| 1 | /* Copyright (C) 1995,1996 Free Software Foundation, Inc. |
| 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 |
| 15 | * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. |
| 16 | * |
| 17 | * As a special exception, the Free Software Foundation gives permission |
| 18 | * for additional uses of the text contained in its release of GUILE. |
| 19 | * |
| 20 | * The exception is that, if you link the GUILE library with other files |
| 21 | * to produce an executable, this does not by itself cause the |
| 22 | * resulting executable to be covered by the GNU General Public License. |
| 23 | * Your use of that executable is in no way restricted on account of |
| 24 | * linking the GUILE library code into it. |
| 25 | * |
| 26 | * This exception does not however invalidate any other reasons why |
| 27 | * the executable file might be covered by the GNU General Public License. |
| 28 | * |
| 29 | * This exception applies only to the code released by the |
| 30 | * Free Software Foundation under the name GUILE. If you copy |
| 31 | * code from other Free Software Foundation releases into a copy of |
| 32 | * GUILE, as the General Public License permits, the exception does |
| 33 | * not apply to the code that you add in this way. To avoid misleading |
| 34 | * anyone as to the status of such modified files, you must delete |
| 35 | * this exception notice from them. |
| 36 | * |
| 37 | * If you write modifications of your own for GUILE, it is your choice |
| 38 | * whether to permit this exception to apply to your modifications. |
| 39 | * If you do not wish that, delete this exception notice. |
| 40 | */ |
| 41 | \f |
| 42 | |
| 43 | #include <stdio.h> |
| 44 | #include "_scm.h" |
| 45 | #include "genio.h" |
| 46 | #include "smob.h" |
| 47 | #include "alist.h" |
| 48 | #include "eval.h" |
| 49 | #include "dynwind.h" |
| 50 | #include "backtrace.h" |
| 51 | #ifdef DEBUG_EXTENSIONS |
| 52 | #include "debug.h" |
| 53 | #endif |
| 54 | #include "continuations.h" |
| 55 | #include "stackchk.h" |
| 56 | |
| 57 | #include "throw.h" |
| 58 | |
| 59 | \f |
| 60 | /* {Catch and Throw} |
| 61 | */ |
| 62 | static int scm_tc16_jmpbuffer; |
| 63 | |
| 64 | #define SCM_JMPBUFP(O) (SCM_TYP16(O) == scm_tc16_jmpbuffer) |
| 65 | #define JBACTIVE(O) (SCM_CAR (O) & (1L << 16L)) |
| 66 | #define ACTIVATEJB(O) (SCM_SETOR_CAR (O, (1L << 16L))) |
| 67 | #define DEACTIVATEJB(O) (SCM_SETAND_CAR (O, ~(1L << 16L))) |
| 68 | |
| 69 | #ifndef DEBUG_EXTENSIONS |
| 70 | #define JBJMPBUF(O) ((jmp_buf*)SCM_CDR (O) ) |
| 71 | #define SETJBJMPBUF SCM_SETCDR |
| 72 | #else |
| 73 | #define SCM_JBDFRAME(O) ((scm_debug_frame*)SCM_CAR (SCM_CDR (O)) ) |
| 74 | #define JBJMPBUF(O) ((jmp_buf*)SCM_CDR (SCM_CDR (O)) ) |
| 75 | #define SCM_SETJBDFRAME(O,X) SCM_SETCAR (SCM_CDR (O), (SCM)(X)) |
| 76 | #define SETJBJMPBUF(O,X) SCM_SETCDR(SCM_CDR (O), X) |
| 77 | |
| 78 | static scm_sizet freejb SCM_P ((SCM jbsmob)); |
| 79 | |
| 80 | static scm_sizet |
| 81 | freejb (jbsmob) |
| 82 | SCM jbsmob; |
| 83 | { |
| 84 | scm_must_free ((char *) SCM_CDR (jbsmob)); |
| 85 | return sizeof (scm_cell); |
| 86 | } |
| 87 | #endif |
| 88 | |
| 89 | static int printjb SCM_P ((SCM exp, SCM port, scm_print_state *pstate)); |
| 90 | static int |
| 91 | printjb (exp, port, pstate) |
| 92 | SCM exp; |
| 93 | SCM port; |
| 94 | scm_print_state *pstate; |
| 95 | { |
| 96 | scm_gen_puts (scm_regular_string, "#<jmpbuffer ", port); |
| 97 | scm_gen_puts (scm_regular_string, JBACTIVE(exp) ? "(active) " : "(inactive) ", port); |
| 98 | scm_intprint((SCM) JBJMPBUF(exp), 16, port); |
| 99 | scm_gen_putc ('>', port); |
| 100 | return 1 ; |
| 101 | } |
| 102 | |
| 103 | static scm_smobfuns jbsmob = { |
| 104 | scm_mark0, |
| 105 | #ifdef DEBUG_EXTENSIONS |
| 106 | freejb, |
| 107 | #else |
| 108 | scm_free0, |
| 109 | #endif |
| 110 | printjb, |
| 111 | 0 |
| 112 | }; |
| 113 | |
| 114 | static SCM make_jmpbuf SCM_P ((void)); |
| 115 | static SCM |
| 116 | make_jmpbuf () |
| 117 | { |
| 118 | SCM answer; |
| 119 | SCM_NEWCELL (answer); |
| 120 | SCM_REDEFER_INTS; |
| 121 | { |
| 122 | #ifdef DEBUG_EXTENSIONS |
| 123 | char *mem = scm_must_malloc (sizeof (scm_cell), "jb"); |
| 124 | SCM_SETCDR (answer, (SCM) mem); |
| 125 | #endif |
| 126 | SCM_SETCAR (answer, scm_tc16_jmpbuffer); |
| 127 | SETJBJMPBUF(answer, (jmp_buf *)0); |
| 128 | DEACTIVATEJB(answer); |
| 129 | } |
| 130 | SCM_REALLOW_INTS; |
| 131 | return answer; |
| 132 | } |
| 133 | |
| 134 | struct jmp_buf_and_retval /* use only on the stack, in scm_catch */ |
| 135 | { |
| 136 | jmp_buf buf; /* must be first */ |
| 137 | SCM throw_tag; |
| 138 | SCM retval; |
| 139 | }; |
| 140 | |
| 141 | |
| 142 | /* scm_internal_catch is the guts of catch. It handles all the |
| 143 | mechanics of setting up a catch target, invoking the catch body, |
| 144 | and perhaps invoking the handler if the body does a throw. |
| 145 | |
| 146 | The function is designed to be usable from C code, but is general |
| 147 | enough to implement all the semantics Guile Scheme expects from |
| 148 | throw. |
| 149 | |
| 150 | TAG is the catch tag. Typically, this is a symbol, but this |
| 151 | function doesn't actually care about that. |
| 152 | |
| 153 | BODY is a pointer to a C function which runs the body of the catch; |
| 154 | this is the code you can throw from. We call it like this: |
| 155 | BODY (BODY_DATA, JMPBUF) |
| 156 | where: |
| 157 | BODY_DATA is just the BODY_DATA argument we received; we pass it |
| 158 | through to BODY as its first argument. The caller can make |
| 159 | BODY_DATA point to anything useful that BODY might need. |
| 160 | JMPBUF is the Scheme jmpbuf object corresponding to this catch, |
| 161 | which we have just created and initialized. |
| 162 | |
| 163 | HANDLER is a pointer to a C function to deal with a throw to TAG, |
| 164 | should one occur. We call it like this: |
| 165 | HANDLER (HANDLER_DATA, TAG, THROW_ARGS) |
| 166 | where |
| 167 | HANDLER_DATA is the HANDLER_DATA argument we recevied; it's the |
| 168 | same idea as BODY_DATA above. |
| 169 | TAG is the tag that the user threw to; usually this is TAG, but |
| 170 | it could be something else if TAG was #t (i.e., a catch-all), |
| 171 | or the user threw to a jmpbuf. |
| 172 | THROW_ARGS is the list of arguments the user passed to the THROW |
| 173 | function. |
| 174 | |
| 175 | BODY_DATA is just a pointer we pass through to BODY. HANDLER_DATA |
| 176 | is just a pointer we pass through to HANDLER. We don't actually |
| 177 | use either of those pointers otherwise ourselves. The idea is |
| 178 | that, if our caller wants to communicate something to BODY or |
| 179 | HANDLER, it can pass a pointer to it as MUMBLE_DATA, which BODY and |
| 180 | HANDLER can then use. Think of it as a way to make BODY and |
| 181 | HANDLER closures, not just functions; MUMBLE_DATA points to the |
| 182 | enclosed variables. |
| 183 | |
| 184 | Of course, it's up to the caller to make sure that any data a |
| 185 | MUMBLE_DATA needs is protected from GC. A common way to do this is |
| 186 | to make MUMBLE_DATA a pointer to data stored in an automatic |
| 187 | structure variable; since the collector must scan the stack for |
| 188 | references anyway, this assures that any references in MUMBLE_DATA |
| 189 | will be found. */ |
| 190 | |
| 191 | SCM |
| 192 | scm_internal_catch (tag, body, body_data, handler, handler_data) |
| 193 | SCM tag; |
| 194 | scm_catch_body_t body; |
| 195 | void *body_data; |
| 196 | scm_catch_handler_t handler; |
| 197 | void *handler_data; |
| 198 | { |
| 199 | struct jmp_buf_and_retval jbr; |
| 200 | SCM jmpbuf; |
| 201 | SCM answer; |
| 202 | |
| 203 | jmpbuf = make_jmpbuf (); |
| 204 | answer = SCM_EOL; |
| 205 | scm_dynwinds = scm_acons (tag, jmpbuf, scm_dynwinds); |
| 206 | SETJBJMPBUF(jmpbuf, &jbr.buf); |
| 207 | #ifdef DEBUG_EXTENSIONS |
| 208 | SCM_SETJBDFRAME(jmpbuf, scm_last_debug_frame); |
| 209 | #endif |
| 210 | if (setjmp (jbr.buf)) |
| 211 | { |
| 212 | SCM throw_tag; |
| 213 | SCM throw_args; |
| 214 | |
| 215 | #ifdef STACK_CHECKING |
| 216 | scm_stack_checking_enabled_p = SCM_STACK_CHECKING_P; |
| 217 | #endif |
| 218 | SCM_REDEFER_INTS; |
| 219 | DEACTIVATEJB (jmpbuf); |
| 220 | scm_dynwinds = SCM_CDR (scm_dynwinds); |
| 221 | SCM_REALLOW_INTS; |
| 222 | throw_args = jbr.retval; |
| 223 | throw_tag = jbr.throw_tag; |
| 224 | jbr.throw_tag = SCM_EOL; |
| 225 | jbr.retval = SCM_EOL; |
| 226 | answer = handler (handler_data, throw_tag, throw_args); |
| 227 | } |
| 228 | else |
| 229 | { |
| 230 | ACTIVATEJB (jmpbuf); |
| 231 | answer = body (body_data, jmpbuf); |
| 232 | SCM_REDEFER_INTS; |
| 233 | DEACTIVATEJB (jmpbuf); |
| 234 | scm_dynwinds = SCM_CDR (scm_dynwinds); |
| 235 | SCM_REALLOW_INTS; |
| 236 | } |
| 237 | return answer; |
| 238 | } |
| 239 | |
| 240 | |
| 241 | /* This is a body function you can pass to scm_internal_catch if you |
| 242 | want the body to be like Scheme's `catch' --- a thunk, or a |
| 243 | function of one argument if the tag is #f. |
| 244 | |
| 245 | DATA contains the Scheme procedure to invoke. If the tag being |
| 246 | caught is #f, then we pass JMPBUF to the body procedure; otherwise, |
| 247 | it gets no arguments. */ |
| 248 | |
| 249 | SCM |
| 250 | scm_body_thunk (body_data, jmpbuf) |
| 251 | void *body_data; |
| 252 | SCM jmpbuf; |
| 253 | { |
| 254 | struct scm_body_thunk_data *c = (struct scm_body_thunk_data *) body_data; |
| 255 | |
| 256 | if (c->tag == SCM_BOOL_F) |
| 257 | return scm_apply (c->body_proc, scm_cons (jmpbuf, SCM_EOL), SCM_EOL); |
| 258 | else |
| 259 | return scm_apply (c->body_proc, SCM_EOL, SCM_EOL); |
| 260 | } |
| 261 | |
| 262 | |
| 263 | /* If the user does a throw to this catch, this function runs a |
| 264 | handler procedure written in Scheme. HANDLER_DATA is a pointer to |
| 265 | an SCM variable holding the Scheme procedure object to invoke. It |
| 266 | ought to be a pointer to an automatic, or the procedure object |
| 267 | should be otherwise protected from GC. */ |
| 268 | SCM |
| 269 | scm_handle_by_proc (handler_data, tag, throw_args) |
| 270 | void *handler_data; |
| 271 | SCM tag; |
| 272 | SCM throw_args; |
| 273 | { |
| 274 | SCM *handler_proc_p = (SCM *) handler_data; |
| 275 | |
| 276 | return scm_apply (*handler_proc_p, scm_cons (tag, throw_args), SCM_EOL); |
| 277 | } |
| 278 | |
| 279 | |
| 280 | SCM_PROC(s_catch, "catch", 3, 0, 0, scm_catch); |
| 281 | SCM |
| 282 | scm_catch (tag, thunk, handler) |
| 283 | SCM tag; |
| 284 | SCM thunk; |
| 285 | SCM handler; |
| 286 | { |
| 287 | struct scm_body_thunk_data c; |
| 288 | |
| 289 | SCM_ASSERT ((tag == SCM_BOOL_F) |
| 290 | || (SCM_NIMP(tag) && SCM_SYMBOLP(tag)) |
| 291 | || (tag == SCM_BOOL_T), |
| 292 | tag, SCM_ARG1, s_catch); |
| 293 | |
| 294 | c.tag = tag; |
| 295 | c.body_proc = thunk; |
| 296 | |
| 297 | /* scm_internal_catch takes care of all the mechanics of setting up |
| 298 | a catch tag; we tell it to call scm_body_thunk to run the body, |
| 299 | and scm_handle_by_proc to deal with any throws to this catch. |
| 300 | The former receives a pointer to c, telling it how to behave. |
| 301 | The latter receives a pointer to HANDLER, so it knows who to call. */ |
| 302 | return scm_internal_catch (tag, |
| 303 | scm_body_thunk, &c, |
| 304 | scm_handle_by_proc, &handler); |
| 305 | } |
| 306 | |
| 307 | |
| 308 | /* The smob tag for lazy_catch smobs. */ |
| 309 | static long tc16_lazy_catch; |
| 310 | |
| 311 | /* This is the structure we put on the wind list for a lazy catch. It |
| 312 | stores the handler function to call, and the data pointer to pass |
| 313 | through to it. It's not a Scheme closure, but it is a function |
| 314 | with data, so the term "closure" is appropriate in its broader |
| 315 | sense. |
| 316 | |
| 317 | (We don't need anything like this in the "eager" catch code, |
| 318 | because the same C frame runs both the body and the handler.) */ |
| 319 | struct lazy_catch { |
| 320 | scm_catch_handler_t handler; |
| 321 | void *handler_data; |
| 322 | }; |
| 323 | |
| 324 | /* Strictly speaking, we could just pass a zero for our print |
| 325 | function, because we don't need to print them. They should never |
| 326 | appear in normal data structures, only in the wind list. However, |
| 327 | it might be nice for debugging someday... */ |
| 328 | static int |
| 329 | print_lazy_catch (SCM closure, SCM port, scm_print_state *pstate) |
| 330 | { |
| 331 | struct lazy_catch *c = (struct lazy_catch *) SCM_CDR (closure); |
| 332 | char buf[200]; |
| 333 | |
| 334 | sprintf (buf, "#<lazy-catch 0x%lx 0x%lx>", |
| 335 | (long) c->handler, (long) c->handler_data); |
| 336 | scm_gen_puts (scm_regular_string, buf, port); |
| 337 | |
| 338 | return 1; |
| 339 | } |
| 340 | |
| 341 | static scm_smobfuns lazy_catch_funs = { |
| 342 | scm_mark0, scm_free0, print_lazy_catch, 0 |
| 343 | }; |
| 344 | |
| 345 | |
| 346 | /* Given a pointer to a lazy catch structure, return a smob for it, |
| 347 |