b80e52b157de61f1d4a22d730e2a9c1cb88caaba
1/*
2 * Handle git attributes. See gitattributes(5) for a description of
3 * the file syntax, and Documentation/technical/api-gitattributes.txt
4 * for a description of the API.
5 *
6 * One basic design decision here is that we are not going to support
7 * an insanely large number of attributes.
8 */
9
10#define NO_THE_INDEX_COMPATIBILITY_MACROS
11#include "cache.h"
12#include "exec_cmd.h"
13#include "attr.h"
14#include "dir.h"
15
16const char git_attr__true[] = "(builtin)true";
17const char git_attr__false[] = "\0(builtin)false";
18static const char git_attr__unknown[] = "(builtin)unknown";
19#define ATTR__TRUE git_attr__true
20#define ATTR__FALSE git_attr__false
21#define ATTR__UNSET NULL
22#define ATTR__UNKNOWN git_attr__unknown
23
24/* This is a randomly chosen prime. */
25#define HASHSIZE 257
26
27#ifndef DEBUG_ATTR
28#define DEBUG_ATTR 0
29#endif
30
31struct git_attr {
32 struct git_attr *next;
33 unsigned h;
34 int attr_nr;
35 int maybe_macro;
36 char name[FLEX_ARRAY];
37};
38static int attr_nr;
39
40static struct git_attr_check *check_all_attr;
41static struct git_attr *(git_attr_hash[HASHSIZE]);
42
43char *git_attr_name(struct git_attr *attr)
44{
45 return attr->name;
46}
47
48static unsigned hash_name(const char *name, int namelen)
49{
50 unsigned val = 0, c;
51
52 while (namelen--) {
53 c = *name++;
54 val = ((val << 7) | (val >> 22)) ^ c;
55 }
56 return val;
57}
58
59static int invalid_attr_name(const char *name, int namelen)
60{
61 /*
62 * Attribute name cannot begin with '-' and must consist of
63 * characters from [-A-Za-z0-9_.].
64 */
65 if (namelen <= 0 || *name == '-')
66 return -1;
67 while (namelen--) {
68 char ch = *name++;
69 if (! (ch == '-' || ch == '.' || ch == '_' ||
70 ('0' <= ch && ch <= '9') ||
71 ('a' <= ch && ch <= 'z') ||
72 ('A' <= ch && ch <= 'Z')) )
73 return -1;
74 }
75 return 0;
76}
77
78static struct git_attr *git_attr_internal(const char *name, int len)
79{
80 unsigned hval = hash_name(name, len);
81 unsigned pos = hval % HASHSIZE;
82 struct git_attr *a;
83
84 for (a = git_attr_hash[pos]; a; a = a->next) {
85 if (a->h == hval &&
86 !memcmp(a->name, name, len) && !a->name[len])
87 return a;
88 }
89
90 if (invalid_attr_name(name, len))
91 return NULL;
92
93 a = xmalloc(sizeof(*a) + len + 1);
94 memcpy(a->name, name, len);
95 a->name[len] = 0;
96 a->h = hval;
97 a->next = git_attr_hash[pos];
98 a->attr_nr = attr_nr++;
99 a->maybe_macro = 0;
100 git_attr_hash[pos] = a;
101
102 REALLOC_ARRAY(check_all_attr, attr_nr);
103 check_all_attr[a->attr_nr].attr = a;
104 check_all_attr[a->attr_nr].value = ATTR__UNKNOWN;
105 return a;
106}
107
108struct git_attr *git_attr(const char *name)
109{
110 return git_attr_internal(name, strlen(name));
111}
112
113/* What does a matched pattern decide? */
114struct attr_state {
115 struct git_attr *attr;
116 const char *setto;
117};
118
119struct pattern {
120 const char *pattern;
121 int patternlen;
122 int nowildcardlen;
123 int flags; /* EXC_FLAG_* */
124};
125
126/*
127 * One rule, as from a .gitattributes file.
128 *
129 * If is_macro is true, then u.attr is a pointer to the git_attr being
130 * defined.
131 *
132 * If is_macro is false, then u.pattern points at the filename pattern
133 * to which the rule applies. (The memory pointed to is part of the
134 * memory block allocated for the match_attr instance.)
135 *
136 * In either case, num_attr is the number of attributes affected by
137 * this rule, and state is an array listing them. The attributes are
138 * listed as they appear in the file (macros unexpanded).
139 */
140struct match_attr {
141 union {
142 struct pattern pat;
143 struct git_attr *attr;
144 } u;
145 char is_macro;
146 unsigned num_attr;
147 struct attr_state state[FLEX_ARRAY];
148};
149
150static const char blank[] = " \t\r\n";
151
152/*
153 * Parse a whitespace-delimited attribute state (i.e., "attr",
154 * "-attr", "!attr", or "attr=value") from the string starting at src.
155 * If e is not NULL, write the results to *e. Return a pointer to the
156 * remainder of the string (with leading whitespace removed), or NULL
157 * if there was an error.
158 */
159static const char *parse_attr(const char *src, int lineno, const char *cp,
160 struct attr_state *e)
161{
162 const char *ep, *equals;
163 int len;
164
165 ep = cp + strcspn(cp, blank);
166 equals = strchr(cp, '=');
167 if (equals && ep < equals)
168 equals = NULL;
169 if (equals)
170 len = equals - cp;
171 else
172 len = ep - cp;
173 if (!e) {
174 if (*cp == '-' || *cp == '!') {
175 cp++;
176 len--;
177 }
178 if (invalid_attr_name(cp, len)) {
179 fprintf(stderr,
180 "%.*s is not a valid attribute name: %s:%d\n",
181 len, cp, src, lineno);
182 return NULL;
183 }
184 } else {
185 if (*cp == '-' || *cp == '!') {
186 e->setto = (*cp == '-') ? ATTR__FALSE : ATTR__UNSET;
187 cp++;
188 len--;
189 }
190 else if (!equals)
191 e->setto = ATTR__TRUE;
192 else {
193 e->setto = xmemdupz(equals + 1, ep - equals - 1);
194 }
195 e->attr = git_attr_internal(cp, len);
196 }
197 return ep + strspn(ep, blank);
198}
199
200static struct match_attr *parse_attr_line(const char *line, const char *src,
201 int lineno, int macro_ok)
202{
203 int namelen;
204 int num_attr, i;
205 const char *cp, *name, *states;
206 struct match_attr *res = NULL;
207 int is_macro;
208
209 cp = line + strspn(line, blank);
210 if (!*cp || *cp == '#')
211 return NULL;
212 name = cp;
213 namelen = strcspn(name, blank);
214 if (strlen(ATTRIBUTE_MACRO_PREFIX) < namelen &&
215 starts_with(name, ATTRIBUTE_MACRO_PREFIX)) {
216 if (!macro_ok) {
217 fprintf(stderr, "%s not allowed: %s:%d\n",
218 name, src, lineno);
219 return NULL;
220 }
221 is_macro = 1;
222 name += strlen(ATTRIBUTE_MACRO_PREFIX);
223 name += strspn(name, blank);
224 namelen = strcspn(name, blank);
225 if (invalid_attr_name(name, namelen)) {
226 fprintf(stderr,
227 "%.*s is not a valid attribute name: %s:%d\n",
228 namelen, name, src, lineno);
229 return NULL;
230 }
231 }
232 else
233 is_macro = 0;
234
235 states = name + namelen;
236 states += strspn(states, blank);
237
238 /* First pass to count the attr_states */
239 for (cp = states, num_attr = 0; *cp; num_attr++) {
240 cp = parse_attr(src, lineno, cp, NULL);
241 if (!cp)
242 return NULL;
243 }
244
245 res = xcalloc(1,
246 sizeof(*res) +
247 sizeof(struct attr_state) * num_attr +
248 (is_macro ? 0 : namelen + 1));
249 if (is_macro) {
250 res->u.attr = git_attr_internal(name, namelen);
251 res->u.attr->maybe_macro = 1;
252 } else {
253 char *p = (char *)&(res->state[num_attr]);
254 memcpy(p, name, namelen);
255 res->u.pat.pattern = p;
256 parse_exclude_pattern(&res->u.pat.pattern,
257 &res->u.pat.patternlen,
258 &res->u.pat.flags,
259 &res->u.pat.nowildcardlen);
260 if (res->u.pat.flags & EXC_FLAG_NEGATIVE) {
261 warning(_("Negative patterns are ignored in git attributes\n"
262 "Use '\\!' for literal leading exclamation."));
263 return NULL;
264 }
265 }
266 res->is_macro = is_macro;
267 res->num_attr = num_attr;
268
269 /* Second pass to fill the attr_states */
270 for (cp = states, i = 0; *cp; i++) {
271 cp = parse_attr(src, lineno, cp, &(res->state[i]));
272 }
273
274 return res;
275}
276
277/*
278 * Like info/exclude and .gitignore, the attribute information can
279 * come from many places.
280 *
281 * (1) .gitattribute file of the same directory;
282 * (2) .gitattribute file of the parent directory if (1) does not have
283 * any match; this goes recursively upwards, just like .gitignore.
284 * (3) $GIT_DIR/info/attributes, which overrides both of the above.
285 *
286 * In the same file, later entries override the earlier match, so in the
287 * global list, we would have entries from info/attributes the earliest
288 * (reading the file from top to bottom), .gitattribute of the root
289 * directory (again, reading the file from top to bottom) down to the
290 * current directory, and then scan the list backwards to find the first match.
291 * This is exactly the same as what is_excluded() does in dir.c to deal with
292 * .gitignore
293 */
294
295static struct attr_stack {
296 struct attr_stack *prev;
297 char *origin;
298 size_t originlen;
299 unsigned num_matches;
300 unsigned alloc;
301 struct match_attr **attrs;
302} *attr_stack;
303
304static void free_attr_elem(struct attr_stack *e)
305{
306 int i;
307 free(e->origin);
308 for (i = 0; i < e->num_matches; i++) {
309 struct match_attr *a = e->attrs[i];
310 int j;
311 for (j = 0; j < a->num_attr; j++) {
312 const char *setto = a->state[j].setto;
313 if (setto == ATTR__TRUE ||
314 setto == ATTR__FALSE ||
315 setto == ATTR__UNSET ||
316 setto == ATTR__UNKNOWN)
317 ;
318 else
319 free((char *) setto);
320 }
321 free(a);
322 }
323 free(e->attrs);
324 free(e);
325}
326
327static const char *builtin_attr[] = {
328 "[attr]binary -diff -merge -text",
329 NULL,
330};
331
332static void handle_attr_line(struct attr_stack *res,
333 const char *line,
334 const char *src,
335 int lineno,
336 int macro_ok)
337{
338 struct match_attr *a;
339
340 a = parse_attr_line(line, src, lineno, macro_ok);
341 if (!a)
342 return;
343 ALLOC_GROW(res->attrs, res->num_matches + 1, res->alloc);
344 res->attrs[res->num_matches++] = a;
345}
346
347static struct attr_stack *read_attr_from_array(const char **list)
348{
349 struct attr_stack *res;
350 const char *line;
351 int lineno = 0;
352
353 res = xcalloc(1, sizeof(*res));
354 while ((line = *(list++)) != NULL)
355 handle_attr_line(res, line, "[builtin]", ++lineno, 1);
356 return res;
357}
358
359static enum git_attr_direction direction;
360static struct index_state *use_index;
361
362static struct attr_stack *read_attr_from_file(const char *path, int macro_ok)
363{
364 FILE *fp = fopen(path, "r");
365 struct attr_stack *res;
366 char buf[2048];
367 int lineno = 0;
368
369 if (!fp) {
370 if (errno != ENOENT && errno != ENOTDIR)
371 warn_on_inaccessible(path);
372 return NULL;
373 }
374 res = xcalloc(1, sizeof(*res));
375 while (fgets(buf, sizeof(buf), fp))
376 handle_attr_line(res, buf, path, ++lineno, macro_ok);
377 fclose(fp);
378 return res;
379}
380
381static struct attr_stack *read_attr_from_index(const char *path, int macro_ok)
382{
383 struct attr_stack *res;
384 char *buf, *sp;
385 int lineno = 0;
386
387 buf = read_blob_data_from_index(use_index ? use_index : &the_index, path, NULL);
388 if (!buf)
389 return NULL;
390
391 res = xcalloc(1, sizeof(*res));
392 for (sp = buf; *sp; ) {
393 char *ep;
394 int more;
395 for (ep = sp; *ep && *ep != '\n'; ep++)
396 ;
397 more = (*ep == '\n');
398 *ep = '\0';
399 handle_attr_line(res, sp, path, ++lineno, macro_ok);
400 sp = ep + more;
401 }
402 free(buf);
403 return res;
404}
405
406static struct attr_stack *read_attr(const char *path, int macro_ok)
407{
408 struct attr_stack *res;
409
410 if (direction == GIT_ATTR_CHECKOUT) {
411 res = read_attr_from_index(path, macro_ok);
412 if (!res)
413 res = read_attr_from_file(path, macro_ok);
414 }
415 else if (direction == GIT_ATTR_CHECKIN) {
416 res = read_attr_from_file(path, macro_ok);
417 if (!res)
418 /*
419 * There is no checked out .gitattributes file there, but
420 * we might have it in the index. We allow operation in a
421 * sparsely checked out work tree, so read from it.
422 */
423 res = read_attr_from_index(path, macro_ok);
424 }
425 else
426 res = read_attr_from_index(path, macro_ok);
427 if (!res)
428 res = xcalloc(1, sizeof(*res));
429 return res;
430}
431
432#if DEBUG_ATTR
433static void debug_info(const char *what, struct attr_stack *elem)
434{
435 fprintf(stderr, "%s: %s\n", what, elem->origin ? elem->origin : "()");
436}
437static void debug_set(const char *what, const char *match, struct git_attr *attr, const void *v)
438{
439 const char *value = v;
440
441 if (ATTR_TRUE(value))
442 value = "set";
443 else if (ATTR_FALSE(value))
444 value = "unset";
445 else if (ATTR_UNSET(value))
446 value = "unspecified";
447
448 fprintf(stderr, "%s: %s => %s (%s)\n",
449 what, attr->name, (char *) value, match);
450}
451#define debug_push(a) debug_info("push", (a))
452#define debug_pop(a) debug_info("pop", (a))
453#else
454#define debug_push(a) do { ; } while (0)
455#define debug_pop(a) do { ; } while (0)
456#define debug_set(a,b,c,d) do { ; } while (0)
457#endif
458
459static void drop_attr_stack(void)
460{
461 while (attr_stack) {
462 struct attr_stack *elem = attr_stack;
463 attr_stack = elem->prev;
464 free_attr_elem(elem);
465 }
466}
467
468static const char *git_etc_gitattributes(void)
469{
470 static const char *system_wide;
471 if (!system_wide)
472 system_wide = system_path(ETC_GITATTRIBUTES);
473 return system_wide;
474}
475
476static int git_attr_system(void)
477{
478 return !git_env_bool("GIT_ATTR_NOSYSTEM", 0);
479}
480
481static void bootstrap_attr_stack(void)
482{
483 struct attr_stack *elem;
484 char *xdg_attributes_file;
485
486 if (attr_stack)
487 return;
488
489 elem = read_attr_from_array(builtin_attr);
490 elem->origin = NULL;
491 elem->prev = attr_stack;
492 attr_stack = elem;
493
494 if (git_attr_system()) {
495 elem = read_attr_from_file(git_etc_gitattributes(), 1);
496 if (elem) {
497 elem->origin = NULL;
498 elem->prev = attr_stack;
499 attr_stack = elem;
500 }
501 }
502
503 if (!git_attributes_file) {
504 home_config_paths(NULL, &xdg_attributes_file, "attributes");
505 git_attributes_file = xdg_attributes_file;
506 }
507 if (git_attributes_file) {
508 elem = read_attr_from_file(git_attributes_file, 1);
509 if (elem) {
510 elem->origin = NULL;
511 elem->prev = attr_stack;
512 attr_stack = elem;
513 }
514 }
515
516 if (!is_bare_repository() || direction == GIT_ATTR_INDEX) {
517 elem = read_attr(GITATTRIBUTES_FILE, 1);
518 elem->origin = xstrdup("");
519 elem->originlen = 0;
520 elem->prev = attr_stack;
521 attr_stack = elem;
522 debug_push(elem);
523 }
524
525 elem = read_attr_from_file(git_path(INFOATTRIBUTES_FILE), 1);
526 if (!elem)
527 elem = xcalloc(1, sizeof(*elem));
528 elem->origin = NULL;
529 elem->prev = attr_stack;
530 attr_stack = elem;
531}
532
533static void prepare_attr_stack(const char *path, int dirlen)
534{
535 struct attr_stack *elem, *info;
536 int len;
537 const char *cp;
538
539 /*
540 * At the bottom of the attribute stack is the built-in
541 * set of attribute definitions, followed by the contents
542 * of $(prefix)/etc/gitattributes and a file specified by
543 * core.attributesfile. Then, contents from
544 * .gitattribute files from directories closer to the
545 * root to the ones in deeper directories are pushed
546 * to the stack. Finally, at the very top of the stack
547 * we always keep the contents of $GIT_DIR/info/attributes.
548 *
549 * When checking, we use entries from near the top of the
550 * stack, preferring $GIT_DIR/info/attributes, then
551 * .gitattributes in deeper directories to shallower ones,
552 * and finally use the built-in set as the default.
553 */
554 bootstrap_attr_stack();
555
556 /*
557 * Pop the "info" one that is always at the top of the stack.
558 */
559 info = attr_stack;
560 attr_stack = info->prev;
561
562 /*
563 * Pop the ones from directories that are not the prefix of
564 * the path we are checking. Break out of the loop when we see
565 * the root one (whose origin is an empty string "") or the builtin
566 * one (whose origin is NULL) without popping it.
567 */
568 while (attr_stack->origin) {
569 int namelen = strlen(attr_stack->origin);
570
571 elem = attr_stack;
572 if (namelen <= dirlen &&
573 !strncmp(elem->origin, path, namelen) &&
574 (!namelen || path[namelen] == '/'))
575 break;
576
577 debug_pop(elem);
578 attr_stack = elem->prev;
579 free_attr_elem(elem);
580 }
581
582 /*
583 * Read from parent directories and push them down
584 */
585 if (!is_bare_repository() || direction == GIT_ATTR_INDEX) {
586 /*
587 * bootstrap_attr_stack() should have added, and the
588 * above loop should have stopped before popping, the
589 * root element whose attr_stack->origin is set to an
590 * empty string.
591 */
592 struct strbuf pathbuf = STRBUF_INIT;
593
594 assert(attr_stack->origin);
595 while (1) {
596 len = strlen(attr_stack->origin);
597 if (dirlen <= len)
598 break;
599 cp = memchr(path + len + 1, '/', dirlen - len - 1);
600 if (!cp)
601 cp = path + dirlen;
602 strbuf_add(&pathbuf, path, cp - path);
603 strbuf_addch(&pathbuf, '/');
604 strbuf_addstr(&pathbuf, GITATTRIBUTES_FILE);
605 elem = read_attr(pathbuf.buf, 0);
606 strbuf_setlen(&pathbuf, cp - path);
607 elem->origin = strbuf_detach(&pathbuf, &elem->originlen);
608 elem->prev = attr_stack;
609 attr_stack = elem;
610 debug_push(elem);
611 }
612
613 strbuf_release(&pathbuf);
614 }
615
616 /*
617 * Finally push the "info" one at the top of the stack.
618 */
619 info->prev = attr_stack;
620 attr_stack = info;
621}
622
623static int path_matches(const char *pathname, int pathlen,
624 int basename_offset,
625 const struct pattern *pat,
626 const char *base, int baselen)
627{
628 const char *pattern = pat->pattern;
629 int prefix = pat->nowildcardlen;
630 int isdir = (pathlen && pathname[pathlen - 1] == '/');
631
632 if ((pat->flags & EXC_FLAG_MUSTBEDIR) && !isdir)
633 return 0;
634
635 if (pat->flags & EXC_FLAG_NODIR) {
636 return match_basename(pathname + basename_offset,
637 pathlen - basename_offset - isdir,
638 pattern, prefix,
639 pat->patternlen, pat->flags);
640 }
641 return match_pathname(pathname, pathlen - isdir,
642 base, baselen,
643 pattern, prefix, pat->patternlen, pat->flags);
644}
645
646static int macroexpand_one(int attr_nr, int rem);
647
648static int fill_one(const char *what, struct match_attr *a, int rem)
649{
650 struct git_attr_check *check = check_all_attr;
651 int i;
652
653 for (i = a->num_attr - 1; 0 < rem && 0 <= i; i--) {
654 struct git_attr *attr = a->state[i].attr;
655 const char **n = &(check[attr->attr_nr].value);
656 const char *v = a->state[i].setto;
657
658 if (*n == ATTR__UNKNOWN) {
659 debug_set(what,
660 a->is_macro ? a->u.attr->name : a->u.pat.pattern,
661 attr, v);
662 *n = v;
663 rem--;
664 rem = macroexpand_one(attr->attr_nr, rem);
665 }
666 }
667 return rem;
668}
669
670static int fill(const char *path, int pathlen, int basename_offset,
671 struct attr_stack *stk, int rem)
672{
673 int i;
674 const char *base = stk->origin ? stk->origin : "";
675
676 for (i = stk->num_matches - 1; 0 < rem && 0 <= i; i--) {
677 struct match_attr *a = stk->attrs[i];
678 if (a->is_macro)
679 continue;
680 if (path_matches(path, pathlen, basename_offset,
681 &a->u.pat, base, stk->originlen))
682 rem = fill_one("fill", a, rem);
683 }
684 return rem;
685}
686
687static int macroexpand_one(int nr, int rem)
688{
689 struct attr_stack *stk;
690 struct match_attr *a = NULL;
691 int i;
692
693 if (check_all_attr[nr].value != ATTR__TRUE ||
694 !check_all_attr[nr].attr->maybe_macro)
695 return rem;
696
697 for (stk = attr_stack; !a && stk; stk = stk->prev)
698 for (i = stk->num_matches - 1; !a && 0 <= i; i--) {
699 struct match_attr *ma = stk->attrs[i];
700 if (!ma->is_macro)
701 continue;
702 if (ma->u.attr->attr_nr == nr)
703 a = ma;
704 }
705
706 if (a)
707 rem = fill_one("expand", a, rem);
708
709 return rem;
710}
711
712/*
713 * Collect all attributes for path into the array pointed to by
714 * check_all_attr.
715 */
716static void collect_all_attrs(const char *path)
717{
718 struct attr_stack *stk;
719 int i, pathlen, rem, dirlen;
720 const char *cp, *last_slash = NULL;
721 int basename_offset;
722
723 for (cp = path; *cp; cp++) {
724 if (*cp == '/' && cp[1])
725 last_slash = cp;
726 }
727 pathlen = cp - path;
728 if (last_slash) {
729 basename_offset = last_slash + 1 - path;
730 dirlen = last_slash - path;
731 } else {
732 basename_offset = 0;
733 dirlen = 0;
734 }
735
736 prepare_attr_stack(path, dirlen);
737 for (i = 0; i < attr_nr; i++)
738 check_all_attr[i].value = ATTR__UNKNOWN;
739
740 rem = attr_nr;
741 for (stk = attr_stack; 0 < rem && stk; stk = stk->prev)
742 rem = fill(path, pathlen, basename_offset, stk, rem);
743}
744
745int git_check_attr(const char *path, int num, struct git_attr_check *check)
746{
747 int i;
748
749 collect_all_attrs(path);
750
751 for (i = 0; i < num; i++) {
752 const char *value = check_all_attr[check[i].attr->attr_nr].value;
753 if (value == ATTR__UNKNOWN)
754 value = ATTR__UNSET;
755 check[i].value = value;
756 }
757
758 return 0;
759}
760
761int git_all_attrs(const char *path, int *num, struct git_attr_check **check)
762{
763 int i, count, j;
764
765 collect_all_attrs(path);
766
767 /* Count the number of attributes that are set. */
768 count = 0;
769 for (i = 0; i < attr_nr; i++) {
770 const char *value = check_all_attr[i].value;
771 if (value != ATTR__UNSET && value != ATTR__UNKNOWN)
772 ++count;
773 }
774 *num = count;
775 *check = xmalloc(sizeof(**check) * count);
776 j = 0;
777 for (i = 0; i < attr_nr; i++) {
778 const char *value = check_all_attr[i].value;
779 if (value != ATTR__UNSET && value != ATTR__UNKNOWN) {
780 (*check)[j].attr = check_all_attr[i].attr;
781 (*check)[j].value = value;
782 ++j;
783 }
784 }
785
786 return 0;
787}
788
789void git_attr_set_direction(enum git_attr_direction new, struct index_state *istate)
790{
791 enum git_attr_direction old = direction;
792
793 if (is_bare_repository() && new != GIT_ATTR_INDEX)
794 die("BUG: non-INDEX attr direction in a bare repo");
795
796 direction = new;
797 if (new != old)
798 drop_attr_stack();
799 use_index = istate;
800}