apropos_db.c

   1 /*      $Id: apropos_db.c,v 1.17 2011/12/01 23:46:26 kristaps Exp $ */
   2 /*
   3  * Copyright (c) 2011 Kristaps Dzonsons <kristaps@bsd.lv>
   4  * Copyright (c) 2011 Ingo Schwarze <schwarze@openbsd.org>
   5  *
   6  * Permission to use, copy, modify, and distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18 #include <assert.h>
  19 #include <fcntl.h>
  20 #include <regex.h>
  21 #include <stdarg.h>
  22 #include <stdint.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26
  27 #include <arpa/inet.h>
  28
  29 #ifdef __linux__
  30 # include <db_185.h>
  31 #else
  32 # include <db.h>
  33 #endif
  34
  35 #include "mandocdb.h"
  36 #include "apropos_db.h"
  37 #include "mandoc.h"
  38
  39 struct  rec {
  40         struct res       res; /* resulting record info */
  41         /*
  42          * Maintain a binary tree for checking the uniqueness of `rec'
  43          * when adding elements to the results array.
  44          * Since the results array is dynamic, use offset in the array
  45          * instead of a pointer to the structure.
  46          */
  47         int              lhs;
  48         int              rhs;
  49         int              matched; /* expression is true */
  50         int             *matches; /* partial truth evaluations */
  51 };
  52
  53 struct  expr {
  54         int              regex; /* is regex? */
  55         int              index; /* index in match array */
  56         uint64_t         mask; /* type-mask */
  57         int              and; /* is rhs of logical AND? */
  58         char            *v; /* search value */
  59         regex_t          re; /* compiled re, if regex */
  60         struct expr     *next; /* next in sequence */
  61         struct expr     *subexpr;
  62 };
  63
  64 struct  type {
  65         uint64_t         mask;
  66         const char      *name;
  67 };
  68
  69 struct  rectree {
  70         struct rec      *node; /* record array for dir tree */
  71         int              len; /* length of record array */
  72 };
  73
  74 static  const struct type types[] = {
  75         { TYPE_An, "An" },
  76         { TYPE_Ar, "Ar" },
  77         { TYPE_At, "At" },
  78         { TYPE_Bsx, "Bsx" },
  79         { TYPE_Bx, "Bx" },
  80         { TYPE_Cd, "Cd" },
  81         { TYPE_Cm, "Cm" },
  82         { TYPE_Dv, "Dv" },
  83         { TYPE_Dx, "Dx" },
  84         { TYPE_Em, "Em" },
  85         { TYPE_Er, "Er" },
  86         { TYPE_Ev, "Ev" },
  87         { TYPE_Fa, "Fa" },
  88         { TYPE_Fl, "Fl" },
  89         { TYPE_Fn, "Fn" },
  90         { TYPE_Fn, "Fo" },
  91         { TYPE_Ft, "Ft" },
  92         { TYPE_Fx, "Fx" },
  93         { TYPE_Ic, "Ic" },
  94         { TYPE_In, "In" },
  95         { TYPE_Lb, "Lb" },
  96         { TYPE_Li, "Li" },
  97         { TYPE_Lk, "Lk" },
  98         { TYPE_Ms, "Ms" },
  99         { TYPE_Mt, "Mt" },
 100         { TYPE_Nd, "Nd" },
 101         { TYPE_Nm, "Nm" },
 102         { TYPE_Nx, "Nx" },
 103         { TYPE_Ox, "Ox" },
 104         { TYPE_Pa, "Pa" },
 105         { TYPE_Rs, "Rs" },
 106         { TYPE_Sh, "Sh" },
 107         { TYPE_Ss, "Ss" },
 108         { TYPE_St, "St" },
 109         { TYPE_Sy, "Sy" },
 110         { TYPE_Tn, "Tn" },
 111         { TYPE_Va, "Va" },
 112         { TYPE_Va, "Vt" },
 113         { TYPE_Xr, "Xr" },
 114         { INT_MAX, "any" },
 115         { 0, NULL }
 116 };
 117
 118 static  DB      *btree_open(void);
 119 static  int      btree_read(const DBT *, const DBT *,
 120                         const struct mchars *,
 121                         struct db_val *, char **);
 122 static  int      expreval(const struct expr *, int *);
 123 static  void     exprexec(const struct expr *,
 124                         const char *, uint64_t, struct rec *);
 125 static  int      exprmark(const struct expr *,
 126                         const char *, uint64_t, int *);
 127 static  struct expr *exprexpr(int, char *[], int *, int *, size_t *);
 128 static  struct expr *exprterm(char *, int);
 129 static  DB      *index_open(void);
 130 static  int      index_read(const DBT *, const DBT *, int,
 131                         const struct mchars *, struct rec *);
 132 static  void     norm_string(const char *,
 133                         const struct mchars *, char **);
 134 static  size_t   norm_utf8(unsigned int, char[7]);
 135 static  void     recfree(struct rec *);
 136 static  int      single_search(struct rectree *, const struct opts *,
 137                         const struct expr *, size_t terms,
 138                         struct mchars *, int);
 139
 140 /*
 141  * Open the keyword mandoc-db database.
 142  */
 143 static DB *
 144 btree_open(void)
 145 {
 146         BTREEINFO        info;
 147         DB              *db;
 148
 149         memset(&info, 0, sizeof(BTREEINFO));
 150         info.flags = R_DUP;
 151
 152         db = dbopen(MANDOC_DB, O_RDONLY, 0, DB_BTREE, &info);
 153         if (NULL != db)
 154                 return(db);
 155
 156         return(NULL);
 157 }
 158
 159 /*
 160  * Read a keyword from the database and normalise it.
 161  * Return 0 if the database is insane, else 1.
 162  */
 163 static int
 164 btree_read(const DBT *k, const DBT *v,
 165                 const struct mchars *mc,
 166                 struct db_val *dbv, char **buf)
 167 {
 168         const struct db_val *vp;
 169
 170         /* Are our sizes sane? */
 171         if (k->size < 2 || sizeof(struct db_val) != v->size)
 172                 return(0);
 173
 174         /* Is our string nil-terminated? */
 175         if ('\0' != ((const char *)k->data)[(int)k->size - 1])
 176                 return(0);
 177
 178         vp = v->data;
 179         norm_string((const char *)k->data, mc, buf);
 180         dbv->rec = ntohl(vp->rec);
 181         dbv->mask = vp->mask;
 182         return(1);
 183 }
 184
 185 /*
 186  * Take a Unicode codepoint and produce its UTF-8 encoding.
 187  * This isn't the best way to do this, but it works.
 188  * The magic numbers are from the UTF-8 packaging.
 189  * They're not as scary as they seem: read the UTF-8 spec for details.
 190  */
 191 static size_t
 192 norm_utf8(unsigned int cp, char out[7])
 193 {
 194         size_t           rc;
 195
 196         rc = 0;
 197
 198         if (cp <= 0x0000007F) {
 199                 rc = 1;
 200                 out[0] = (char)cp;
 201         } else if (cp <= 0x000007FF) {
 202                 rc = 2;
 203                 out[0] = (cp >> 6  & 31) | 192;
 204                 out[1] = (cp       & 63) | 128;
 205         } else if (cp <= 0x0000FFFF) {
 206                 rc = 3;
 207                 out[0] = (cp >> 12 & 15) | 224;
 208                 out[1] = (cp >> 6  & 63) | 128;
 209                 out[2] = (cp       & 63) | 128;
 210         } else if (cp <= 0x001FFFFF) {
 211                 rc = 4;
 212                 out[0] = (cp >> 18 & 7) | 240;
 213                 out[1] = (cp >> 12 & 63) | 128;
 214                 out[2] = (cp >> 6  & 63) | 128;
 215                 out[3] = (cp       & 63) | 128;
 216         } else if (cp <= 0x03FFFFFF) {
 217                 rc = 5;
 218                 out[0] = (cp >> 24 & 3) | 248;
 219                 out[1] = (cp >> 18 & 63) | 128;
 220                 out[2] = (cp >> 12 & 63) | 128;
 221                 out[3] = (cp >> 6  & 63) | 128;
 222                 out[4] = (cp       & 63) | 128;
 223         } else if (cp <= 0x7FFFFFFF) {
 224                 rc = 6;
 225                 out[0] = (cp >> 30 & 1) | 252;
 226                 out[1] = (cp >> 24 & 63) | 128;
 227                 out[2] = (cp >> 18 & 63) | 128;
 228                 out[3] = (cp >> 12 & 63) | 128;
 229                 out[4] = (cp >> 6  & 63) | 128;
 230                 out[5] = (cp       & 63) | 128;
 231         } else
 232                 return(0);
 233
 234         out[rc] = '\0';
 235         return(rc);
 236 }
 237
 238 /*
 239  * Normalise strings from the index and database.
 240  * These strings are escaped as defined by mandoc_char(7) along with
 241  * other goop in mandoc.h (e.g., soft hyphens).
 242  * This function normalises these into a nice UTF-8 string.
 243  * Returns 0 if the database is fucked.
 244  */
 245 static void
 246 norm_string(const char *val, const struct mchars *mc, char **buf)
 247 {
 248         size_t            sz, bsz;
 249         char              utfbuf[7];
 250         const char       *seq, *cpp;
 251         int               len, u, pos;
 252         enum mandoc_esc   esc;
 253         static const char res[] = { '\\', '\t',
 254                                 ASCII_NBRSP, ASCII_HYPH, '\0' };
 255
 256         /* Pre-allocate by the length of the input */
 257
 258         bsz = strlen(val) + 1;
 259         *buf = mandoc_realloc(*buf, bsz);
 260         pos = 0;
 261
 262         while ('\0' != *val) {
 263                 /*
 264                  * Halt on the first escape sequence.
 265                  * This also halts on the end of string, in which case
 266                  * we just copy, fallthrough, and exit the loop.
 267                  */
 268                 if ((sz = strcspn(val, res)) > 0) {
 269                         memcpy(&(*buf)[pos], val, sz);
 270                         pos += (int)sz;
 271                         val += (int)sz;
 272                 }
 273
 274                 if (ASCII_HYPH == *val) {
 275                         (*buf)[pos++] = '-';
 276                         val++;
 277                         continue;
 278                 } else if ('\t' == *val || ASCII_NBRSP == *val) {
 279                         (*buf)[pos++] = ' ';
 280                         val++;
 281                         continue;
 282                 } else if ('\\' != *val)
 283                         break;
 284
 285                 /* Read past the slash. */
 286
 287                 val++;
 288                 u = 0;
 289
 290                 /*
 291                  * Parse the escape sequence and see if it's a
 292                  * predefined character or special character.
 293                  */
 294
 295                 esc = mandoc_escape(&val, &seq, &len);
 296                 if (ESCAPE_ERROR == esc)
 297                         break;
 298
 299                 /*
 300                  * XXX - this just does UTF-8, but we need to know
 301                  * beforehand whether we should do text substitution.
 302                  */
 303
 304                 switch (esc) {
 305                 case (ESCAPE_SPECIAL):
 306                         if (0 != (u = mchars_spec2cp(mc, seq, len)))
 307                                 break;
 308                         /* FALLTHROUGH */
 309                 default:
 310                         continue;
 311                 }
 312
 313                 /*
 314                  * If we have a Unicode codepoint, try to convert that
 315                  * to a UTF-8 byte string.
 316                  */
 317
 318                 cpp = utfbuf;
 319                 if (0 == (sz = norm_utf8(u, utfbuf)))
 320                         continue;
 321
 322                 /* Copy the rendered glyph into the stream. */
 323
 324                 sz = strlen(cpp);
 325                 bsz += sz;
 326
 327                 *buf = mandoc_realloc(*buf, bsz);
 328
 329                 memcpy(&(*buf)[pos], cpp, sz);
 330                 pos += (int)sz;
 331         }
 332
 333         (*buf)[pos] = '\0';
 334 }
 335
 336 /*
 337  * Open the filename-index mandoc-db database.
 338  * Returns NULL if opening failed.
 339  */
 340 static DB *
 341 index_open(void)
 342 {
 343         DB              *db;
 344
 345         db = dbopen(MANDOC_IDX, O_RDONLY, 0, DB_RECNO, NULL);
 346         if (NULL != db)
 347                 return(db);
 348
 349         return(NULL);
 350 }
 351
 352 /*
 353  * Safely unpack from an index file record into the structure.
 354  * Returns 1 if an entry was unpacked, 0 if the database is insane.
 355  */
 356 static int
 357 index_read(const DBT *key, const DBT *val, int index,
 358                 const struct mchars *mc, struct rec *rec)
 359 {
 360         size_t           left;
 361         char            *np, *cp;
 362
 363 #define INDEX_BREAD(_dst) \
 364         do { \
 365                 if (NULL == (np = memchr(cp, '\0', left))) \
 366                         return(0); \
 367                 norm_string(cp, mc, &(_dst)); \
 368                 left -= (np - cp) + 1; \
 369                 cp = np + 1; \
 370         } while (/* CONSTCOND */ 0)
 371
 372         left = val->size;
 373         cp = (char *)val->data;
 374
 375         rec->res.rec = *(recno_t *)key->data;
 376         rec->res.volume = index;
 377
 378         INDEX_BREAD(rec->res.type);
 379         INDEX_BREAD(rec->res.file);
 380         INDEX_BREAD(rec->res.cat);
 381         INDEX_BREAD(rec->res.title);
 382         INDEX_BREAD(rec->res.arch);
 383         INDEX_BREAD(rec->res.desc);
 384         return(1);
 385 }
 386
 387 /*
 388  * Search mandocdb databases in paths for expression "expr".
 389  * Filter out by "opts".
 390  * Call "res" with the results, which may be zero.
 391  * Return 0 if there was a database error, else return 1.
 392  */
 393 int
 394 apropos_search(int pathsz, char **paths, const struct opts *opts,
 395                 const struct expr *expr, size_t terms, void *arg,
 396                 void (*res)(struct res *, size_t, void *))
 397 {
 398         struct rectree   tree;
 399         struct mchars   *mc;
 400         struct res      *ress;
 401         int              i, mlen, rc;
 402
 403         memset(&tree, 0, sizeof(struct rectree));
 404
 405         rc = 0;
 406         mc = mchars_alloc();
 407
 408         /*
 409          * Main loop.  Change into the directory containing manpage
 410          * databases.  Run our expession over each database in the set.
 411          */
 412
 413         for (i = 0; i < pathsz; i++) {
 414                 if (chdir(paths[i]))
 415                         continue;
 416                 if ( ! single_search(&tree, opts, expr, terms, mc, i))
 417                         goto out;
 418         }
 419
 420         /*
 421          * Count matching files, transfer to a "clean" array, then feed
 422          * them to the output handler.
 423          */
 424
 425         for (mlen = i = 0; i < tree.len; i++)
 426                 if (tree.node[i].matched)
 427                         mlen++;
 428
 429         ress = mandoc_malloc(mlen * sizeof(struct res));
 430
 431         for (mlen = i = 0; i < tree.len; i++)
 432                 if (tree.node[i].matched)
 433                         memcpy(&ress[mlen++], &tree.node[i].res,
 434                                         sizeof(struct res));
 435
 436         (*res)(ress, mlen, arg);
 437         free(ress);
 438
 439         rc = 1;
 440 out:
 441         for (i = 0; i < tree.len; i++)
 442                 recfree(&tree.node[i]);
 443
 444         free(tree.node);
 445         mchars_free(mc);
 446         return(rc);
 447 }
 448
 449 static int
 450 single_search(struct rectree *tree, const struct opts *opts,
 451                 const struct expr *expr, size_t terms,
 452                 struct mchars *mc, int vol)
 453 {
 454         int              root, leaf, ch;
 455         DBT              key, val;
 456         DB              *btree, *idx;
 457         char            *buf;
 458         struct rec      *rs;
 459         struct rec       r;
 460         struct db_val    vb;
 461
 462         root    = -1;
 463         leaf    = -1;
 464         btree   = NULL;
 465         idx     = NULL;
 466         buf     = NULL;
 467         rs      = tree->node;
 468
 469         memset(&r, 0, sizeof(struct rec));
 470
 471         if (NULL == (btree = btree_open()))
 472                 return(1);
 473
 474         if (NULL == (idx = index_open())) {
 475                 (*btree->close)(btree);
 476                 return(1);
 477         }
 478
 479         while (0 == (ch = (*btree->seq)(btree, &key, &val, R_NEXT))) {
 480                 if ( ! btree_read(&key, &val, mc, &vb, &buf))
 481                         break;
 482
 483                 /*
 484                  * See if this keyword record matches any of the
 485                  * expressions we have stored.
 486                  */
 487                 if ( ! exprmark(expr, buf, vb.mask, NULL))
 488                         continue;
 489
 490                 /*
 491                  * O(log n) scan for prior records.  Since a record
 492                  * number is unbounded, this has decent performance over
 493                  * a complex hash function.
 494                  */
 495
 496                 for (leaf = root; leaf >= 0; )
 497                         if (vb.rec > rs[leaf].res.rec &&
 498                                         rs[leaf].rhs >= 0)
 499                                 leaf = rs[leaf].rhs;
 500                         else if (vb.rec < rs[leaf].res.rec &&
 501                                         rs[leaf].lhs >= 0)
 502                                 leaf = rs[leaf].lhs;
 503                         else
 504                                 break;
 505
 506                 /*
 507                  * If we find a record, see if it has already evaluated
 508                  * to true.  If it has, great, just keep going.  If not,
 509                  * try to evaluate it now and continue anyway.
 510                  */
 511
 512                 if (leaf >= 0 && rs[leaf].res.rec == vb.rec) {
 513                         if (0 == rs[leaf].matched)
 514                                 exprexec(expr, buf, vb.mask, &rs[leaf]);
 515                         continue;
 516                 }
 517
 518                 /*
 519                  * We have a new file to examine.
 520                  * Extract the manpage's metadata from the index
 521                  * database, then begin partial evaluation.
 522                  */
 523
 524                 key.data = &vb.rec;
 525                 key.size = sizeof(recno_t);
 526
 527                 if (0 != (*idx->get)(idx, &key, &val, 0))
 528                         break;
 529
 530                 r.lhs = r.rhs = -1;
 531                 if ( ! index_read(&key, &val, vol, mc, &r))
 532                         break;
 533
 534                 /* XXX: this should be elsewhere, I guess? */
 535
 536                 if (opts->cat && strcasecmp(opts->cat, r.res.cat))
 537                         continue;
 538                 if (opts->arch && strcasecmp(opts->arch, r.res.arch))
 539                         continue;
 540
 541                 tree->node = rs = mandoc_realloc
 542                         (rs, (tree->len + 1) * sizeof(struct rec));
 543
 544                 memcpy(&rs[tree->len], &r, sizeof(struct rec));
 545                 rs[tree->len].matches =
 546                         mandoc_calloc(terms, sizeof(int));
 547
 548                 exprexec(expr, buf, vb.mask, &rs[tree->len]);
 549
 550                 /* Append to our tree. */
 551
 552                 if (leaf >= 0) {
 553                         if (vb.rec > rs[leaf].res.rec)
 554                                 rs[leaf].rhs = tree->len;
 555                         else
 556                                 rs[leaf].lhs = tree->len;
 557                 } else
 558                         root = tree->len;
 559
 560                 memset(&r, 0, sizeof(struct rec));
 561                 tree->len++;
 562         }
 563
 564         (*btree->close)(btree);
 565         (*idx->close)(idx);
 566
 567         free(buf);
 568         return(1 == ch);
 569 }
 570
 571 static void
 572 recfree(struct rec *rec)
 573 {
 574
 575         free(rec->res.type);
 576         free(rec->res.file);
 577         free(rec->res.cat);
 578         free(rec->res.title);
 579         free(rec->res.arch);
 580         free(rec->res.desc);
 581
 582         free(rec->matches);
 583 }
 584
 585 /*
 586  * Compile a list of straight-up terms.
 587  * The arguments are re-written into ~[[:<:]]term[[:>:]], or "term"
 588  * surrounded by word boundaries, then pumped through exprterm().
 589  * Terms are case-insensitive.
 590  * This emulates whatis(1) behaviour.
 591  */
 592 struct expr *
 593 termcomp(int argc, char *argv[], size_t *tt)
 594 {
 595         char            *buf;
 596         int              pos;
 597         struct expr     *e, *next;
 598         size_t           sz;
 599
 600         buf = NULL;
 601         e = NULL;
 602         *tt = 0;
 603
 604         for (pos = argc - 1; pos >= 0; pos--) {
 605                 sz = strlen(argv[pos]) + 18;
 606                 buf = mandoc_realloc(buf, sz);
 607                 strlcpy(buf, "Nm~[[:<:]]", sz);
 608                 strlcat(buf, argv[pos], sz);
 609                 strlcat(buf, "[[:>:]]", sz);
 610                 if (NULL == (next = exprterm(buf, 0))) {
 611                         free(buf);
 612                         exprfree(e);
 613                         return(NULL);
 614                 }
 615                 next->next = e;
 616                 e = next;
 617                 (*tt)++;
 618         }
 619
 620         free(buf);
 621         return(e);
 622 }
 623
 624 /*
 625  * Compile a sequence of logical expressions.
 626  * See apropos.1 for a grammar of this sequence.
 627  */
 628 struct expr *
 629 exprcomp(int argc, char *argv[], size_t *tt)
 630 {
 631         int              pos, lvl;
 632         struct expr     *e;
 633
 634         pos = lvl = 0;
 635         *tt = 0;
 636
 637         e = exprexpr(argc, argv, &pos, &lvl, tt);
 638
 639         if (0 == lvl && pos >= argc)
 640                 return(e);
 641
 642         exprfree(e);
 643         return(NULL);
 644 }
 645
 646 /*
 647  * Compile an array of tokens into an expression.
 648  * An informal expression grammar is defined in apropos(1).
 649  * Return NULL if we fail doing so.  All memory will be cleaned up.
 650  * Return the root of the expression sequence if alright.
 651  */
 652 static struct expr *
 653 exprexpr(int argc, char *argv[], int *pos, int *lvl, size_t *tt)
 654 {
 655         struct expr     *e, *first, *next;
 656         int              log;
 657
 658         first = next = NULL;
 659
 660         for ( ; *pos < argc; (*pos)++) {
 661                 e = next;
 662
 663                 /*
 664                  * Close out a subexpression.
 665                  */
 666
 667                 if (NULL != e && 0 == strcmp(")", argv[*pos])) {
 668                         if (--(*lvl) < 0)
 669                                 goto err;
 670                         break;
 671                 }
 672
 673                 /*
 674                  * Small note: if we're just starting, don't let "-a"
 675                  * and "-o" be considered logical operators: they're
 676                  * just tokens unless pairwise joining, in which case we
 677                  * record their existence (or assume "OR").
 678                  */
 679                 log = 0;
 680
 681                 if (NULL != e && 0 == strcmp("-a", argv[*pos]))
 682                         log = 1;
 683                 else if (NULL != e && 0 == strcmp("-o", argv[*pos]))
 684                         log = 2;
 685
 686                 if (log > 0 && ++(*pos) >= argc)
 687                         goto err;
 688
 689                 /*
 690                  * Now we parse the term part.  This can begin with
 691                  * "-i", in which case the expression is case
 692                  * insensitive.
 693                  */
 694
 695                 if (0 == strcmp("(", argv[*pos])) {
 696                         ++(*pos);
 697                         ++(*lvl);
 698                         next = mandoc_calloc(1, sizeof(struct expr));
 699                         next->subexpr = exprexpr(argc, argv, pos, lvl, tt);
 700                         if (NULL == next->subexpr) {
 701                                 free(next);
 702                                 next = NULL;
 703                         }
 704                 } else if (0 == strcmp("-i", argv[*pos])) {
 705                         if (++(*pos) >= argc)
 706                                 goto err;
 707                         next = exprterm(argv[*pos], 0);
 708                 } else
 709                         next = exprterm(argv[*pos], 1);
 710
 711                 if (NULL == next)
 712                         goto err;
 713
 714                 next->and = log == 1;
 715                 next->index = (int)(*tt)++;
 716
 717                 /* Append to our chain of expressions. */
 718
 719                 if (NULL == first) {
 720                         assert(NULL == e);
 721                         first = next;
 722                 } else {
 723                         assert(NULL != e);
 724                         e->next = next;
 725                 }
 726         }
 727
 728         return(first);
 729 err:
 730         exprfree(first);
 731         return(NULL);
 732 }
 733
 734 /*
 735  * Parse a terminal expression with the grammar as defined in
 736  * apropos(1).
 737  * Return NULL if we fail the parse.
 738  */
 739 static struct expr *
 740 exprterm(char *buf, int cs)
 741 {
 742         struct expr      e;
 743         struct expr     *p;
 744         char            *key;
 745         int              i;
 746
 747         memset(&e, 0, sizeof(struct expr));
 748
 749         /* Choose regex or substring match. */
 750
 751         if (NULL == (e.v = strpbrk(buf, "=~"))) {
 752                 e.regex = 0;
 753                 e.v = buf;
 754         } else {
 755                 e.regex = '~' == *e.v;
 756                 *e.v++ = '\0';
 757         }
 758
 759         /* Determine the record types to search for. */
 760
 761         e.mask = 0;
 762         if (buf < e.v) {
 763                 while (NULL != (key = strsep(&buf, ","))) {
 764                         i = 0;
 765                         while (types[i].mask &&
 766                                         strcmp(types[i].name, key))
 767                                 i++;
 768                         e.mask |= types[i].mask;
 769                 }
 770         }
 771         if (0 == e.mask)
 772                 e.mask = TYPE_Nm | TYPE_Nd;
 773
 774         if (e.regex) {
 775                 i = REG_EXTENDED | REG_NOSUB | (cs ? 0 : REG_ICASE);
 776                 if (regcomp(&e.re, e.v, i))
 777                         return(NULL);
 778         }
 779
 780         e.v = mandoc_strdup(e.v);
 781
 782         p = mandoc_calloc(1, sizeof(struct expr));
 783         memcpy(p, &e, sizeof(struct expr));
 784         return(p);
 785 }
 786
 787 void
 788 exprfree(struct expr *p)
 789 {
 790         struct expr     *pp;
 791
 792         while (NULL != p) {
 793                 if (p->subexpr)
 794                         exprfree(p->subexpr);
 795                 if (p->regex)
 796                         regfree(&p->re);
 797                 free(p->v);
 798                 pp = p->next;
 799                 free(p);
 800                 p = pp;
 801         }
 802 }
 803
 804 static int
 805 exprmark(const struct expr *p, const char *cp,
 806                 uint64_t mask, int *ms)
 807 {
 808
 809         for ( ; p; p = p->next) {
 810                 if (p->subexpr) {
 811                         if (exprmark(p->subexpr, cp, mask, ms))
 812                                 return(1);
 813                         continue;
 814                 } else if ( ! (mask & p->mask))
 815                         continue;
 816
 817                 if (p->regex) {
 818                         if (regexec(&p->re, cp, 0, NULL, 0))
 819                                 continue;
 820                 } else if (NULL == strcasestr(cp, p->v))
 821                         continue;
 822
 823                 if (NULL == ms)
 824                         return(1);
 825                 else
 826                         ms[p->index] = 1;
 827         }
 828
 829         return(0);
 830 }
 831
 832 static int
 833 expreval(const struct expr *p, int *ms)
 834 {
 835         int              match;
 836
 837         /*
 838          * AND has precedence over OR.  Analysis is left-right, though
 839          * it doesn't matter because there are no side-effects.
 840          * Thus, step through pairwise ANDs and accumulate their Boolean
 841          * evaluation.  If we encounter a single true AND collection or
 842          * standalone term, the whole expression is true (by definition
 843          * of OR).
 844          */
 845
 846         for (match = 0; p && ! match; p = p->next) {
 847                 /* Evaluate a subexpression, if applicable. */
 848                 if (p->subexpr && ! ms[p->index])
 849                         ms[p->index] = expreval(p->subexpr, ms);
 850
 851                 match = ms[p->index];
 852                 for ( ; p->next && p->next->and; p = p->next) {
 853                         /* Evaluate a subexpression, if applicable. */
 854                         if (p->next->subexpr && ! ms[p->next->index])
 855                                 ms[p->next->index] =
 856                                         expreval(p->next->subexpr, ms);
 857                         match = match && ms[p->next->index];
 858                 }
 859         }
 860
 861         return(match);
 862 }
 863
 864 /*
 865  * First, update the array of terms for which this expression evaluates
 866  * to true.
 867  * Second, logically evaluate all terms over the updated array of truth
 868  * values.
 869  * If this evaluates to true, mark the expression as satisfied.
 870  */
 871 static void
 872 exprexec(const struct expr *e, const char *cp,
 873                 uint64_t mask, struct rec *r)
 874 {
 875
 876         assert(0 == r->matched);
 877         exprmark(e, cp, mask, r->matches);
 878         r->matched = expreval(e, r->matches);
 879 }