
499 | \f | |
500 | ||
9de87eea MV |
501 | struct c_data { |
502 | void *(*func) (void *); | |
503 | void *data; | |
504 | void *result; | |
505 | }; | |
506 | ||
507 | static SCM | |
508 | c_body (void *d) | |
509 | { | |
510 | struct c_data *data = (struct c_data *)d; | |
511 | data->result = data->func (data->data); | |
512 | return SCM_UNSPECIFIED; | |
513 | } | |
514 | ||
515 | static SCM | |
516 | c_handler (void *d, SCM tag, SCM args) | |
517 | { | |
e309f3bf AW |
518 | struct c_data *data; |
519 | ||
520 | /* If TAG is `quit', exit() the process. */ | |
521 | if (scm_is_eq (tag, scm_from_latin1_symbol ("quit"))) | |
522 | exit (scm_exit_status (args)); | |
523 | ||
524 | data = (struct c_data *)d; | |
9de87eea MV |
525 | data->result = NULL; |
526 | return SCM_UNSPECIFIED; | |
527 | } | |
528 | ||
e309f3bf AW |
529 | static SCM |
530 | pre_unwind_handler (void *error_port, SCM tag, SCM args) | |
531 | { | |
532 | /* Print the exception unless TAG is `quit'. */ | |
533 | if (!scm_is_eq (tag, scm_from_latin1_symbol ("quit"))) | |
534 | print_exception_and_backtrace (PTR2SCM (error_port), tag, args); | |
535 | ||
536 | return SCM_UNSPECIFIED; | |
537 | } | |
538 | ||
9de87eea MV |
539 | void * |
540 | scm_c_with_continuation_barrier (void *(*func) (void *), void *data) | |
541 | { | |
542 | struct c_data c_data; | |
543 | c_data.func = func; | |
544 | c_data.data = data; | |
545 | scm_i_with_continuation_barrier (c_body, &c_data, | |
43e01b1e | 546 | c_handler, &c_data, |
e309f3bf AW |
547 | pre_unwind_handler, |
548 | SCM2PTR (scm_current_error_port ())); | |
9de87eea MV |
549 | return c_data.result; |
550 | } | |
551 | ||
552 | struct scm_data { | |
553 | SCM proc; | |
554 | }; | |
555 | ||
556 | static SCM | |
557 | scm_body (void *d) | |
558 | { | |
559 | struct scm_data *data = (struct scm_data *)d; | |
560 | return scm_call_0 (data->proc); | |
561 | } | |
562 | ||
563 | static SCM | |
564 | scm_handler (void *d, SCM tag, SCM args) | |
565 | { | |
e309f3bf AW |
566 | /* Print a message. Note that if TAG is `quit', this will exit() the |
567 | process. */ | |
568 | scm_handle_by_message_noexit (NULL, tag, args); | |
569 | ||
9de87eea MV |
570 | return SCM_BOOL_F; |
571 | } | |
572 | ||
573 | SCM_DEFINE (scm_with_continuation_barrier, "with-continuation-barrier", 1,0,0, | |
574 | (SCM proc), | |
69d2000d MV |
575 | "Call @var{proc} and return its result. Do not allow the invocation of\n" |
576 | "continuations that would leave or enter the dynamic extent of the call\n" | |
577 | "to @code{with-continuation-barrier}. Such an attempt causes an error\n" | |
578 | "to be signaled.\n" | |
579 | "\n" | |
580 | "Throws (such as errors) that are not caught from within @var{proc} are\n" | |
581 | "caught by @code{with-continuation-barrier}. In that case, a short\n" | |
582 | "message is printed to the current error port and @code{#f} is returned.\n" | |
583 | "\n" | |
584 | "Thus, @code{with-continuation-barrier} returns exactly once.\n") | |
9de87eea MV |
585 | #define FUNC_NAME s_scm_with_continuation_barrier |
586 | { | |
587 | struct scm_data scm_data; | |
588 | scm_data.proc = proc; | |
589 | return scm_i_with_continuation_barrier (scm_body, &scm_data, | |
43e01b1e | 590 | scm_handler, &scm_data, |
e309f3bf AW |
591 | pre_unwind_handler, |
592 | SCM2PTR (scm_current_error_port ())); | |
9de87eea MV |
593 | } |
594 | #undef FUNC_NAME | |
db4b4ca6 | 595 | |
0f2d19dd JB |
596 | void |
597 | scm_init_continuations () | |
0f2d19dd | 598 | { |
1d1cae0e AW |
599 | tc16_continuation = scm_make_smob_type ("continuation", 0); |
600 | scm_set_smob_print (tc16_continuation, continuation_print); | |
a0599745 | 601 | #include "libguile/continuations.x" |
0f2d19dd JB |
602 | } |
603 | ||
89e00824 ML |
604 | /* |
605 | Local Variables: | |
606 | c-file-style: "gnu" | |
607 | End: | |
608 | */ |