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3185942a JA |
1 | /* unwind_prot.c - a simple unwind-protect system for internal variables */ |
2 | ||
726f6388 JA |
3 | /* I can't stand it anymore! Please can't we just write the |
4 | whole Unix system in lisp or something? */ | |
5 | ||
3185942a | 6 | /* Copyright (C) 1987-2009 Free Software Foundation, Inc. |
726f6388 | 7 | |
3185942a | 8 | This file is part of GNU Bash, the Bourne Again SHell. |
726f6388 | 9 | |
3185942a JA |
10 | Bash is free software: you can redistribute it and/or modify |
11 | it under the terms of the GNU General Public License as published by | |
12 | the Free Software Foundation, either version 3 of the License, or | |
13 | (at your option) any later version. | |
726f6388 | 14 | |
3185942a JA |
15 | Bash is distributed in the hope that it will be useful, |
16 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | GNU General Public License for more details. | |
726f6388 | 19 | |
3185942a JA |
20 | You should have received a copy of the GNU General Public License |
21 | along with Bash. If not, see <http://www.gnu.org/licenses/>. | |
22 | */ | |
726f6388 JA |
23 | |
24 | /* **************************************************************** */ | |
25 | /* */ | |
26 | /* Unwind Protection Scheme for Bash */ | |
27 | /* */ | |
28 | /* **************************************************************** */ | |
726f6388 | 29 | #include "config.h" |
ccc6cda3 JA |
30 | |
31 | #include "bashtypes.h" | |
d166f048 JA |
32 | #include "bashansi.h" |
33 | ||
ccc6cda3 JA |
34 | #if defined (HAVE_UNISTD_H) |
35 | # include <unistd.h> | |
36 | #endif | |
37 | ||
f73dda09 JA |
38 | #if STDC_HEADERS |
39 | # include <stddef.h> | |
40 | #endif | |
41 | ||
42 | #ifndef offsetof | |
43 | # define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER) | |
44 | #endif | |
45 | ||
726f6388 JA |
46 | #include "command.h" |
47 | #include "general.h" | |
48 | #include "unwind_prot.h" | |
ccc6cda3 | 49 | #include "sig.h" |
ac50fbac | 50 | #include "quit.h" |
495aee44 | 51 | #include "error.h" /* for internal_warning */ |
a0c0a00f | 52 | #include "ocache.h" |
726f6388 | 53 | |
f73dda09 | 54 | /* Structure describing a saved variable and the value to restore it to. */ |
d166f048 | 55 | typedef struct { |
f73dda09 | 56 | char *variable; |
d166f048 | 57 | int size; |
f73dda09 | 58 | char desired_setting[1]; /* actual size is `size' */ |
d166f048 JA |
59 | } SAVED_VAR; |
60 | ||
f73dda09 JA |
61 | /* If HEAD.CLEANUP is null, then ARG.V contains a tag to throw back to. |
62 | If HEAD.CLEANUP is restore_variable, then SV.V contains the saved | |
63 | variable. Otherwise, call HEAD.CLEANUP (ARG.V) to clean up. */ | |
64 | typedef union uwp { | |
65 | struct uwp_head { | |
66 | union uwp *next; | |
67 | Function *cleanup; | |
68 | } head; | |
69 | struct { | |
70 | struct uwp_head uwp_head; | |
71 | char *v; | |
72 | } arg; | |
73 | struct { | |
74 | struct uwp_head uwp_head; | |
75 | SAVED_VAR v; | |
76 | } sv; | |
77 | } UNWIND_ELT; | |
78 | ||
79 | static void without_interrupts __P((VFunction *, char *, char *)); | |
80 | static void unwind_frame_discard_internal __P((char *, char *)); | |
81 | static void unwind_frame_run_internal __P((char *, char *)); | |
82 | static void add_unwind_protect_internal __P((Function *, char *)); | |
83 | static void remove_unwind_protect_internal __P((char *, char *)); | |
84 | static void run_unwind_protects_internal __P((char *, char *)); | |
85 | static void clear_unwind_protects_internal __P((char *, char *)); | |
86 | static inline void restore_variable __P((SAVED_VAR *)); | |
87 | static void unwind_protect_mem_internal __P((char *, char *)); | |
726f6388 JA |
88 | |
89 | static UNWIND_ELT *unwind_protect_list = (UNWIND_ELT *)NULL; | |
90 | ||
a0c0a00f CR |
91 | /* Allocating from a cache of unwind-protect elements */ |
92 | #define UWCACHESIZE 128 | |
93 | ||
94 | sh_obj_cache_t uwcache = {0, 0, 0}; | |
95 | ||
96 | #if 0 | |
7117c2d2 JA |
97 | #define uwpalloc(elt) (elt) = (UNWIND_ELT *)xmalloc (sizeof (UNWIND_ELT)) |
98 | #define uwpfree(elt) free(elt) | |
a0c0a00f CR |
99 | #else |
100 | #define uwpalloc(elt) ocache_alloc (uwcache, UNWIND_ELT, elt) | |
101 | #define uwpfree(elt) ocache_free (uwcache, UNWIND_ELT, elt) | |
102 | #endif | |
103 | ||
104 | void | |
105 | uwp_init () | |
106 | { | |
107 | ocache_create (uwcache, UNWIND_ELT, UWCACHESIZE); | |
108 | } | |
726f6388 JA |
109 | |
110 | /* Run a function without interrupts. This relies on the fact that the | |
111 | FUNCTION cannot change the value of interrupt_immediately. (I.e., does | |
112 | not call QUIT (). */ | |
113 | static void | |
114 | without_interrupts (function, arg1, arg2) | |
115 | VFunction *function; | |
116 | char *arg1, *arg2; | |
117 | { | |
118 | int old_interrupt_immediately; | |
119 | ||
120 | old_interrupt_immediately = interrupt_immediately; | |
121 | interrupt_immediately = 0; | |
122 | ||
123 | (*function)(arg1, arg2); | |
124 | ||
125 | interrupt_immediately = old_interrupt_immediately; | |
126 | } | |
127 | ||
128 | /* Start the beginning of a region. */ | |
129 | void | |
130 | begin_unwind_frame (tag) | |
131 | char *tag; | |
132 | { | |
133 | add_unwind_protect ((Function *)NULL, tag); | |
134 | } | |
135 | ||
136 | /* Discard the unwind protects back to TAG. */ | |
137 | void | |
138 | discard_unwind_frame (tag) | |
139 | char *tag; | |
140 | { | |
141 | if (unwind_protect_list) | |
142 | without_interrupts (unwind_frame_discard_internal, tag, (char *)NULL); | |
143 | } | |
144 | ||
145 | /* Run the unwind protects back to TAG. */ | |
146 | void | |
147 | run_unwind_frame (tag) | |
148 | char *tag; | |
149 | { | |
150 | if (unwind_protect_list) | |
151 | without_interrupts (unwind_frame_run_internal, tag, (char *)NULL); | |
152 | } | |
153 | ||
154 | /* Add the function CLEANUP with ARG to the list of unwindable things. */ | |
155 | void | |
156 | add_unwind_protect (cleanup, arg) | |
157 | Function *cleanup; | |
158 | char *arg; | |
159 | { | |
160 | without_interrupts (add_unwind_protect_internal, (char *)cleanup, arg); | |
161 | } | |
162 | ||
163 | /* Remove the top unwind protect from the list. */ | |
164 | void | |
165 | remove_unwind_protect () | |
166 | { | |
167 | if (unwind_protect_list) | |
168 | without_interrupts | |
169 | (remove_unwind_protect_internal, (char *)NULL, (char *)NULL); | |
170 | } | |
171 | ||
172 | /* Run the list of cleanup functions in unwind_protect_list. */ | |
173 | void | |
174 | run_unwind_protects () | |
175 | { | |
176 | if (unwind_protect_list) | |
177 | without_interrupts | |
178 | (run_unwind_protects_internal, (char *)NULL, (char *)NULL); | |
179 | } | |
180 | ||
28ef6c31 JA |
181 | /* Erase the unwind-protect list. If flags is 1, free the elements. */ |
182 | void | |
183 | clear_unwind_protect_list (flags) | |
184 | int flags; | |
185 | { | |
f73dda09 JA |
186 | char *flag; |
187 | ||
28ef6c31 | 188 | if (unwind_protect_list) |
f73dda09 JA |
189 | { |
190 | flag = flags ? "" : (char *)NULL; | |
191 | without_interrupts | |
192 | (clear_unwind_protects_internal, flag, (char *)NULL); | |
193 | } | |
28ef6c31 JA |
194 | } |
195 | ||
3185942a JA |
196 | int |
197 | have_unwind_protects () | |
198 | { | |
199 | return (unwind_protect_list != 0); | |
200 | } | |
201 | ||
a0c0a00f CR |
202 | int |
203 | unwind_protect_tag_on_stack (tag) | |
204 | const char *tag; | |
205 | { | |
206 | UNWIND_ELT *elt; | |
207 | ||
208 | elt = unwind_protect_list; | |
209 | while (elt) | |
210 | { | |
211 | if (elt->head.cleanup == 0 && STREQ (elt->arg.v, tag)) | |
212 | return 1; | |
213 | elt = elt->head.next; | |
214 | } | |
215 | return 0; | |
216 | } | |
217 | ||
726f6388 JA |
218 | /* **************************************************************** */ |
219 | /* */ | |
28ef6c31 | 220 | /* The Actual Functions */ |
726f6388 JA |
221 | /* */ |
222 | /* **************************************************************** */ | |
223 | ||
224 | static void | |
225 | add_unwind_protect_internal (cleanup, arg) | |
226 | Function *cleanup; | |
227 | char *arg; | |
228 | { | |
229 | UNWIND_ELT *elt; | |
230 | ||
7117c2d2 | 231 | uwpalloc (elt); |
f73dda09 JA |
232 | elt->head.next = unwind_protect_list; |
233 | elt->head.cleanup = cleanup; | |
234 | elt->arg.v = arg; | |
726f6388 JA |
235 | unwind_protect_list = elt; |
236 | } | |
237 | ||
238 | static void | |
28ef6c31 JA |
239 | remove_unwind_protect_internal (ignore1, ignore2) |
240 | char *ignore1, *ignore2; | |
726f6388 | 241 | { |
d166f048 | 242 | UNWIND_ELT *elt; |
726f6388 | 243 | |
d166f048 | 244 | elt = unwind_protect_list; |
726f6388 JA |
245 | if (elt) |
246 | { | |
f73dda09 | 247 | unwind_protect_list = unwind_protect_list->head.next; |
7117c2d2 | 248 | uwpfree (elt); |
726f6388 JA |
249 | } |
250 | } | |
251 | ||
252 | static void | |
28ef6c31 JA |
253 | run_unwind_protects_internal (ignore1, ignore2) |
254 | char *ignore1, *ignore2; | |
726f6388 | 255 | { |
f73dda09 | 256 | unwind_frame_run_internal ((char *) NULL, (char *) NULL); |
726f6388 JA |
257 | } |
258 | ||
259 | static void | |
28ef6c31 JA |
260 | clear_unwind_protects_internal (flag, ignore) |
261 | char *flag, *ignore; | |
262 | { | |
f73dda09 | 263 | if (flag) |
28ef6c31 JA |
264 | { |
265 | while (unwind_protect_list) | |
266 | remove_unwind_protect_internal ((char *)NULL, (char *)NULL); | |
267 | } | |
268 | unwind_protect_list = (UNWIND_ELT *)NULL; | |
269 | } | |
270 | ||
271 | static void | |
272 | unwind_frame_discard_internal (tag, ignore) | |
273 | char *tag, *ignore; | |
726f6388 JA |
274 | { |
275 | UNWIND_ELT *elt; | |
495aee44 | 276 | int found; |
726f6388 | 277 | |
495aee44 | 278 | found = 0; |
726f6388 JA |
279 | while (elt = unwind_protect_list) |
280 | { | |
f73dda09 JA |
281 | unwind_protect_list = unwind_protect_list->head.next; |
282 | if (elt->head.cleanup == 0 && (STREQ (elt->arg.v, tag))) | |
726f6388 | 283 | { |
7117c2d2 | 284 | uwpfree (elt); |
495aee44 | 285 | found = 1; |
726f6388 JA |
286 | break; |
287 | } | |
288 | else | |
7117c2d2 | 289 | uwpfree (elt); |
726f6388 | 290 | } |
495aee44 CR |
291 | |
292 | if (found == 0) | |
293 | internal_warning ("unwind_frame_discard: %s: frame not found", tag); | |
726f6388 JA |
294 | } |
295 | ||
f73dda09 JA |
296 | /* Restore the value of a variable, based on the contents of SV. |
297 | sv->desired_setting is a block of memory SIZE bytes long holding the | |
298 | value itself. This block of memory is copied back into the variable. */ | |
299 | static inline void | |
300 | restore_variable (sv) | |
301 | SAVED_VAR *sv; | |
302 | { | |
303 | FASTCOPY (sv->desired_setting, sv->variable, sv->size); | |
304 | } | |
305 | ||
726f6388 | 306 | static void |
28ef6c31 JA |
307 | unwind_frame_run_internal (tag, ignore) |
308 | char *tag, *ignore; | |
726f6388 JA |
309 | { |
310 | UNWIND_ELT *elt; | |
495aee44 | 311 | int found; |
726f6388 | 312 | |
495aee44 | 313 | found = 0; |
726f6388 JA |
314 | while (elt = unwind_protect_list) |
315 | { | |
f73dda09 | 316 | unwind_protect_list = elt->head.next; |
726f6388 JA |
317 | |
318 | /* If tag, then compare. */ | |
495aee44 | 319 | if (elt->head.cleanup == 0) |
726f6388 | 320 | { |
f73dda09 | 321 | if (tag && STREQ (elt->arg.v, tag)) |
726f6388 | 322 | { |
7117c2d2 | 323 | uwpfree (elt); |
495aee44 | 324 | found = 1; |
726f6388 JA |
325 | break; |
326 | } | |
726f6388 JA |
327 | } |
328 | else | |
329 | { | |
f73dda09 JA |
330 | if (elt->head.cleanup == (Function *) restore_variable) |
331 | restore_variable (&elt->sv.v); | |
332 | else | |
333 | (*(elt->head.cleanup)) (elt->arg.v); | |
726f6388 | 334 | } |
726f6388 | 335 | |
7117c2d2 | 336 | uwpfree (elt); |
f73dda09 | 337 | } |
495aee44 CR |
338 | if (tag && found == 0) |
339 | internal_warning ("unwind_frame_run: %s: frame not found", tag); | |
d166f048 | 340 | } |
726f6388 | 341 | |
726f6388 | 342 | static void |
f73dda09 JA |
343 | unwind_protect_mem_internal (var, psize) |
344 | char *var; | |
345 | char *psize; | |
726f6388 | 346 | { |
f73dda09 JA |
347 | int size, allocated; |
348 | UNWIND_ELT *elt; | |
726f6388 | 349 | |
f73dda09 JA |
350 | size = *(int *) psize; |
351 | allocated = size + offsetof (UNWIND_ELT, sv.v.desired_setting[0]); | |
352 | elt = (UNWIND_ELT *)xmalloc (allocated); | |
353 | elt->head.next = unwind_protect_list; | |
354 | elt->head.cleanup = (Function *) restore_variable; | |
355 | elt->sv.v.variable = var; | |
356 | elt->sv.v.size = size; | |
357 | FASTCOPY (var, elt->sv.v.desired_setting, size); | |
358 | unwind_protect_list = elt; | |
726f6388 JA |
359 | } |
360 | ||
361 | /* Save the value of a variable so it will be restored when unwind-protects | |
f73dda09 JA |
362 | are run. VAR is a pointer to the variable. SIZE is the size in |
363 | bytes of VAR. */ | |
726f6388 | 364 | void |
f73dda09 JA |
365 | unwind_protect_mem (var, size) |
366 | char *var; | |
726f6388 JA |
367 | int size; |
368 | { | |
f73dda09 | 369 | without_interrupts (unwind_protect_mem_internal, var, (char *) &size); |
726f6388 | 370 | } |
495aee44 CR |
371 | |
372 | #if defined (DEBUG) | |
373 | #include <stdio.h> | |
374 | ||
375 | void | |
376 | print_unwind_protect_tags () | |
377 | { | |
378 | UNWIND_ELT *elt; | |
379 | ||
380 | elt = unwind_protect_list; | |
381 | while (elt) | |
382 | { | |
495aee44 CR |
383 | if (elt->head.cleanup == 0) |
384 | fprintf(stderr, "tag: %s\n", elt->arg.v); | |
a0c0a00f | 385 | elt = elt->head.next; |
495aee44 CR |
386 | } |
387 | } | |
388 | #endif |