]>
Commit | Line | Data |
---|---|---|
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 | ||
8868edaf | 6 | /* Copyright (C) 1987-2020 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 | ||
8868edaf CR |
79 | static void without_interrupts PARAMS((VFunction *, char *, char *)); |
80 | static void unwind_frame_discard_internal PARAMS((char *, char *)); | |
81 | static void unwind_frame_run_internal PARAMS((char *, char *)); | |
82 | static void add_unwind_protect_internal PARAMS((Function *, char *)); | |
83 | static void remove_unwind_protect_internal PARAMS((char *, char *)); | |
84 | static void run_unwind_protects_internal PARAMS((char *, char *)); | |
85 | static void clear_unwind_protects_internal PARAMS((char *, char *)); | |
86 | static inline void restore_variable PARAMS((SAVED_VAR *)); | |
87 | static void unwind_protect_mem_internal PARAMS((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 | |
8868edaf | 111 | FUNCTION cannot call QUIT (). */ |
726f6388 JA |
112 | static void |
113 | without_interrupts (function, arg1, arg2) | |
114 | VFunction *function; | |
115 | char *arg1, *arg2; | |
116 | { | |
726f6388 | 117 | (*function)(arg1, arg2); |
726f6388 JA |
118 | } |
119 | ||
120 | /* Start the beginning of a region. */ | |
121 | void | |
122 | begin_unwind_frame (tag) | |
123 | char *tag; | |
124 | { | |
125 | add_unwind_protect ((Function *)NULL, tag); | |
126 | } | |
127 | ||
128 | /* Discard the unwind protects back to TAG. */ | |
129 | void | |
130 | discard_unwind_frame (tag) | |
131 | char *tag; | |
132 | { | |
133 | if (unwind_protect_list) | |
134 | without_interrupts (unwind_frame_discard_internal, tag, (char *)NULL); | |
135 | } | |
136 | ||
137 | /* Run the unwind protects back to TAG. */ | |
138 | void | |
139 | run_unwind_frame (tag) | |
140 | char *tag; | |
141 | { | |
142 | if (unwind_protect_list) | |
143 | without_interrupts (unwind_frame_run_internal, tag, (char *)NULL); | |
144 | } | |
145 | ||
146 | /* Add the function CLEANUP with ARG to the list of unwindable things. */ | |
147 | void | |
148 | add_unwind_protect (cleanup, arg) | |
149 | Function *cleanup; | |
150 | char *arg; | |
151 | { | |
152 | without_interrupts (add_unwind_protect_internal, (char *)cleanup, arg); | |
153 | } | |
154 | ||
155 | /* Remove the top unwind protect from the list. */ | |
156 | void | |
157 | remove_unwind_protect () | |
158 | { | |
159 | if (unwind_protect_list) | |
160 | without_interrupts | |
161 | (remove_unwind_protect_internal, (char *)NULL, (char *)NULL); | |
162 | } | |
163 | ||
164 | /* Run the list of cleanup functions in unwind_protect_list. */ | |
165 | void | |
166 | run_unwind_protects () | |
167 | { | |
168 | if (unwind_protect_list) | |
169 | without_interrupts | |
170 | (run_unwind_protects_internal, (char *)NULL, (char *)NULL); | |
171 | } | |
172 | ||
28ef6c31 JA |
173 | /* Erase the unwind-protect list. If flags is 1, free the elements. */ |
174 | void | |
175 | clear_unwind_protect_list (flags) | |
176 | int flags; | |
177 | { | |
f73dda09 JA |
178 | char *flag; |
179 | ||
28ef6c31 | 180 | if (unwind_protect_list) |
f73dda09 JA |
181 | { |
182 | flag = flags ? "" : (char *)NULL; | |
183 | without_interrupts | |
184 | (clear_unwind_protects_internal, flag, (char *)NULL); | |
185 | } | |
28ef6c31 JA |
186 | } |
187 | ||
3185942a JA |
188 | int |
189 | have_unwind_protects () | |
190 | { | |
191 | return (unwind_protect_list != 0); | |
192 | } | |
193 | ||
a0c0a00f CR |
194 | int |
195 | unwind_protect_tag_on_stack (tag) | |
196 | const char *tag; | |
197 | { | |
198 | UNWIND_ELT *elt; | |
199 | ||
200 | elt = unwind_protect_list; | |
201 | while (elt) | |
202 | { | |
203 | if (elt->head.cleanup == 0 && STREQ (elt->arg.v, tag)) | |
204 | return 1; | |
205 | elt = elt->head.next; | |
206 | } | |
207 | return 0; | |
208 | } | |
209 | ||
726f6388 JA |
210 | /* **************************************************************** */ |
211 | /* */ | |
28ef6c31 | 212 | /* The Actual Functions */ |
726f6388 JA |
213 | /* */ |
214 | /* **************************************************************** */ | |
215 | ||
216 | static void | |
217 | add_unwind_protect_internal (cleanup, arg) | |
218 | Function *cleanup; | |
219 | char *arg; | |
220 | { | |
221 | UNWIND_ELT *elt; | |
222 | ||
7117c2d2 | 223 | uwpalloc (elt); |
f73dda09 JA |
224 | elt->head.next = unwind_protect_list; |
225 | elt->head.cleanup = cleanup; | |
226 | elt->arg.v = arg; | |
726f6388 JA |
227 | unwind_protect_list = elt; |
228 | } | |
229 | ||
230 | static void | |
28ef6c31 JA |
231 | remove_unwind_protect_internal (ignore1, ignore2) |
232 | char *ignore1, *ignore2; | |
726f6388 | 233 | { |
d166f048 | 234 | UNWIND_ELT *elt; |
726f6388 | 235 | |
d166f048 | 236 | elt = unwind_protect_list; |
726f6388 JA |
237 | if (elt) |
238 | { | |
f73dda09 | 239 | unwind_protect_list = unwind_protect_list->head.next; |
7117c2d2 | 240 | uwpfree (elt); |
726f6388 JA |
241 | } |
242 | } | |
243 | ||
244 | static void | |
28ef6c31 JA |
245 | run_unwind_protects_internal (ignore1, ignore2) |
246 | char *ignore1, *ignore2; | |
726f6388 | 247 | { |
f73dda09 | 248 | unwind_frame_run_internal ((char *) NULL, (char *) NULL); |
726f6388 JA |
249 | } |
250 | ||
251 | static void | |
28ef6c31 JA |
252 | clear_unwind_protects_internal (flag, ignore) |
253 | char *flag, *ignore; | |
254 | { | |
f73dda09 | 255 | if (flag) |
28ef6c31 JA |
256 | { |
257 | while (unwind_protect_list) | |
258 | remove_unwind_protect_internal ((char *)NULL, (char *)NULL); | |
259 | } | |
260 | unwind_protect_list = (UNWIND_ELT *)NULL; | |
261 | } | |
262 | ||
263 | static void | |
264 | unwind_frame_discard_internal (tag, ignore) | |
265 | char *tag, *ignore; | |
726f6388 JA |
266 | { |
267 | UNWIND_ELT *elt; | |
495aee44 | 268 | int found; |
726f6388 | 269 | |
495aee44 | 270 | found = 0; |
726f6388 JA |
271 | while (elt = unwind_protect_list) |
272 | { | |
f73dda09 JA |
273 | unwind_protect_list = unwind_protect_list->head.next; |
274 | if (elt->head.cleanup == 0 && (STREQ (elt->arg.v, tag))) | |
726f6388 | 275 | { |
7117c2d2 | 276 | uwpfree (elt); |
495aee44 | 277 | found = 1; |
726f6388 JA |
278 | break; |
279 | } | |
280 | else | |
7117c2d2 | 281 | uwpfree (elt); |
726f6388 | 282 | } |
495aee44 CR |
283 | |
284 | if (found == 0) | |
285 | internal_warning ("unwind_frame_discard: %s: frame not found", tag); | |
726f6388 JA |
286 | } |
287 | ||
f73dda09 JA |
288 | /* Restore the value of a variable, based on the contents of SV. |
289 | sv->desired_setting is a block of memory SIZE bytes long holding the | |
290 | value itself. This block of memory is copied back into the variable. */ | |
291 | static inline void | |
292 | restore_variable (sv) | |
293 | SAVED_VAR *sv; | |
294 | { | |
295 | FASTCOPY (sv->desired_setting, sv->variable, sv->size); | |
296 | } | |
297 | ||
726f6388 | 298 | static void |
28ef6c31 JA |
299 | unwind_frame_run_internal (tag, ignore) |
300 | char *tag, *ignore; | |
726f6388 JA |
301 | { |
302 | UNWIND_ELT *elt; | |
495aee44 | 303 | int found; |
726f6388 | 304 | |
495aee44 | 305 | found = 0; |
726f6388 JA |
306 | while (elt = unwind_protect_list) |
307 | { | |
f73dda09 | 308 | unwind_protect_list = elt->head.next; |
726f6388 JA |
309 | |
310 | /* If tag, then compare. */ | |
495aee44 | 311 | if (elt->head.cleanup == 0) |
726f6388 | 312 | { |
f73dda09 | 313 | if (tag && STREQ (elt->arg.v, tag)) |
726f6388 | 314 | { |
7117c2d2 | 315 | uwpfree (elt); |
495aee44 | 316 | found = 1; |
726f6388 JA |
317 | break; |
318 | } | |
726f6388 JA |
319 | } |
320 | else | |
321 | { | |
f73dda09 JA |
322 | if (elt->head.cleanup == (Function *) restore_variable) |
323 | restore_variable (&elt->sv.v); | |
324 | else | |
325 | (*(elt->head.cleanup)) (elt->arg.v); | |
726f6388 | 326 | } |
726f6388 | 327 | |
7117c2d2 | 328 | uwpfree (elt); |
f73dda09 | 329 | } |
495aee44 CR |
330 | if (tag && found == 0) |
331 | internal_warning ("unwind_frame_run: %s: frame not found", tag); | |
d166f048 | 332 | } |
726f6388 | 333 | |
726f6388 | 334 | static void |
f73dda09 JA |
335 | unwind_protect_mem_internal (var, psize) |
336 | char *var; | |
337 | char *psize; | |
726f6388 | 338 | { |
f73dda09 JA |
339 | int size, allocated; |
340 | UNWIND_ELT *elt; | |
726f6388 | 341 | |
f73dda09 JA |
342 | size = *(int *) psize; |
343 | allocated = size + offsetof (UNWIND_ELT, sv.v.desired_setting[0]); | |
8868edaf CR |
344 | if (allocated < sizeof (UNWIND_ELT)) |
345 | allocated = sizeof (UNWIND_ELT); | |
f73dda09 JA |
346 | elt = (UNWIND_ELT *)xmalloc (allocated); |
347 | elt->head.next = unwind_protect_list; | |
348 | elt->head.cleanup = (Function *) restore_variable; | |
349 | elt->sv.v.variable = var; | |
350 | elt->sv.v.size = size; | |
351 | FASTCOPY (var, elt->sv.v.desired_setting, size); | |
352 | unwind_protect_list = elt; | |
726f6388 JA |
353 | } |
354 | ||
355 | /* Save the value of a variable so it will be restored when unwind-protects | |
f73dda09 JA |
356 | are run. VAR is a pointer to the variable. SIZE is the size in |
357 | bytes of VAR. */ | |
726f6388 | 358 | void |
f73dda09 JA |
359 | unwind_protect_mem (var, size) |
360 | char *var; | |
726f6388 JA |
361 | int size; |
362 | { | |
f73dda09 | 363 | without_interrupts (unwind_protect_mem_internal, var, (char *) &size); |
726f6388 | 364 | } |
495aee44 CR |
365 | |
366 | #if defined (DEBUG) | |
367 | #include <stdio.h> | |
368 | ||
369 | void | |
370 | print_unwind_protect_tags () | |
371 | { | |
372 | UNWIND_ELT *elt; | |
373 | ||
374 | elt = unwind_protect_list; | |
375 | while (elt) | |
376 | { | |
495aee44 CR |
377 | if (elt->head.cleanup == 0) |
378 | fprintf(stderr, "tag: %s\n", elt->arg.v); | |
a0c0a00f | 379 | elt = elt->head.next; |
495aee44 CR |
380 | } |
381 | } | |
382 | #endif |