contrib/mdocml/apropos_db.c

   1 /*      $Id: apropos_db.c,v 1.32.2.3 2013/10/10 23:43:04 schwarze Exp $ */
   2 /*
   3  * Copyright (c) 2011, 2012 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 #ifdef HAVE_CONFIG_H
  19 #include "config.h"
  20 #endif
  21
  22 #include <sys/param.h>
  23
  24 #include <assert.h>
  25 #include <fcntl.h>
  26 #include <regex.h>
  27 #include <stdarg.h>
  28 #include <stdint.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <unistd.h>
  32
  33 #if defined(__APPLE__)
  34 # include <libkern/OSByteOrder.h>
  35 #elif defined(__linux__)
  36 # include <endian.h>
  37 #elif defined(__sun)
  38 # include <sys/byteorder.h>
  39 #else
  40 # include <sys/endian.h>
  41 #endif
  42
  43 #if defined(__linux__) || defined(__sun)
  44 # include <db_185.h>
  45 #else
  46 # include <db.h>
  47 #endif
  48
  49 #include "mandocdb.h"
  50 #include "apropos_db.h"
  51 #include "mandoc.h"
  52
  53 #define RESFREE(_x) \
  54         do { \
  55                 free((_x)->file); \
  56                 free((_x)->cat); \
  57                 free((_x)->title); \
  58                 free((_x)->arch); \
  59                 free((_x)->desc); \
  60                 free((_x)->matches); \
  61         } while (/*CONSTCOND*/0)
  62
  63 struct  expr {
  64         int              regex; /* is regex? */
  65         int              index; /* index in match array */
  66         uint64_t         mask; /* type-mask */
  67         int              and; /* is rhs of logical AND? */
  68         char            *v; /* search value */
  69         regex_t          re; /* compiled re, if regex */
  70         struct expr     *next; /* next in sequence */
  71         struct expr     *subexpr;
  72 };
  73
  74 struct  type {
  75         uint64_t         mask;
  76         const char      *name;
  77 };
  78
  79 struct  rectree {
  80         struct res      *node; /* record array for dir tree */
  81         int              len; /* length of record array */
  82 };
  83
  84 static  const struct type types[] = {
  85         { TYPE_An, "An" },
  86         { TYPE_Ar, "Ar" },
  87         { TYPE_At, "At" },
  88         { TYPE_Bsx, "Bsx" },
  89         { TYPE_Bx, "Bx" },
  90         { TYPE_Cd, "Cd" },
  91         { TYPE_Cm, "Cm" },
  92         { TYPE_Dv, "Dv" },
  93         { TYPE_Dx, "Dx" },
  94         { TYPE_Em, "Em" },
  95         { TYPE_Er, "Er" },
  96         { TYPE_Ev, "Ev" },
  97         { TYPE_Fa, "Fa" },
  98         { TYPE_Fl, "Fl" },
  99         { TYPE_Fn, "Fn" },
 100         { TYPE_Fn, "Fo" },
 101         { TYPE_Ft, "Ft" },
 102         { TYPE_Fx, "Fx" },
 103         { TYPE_Ic, "Ic" },
 104         { TYPE_In, "In" },
 105         { TYPE_Lb, "Lb" },
 106         { TYPE_Li, "Li" },
 107         { TYPE_Lk, "Lk" },
 108         { TYPE_Ms, "Ms" },
 109         { TYPE_Mt, "Mt" },
 110         { TYPE_Nd, "Nd" },
 111         { TYPE_Nm, "Nm" },
 112         { TYPE_Nx, "Nx" },
 113         { TYPE_Ox, "Ox" },
 114         { TYPE_Pa, "Pa" },
 115         { TYPE_Rs, "Rs" },
 116         { TYPE_Sh, "Sh" },
 117         { TYPE_Ss, "Ss" },
 118         { TYPE_St, "St" },
 119         { TYPE_Sy, "Sy" },
 120         { TYPE_Tn, "Tn" },
 121         { TYPE_Va, "Va" },
 122         { TYPE_Va, "Vt" },
 123         { TYPE_Xr, "Xr" },
 124         { UINT64_MAX, "any" },
 125         { 0, NULL }
 126 };
 127
 128 static  DB      *btree_open(void);
 129 static  int      btree_read(const DBT *, const DBT *,
 130                         const struct mchars *,
 131                         uint64_t *, recno_t *, char **);
 132 static  int      expreval(const struct expr *, int *);
 133 static  void     exprexec(const struct expr *,
 134                         const char *, uint64_t, struct res *);
 135 static  int      exprmark(const struct expr *,
 136                         const char *, uint64_t, int *);
 137 static  struct expr *exprexpr(int, char *[], int *, int *, size_t *);
 138 static  struct expr *exprterm(char *, int);
 139 static  DB      *index_open(void);
 140 static  int      index_read(const DBT *, const DBT *, int,
 141                         const struct mchars *, struct res *);
 142 static  void     norm_string(const char *,
 143                         const struct mchars *, char **);
 144 static  size_t   norm_utf8(unsigned int, char[7]);
 145 static  int      single_search(struct rectree *, const struct opts *,
 146                         const struct expr *, size_t terms,
 147                         struct mchars *, int);
 148
 149 /*
 150  * Open the keyword mandoc-db database.
 151  */
 152 static DB *
 153 btree_open(void)
 154 {
 155         BTREEINFO        info;
 156         DB              *db;
 157
 158         memset(&info, 0, sizeof(BTREEINFO));
 159         info.lorder = 4321;
 160         info.flags = R_DUP;
 161
 162         db = dbopen(MANDOC_DB, O_RDONLY, 0, DB_BTREE, &info);
 163         if (NULL != db)
 164                 return(db);
 165
 166         return(NULL);
 167 }
 168
 169 /*
 170  * Read a keyword from the database and normalise it.
 171  * Return 0 if the database is insane, else 1.
 172  */
 173 static int
 174 btree_read(const DBT *k, const DBT *v, const struct mchars *mc,
 175                 uint64_t *mask, recno_t *rec, char **buf)
 176 {
 177         uint64_t         vbuf[2];
 178
 179         /* Are our sizes sane? */
 180         if (k->size < 2 || sizeof(vbuf) != v->size)
 181                 return(0);
 182
 183         /* Is our string nil-terminated? */
 184         if ('\0' != ((const char *)k->data)[(int)k->size - 1])
 185                 return(0);
 186
 187         norm_string((const char *)k->data, mc, buf);
 188         memcpy(vbuf, v->data, v->size);
 189         *mask = betoh64(vbuf[0]);
 190         *rec  = betoh64(vbuf[1]);
 191         return(1);
 192 }
 193
 194 /*
 195  * Take a Unicode codepoint and produce its UTF-8 encoding.
 196  * This isn't the best way to do this, but it works.
 197  * The magic numbers are from the UTF-8 packaging.
 198  * They're not as scary as they seem: read the UTF-8 spec for details.
 199  */
 200 static size_t
 201 norm_utf8(unsigned int cp, char out[7])
 202 {
 203         int              rc;
 204
 205         rc = 0;
 206
 207         if (cp <= 0x0000007F) {
 208                 rc = 1;
 209                 out[0] = (char)cp;
 210         } else if (cp <= 0x000007FF) {
 211                 rc = 2;
 212                 out[0] = (cp >> 6  & 31) | 192;
 213                 out[1] = (cp       & 63) | 128;
 214         } else if (cp <= 0x0000FFFF) {
 215                 rc = 3;
 216                 out[0] = (cp >> 12 & 15) | 224;
 217                 out[1] = (cp >> 6  & 63) | 128;
 218                 out[2] = (cp       & 63) | 128;
 219         } else if (cp <= 0x001FFFFF) {
 220                 rc = 4;
 221                 out[0] = (cp >> 18 & 7) | 240;
 222                 out[1] = (cp >> 12 & 63) | 128;
 223                 out[2] = (cp >> 6  & 63) | 128;
 224                 out[3] = (cp       & 63) | 128;
 225         } else if (cp <= 0x03FFFFFF) {
 226                 rc = 5;
 227                 out[0] = (cp >> 24 & 3) | 248;
 228                 out[1] = (cp >> 18 & 63) | 128;
 229                 out[2] = (cp >> 12 & 63) | 128;
 230                 out[3] = (cp >> 6  & 63) | 128;
 231                 out[4] = (cp       & 63) | 128;
 232         } else if (cp <= 0x7FFFFFFF) {
 233                 rc = 6;
 234                 out[0] = (cp >> 30 & 1) | 252;
 235                 out[1] = (cp >> 24 & 63) | 128;
 236                 out[2] = (cp >> 18 & 63) | 128;
 237                 out[3] = (cp >> 12 & 63) | 128;
 238                 out[4] = (cp >> 6  & 63) | 128;
 239                 out[5] = (cp       & 63) | 128;
 240         } else
 241                 return(0);
 242
 243         out[rc] = '\0';
 244         return((size_t)rc);
 245 }
 246
 247 /*
 248  * Normalise strings from the index and database.
 249  * These strings are escaped as defined by mandoc_char(7) along with
 250  * other goop in mandoc.h (e.g., soft hyphens).
 251  * This function normalises these into a nice UTF-8 string.
 252  * Returns 0 if the database is fucked.
 253  */
 254 static void
 255 norm_string(const char *val, const struct mchars *mc, char **buf)
 256 {
 257         size_t            sz, bsz;
 258         char              utfbuf[7];
 259         const char       *seq, *cpp;
 260         int               len, u, pos;
 261         enum mandoc_esc   esc;
 262         static const char res[] = { '\\', '\t',
 263                                 ASCII_NBRSP, ASCII_HYPH, '\0' };
 264
 265         /* Pre-allocate by the length of the input */
 266
 267         bsz = strlen(val) + 1;
 268         *buf = mandoc_realloc(*buf, bsz);
 269         pos = 0;
 270
 271         while ('\0' != *val) {
 272                 /*
 273                  * Halt on the first escape sequence.
 274                  * This also halts on the end of string, in which case
 275                  * we just copy, fallthrough, and exit the loop.
 276                  */
 277                 if ((sz = strcspn(val, res)) > 0) {
 278                         memcpy(&(*buf)[pos], val, sz);
 279                         pos += (int)sz;
 280                         val += (int)sz;
 281                 }
 282
 283                 if (ASCII_HYPH == *val) {
 284                         (*buf)[pos++] = '-';
 285                         val++;
 286                         continue;
 287                 } else if ('\t' == *val || ASCII_NBRSP == *val) {
 288                         (*buf)[pos++] = ' ';
 289                         val++;
 290                         continue;
 291                 } else if ('\\' != *val)
 292                         break;
 293
 294                 /* Read past the slash. */
 295
 296                 val++;
 297                 u = 0;
 298
 299                 /*
 300                  * Parse the escape sequence and see if it's a
 301                  * predefined character or special character.
 302                  */
 303
 304                 esc = mandoc_escape(&val, &seq, &len);
 305                 if (ESCAPE_ERROR == esc)
 306                         break;
 307
 308                 /*
 309                  * XXX - this just does UTF-8, but we need to know
 310                  * beforehand whether we should do text substitution.
 311                  */
 312
 313                 switch (esc) {
 314                 case (ESCAPE_SPECIAL):
 315                         if (0 != (u = mchars_spec2cp(mc, seq, len)))
 316                                 break;
 317                         /* FALLTHROUGH */
 318                 default:
 319                         continue;
 320                 }
 321
 322                 /*
 323                  * If we have a Unicode codepoint, try to convert that
 324                  * to a UTF-8 byte string.
 325                  */
 326
 327                 cpp = utfbuf;
 328                 if (0 == (sz = norm_utf8(u, utfbuf)))
 329                         continue;
 330
 331                 /* Copy the rendered glyph into the stream. */
 332
 333                 sz = strlen(cpp);
 334                 bsz += sz;
 335
 336                 *buf = mandoc_realloc(*buf, bsz);
 337
 338                 memcpy(&(*buf)[pos], cpp, sz);
 339                 pos += (int)sz;
 340         }
 341
 342         (*buf)[pos] = '\0';
 343 }
 344
 345 /*
 346  * Open the filename-index mandoc-db database.
 347  * Returns NULL if opening failed.
 348  */
 349 static DB *
 350 index_open(void)
 351 {
 352         DB              *db;
 353
 354         db = dbopen(MANDOC_IDX, O_RDONLY, 0, DB_RECNO, NULL);
 355         if (NULL != db)
 356                 return(db);
 357
 358         return(NULL);
 359 }
 360
 361 /*
 362  * Safely unpack from an index file record into the structure.
 363  * Returns 1 if an entry was unpacked, 0 if the database is insane.
 364  */
 365 static int
 366 index_read(const DBT *key, const DBT *val, int index,
 367                 const struct mchars *mc, struct res *rec)
 368 {
 369         size_t           left;
 370         char            *np, *cp;
 371         char             type;
 372
 373 #define INDEX_BREAD(_dst) \
 374         do { \
 375                 if (NULL == (np = memchr(cp, '\0', left))) \
 376                         return(0); \
 377                 norm_string(cp, mc, &(_dst)); \
 378                 left -= (np - cp) + 1; \
 379                 cp = np + 1; \
 380         } while (/* CONSTCOND */ 0)
 381
 382         if (0 == (left = val->size))
 383                 return(0);
 384
 385         cp = val->data;
 386         assert(sizeof(recno_t) == key->size);
 387         memcpy(&rec->rec, key->data, key->size);
 388         rec->volume = index;
 389
 390         if ('d' == (type = *cp++))
 391                 rec->type = RESTYPE_MDOC;
 392         else if ('a' == type)
 393                 rec->type = RESTYPE_MAN;
 394         else if ('c' == type)
 395                 rec->type = RESTYPE_CAT;
 396         else
 397                 return(0);
 398
 399         left--;
 400         INDEX_BREAD(rec->file);
 401         INDEX_BREAD(rec->cat);
 402         INDEX_BREAD(rec->title);
 403         INDEX_BREAD(rec->arch);
 404         INDEX_BREAD(rec->desc);
 405         return(1);
 406 }
 407
 408 /*
 409  * Search mandocdb databases in paths for expression "expr".
 410  * Filter out by "opts".
 411  * Call "res" with the results, which may be zero.
 412  * Return 0 if there was a database error, else return 1.
 413  */
 414 int
 415 apropos_search(int pathsz, char **paths, const struct opts *opts,
 416                 const struct expr *expr, size_t terms, void *arg,
 417                 size_t *sz, struct res **resp,
 418                 void (*res)(struct res *, size_t, void *))
 419 {
 420         struct rectree   tree;
 421         struct mchars   *mc;
 422         int              i;
 423
 424         memset(&tree, 0, sizeof(struct rectree));
 425
 426         mc = mchars_alloc();
 427         *sz = 0;
 428         *resp = NULL;
 429
 430         /*
 431          * Main loop.  Change into the directory containing manpage
 432          * databases.  Run our expession over each database in the set.
 433          */
 434
 435         for (i = 0; i < pathsz; i++) {
 436                 assert('/' == paths[i][0]);
 437                 if (chdir(paths[i]))
 438                         continue;
 439                 if (single_search(&tree, opts, expr, terms, mc, i))
 440                         continue;
 441
 442                 resfree(tree.node, tree.len);
 443                 mchars_free(mc);
 444                 return(0);
 445         }
 446
 447         (*res)(tree.node, tree.len, arg);
 448         *sz = tree.len;
 449         *resp = tree.node;
 450         mchars_free(mc);
 451         return(1);
 452 }
 453
 454 static int
 455 single_search(struct rectree *tree, const struct opts *opts,
 456                 const struct expr *expr, size_t terms,
 457                 struct mchars *mc, int vol)
 458 {
 459         int              root, leaf, ch;
 460         DBT              key, val;
 461         DB              *btree, *idx;
 462         char            *buf;
 463         struct res      *rs;
 464         struct res       r;
 465         uint64_t         mask;
 466         recno_t          rec;
 467
 468         root    = -1;
 469         leaf    = -1;
 470         btree   = NULL;
 471         idx     = NULL;
 472         buf     = NULL;
 473         rs      = tree->node;
 474
 475         memset(&r, 0, sizeof(struct res));
 476
 477         if (NULL == (btree = btree_open()))
 478                 return(1);
 479
 480         if (NULL == (idx = index_open())) {
 481                 (*btree->close)(btree);
 482                 return(1);
 483         }
 484
 485         while (0 == (ch = (*btree->seq)(btree, &key, &val, R_NEXT))) {
 486                 if ( ! btree_read(&key, &val, mc, &mask, &rec, &buf))
 487                         break;
 488
 489                 /*
 490                  * See if this keyword record matches any of the
 491                  * expressions we have stored.
 492                  */
 493                 if ( ! exprmark(expr, buf, mask, NULL))
 494                         continue;
 495
 496                 /*
 497                  * O(log n) scan for prior records.  Since a record
 498                  * number is unbounded, this has decent performance over
 499                  * a complex hash function.
 500                  */
 501
 502                 for (leaf = root; leaf >= 0; )
 503                         if (rec > rs[leaf].rec &&
 504                                         rs[leaf].rhs >= 0)
 505                                 leaf = rs[leaf].rhs;
 506                         else if (rec < rs[leaf].rec &&
 507                                         rs[leaf].lhs >= 0)
 508                                 leaf = rs[leaf].lhs;
 509                         else
 510                                 break;
 511
 512                 /*
 513                  * If we find a record, see if it has already evaluated
 514                  * to true.  If it has, great, just keep going.  If not,
 515                  * try to evaluate it now and continue anyway.
 516                  */
 517
 518                 if (leaf >= 0 && rs[leaf].rec == rec) {
 519                         if (0 == rs[leaf].matched)
 520                                 exprexec(expr, buf, mask, &rs[leaf]);
 521                         continue;
 522                 }
 523
 524                 /*
 525                  * We have a new file to examine.
 526                  * Extract the manpage's metadata from the index
 527                  * database, then begin partial evaluation.
 528                  */
 529
 530                 key.data = &rec;
 531                 key.size = sizeof(recno_t);
 532
 533                 if (0 != (*idx->get)(idx, &key, &val, 0))
 534                         break;
 535
 536                 r.lhs = r.rhs = -1;
 537                 if ( ! index_read(&key, &val, vol, mc, &r))
 538                         break;
 539
 540                 /* XXX: this should be elsewhere, I guess? */
 541
 542                 if (opts->cat && strcasecmp(opts->cat, r.cat))
 543                         continue;
 544
 545                 if (opts->arch && *r.arch)
 546                         if (strcasecmp(opts->arch, r.arch))
 547                                 continue;
 548
 549                 tree->node = rs = mandoc_realloc
 550                         (rs, (tree->len + 1) * sizeof(struct res));
 551
 552                 memcpy(&rs[tree->len], &r, sizeof(struct res));
 553                 memset(&r, 0, sizeof(struct res));
 554                 rs[tree->len].matches =
 555                         mandoc_calloc(terms, sizeof(int));
 556
 557                 exprexec(expr, buf, mask, &rs[tree->len]);
 558
 559                 /* Append to our tree. */
 560
 561                 if (leaf >= 0) {
 562                         if (rec > rs[leaf].rec)
 563                                 rs[leaf].rhs = tree->len;
 564                         else
 565                                 rs[leaf].lhs = tree->len;
 566                 } else
 567                         root = tree->len;
 568
 569                 tree->len++;
 570         }
 571
 572         (*btree->close)(btree);
 573         (*idx->close)(idx);
 574
 575         free(buf);
 576         RESFREE(&r);
 577         return(1 == ch);
 578 }
 579
 580 void
 581 resfree(struct res *rec, size_t sz)
 582 {
 583         size_t           i;
 584
 585         for (i = 0; i < sz; i++)
 586                 RESFREE(&rec[i]);
 587         free(rec);
 588 }
 589
 590 /*
 591  * Compile a list of straight-up terms.
 592  * The arguments are re-written into ~[[:<:]]term[[:>:]], or "term"
 593  * surrounded by word boundaries, then pumped through exprterm().
 594  * Terms are case-insensitive.
 595  * This emulates whatis(1) behaviour.
 596  */
 597 struct expr *
 598 termcomp(int argc, char *argv[], size_t *tt)
 599 {
 600         char            *buf;
 601         int              pos;
 602         struct expr     *e, *next;
 603         size_t           sz;
 604
 605         buf = NULL;
 606         e = NULL;
 607         *tt = 0;
 608
 609         for (pos = argc - 1; pos >= 0; pos--) {
 610                 sz = strlen(argv[pos]) + 18;
 611                 buf = mandoc_realloc(buf, sz);
 612                 strlcpy(buf, "Nm~[[:<:]]", sz);
 613                 strlcat(buf, argv[pos], sz);
 614                 strlcat(buf, "[[:>:]]", sz);
 615                 if (NULL == (next = exprterm(buf, 0))) {
 616                         free(buf);
 617                         exprfree(e);
 618                         return(NULL);
 619                 }
 620                 next->next = e;
 621                 e = next;
 622                 (*tt)++;
 623         }
 624
 625         free(buf);
 626         return(e);
 627 }
 628
 629 /*
 630  * Compile a sequence of logical expressions.
 631  * See apropos.1 for a grammar of this sequence.
 632  */
 633 struct expr *
 634 exprcomp(int argc, char *argv[], size_t *tt)
 635 {
 636         int              pos, lvl;
 637         struct expr     *e;
 638
 639         pos = lvl = 0;
 640         *tt = 0;
 641
 642         e = exprexpr(argc, argv, &pos, &lvl, tt);
 643
 644         if (0 == lvl && pos >= argc)
 645                 return(e);
 646
 647         exprfree(e);
 648         return(NULL);
 649 }
 650
 651 /*
 652  * Compile an array of tokens into an expression.
 653  * An informal expression grammar is defined in apropos(1).
 654  * Return NULL if we fail doing so.  All memory will be cleaned up.
 655  * Return the root of the expression sequence if alright.
 656  */
 657 static struct expr *
 658 exprexpr(int argc, char *argv[], int *pos, int *lvl, size_t *tt)
 659 {
 660         struct expr     *e, *first, *next;
 661         int              log;
 662
 663         first = next = NULL;
 664
 665         for ( ; *pos < argc; (*pos)++) {
 666                 e = next;
 667
 668                 /*
 669                  * Close out a subexpression.
 670                  */
 671
 672                 if (NULL != e && 0 == strcmp(")", argv[*pos])) {
 673                         if (--(*lvl) < 0)
 674                                 goto err;
 675                         break;
 676                 }
 677
 678                 /*
 679                  * Small note: if we're just starting, don't let "-a"
 680                  * and "-o" be considered logical operators: they're
 681                  * just tokens unless pairwise joining, in which case we
 682                  * record their existence (or assume "OR").
 683                  */
 684                 log = 0;
 685
 686                 if (NULL != e && 0 == strcmp("-a", argv[*pos]))
 687                         log = 1;
 688                 else if (NULL != e && 0 == strcmp("-o", argv[*pos]))
 689                         log = 2;
 690
 691                 if (log > 0 && ++(*pos) >= argc)
 692                         goto err;
 693
 694                 /*
 695                  * Now we parse the term part.  This can begin with
 696                  * "-i", in which case the expression is case
 697                  * insensitive.
 698                  */
 699
 700                 if (0 == strcmp("(", argv[*pos])) {
 701                         ++(*pos);
 702                         ++(*lvl);
 703                         next = mandoc_calloc(1, sizeof(struct expr));
 704                         next->subexpr = exprexpr(argc, argv, pos, lvl, tt);
 705                         if (NULL == next->subexpr) {
 706                                 free(next);
 707                                 next = NULL;
 708                         }
 709                 } else if (0 == strcmp("-i", argv[*pos])) {
 710                         if (++(*pos) >= argc)
 711                                 goto err;
 712                         next = exprterm(argv[*pos], 0);
 713                 } else
 714                         next = exprterm(argv[*pos], 1);
 715
 716                 if (NULL == next)
 717                         goto err;
 718
 719                 next->and = log == 1;
 720                 next->index = (int)(*tt)++;
 721
 722                 /* Append to our chain of expressions. */
 723
 724                 if (NULL == first) {
 725                         assert(NULL == e);
 726                         first = next;
 727                 } else {
 728                         assert(NULL != e);
 729                         e->next = next;
 730                 }
 731         }
 732
 733         return(first);
 734 err:
 735         exprfree(first);
 736         return(NULL);
 737 }
 738
 739 /*
 740  * Parse a terminal expression with the grammar as defined in
 741  * apropos(1).
 742  * Return NULL if we fail the parse.
 743  */
 744 static struct expr *
 745 exprterm(char *buf, int cs)
 746 {
 747         struct expr      e;
 748         struct expr     *p;
 749         char            *key;
 750         int              i;
 751
 752         memset(&e, 0, sizeof(struct expr));
 753
 754         /* Choose regex or substring match. */
 755
 756         if (NULL == (e.v = strpbrk(buf, "=~"))) {
 757                 e.regex = 0;
 758                 e.v = buf;
 759         } else {
 760                 e.regex = '~' == *e.v;
 761                 *e.v++ = '\0';
 762         }
 763
 764         /* Determine the record types to search for. */
 765
 766         e.mask = 0;
 767         if (buf < e.v) {
 768                 while (NULL != (key = strsep(&buf, ","))) {
 769                         i = 0;
 770                         while (types[i].mask &&
 771                                         strcmp(types[i].name, key))
 772                                 i++;
 773                         e.mask |= types[i].mask;
 774                 }
 775         }
 776         if (0 == e.mask)
 777                 e.mask = TYPE_Nm | TYPE_Nd;
 778
 779         if (e.regex) {
 780                 i = REG_EXTENDED | REG_NOSUB | (cs ? 0 : REG_ICASE);
 781                 if (regcomp(&e.re, e.v, i))
 782                         return(NULL);
 783         }
 784
 785         e.v = mandoc_strdup(e.v);
 786
 787         p = mandoc_calloc(1, sizeof(struct expr));
 788         memcpy(p, &e, sizeof(struct expr));
 789         return(p);
 790 }
 791
 792 void
 793 exprfree(struct expr *p)
 794 {
 795         struct expr     *pp;
 796
 797         while (NULL != p) {
 798                 if (p->subexpr)
 799                         exprfree(p->subexpr);
 800                 if (p->regex)
 801                         regfree(&p->re);
 802                 free(p->v);
 803                 pp = p->next;
 804                 free(p);
 805                 p = pp;
 806         }
 807 }
 808
 809 static int
 810 exprmark(const struct expr *p, const char *cp,
 811                 uint64_t mask, int *ms)
 812 {
 813
 814         for ( ; p; p = p->next) {
 815                 if (p->subexpr) {
 816                         if (exprmark(p->subexpr, cp, mask, ms))
 817                                 return(1);
 818                         continue;
 819                 } else if ( ! (mask & p->mask))
 820                         continue;
 821
 822                 if (p->regex) {
 823                         if (regexec(&p->re, cp, 0, NULL, 0))
 824                                 continue;
 825                 } else if (NULL == strcasestr(cp, p->v))
 826                         continue;
 827
 828                 if (NULL == ms)
 829                         return(1);
 830                 else
 831                         ms[p->index] = 1;
 832         }
 833
 834         return(0);
 835 }
 836
 837 static int
 838 expreval(const struct expr *p, int *ms)
 839 {
 840         int              match;
 841
 842         /*
 843          * AND has precedence over OR.  Analysis is left-right, though
 844          * it doesn't matter because there are no side-effects.
 845          * Thus, step through pairwise ANDs and accumulate their Boolean
 846          * evaluation.  If we encounter a single true AND collection or
 847          * standalone term, the whole expression is true (by definition
 848          * of OR).
 849          */
 850
 851         for (match = 0; p && ! match; p = p->next) {
 852                 /* Evaluate a subexpression, if applicable. */
 853                 if (p->subexpr && ! ms[p->index])
 854                         ms[p->index] = expreval(p->subexpr, ms);
 855
 856                 match = ms[p->index];
 857                 for ( ; p->next && p->next->and; p = p->next) {
 858                         /* Evaluate a subexpression, if applicable. */
 859                         if (p->next->subexpr && ! ms[p->next->index])
 860                                 ms[p->next->index] =
 861                                         expreval(p->next->subexpr, ms);
 862                         match = match && ms[p->next->index];
 863                 }
 864         }
 865
 866         return(match);
 867 }
 868
 869 /*
 870  * First, update the array of terms for which this expression evaluates
 871  * to true.
 872  * Second, logically evaluate all terms over the updated array of truth
 873  * values.
 874  * If this evaluates to true, mark the expression as satisfied.
 875  */
 876 static void
 877 exprexec(const struct expr *e, const char *cp,
 878                 uint64_t mask, struct res *r)
 879 {
 880
 881         assert(0 == r->matched);
 882         exprmark(e, cp, mask, r->matches);
 883         r->matched = expreval(e, r->matches);
 884 }