Bug Summary

File:kwset.c
Location:line 462, column 19
Description:Access to field 'next' results in a dereference of a null pointer (loaded from field 'trie')

Annotated Source Code

1/*
2 * This file has been copied from commit e7ac713d^ in the GNU grep git
3 * repository. A few small changes have been made to adapt the code to
4 * Git.
5 */
6
7/* kwset.c - search for any of a set of keywords.
8 Copyright 1989, 1998, 2000, 2005 Free Software Foundation, Inc.
9
10 This program 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 2, or (at your option)
13 any later version.
14
15 This program 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.
19
20 You should have received a copy of the GNU General Public License
21 along with this program; if not, write to the Free Software
22 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA
23 02110-1301, USA. */
24
25/* Written August 1989 by Mike Haertel.
26 The author may be reached (Email) at the address mike@ai.mit.edu,
27 or (US mail) as Mike Haertel c/o Free Software Foundation. */
28
29/* The algorithm implemented by these routines bears a startling resemblance
30 to one discovered by Beate Commentz-Walter, although it is not identical.
31 See "A String Matching Algorithm Fast on the Average," Technical Report,
32 IBM-Germany, Scientific Center Heidelberg, Tiergartenstrasse 15, D-6900
33 Heidelberg, Germany. See also Aho, A.V., and M. Corasick, "Efficient
34 String Matching: An Aid to Bibliographic Search," CACM June 1975,
35 Vol. 18, No. 6, which describes the failure function used below. */
36
37#include "cache.h"
38
39#include "kwset.h"
40#include "compat/obstack.h"
41
42#define NCHAR((127*2 +1) + 1) (UCHAR_MAX(127*2 +1) + 1)
43#define obstack_chunk_allocxmalloc xmalloc
44#define obstack_chunk_freefree free
45
46#define U(c)((unsigned char) (c)) ((unsigned char) (c))
47
48/* Balanced tree of edges and labels leaving a given trie node. */
49struct tree
50{
51 struct tree *llink; /* Left link; MUST be first field. */
52 struct tree *rlink; /* Right link (to larger labels). */
53 struct trie *trie; /* Trie node pointed to by this edge. */
54 unsigned char label; /* Label on this edge. */
55 char balance; /* Difference in depths of subtrees. */
56};
57
58/* Node of a trie representing a set of reversed keywords. */
59struct trie
60{
61 unsigned int accepting; /* Word index of accepted word, or zero. */
62 struct tree *links; /* Tree of edges leaving this node. */
63 struct trie *parent; /* Parent of this node. */
64 struct trie *next; /* List of all trie nodes in level order. */
65 struct trie *fail; /* Aho-Corasick failure function. */
66 int depth; /* Depth of this node from the root. */
67 int shift; /* Shift function for search failures. */
68 int maxshift; /* Max shift of self and descendants. */
69};
70
71/* Structure returned opaquely to the caller, containing everything. */
72struct kwset
73{
74 struct obstack obstack; /* Obstack for node allocation. */
75 int words; /* Number of words in the trie. */
76 struct trie *trie; /* The trie itself. */
77 int mind; /* Minimum depth of an accepting node. */
78 int maxd; /* Maximum depth of any node. */
79 unsigned char delta[NCHAR((127*2 +1) + 1)]; /* Delta table for rapid search. */
80 struct trie *next[NCHAR((127*2 +1) + 1)]; /* Table of children of the root. */
81 char *target; /* Target string if there's only one. */
82 int mind2; /* Used in Boyer-Moore search for one string. */
83 unsigned char const *trans; /* Character translation table. */
84};
85
86/* Allocate and initialize a keyword set object, returning an opaque
87 pointer to it. Return NULL if memory is not available. */
88kwset_t
89kwsalloc (unsigned char const *trans)
90{
91 struct kwset *kwset;
92
93 kwset = (struct kwset *) xmalloc(sizeof (struct kwset));
94
95 obstack_init(&kwset->obstack)_obstack_begin ((&kwset->obstack), 0, 0, (void *(*) (long
)) xmalloc, (void (*) (void *)) free);
96 kwset->words = 0;
97 kwset->trie
98 = (struct trie *) obstack_alloc(&kwset->obstack, sizeof (struct trie))__extension__ ({ struct obstack *__h = (&kwset->obstack
); __extension__ ({ struct obstack *__o = (__h); int __len = (
(sizeof (struct trie))); if (__o->chunk_limit - __o->next_free
< __len) _obstack_newchunk (__o, __len); ((__o)->next_free
+= (__len)); (void) 0; }); __extension__ ({ struct obstack *
__o1 = (__h); void *__value = (void *) __o1->object_base; if
(__o1->next_free == __value) __o1->maybe_empty_object =
1; __o1->next_free = ((sizeof (long int) < sizeof (void
*) ? (__o1->object_base) : (char *) 0) + (((__o1->next_free
) - (sizeof (long int) < sizeof (void *) ? (__o1->object_base
) : (char *) 0) + (__o1->alignment_mask)) & ~(__o1->
alignment_mask))); if (__o1->next_free - (char *)__o1->
chunk > __o1->chunk_limit - (char *)__o1->chunk) __o1
->next_free = __o1->chunk_limit; __o1->object_base =
__o1->next_free; __value; }); });
99 if (!kwset->trie)
100 {
101 kwsfree((kwset_t) kwset);
102 return NULL((void*)0);
103 }
104 kwset->trie->accepting = 0;
105 kwset->trie->links = NULL((void*)0);
106 kwset->trie->parent = NULL((void*)0);
107 kwset->trie->next = NULL((void*)0);
108 kwset->trie->fail = NULL((void*)0);
109 kwset->trie->depth = 0;
110 kwset->trie->shift = 0;
111 kwset->mind = INT_MAX2147483647;
112 kwset->maxd = -1;
113 kwset->target = NULL((void*)0);
114 kwset->trans = trans;
115
116 return (kwset_t) kwset;
117}
118
119/* This upper bound is valid for CHAR_BIT >= 4 and
120 exact for CHAR_BIT in { 4..11, 13, 15, 17, 19 }. */
121#define DEPTH_SIZE(8 + 8/2) (CHAR_BIT8 + CHAR_BIT8/2)
122
123/* Add the given string to the contents of the keyword set. Return NULL
124 for success, an error message otherwise. */
125const char *
126kwsincr (kwset_t kws, char const *text, size_t len)
127{
128 struct kwset *kwset;
129 register struct trie *trie;
130 register unsigned char label;
131 register struct tree *link;
132 register int depth;
133 struct tree *links[DEPTH_SIZE(8 + 8/2)];
134 enum { L, R } dirs[DEPTH_SIZE(8 + 8/2)];
135 struct tree *t, *r, *l, *rl, *lr;
136
137 kwset = (struct kwset *) kws;
138 trie = kwset->trie;
139 text += len;
140
141 /* Descend the trie (built of reversed keywords) character-by-character,
142 installing new nodes when necessary. */
143 while (len--)
144 {
145 label = kwset->trans ? kwset->trans[U(*--text)((unsigned char) (*--text))] : *--text;
146
147 /* Descend the tree of outgoing links for this trie node,
148 looking for the current character and keeping track
149 of the path followed. */
150 link = trie->links;
151 links[0] = (struct tree *) &trie->links;
152 dirs[0] = L;
153 depth = 1;
154
155 while (link && label != link->label)
156 {
157 links[depth] = link;
158 if (label < link->label)
159 dirs[depth++] = L, link = link->llink;
160 else
161 dirs[depth++] = R, link = link->rlink;
162 }
163
164 /* The current character doesn't have an outgoing link at
165 this trie node, so build a new trie node and install
166 a link in the current trie node's tree. */
167 if (!link)
168 {
169 link = (struct tree *) obstack_alloc(&kwset->obstack,__extension__ ({ struct obstack *__h = (&kwset->obstack
); __extension__ ({ struct obstack *__o = (__h); int __len = (
(sizeof (struct tree))); if (__o->chunk_limit - __o->next_free
< __len) _obstack_newchunk (__o, __len); ((__o)->next_free
+= (__len)); (void) 0; }); __extension__ ({ struct obstack *
__o1 = (__h); void *__value = (void *) __o1->object_base; if
(__o1->next_free == __value) __o1->maybe_empty_object =
1; __o1->next_free = ((sizeof (long int) < sizeof (void
*) ? (__o1->object_base) : (char *) 0) + (((__o1->next_free
) - (sizeof (long int) < sizeof (void *) ? (__o1->object_base
) : (char *) 0) + (__o1->alignment_mask)) & ~(__o1->
alignment_mask))); if (__o1->next_free - (char *)__o1->
chunk > __o1->chunk_limit - (char *)__o1->chunk) __o1
->next_free = __o1->chunk_limit; __o1->object_base =
__o1->next_free; __value; }); })
170 sizeof (struct tree))__extension__ ({ struct obstack *__h = (&kwset->obstack
); __extension__ ({ struct obstack *__o = (__h); int __len = (
(sizeof (struct tree))); if (__o->chunk_limit - __o->next_free
< __len) _obstack_newchunk (__o, __len); ((__o)->next_free
+= (__len)); (void) 0; }); __extension__ ({ struct obstack *
__o1 = (__h); void *__value = (void *) __o1->object_base; if
(__o1->next_free == __value) __o1->maybe_empty_object =
1; __o1->next_free = ((sizeof (long int) < sizeof (void
*) ? (__o1->object_base) : (char *) 0) + (((__o1->next_free
) - (sizeof (long int) < sizeof (void *) ? (__o1->object_base
) : (char *) 0) + (__o1->alignment_mask)) & ~(__o1->
alignment_mask))); if (__o1->next_free - (char *)__o1->
chunk > __o1->chunk_limit - (char *)__o1->chunk) __o1
->next_free = __o1->chunk_limit; __o1->object_base =
__o1->next_free; __value; }); });
171 if (!link)
172 return "memory exhausted";
173 link->llink = NULL((void*)0);
174 link->rlink = NULL((void*)0);
175 link->trie = (struct trie *) obstack_alloc(&kwset->obstack,__extension__ ({ struct obstack *__h = (&kwset->obstack
); __extension__ ({ struct obstack *__o = (__h); int __len = (
(sizeof (struct trie))); if (__o->chunk_limit - __o->next_free
< __len) _obstack_newchunk (__o, __len); ((__o)->next_free
+= (__len)); (void) 0; }); __extension__ ({ struct obstack *
__o1 = (__h); void *__value = (void *) __o1->object_base; if
(__o1->next_free == __value) __o1->maybe_empty_object =
1; __o1->next_free = ((sizeof (long int) < sizeof (void
*) ? (__o1->object_base) : (char *) 0) + (((__o1->next_free
) - (sizeof (long int) < sizeof (void *) ? (__o1->object_base
) : (char *) 0) + (__o1->alignment_mask)) & ~(__o1->
alignment_mask))); if (__o1->next_free - (char *)__o1->
chunk > __o1->chunk_limit - (char *)__o1->chunk) __o1
->next_free = __o1->chunk_limit; __o1->object_base =
__o1->next_free; __value; }); })
176 sizeof (struct trie))__extension__ ({ struct obstack *__h = (&kwset->obstack
); __extension__ ({ struct obstack *__o = (__h); int __len = (
(sizeof (struct trie))); if (__o->chunk_limit - __o->next_free
< __len) _obstack_newchunk (__o, __len); ((__o)->next_free
+= (__len)); (void) 0; }); __extension__ ({ struct obstack *
__o1 = (__h); void *__value = (void *) __o1->object_base; if
(__o1->next_free == __value) __o1->maybe_empty_object =
1; __o1->next_free = ((sizeof (long int) < sizeof (void
*) ? (__o1->object_base) : (char *) 0) + (((__o1->next_free
) - (sizeof (long int) < sizeof (void *) ? (__o1->object_base
) : (char *) 0) + (__o1->alignment_mask)) & ~(__o1->
alignment_mask))); if (__o1->next_free - (char *)__o1->
chunk > __o1->chunk_limit - (char *)__o1->chunk) __o1
->next_free = __o1->chunk_limit; __o1->object_base =
__o1->next_free; __value; }); });
177 if (!link->trie)
178 {
179 obstack_free(&kwset->obstack, link)__extension__ ({ struct obstack *__o = (&kwset->obstack
); void *__obj = (link); if (__obj > (void *)__o->chunk
&& __obj < (void *)__o->chunk_limit) __o->next_free
= __o->object_base = (char *)__obj; else (obstack_free) (
__o, __obj); });
180 return "memory exhausted";
181 }
182 link->trie->accepting = 0;
183 link->trie->links = NULL((void*)0);
184 link->trie->parent = trie;
185 link->trie->next = NULL((void*)0);
186 link->trie->fail = NULL((void*)0);
187 link->trie->depth = trie->depth + 1;
188 link->trie->shift = 0;
189 link->label = label;
190 link->balance = 0;
191
192 /* Install the new tree node in its parent. */
193 if (dirs[--depth] == L)
194 links[depth]->llink = link;
195 else
196 links[depth]->rlink = link;
197
198 /* Back up the tree fixing the balance flags. */
199 while (depth && !links[depth]->balance)
200 {
201 if (dirs[depth] == L)
202 --links[depth]->balance;
203 else
204 ++links[depth]->balance;
205 --depth;
206 }
207
208 /* Rebalance the tree by pointer rotations if necessary. */
209 if (depth && ((dirs[depth] == L && --links[depth]->balance)
210 || (dirs[depth] == R && ++links[depth]->balance)))
211 {
212 switch (links[depth]->balance)
213 {
214 case (char) -2:
215 switch (dirs[depth + 1])
216 {
217 case L:
218 r = links[depth], t = r->llink, rl = t->rlink;
219 t->rlink = r, r->llink = rl;
220 t->balance = r->balance = 0;
221 break;
222 case R:
223 r = links[depth], l = r->llink, t = l->rlink;
224 rl = t->rlink, lr = t->llink;
225 t->llink = l, l->rlink = lr, t->rlink = r, r->llink = rl;
226 l->balance = t->balance != 1 ? 0 : -1;
227 r->balance = t->balance != (char) -1 ? 0 : 1;
228 t->balance = 0;
229 break;
230 default:
231 abort ();
232 }
233 break;
234 case 2:
235 switch (dirs[depth + 1])
236 {
237 case R:
238 l = links[depth], t = l->rlink, lr = t->llink;
239 t->llink = l, l->rlink = lr;
240 t->balance = l->balance = 0;
241 break;
242 case L:
243 l = links[depth], r = l->rlink, t = r->llink;
244 lr = t->llink, rl = t->rlink;
245 t->llink = l, l->rlink = lr, t->rlink = r, r->llink = rl;
246 l->balance = t->balance != 1 ? 0 : -1;
247 r->balance = t->balance != (char) -1 ? 0 : 1;
248 t->balance = 0;
249 break;
250 default:
251 abort ();
252 }
253 break;
254 default:
255 abort ();
256 }
257
258 if (dirs[depth - 1] == L)
259 links[depth - 1]->llink = t;
260 else
261 links[depth - 1]->rlink = t;
262 }
263 }
264
265 trie = link->trie;
266 }
267
268 /* Mark the node we finally reached as accepting, encoding the
269 index number of this word in the keyword set so far. */
270 if (!trie->accepting)
271 trie->accepting = 1 + 2 * kwset->words;
272 ++kwset->words;
273
274 /* Keep track of the longest and shortest string of the keyword set. */
275 if (trie->depth < kwset->mind)
276 kwset->mind = trie->depth;
277 if (trie->depth > kwset->maxd)
278 kwset->maxd = trie->depth;
279
280 return NULL((void*)0);
281}
282
283/* Enqueue the trie nodes referenced from the given tree in the
284 given queue. */
285static void
286enqueue (struct tree *tree, struct trie **last)
287{
288 if (!tree)
289 return;
290 enqueue(tree->llink, last);
291 enqueue(tree->rlink, last);
292 (*last) = (*last)->next = tree->trie;
293}
294
295/* Compute the Aho-Corasick failure function for the trie nodes referenced
296 from the given tree, given the failure function for their parent as
297 well as a last resort failure node. */
298static void
299treefails (register struct tree const *tree, struct trie const *fail,
300 struct trie *recourse)
301{
302 register struct tree *link;
303
304 if (!tree)
305 return;
306
307 treefails(tree->llink, fail, recourse);
308 treefails(tree->rlink, fail, recourse);
309
310 /* Find, in the chain of fails going back to the root, the first
311 node that has a descendant on the current label. */
312 while (fail)
313 {
314 link = fail->links;
315 while (link && tree->label != link->label)
316 if (tree->label < link->label)
317 link = link->llink;
318 else
319 link = link->rlink;
320 if (link)
321 {
322 tree->trie->fail = link->trie;
323 return;
324 }
325 fail = fail->fail;
326 }
327
328 tree->trie->fail = recourse;
329}
330
331/* Set delta entries for the links of the given tree such that
332 the preexisting delta value is larger than the current depth. */
333static void
334treedelta (register struct tree const *tree,
335 register unsigned int depth,
336 unsigned char delta[])
337{
338 if (!tree)
339 return;
340 treedelta(tree->llink, depth, delta);
341 treedelta(tree->rlink, depth, delta);
342 if (depth < delta[tree->label])
343 delta[tree->label] = depth;
344}
345
346/* Return true if A has every label in B. */
347static int
348hasevery (register struct tree const *a, register struct tree const *b)
349{
350 if (!b)
351 return 1;
352 if (!hasevery(a, b->llink))
353 return 0;
354 if (!hasevery(a, b->rlink))
355 return 0;
356 while (a && b->label != a->label)
357 if (b->label < a->label)
358 a = a->llink;
359 else
360 a = a->rlink;
361 return !!a;
362}
363
364/* Compute a vector, indexed by character code, of the trie nodes
365 referenced from the given tree. */
366static void
367treenext (struct tree const *tree, struct trie *next[])
368{
369 if (!tree)
370 return;
371 treenext(tree->llink, next);
372 treenext(tree->rlink, next);
373 next[tree->label] = tree->trie;
374}
375
376/* Compute the shift for each trie node, as well as the delta
377 table and next cache for the given keyword set. */
378const char *
379kwsprep (kwset_t kws)
380{
381 register struct kwset *kwset;
382 register int i;
383 register struct trie *curr;
384 register unsigned char const *trans;
385 unsigned char delta[NCHAR((127*2 +1) + 1)];
386
387 kwset = (struct kwset *) kws;
388
389 /* Initial values for the delta table; will be changed later. The
390 delta entry for a given character is the smallest depth of any
391 node at which an outgoing edge is labeled by that character. */
392 memset(delta, kwset->mind < UCHAR_MAX ? kwset->mind : UCHAR_MAX, NCHAR)__builtin___memset_chk (delta, kwset->mind < (127*2 +1)
? kwset->mind : (127*2 +1), ((127*2 +1) + 1), __builtin_object_size
(delta, 0));
393
394 /* Check if we can use the simple boyer-moore algorithm, instead
395 of the hairy commentz-walter algorithm. */
396 if (kwset->words == 1 && kwset->trans == NULL((void*)0))
397 {
398 char c;
399
400 /* Looking for just one string. Extract it from the trie. */
401 kwset->target = obstack_alloc(&kwset->obstack, kwset->mind)__extension__ ({ struct obstack *__h = (&kwset->obstack
); __extension__ ({ struct obstack *__o = (__h); int __len = (
(kwset->mind)); if (__o->chunk_limit - __o->next_free
< __len) _obstack_newchunk (__o, __len); ((__o)->next_free
+= (__len)); (void) 0; }); __extension__ ({ struct obstack *
__o1 = (__h); void *__value = (void *) __o1->object_base; if
(__o1->next_free == __value) __o1->maybe_empty_object =
1; __o1->next_free = ((sizeof (long int) < sizeof (void
*) ? (__o1->object_base) : (char *) 0) + (((__o1->next_free
) - (sizeof (long int) < sizeof (void *) ? (__o1->object_base
) : (char *) 0) + (__o1->alignment_mask)) & ~(__o1->
alignment_mask))); if (__o1->next_free - (char *)__o1->
chunk > __o1->chunk_limit - (char *)__o1->chunk) __o1
->next_free = __o1->chunk_limit; __o1->object_base =
__o1->next_free; __value; }); });
402 if (!kwset->target)
403 return "memory exhausted";
404 for (i = kwset->mind - 1, curr = kwset->trie; i >= 0; --i)
405 {
406 kwset->target[i] = curr->links->label;
407 curr = curr->links->trie;
408 }
409 /* Build the Boyer Moore delta. Boy that's easy compared to CW. */
410 for (i = 0; i < kwset->mind; ++i)
411 delta[U(kwset->target[i])((unsigned char) (kwset->target[i]))] = kwset->mind - (i + 1);
412 /* Find the minimal delta2 shift that we might make after
413 a backwards match has failed. */
414 c = kwset->target[kwset->mind - 1];
415 for (i = kwset->mind - 2; i >= 0; --i)
416 if (kwset->target[i] == c)
417 break;
418 kwset->mind2 = kwset->mind - (i + 1);
419 }
420 else
421 {
422 register struct trie *fail;
423 struct trie *last, *next[NCHAR((127*2 +1) + 1)];
424
425 /* Traverse the nodes of the trie in level order, simultaneously
426 computing the delta table, failure function, and shift function. */
427 for (curr = last = kwset->trie; curr; curr = curr->next)
1
Assuming pointer value is null
→
2
←
Loop condition is false. Execution continues on line 462
→
428 {
429 /* Enqueue the immediate descendants in the level order queue. */
430 enqueue(curr->links, &last);
431
432 curr->shift = kwset->mind;
433 curr->maxshift = kwset->mind;
434
435 /* Update the delta table for the descendants of this node. */
436 treedelta(curr->links, curr->depth, delta);
437
438 /* Compute the failure function for the descendants of this node. */
439 treefails(curr->links, curr->fail, kwset->trie);
440
441 /* Update the shifts at each node in the current node's chain
442 of fails back to the root. */
443 for (fail = curr->fail; fail; fail = fail->fail)
444 {
445 /* If the current node has some outgoing edge that the fail
446 doesn't, then the shift at the fail should be no larger
447 than the difference of their depths. */
448 if (!hasevery(fail->links, curr->links))
449 if (curr->depth - fail->depth < fail->shift)
450 fail->shift = curr->depth - fail->depth;
451
452 /* If the current node is accepting then the shift at the
453 fail and its descendants should be no larger than the
454 difference of their depths. */
455 if (curr->accepting && fail->maxshift > curr->depth - fail->depth)
456 fail->maxshift = curr->depth - fail->depth;
457 }
458 }
459
460 /* Traverse the trie in level order again, fixing up all nodes whose
461 shift exceeds their inherited maxshift. */
462 for (curr = kwset->trie->next; curr; curr = curr->next)
3
←
Access to field 'next' results in a dereference of a null pointer (loaded from field 'trie')
463 {
464 if (curr->maxshift > curr->parent->maxshift)
465 curr->maxshift = curr->parent->maxshift;
466 if (curr->shift > curr->maxshift)
467 curr->shift = curr->maxshift;
468 }
469
470 /* Create a vector, indexed by character code, of the outgoing links
471 from the root node. */
472 for (i = 0; i < NCHAR((127*2 +1) + 1); ++i)
473 next[i] = NULL((void*)0);
474 treenext(kwset->trie->links, next);
475
476 if ((trans = kwset->trans) != NULL((void*)0))
477 for (i = 0; i < NCHAR((127*2 +1) + 1); ++i)
478 kwset->next[i] = next[U(trans[i])((unsigned char) (trans[i]))];
479 else
480 memcpy(kwset->next, next, NCHAR * sizeof(struct trie *))__builtin___memcpy_chk (kwset->next, next, ((127*2 +1) + 1
) * sizeof(struct trie *), __builtin_object_size (kwset->next
, 0));
481 }
482
483 /* Fix things up for any translation table. */
484 if ((trans = kwset->trans) != NULL((void*)0))
485 for (i = 0; i < NCHAR((127*2 +1) + 1); ++i)
486 kwset->delta[i] = delta[U(trans[i])((unsigned char) (trans[i]))];
487 else
488 memcpy(kwset->delta, delta, NCHAR)__builtin___memcpy_chk (kwset->delta, delta, ((127*2 +1) +
1), __builtin_object_size (kwset->delta, 0));
489
490 return NULL((void*)0);
491}
492
493/* Fast boyer-moore search. */
494static size_t
495bmexec (kwset_t kws, char const *text, size_t size)
496{
497 struct kwset const *kwset;
498 register unsigned char const *d1;
499 register char const *ep, *sp, *tp;
500 register int d, gc, i, len, md2;
501
502 kwset = (struct kwset const *) kws;
503 len = kwset->mind;
504
505 if (len == 0)
506 return 0;
507 if (len > size)
508 return -1;
509 if (len == 1)
510 {
511 tp = memchr (text, kwset->target[0], size);
512 return tp ? tp - text : -1;
513 }
514
515 d1 = kwset->delta;
516 sp = kwset->target + len;
517 gc = U(sp[-2])((unsigned char) (sp[-2]));
518 md2 = kwset->mind2;
519 tp = text + len;
520
521 /* Significance of 12: 1 (initial offset) + 10 (skip loop) + 1 (md2). */
522 if (size > 12 * len)
523 /* 11 is not a bug, the initial offset happens only once. */
524 for (ep = text + size - 11 * len;;)
525 {
526 while (tp <= ep)
527 {
528 d = d1[U(tp[-1])((unsigned char) (tp[-1]))], tp += d;
529 d = d1[U(tp[-1])((unsigned char) (tp[-1]))], tp += d;
530 if (d == 0)
531 goto found;
532 d = d1[U(tp[-1])((unsigned char) (tp[-1]))], tp += d;
533 d = d1[U(tp[-1])((unsigned char) (tp[-1]))], tp += d;
534 d = d1[U(tp[-1])((unsigned char) (tp[-1]))], tp += d;
535 if (d == 0)
536 goto found;
537 d = d1[U(tp[-1])((unsigned char) (tp[-1]))], tp += d;
538 d = d1[U(tp[-1])((unsigned char) (tp[-1]))], tp += d;
539 d = d1[U(tp[-1])((unsigned char) (tp[-1]))], tp += d;
540 if (d == 0)
541 goto found;
542 d = d1[U(tp[-1])((unsigned char) (tp[-1]))], tp += d;
543 d = d1[U(tp[-1])((unsigned char) (tp[-1]))], tp += d;
544 }
545 break;
546 found:
547 if (U(tp[-2])((unsigned char) (tp[-2])) == gc)
548 {
549 for (i = 3; i <= len && U(tp[-i])((unsigned char) (tp[-i])) == U(sp[-i])((unsigned char) (sp[-i])); ++i)
550 ;
551 if (i > len)
552 return tp - len - text;
553 }
554 tp += md2;
555 }
556
557 /* Now we have only a few characters left to search. We
558 carefully avoid ever producing an out-of-bounds pointer. */
559 ep = text + size;
560 d = d1[U(tp[-1])((unsigned char) (tp[-1]))];
561 while (d <= ep - tp)
562 {
563 d = d1[U((tp += d)[-1])((unsigned char) ((tp += d)[-1]))];
564 if (d != 0)
565 continue;
566 if (U(tp[-2])((unsigned char) (tp[-2])) == gc)
567 {
568 for (i = 3; i <= len && U(tp[-i])((unsigned char) (tp[-i])) == U(sp[-i])((unsigned char) (sp[-i])); ++i)
569 ;
570 if (i > len)
571 return tp - len - text;
572 }
573 d = md2;
574 }
575
576 return -1;
577}
578
579/* Hairy multiple string search. */
580static size_t
581cwexec (kwset_t kws, char const *text, size_t len, struct kwsmatch *kwsmatch)
582{
583 struct kwset const *kwset;
584 struct trie * const *next;
585 struct trie const *trie;
586 struct trie const *accept;
587 char const *beg, *lim, *mch, *lmch;
588 register unsigned char c;
589 register unsigned char const *delta;
590 register int d;
591 register char const *end, *qlim;
592 register struct tree const *tree;
593 register unsigned char const *trans;
594
595 accept = NULL((void*)0);
596
597 /* Initialize register copies and look for easy ways out. */
598 kwset = (struct kwset *) kws;
599 if (len < kwset->mind)
600 return -1;
601 next = kwset->next;
602 delta = kwset->delta;
603 trans = kwset->trans;
604 lim = text + len;
605 end = text;
606 if ((d = kwset->mind) != 0)
607 mch = NULL((void*)0);
608 else
609 {
610 mch = text, accept = kwset->trie;
611 goto match;
612 }
613
614 if (len >= 4 * kwset->mind)
615 qlim = lim - 4 * kwset->mind;
616 else
617 qlim = NULL((void*)0);
618
619 while (lim - end >= d)
620 {
621 if (qlim && end <= qlim)
622 {
623 end += d - 1;
624 while ((d = delta[c = *end]) && end < qlim)
625 {
626 end += d;
627 end += delta[U(*end)((unsigned char) (*end))];
628 end += delta[U(*end)((unsigned char) (*end))];
629 }
630 ++end;
631 }
632 else
633 d = delta[c = (end += d)[-1]];
634 if (d)
635 continue;
636 beg = end - 1;
637 trie = next[c];
638 if (trie->accepting)
639 {
640 mch = beg;
641 accept = trie;
642 }
643 d = trie->shift;
644 while (beg > text)
645 {
646 c = trans ? trans[U(*--beg)((unsigned char) (*--beg))] : *--beg;
647 tree = trie->links;
648 while (tree && c != tree->label)
649 if (c < tree->label)
650 tree = tree->llink;
651 else
652 tree = tree->rlink;
653 if (tree)
654 {
655 trie = tree->trie;
656 if (trie->accepting)
657 {
658 mch = beg;
659 accept = trie;
660 }
661 }
662 else
663 break;
664 d = trie->shift;
665 }
666 if (mch)
667 goto match;
668 }
669 return -1;
670
671 match:
672 /* Given a known match, find the longest possible match anchored
673 at or before its starting point. This is nearly a verbatim
674 copy of the preceding main search loops. */
675 if (lim - mch > kwset->maxd)
676 lim = mch + kwset->maxd;
677 lmch = NULL((void*)0);
678 d = 1;
679 while (lim - end >= d)
680 {
681 if ((d = delta[c = (end += d)[-1]]) != 0)
682 continue;
683 beg = end - 1;
684 if (!(trie = next[c]))
685 {
686 d = 1;
687 continue;
688 }
689 if (trie->accepting && beg <= mch)
690 {
691 lmch = beg;
692 accept = trie;
693 }
694 d = trie->shift;
695 while (beg > text)
696 {
697 c = trans ? trans[U(*--beg)((unsigned char) (*--beg))] : *--beg;
698 tree = trie->links;
699 while (tree && c != tree->label)
700 if (c < tree->label)
701 tree = tree->llink;
702 else
703 tree = tree->rlink;
704 if (tree)
705 {
706 trie = tree->trie;
707 if (trie->accepting && beg <= mch)
708 {
709 lmch = beg;
710 accept = trie;
711 }
712 }
713 else
714 break;
715 d = trie->shift;
716 }
717 if (lmch)
718 {
719 mch = lmch;
720 goto match;
721 }
722 if (!d)
723 d = 1;
724 }
725
726 if (kwsmatch)
727 {
728 kwsmatch->index = accept->accepting / 2;
729 kwsmatch->offset[0] = mch - text;
730 kwsmatch->size[0] = accept->depth;
731 }
732 return mch - text;
733}
734
735/* Search through the given text for a match of any member of the
736 given keyword set. Return a pointer to the first character of
737 the matching substring, or NULL if no match is found. If FOUNDLEN
738 is non-NULL store in the referenced location the length of the
739 matching substring. Similarly, if FOUNDIDX is non-NULL, store
740 in the referenced location the index number of the particular
741 keyword matched. */
742size_t
743kwsexec (kwset_t kws, char const *text, size_t size,
744 struct kwsmatch *kwsmatch)
745{
746 struct kwset const *kwset = (struct kwset *) kws;
747 if (kwset->words == 1 && kwset->trans == NULL((void*)0))
748 {
749 size_t ret = bmexec (kws, text, size);
750 if (kwsmatch != NULL((void*)0) && ret != (size_t) -1)
751 {
752 kwsmatch->index = 0;
753 kwsmatch->offset[0] = ret;
754 kwsmatch->size[0] = kwset->mind;
755 }
756 return ret;
757 }
758 else
759 return cwexec(kws, text, size, kwsmatch);
760}
761
762/* Free the components of the given keyword set. */
763void
764kwsfree (kwset_t kws)
765{
766 struct kwset *kwset;
767
768 kwset = (struct kwset *) kws;
769 obstack_free(&kwset->obstack, NULL)__extension__ ({ struct obstack *__o = (&kwset->obstack
); void *__obj = (((void*)0)); if (__obj > (void *)__o->
chunk && __obj < (void *)__o->chunk_limit) __o->
next_free = __o->object_base = (char *)__obj; else (obstack_free
) (__o, __obj); });
770 free(kws);
771}