70322ae3 |
1 | /* |
2 | * trie.c: implementation of trie.h. |
3 | */ |
4 | |
5 | #include <assert.h> |
6 | #include <stdio.h> |
7 | #include <string.h> |
8 | #include <stdlib.h> |
9 | #include <errno.h> |
10 | |
11 | #include <sys/types.h> |
12 | #include <unistd.h> |
13 | |
14 | #include "malloc.h" |
15 | #include "trie.h" |
16 | |
17 | #define alignof(typ) ( offsetof(struct { char c; typ t; }, t) ) |
18 | |
373a02e5 |
19 | extern char pathsep; |
20 | |
70322ae3 |
21 | /* |
22 | * Compare functions for pathnames. Returns the relative order of |
23 | * the names, like strcmp; also passes back the offset of the |
24 | * first differing character if desired. |
25 | */ |
26 | static int trieccmp(unsigned char a, unsigned char b) |
27 | { |
373a02e5 |
28 | a = (a == '\0' ? '\0' : a == pathsep ? '\1' : a+1); |
29 | b = (b == '\0' ? '\0' : b == pathsep ? '\1' : b+1); |
30 | return (int)a - (int)b; |
70322ae3 |
31 | } |
32 | |
33 | static int triencmp(const char *a, size_t alen, |
34 | const char *b, size_t blen, int *offset) |
35 | { |
36 | int off = 0; |
37 | while (off < alen && off < blen && a[off] == b[off]) |
38 | off++; |
39 | if (offset) |
40 | *offset = off; |
41 | if (off == alen || off == blen) return (off == blen) - (off == alen); |
42 | return trieccmp(a[off], b[off]); |
43 | } |
44 | |
45 | static int triecmp(const char *a, const char *b, int *offset) |
46 | { |
47 | return triencmp(a, strlen(a), b, strlen(b), offset); |
48 | } |
49 | |
50 | /* ---------------------------------------------------------------------- |
51 | * Trie node structures. |
52 | * |
53 | * The trie format stored in the file consists of three distinct |
54 | * node types, each with a distinguishing type field at the start. |
55 | * |
56 | * TRIE_LEAF is a leaf node; it contains an actual trie_file |
57 | * structure, and indicates that when you're searching down the |
58 | * trie with a string, you should now expect to encounter |
59 | * end-of-string. |
60 | * |
61 | * TRIE_SWITCH indicates that the set of strings in the trie |
62 | * include strings with more than one distinct character after the |
63 | * prefix leading up to this point. Hence, it stores multiple |
64 | * subnode pointers and a different single character for each one. |
65 | * |
66 | * TRIE_STRING indicates that at this point everything in the trie |
67 | * has the same next few characters; it stores a single mandatory |
68 | * string fragment and exactly one subnode pointer. |
69 | */ |
70 | enum { |
71 | TRIE_LEAF = 0x7fffe000, |
72 | TRIE_SWITCH, |
73 | TRIE_STRING |
74 | }; |
75 | |
76 | struct trie_common { |
77 | int type; |
78 | }; |
79 | |
80 | struct trie_switchentry { |
81 | off_t subnode; |
82 | int subcount; |
83 | }; |
84 | |
85 | struct trie_leaf { |
86 | struct trie_common c; |
87 | struct trie_file file; |
88 | }; |
89 | |
90 | struct trie_switch { |
91 | struct trie_common c; |
92 | /* |
93 | * sw[0] to sw[len-1] give the subnode pointers and element |
94 | * counts. At &sw[len] is stored len single bytes which are |
95 | * the characters corresponding to each subnode. |
96 | */ |
97 | int len; |
98 | struct trie_switchentry sw[]; |
99 | }; |
100 | |
101 | struct trie_string { |
102 | struct trie_common c; |
103 | int stringlen; |
104 | off_t subnode; |
105 | char string[]; |
106 | }; |
107 | |
108 | struct trie_header { |
109 | unsigned long magic; |
110 | off_t root, indexroot; |
111 | int count; |
112 | size_t maxpathlen; |
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113 | int pathsep; |
70322ae3 |
114 | }; |
115 | |
116 | /* Union only used for computing alignment */ |
117 | union trie_node { |
118 | struct trie_leaf leaf; |
119 | struct { /* fake trie_switch with indeterminate array length filled in */ |
120 | struct trie_common c; |
121 | int len; |
122 | struct trie_switchentry sw[1]; |
123 | } sw; |
124 | struct { /* fake trie_string with indeterminate array length filled in */ |
125 | struct trie_common c; |
126 | int stringlen; |
127 | off_t subnode; |
128 | char string[1]; |
129 | } str; |
130 | }; |
131 | #define TRIE_MAGIC 0x75646761UL |
132 | #define TRIE_ALIGN alignof(union trie_node) |
133 | |
134 | /* ---------------------------------------------------------------------- |
135 | * Trie-building functions. |
136 | */ |
137 | |
138 | struct tbswitch { |
139 | int len; |
140 | char c[256]; |
141 | off_t off[256]; |
142 | int count[256]; |
143 | }; |
144 | |
145 | struct triebuild { |
146 | int fd; |
147 | off_t offset; |
148 | char *lastpath; |
149 | int lastlen, lastsize; |
150 | off_t lastoff; |
151 | struct tbswitch *switches; |
152 | int switchsize; |
153 | size_t maxpathlen; |
154 | }; |
155 | |
156 | static void tb_seek(triebuild *tb, off_t off) |
157 | { |
158 | tb->offset = off; |
159 | if (lseek(tb->fd, off, SEEK_SET) < 0) { |
160 | fprintf(stderr, "agedu: lseek: %s\n", strerror(errno)); |
161 | exit(1); |
162 | } |
163 | } |
164 | |
165 | static void tb_write(triebuild *tb, const void *buf, size_t len) |
166 | { |
167 | tb->offset += len; |
168 | while (len > 0) { |
169 | int ret = write(tb->fd, buf, len); |
170 | if (ret < 0) { |
171 | fprintf(stderr, "agedu: write: %s\n", strerror(errno)); |
172 | exit(1); |
173 | } |
174 | len -= ret; |
175 | buf = (const void *)((const char *)buf + ret); |
176 | } |
177 | } |
178 | |
179 | static char trie_align_zeroes[TRIE_ALIGN]; |
180 | |
181 | static void tb_align(triebuild *tb) |
182 | { |
183 | int off = (TRIE_ALIGN - ((tb)->offset % TRIE_ALIGN)) % TRIE_ALIGN; |
184 | tb_write(tb, trie_align_zeroes, off); |
185 | } |
186 | |
187 | triebuild *triebuild_new(int fd) |
188 | { |
189 | triebuild *tb = snew(triebuild); |
190 | struct trie_header th; |
191 | |
192 | tb->fd = fd; |
193 | tb->lastpath = NULL; |
194 | tb->lastlen = tb->lastsize = 0; |
195 | tb->lastoff = 0; |
196 | tb->switches = NULL; |
197 | tb->switchsize = 0; |
198 | tb->maxpathlen = 0; |
199 | |
200 | th.magic = TRIE_MAGIC; |
201 | th.root = th.count = 0; |
202 | th.indexroot = 0; |
203 | th.maxpathlen = 0; |
269fa2d1 |
204 | th.pathsep = (unsigned char)pathsep; |
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205 | |
206 | tb_seek(tb, 0); |
207 | tb_write(tb, &th, sizeof(th)); |
208 | |
209 | return tb; |
210 | } |
211 | |
212 | static off_t triebuild_unwind(triebuild *tb, int targetdepth, int *outcount) |
213 | { |
214 | off_t offset; |
215 | int count, depth; |
216 | |
217 | if (tb->lastoff == 0) { |
218 | *outcount = 0; |
219 | return 0; |
220 | } |
221 | |
222 | offset = tb->lastoff; |
223 | count = 1; |
224 | depth = tb->lastlen + 1; |
225 | |
226 | assert(depth >= targetdepth); |
227 | |
228 | while (depth > targetdepth) { |
229 | int odepth = depth; |
230 | while (depth > targetdepth && |
231 | (depth-1 > tb->switchsize || tb->switches[depth-1].len == 0)) |
232 | depth--; |
233 | if (odepth > depth) { |
234 | /* |
235 | * Write out a string node. |
236 | */ |
237 | size_t nodesize = sizeof(struct trie_string) + odepth - depth; |
238 | struct trie_string *st = (struct trie_string *)smalloc(nodesize); |
239 | st->c.type = TRIE_STRING; |
240 | st->stringlen = odepth - depth; |
241 | st->subnode = offset; |
242 | memcpy(st->string, tb->lastpath + depth, odepth - depth); |
243 | tb_align(tb); |
244 | offset = tb->offset; |
245 | tb_write(tb, st, nodesize); |
246 | sfree(st); |
247 | } |
248 | |
249 | assert(depth >= targetdepth); |
250 | if (depth <= targetdepth) |
251 | break; |
252 | |
253 | /* |
254 | * Now we expect to be sitting just below a switch node. |
255 | * Add our final entry to it and write it out. |
256 | */ |
257 | depth--; |
258 | { |
259 | struct trie_switch *sw; |
260 | char *chars; |
261 | size_t nodesize; |
262 | int swlen = tb->switches[depth].len; |
263 | int i; |
264 | |
265 | assert(swlen > 0); |
266 | |
267 | tb->switches[depth].c[swlen] = tb->lastpath[depth]; |
268 | tb->switches[depth].off[swlen] = offset; |
269 | tb->switches[depth].count[swlen] = count; |
270 | swlen++; |
271 | |
272 | nodesize = sizeof(struct trie_switch) + |
273 | swlen * sizeof(struct trie_switchentry) + swlen; |
274 | sw = (struct trie_switch *)smalloc(nodesize); |
275 | chars = (char *)&sw->sw[swlen]; |
276 | |
277 | sw->c.type = TRIE_SWITCH; |
278 | sw->len = swlen; |
279 | count = 0; |
280 | for (i = 0; i < swlen; i++) { |
281 | sw->sw[i].subnode = tb->switches[depth].off[i]; |
282 | sw->sw[i].subcount = tb->switches[depth].count[i]; |
283 | chars[i] = tb->switches[depth].c[i]; |
284 | |
285 | count += tb->switches[depth].count[i]; |
286 | } |
287 | |
288 | tb_align(tb); |
289 | offset = tb->offset; |
290 | tb_write(tb, sw, nodesize); |
291 | sfree(sw); |
292 | |
293 | tb->switches[depth].len = 0; /* clear this node */ |
294 | } |
295 | } |
296 | |
297 | *outcount = count; |
298 | return offset; |
299 | } |
300 | |
301 | void triebuild_add(triebuild *tb, const char *pathname, |
302 | const struct trie_file *file) |
303 | { |
304 | int pathlen = strlen(pathname); |
305 | int depth; |
306 | |
307 | if (tb->maxpathlen < pathlen+1) |
308 | tb->maxpathlen = pathlen+1; |
309 | |
310 | if (tb->lastpath) { |
311 | off_t offset; |
312 | int count; |
313 | |
314 | /* |
315 | * Find the first differing character between this pathname |
316 | * and the previous one. |
317 | */ |
318 | int ret = triecmp(tb->lastpath, pathname, &depth); |
319 | assert(ret < 0); |
320 | |
321 | /* |
322 | * Finalise all nodes above this depth. |
323 | */ |
324 | offset = triebuild_unwind(tb, depth+1, &count); |
325 | |
326 | /* |
327 | * Add the final node we just acquired to the switch node |
328 | * at our chosen depth, creating it if it isn't already |
329 | * there. |
330 | */ |
331 | if (tb->switchsize <= depth) { |
332 | int oldsize = tb->switchsize; |
333 | tb->switchsize = depth * 3 / 2 + 64; |
334 | tb->switches = sresize(tb->switches, tb->switchsize, |
335 | struct tbswitch); |
336 | while (oldsize < tb->switchsize) |
337 | tb->switches[oldsize++].len = 0; |
338 | } |
339 | |
340 | tb->switches[depth].c[tb->switches[depth].len] = tb->lastpath[depth]; |
341 | tb->switches[depth].off[tb->switches[depth].len] = offset; |
342 | tb->switches[depth].count[tb->switches[depth].len] = count; |
343 | tb->switches[depth].len++; |
344 | } |
345 | |
346 | /* |
347 | * Write out a leaf node for the new file, and remember its |
348 | * file offset. |
349 | */ |
350 | { |
351 | struct trie_leaf leaf; |
352 | |
353 | leaf.c.type = TRIE_LEAF; |
354 | leaf.file = *file; /* structure copy */ |
355 | |
356 | tb_align(tb); |
357 | tb->lastoff = tb->offset; |
358 | tb_write(tb, &leaf, sizeof(leaf)); |
359 | } |
360 | |
361 | /* |
362 | * Store this pathname for comparison with the next one. |
363 | */ |
364 | if (tb->lastsize < pathlen+1) { |
365 | tb->lastsize = pathlen * 3 / 2 + 64; |
366 | tb->lastpath = sresize(tb->lastpath, tb->lastsize, char); |
367 | } |
368 | strcpy(tb->lastpath, pathname); |
369 | tb->lastlen = pathlen; |
370 | } |
371 | |
372 | int triebuild_finish(triebuild *tb) |
373 | { |
374 | struct trie_header th; |
375 | |
376 | th.magic = TRIE_MAGIC; |
377 | th.root = triebuild_unwind(tb, 0, &th.count); |
378 | th.indexroot = 0; |
379 | th.maxpathlen = tb->maxpathlen; |
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380 | th.pathsep = (unsigned char)pathsep; |
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381 | |
382 | tb_seek(tb, 0); |
383 | tb_write(tb, &th, sizeof(th)); |
384 | |
385 | return th.count; |
386 | } |
387 | |
388 | void triebuild_free(triebuild *tb) |
389 | { |
390 | sfree(tb->switches); |
391 | sfree(tb->lastpath); |
392 | sfree(tb); |
393 | } |
394 | |
395 | /* ---------------------------------------------------------------------- |
396 | * Querying functions. |
397 | */ |
398 | |
399 | #define NODE(t, off, type) \ |
400 | ((const struct type *)((const char *)(t) + (off))) |
401 | |
402 | size_t trie_maxpathlen(const void *t) |
403 | { |
404 | const struct trie_header *hdr = NODE(t, 0, trie_header); |
405 | return hdr->maxpathlen; |
406 | } |
407 | |
408 | unsigned long trie_before(const void *t, const char *pathname) |
409 | { |
410 | const struct trie_header *hdr = NODE(t, 0, trie_header); |
411 | int ret = 0, lastcount = hdr->count; |
412 | int len = 1 + strlen(pathname), depth = 0; |
413 | off_t off = hdr->root; |
414 | |
415 | while (1) { |
416 | const struct trie_common *node = NODE(t, off, trie_common); |
417 | if (node->type == TRIE_LEAF) { |
418 | if (depth < len) |
419 | ret += lastcount; /* _shouldn't_ happen, but in principle */ |
420 | return ret; |
421 | } else if (node->type == TRIE_STRING) { |
422 | const struct trie_string *st = NODE(t, off, trie_string); |
423 | |
424 | int offset; |
425 | int cmp = triencmp(st->string, st->stringlen, |
426 | pathname + depth, len-depth, &offset); |
427 | |
428 | if (offset < st->stringlen) { |
429 | if (cmp < 0) |
430 | ret += lastcount; |
431 | return ret; |
432 | } |
433 | |
434 | depth += st->stringlen; |
435 | off = st->subnode; |
436 | } else if (node->type == TRIE_SWITCH) { |
437 | const struct trie_switch *sw = NODE(t, off, trie_switch); |
438 | const char *chars = (const char *)&sw->sw[sw->len]; |
439 | int i; |
440 | |
441 | for (i = 0; i < sw->len; i++) { |
442 | int c = chars[i]; |
443 | int cmp = trieccmp(pathname[depth], c); |
444 | if (cmp > 0) |
445 | ret += sw->sw[i].subcount; |
446 | else if (cmp < 0) |
447 | return ret; |
448 | else { |
449 | off = sw->sw[i].subnode; |
450 | lastcount = sw->sw[i].subcount; |
451 | depth++; |
452 | break; |
453 | } |
454 | } |
455 | if (i == sw->len) |
456 | return ret; |
457 | } |
458 | } |
459 | } |
460 | |
461 | void trie_getpath(const void *t, unsigned long n, char *buf) |
462 | { |
463 | const struct trie_header *hdr = NODE(t, 0, trie_header); |
464 | int depth = 0; |
465 | off_t off = hdr->root; |
466 | |
467 | while (1) { |
468 | const struct trie_common *node = NODE(t, off, trie_common); |
469 | if (node->type == TRIE_LEAF) { |
470 | assert(depth > 0 && buf[depth-1] == '\0'); |
471 | return; |
472 | } else if (node->type == TRIE_STRING) { |
473 | const struct trie_string *st = NODE(t, off, trie_string); |
474 | |
475 | memcpy(buf + depth, st->string, st->stringlen); |
476 | depth += st->stringlen; |
477 | off = st->subnode; |
478 | } else if (node->type == TRIE_SWITCH) { |
479 | const struct trie_switch *sw = NODE(t, off, trie_switch); |
480 | const char *chars = (const char *)&sw->sw[sw->len]; |
481 | int i; |
482 | |
483 | for (i = 0; i < sw->len; i++) { |
484 | if (n < sw->sw[i].subcount) { |
485 | buf[depth++] = chars[i]; |
486 | off = sw->sw[i].subnode; |
487 | break; |
488 | } else |
489 | n -= sw->sw[i].subcount; |
490 | } |
491 | assert(i < sw->len); |
492 | } |
493 | } |
494 | } |
495 | |
496 | unsigned long trie_count(const void *t) |
497 | { |
498 | const struct trie_header *hdr = NODE(t, 0, trie_header); |
499 | return hdr->count; |
500 | } |
501 | |
269fa2d1 |
502 | char trie_pathsep(const void *t) |
503 | { |
504 | const struct trie_header *hdr = NODE(t, 0, trie_header); |
505 | return (char)hdr->pathsep; |
506 | } |
507 | |
70322ae3 |
508 | struct triewalk_switch { |
509 | const struct trie_switch *sw; |
510 | int pos, depth, count; |
511 | }; |
512 | struct triewalk { |
513 | const void *t; |
514 | struct triewalk_switch *switches; |
515 | int nswitches, switchsize; |
516 | int count; |
517 | }; |
518 | triewalk *triewalk_new(const void *vt) |
519 | { |
520 | triewalk *tw = snew(triewalk); |
521 | |
522 | tw->t = (const char *)vt; |
523 | tw->switches = NULL; |
524 | tw->switchsize = 0; |
525 | tw->nswitches = -1; |
526 | tw->count = 0; |
527 | |
528 | return tw; |
529 | } |
530 | const struct trie_file *triewalk_next(triewalk *tw, char *buf) |
531 | { |
532 | off_t off; |
533 | int depth; |
534 | |
535 | if (tw->nswitches < 0) { |
536 | const struct trie_header *hdr = NODE(tw->t, 0, trie_header); |
537 | off = hdr->root; |
538 | depth = 0; |
539 | tw->nswitches = 0; |
540 | } else { |
541 | while (1) { |
542 | int swpos; |
543 | const struct trie_switch *sw; |
544 | const char *chars; |
545 | |
546 | if (tw->nswitches == 0) { |
547 | assert(tw->count == NODE(tw->t, 0, trie_header)->count); |
548 | return NULL; /* run out of trie */ |
549 | } |
550 | |
551 | swpos = tw->switches[tw->nswitches-1].pos; |
552 | sw = tw->switches[tw->nswitches-1].sw; |
553 | chars = (const char *)&sw->sw[sw->len]; |
554 | |
555 | if (swpos < sw->len) { |
556 | depth = tw->switches[tw->nswitches-1].depth; |
557 | off = sw->sw[swpos].subnode; |
558 | if (buf) |
559 | buf[depth++] = chars[swpos]; |
560 | assert(tw->count == tw->switches[tw->nswitches-1].count); |
561 | tw->switches[tw->nswitches-1].count += sw->sw[swpos].subcount; |
562 | tw->switches[tw->nswitches-1].pos++; |
563 | break; |
564 | } |
565 | |
566 | tw->nswitches--; |
567 | } |
568 | } |
569 | |
570 | while (1) { |
571 | const struct trie_common *node = NODE(tw->t, off, trie_common); |
572 | if (node->type == TRIE_LEAF) { |
573 | const struct trie_leaf *lf = NODE(tw->t, off, trie_leaf); |
574 | if (buf) |
575 | assert(depth > 0 && buf[depth-1] == '\0'); |
576 | tw->count++; |
577 | return &lf->file; |
578 | } else if (node->type == TRIE_STRING) { |
579 | const struct trie_string *st = NODE(tw->t, off, trie_string); |
580 | |
581 | if (buf) |
582 | memcpy(buf + depth, st->string, st->stringlen); |
583 | depth += st->stringlen; |
584 | off = st->subnode; |
585 | } else if (node->type == TRIE_SWITCH) { |
586 | const struct trie_switch *sw = NODE(tw->t, off, trie_switch); |
587 | const char *chars = (const char *)&sw->sw[sw->len]; |
588 | |
589 | if (tw->nswitches >= tw->switchsize) { |
590 | tw->switchsize = tw->nswitches * 3 / 2 + 32; |
591 | tw->switches = sresize(tw->switches, tw->switchsize, |
592 | struct triewalk_switch); |
593 | } |
594 | |
595 | tw->switches[tw->nswitches].sw = sw; |
596 | tw->switches[tw->nswitches].pos = 1; |
597 | tw->switches[tw->nswitches].depth = depth; |
598 | tw->switches[tw->nswitches].count = tw->count + sw->sw[0].subcount; |
599 | off = sw->sw[0].subnode; |
600 | if (buf) |
601 | buf[depth++] = chars[0]; |
602 | tw->nswitches++; |
603 | } |
604 | } |
605 | } |
606 | void triewalk_free(triewalk *tw) |
607 | { |
608 | sfree(tw->switches); |
609 | sfree(tw); |
610 | } |
611 | |
612 | void trie_set_index_offset(void *t, off_t ptr) |
613 | { |
614 | ((struct trie_header *)t)->indexroot = ptr; |
615 | } |
616 | off_t trie_get_index_offset(const void *t) |
617 | { |
618 | return ((const struct trie_header *)t)->indexroot; |
619 | } |
256c29a2 |
620 | |
621 | void make_successor(char *pathbuf) |
622 | { |
623 | int len = strlen(pathbuf); |
624 | if (len > 0 && pathbuf[len-1] == pathsep) |
625 | len--; |
626 | pathbuf[len] = '\001'; |
627 | pathbuf[len+1] = '\0'; |
628 | } |