apropos_db.c

   1 /*      $Id: apropos_db.c,v 1.21 2011/12/03 18:47:09 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 #ifdef HAVE_CONFIG_H
  19 #include "config.h"
  20 #endif
  21
  22 #include <assert.h>
  23 #include <fcntl.h>
  24 #include <regex.h>
  25 #include <stdarg.h>
  26 #include <stdint.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <unistd.h>
  30
  31 #if defined(__linux__)
  32 # include <endian.h>
  33 # include <db_185.h>
  34 #elif defined(__APPLE__)
  35 # include <libkern/OSByteOrder.h>
  36 # include <db.h>
  37 #else
  38 # include <db.h>
  39 #endif
  40
  41 #include "mandocdb.h"
  42 #include "apropos_db.h"
  43 #include "mandoc.h"
  44
  45 struct  rec {
  46         struct res       res; /* resulting record info */
  47         /*
  48          * Maintain a binary tree for checking the uniqueness of `rec'
  49          * when adding elements to the results array.
  50          * Since the results array is dynamic, use offset in the array
  51          * instead of a pointer to the structure.
  52          */
  53         int              lhs;
  54         int              rhs;
  55         int              matched; /* expression is true */
  56         int             *matches; /* partial truth evaluations */
  57 };
  58
  59 struct  expr {
  60         int              regex; /* is regex? */
  61         int              index; /* index in match array */
  62         uint64_t         mask; /* type-mask */
  63         int              and; /* is rhs of logical AND? */
  64         char            *v; /* search value */
  65         regex_t          re; /* compiled re, if regex */
  66         struct expr     *next; /* next in sequence */
  67         struct expr     *subexpr;
  68 };
  69
  70 struct  type {
  71         uint64_t         mask;
  72         const char      *name;
  73 };
  74
  75 struct  rectree {
  76         struct rec      *node; /* record array for dir tree */
  77         int              len; /* length of record array */
  78 };
  79
  80 static  const struct type types[] = {
  81         { TYPE_An, "An" },
  82         { TYPE_Ar, "Ar" },
  83         { TYPE_At, "At" },
  84         { TYPE_Bsx, "Bsx" },
  85         { TYPE_Bx, "Bx" },
  86         { TYPE_Cd, "Cd" },
  87         { TYPE_Cm, "Cm" },
  88         { TYPE_Dv, "Dv" },
  89         { TYPE_Dx, "Dx" },
  90         { TYPE_Em, "Em" },
  91         { TYPE_Er, "Er" },
  92         { TYPE_Ev, "Ev" },
  93         { TYPE_Fa, "Fa" },
  94         { TYPE_Fl, "Fl" },
  95         { TYPE_Fn, "Fn" },
  96         { TYPE_Fn, "Fo" },
  97         { TYPE_Ft, "Ft" },
  98         { TYPE_Fx, "Fx" },
  99         { TYPE_Ic, "Ic" },
 100         { TYPE_In, "In" },
 101         { TYPE_Lb, "Lb" },
 102         { TYPE_Li, "Li" },
 103         { TYPE_Lk, "Lk" },
 104         { TYPE_Ms, "Ms" },
 105         { TYPE_Mt, "Mt" },
 106         { TYPE_Nd, "Nd" },
 107         { TYPE_Nm, "Nm" },
 108         { TYPE_Nx, "Nx" },
 109         { TYPE_Ox, "Ox" },
 110         { TYPE_Pa, "Pa" },
 111         { TYPE_Rs, "Rs" },
 112         { TYPE_Sh, "Sh" },
 113         { TYPE_Ss, "Ss" },
 114         { TYPE_St, "St" },
 115         { TYPE_Sy, "Sy" },
 116         { TYPE_Tn, "Tn" },
 117         { TYPE_Va, "Va" },
 118         { TYPE_Va, "Vt" },
 119         { TYPE_Xr, "Xr" },
 120         { INT_MAX, "any" },
 121         { 0, NULL }
 122 };
 123
 124 static  DB      *btree_open(void);
 125 static  int      btree_read(const DBT *, const DBT *,
 126                         const struct mchars *,
 127                         struct db_val *, char **);
 128 static  int      expreval(const struct expr *, int *);
 129 static  void     exprexec(const struct expr *,
 130                         const char *, uint64_t, struct rec *);
 131 static  int      exprmark(const struct expr *,
 132                         const char *, uint64_t, int *);
 133 static  struct expr *exprexpr(int, char *[], int *, int *, size_t *);
 134 static  struct expr *exprterm(char *, int);
 135 static  DB      *index_open(void);
 136 static  int      index_read(const DBT *, const DBT *, int,
 137                         const struct mchars *, struct rec *);
 138 static  void     norm_string(const char *,
 139                         const struct mchars *, char **);
 140 static  size_t   norm_utf8(unsigned int, char[7]);
 141 static  void     recfree(struct rec *);
 142 static  int      single_search(struct rectree *, const struct opts *,
 143                         const struct expr *, size_t terms,
 144                         struct mchars *, int);
 145
 146 /*
 147  * Open the keyword mandoc-db database.
 148  */
 149 static DB *
 150 btree_open(void)
 151 {
 152         BTREEINFO        info;
 153         DB              *db;
 154
 155         memset(&info, 0, sizeof(BTREEINFO));
 156         info.flags = R_DUP;
 157
 158         db = dbopen(MANDOC_DB, O_RDONLY, 0, DB_BTREE, &info);
 159         if (NULL != db)
 160                 return(db);
 161
 162         return(NULL);
 163 }
 164
 165 /*
 166  * Read a keyword from the database and normalise it.
 167  * Return 0 if the database is insane, else 1.
 168  */
 169 static int
 170 btree_read(const DBT *k, const DBT *v,
 171                 const struct mchars *mc,
 172                 struct db_val *dbv, char **buf)
 173 {
 174         const struct db_val *vp;
 175
 176         /* Are our sizes sane? */
 177         if (k->size < 2 || sizeof(struct db_val) != v->size)
 178                 return(0);
 179
 180         /* Is our string nil-terminated? */
 181         if ('\0' != ((const char *)k->data)[(int)k->size - 1])
 182                 return(0);
 183
 184         vp = v->data;
 185         norm_string((const char *)k->data, mc, buf);
 186         dbv->rec = betoh32(vp->rec);
 187         dbv->mask = betoh64(vp->mask);
 188         return(1);
 189 }
 190
 191 /*
 192  * Take a Unicode codepoint and produce its UTF-8 encoding.
 193  * This isn't the best way to do this, but it works.
 194  * The magic numbers are from the UTF-8 packaging.
 195  * They're not as scary as they seem: read the UTF-8 spec for details.
 196  */
 197 static size_t
 198 norm_utf8(unsigned int cp, char out[7])
 199 {
 200         size_t           rc;
 201
 202         rc = 0;
 203
 204         if (cp <= 0x0000007F) {
 205                 rc = 1;
 206                 out[0] = (char)cp;
 207         } else if (cp <= 0x000007FF) {
 208                 rc = 2;
 209                 out[0] = (cp >> 6  & 31) | 192;
 210                 out[1] = (cp       & 63) | 128;
 211         } else if (cp <= 0x0000FFFF) {
 212                 rc = 3;
 213                 out[0] = (cp >> 12 & 15) | 224;
 214                 out[1] = (cp >> 6  & 63) | 128;
 215                 out[2] = (cp       & 63) | 128;
 216         } else if (cp <= 0x001FFFFF) {
 217                 rc = 4;
 218                 out[0] = (cp >> 18 & 7) | 240;
 219                 out[1] = (cp >> 12 & 63) | 128;
 220                 out[2] = (cp >> 6  & 63) | 128;
 221                 out[3] = (cp       & 63) | 128;
 222         } else if (cp <= 0x03FFFFFF) {
 223                 rc = 5;
 224                 out[0] = (cp >> 24 & 3) | 248;
 225                 out[1] = (cp >> 18 & 63) | 128;
 226                 out[2] = (cp >> 12 & 63) | 128;
 227                 out[3] = (cp >> 6  & 63) | 128;
 228                 out[4] = (cp       & 63) | 128;
 229         } else if (cp <= 0x7FFFFFFF) {
 230                 rc = 6;
 231                 out[0] = (cp >> 30 & 1) | 252;
 232                 out[1] = (cp >> 24 & 63) | 128;
 233                 out[2] = (cp >> 18 & 63) | 128;
 234                 out[3] = (cp >> 12 & 63) | 128;
 235                 out[4] = (cp >> 6  & 63) | 128;
 236                 out[5] = (cp       & 63) | 128;
 237         } else
 238                 return(0);
 239
 240         out[rc] = '\0';
 241         return(rc);
 242 }
 243
 244 /*
 245  * Normalise strings from the index and database.
 246  * These strings are escaped as defined by mandoc_char(7) along with
 247  * other goop in mandoc.h (e.g., soft hyphens).
 248  * This function normalises these into a nice UTF-8 string.
 249  * Returns 0 if the database is fucked.
 250  */
 251 static void
 252 norm_string(const char *val, const struct mchars *mc, char **buf)
 253 {
 254         size_t            sz, bsz;
 255         char              utfbuf[7];
 256         const char       *seq, *cpp;
 257         int               len, u, pos;
 258         enum mandoc_esc   esc;
 259         static const char res[] = { '\\', '\t',
 260                                 ASCII_NBRSP, ASCII_HYPH, '\0' };
 261
 262         /* Pre-allocate by the length of the input */
 263
 264         bsz = strlen(val) + 1;
 265         *buf = mandoc_realloc(*buf, bsz);
 266         pos = 0;
 267
 268         while ('\0' != *val) {
 269                 /*
 270                  * Halt on the first escape sequence.
 271                  * This also halts on the end of string, in which case
 272                  * we just copy, fallthrough, and exit the loop.
 273                  */
 274                 if ((sz = strcspn(val, res)) > 0) {
 275                         memcpy(&(*buf)[pos], val, sz);
 276                         pos += (int)sz;
 277                         val += (int)sz;
 278                 }
 279
 280                 if (ASCII_HYPH == *val) {
 281                         (*buf)[pos++] = '-';
 282                         val++;
 283                         continue;
 284                 } else if ('\t' == *val || ASCII_NBRSP == *val) {
 285                         (*buf)[pos++] = ' ';
 286                         val++;
 287                         continue;
 288                 } else if ('\\' != *val)
 289                         break;
 290
 291                 /* Read past the slash. */
 292
 293                 val++;
 294                 u = 0;
 295
 296                 /*
 297                  * Parse the escape sequence and see if it's a
 298                  * predefined character or special character.
 299                  */
 300
 301                 esc = mandoc_escape(&val, &seq, &len);
 302                 if (ESCAPE_ERROR == esc)
 303                         break;
 304
 305                 /*
 306                  * XXX - this just does UTF-8, but we need to know
 307                  * beforehand whether we should do text substitution.
 308                  */
 309
 310                 switch (esc) {
 311                 case (ESCAPE_SPECIAL):
 312                         if (0 != (u = mchars_spec2cp(mc, seq, len)))
 313                                 break;
 314                         /* FALLTHROUGH */
 315                 default:
 316                         continue;
 317                 }
 318
 319                 /*
 320                  * If we have a Unicode codepoint, try to convert that
 321                  * to a UTF-8 byte string.
 322                  */
 323
 324                 cpp = utfbuf;
 325                 if (0 == (sz = norm_utf8(u, utfbuf)))
 326                         continue;
 327
 328                 /* Copy the rendered glyph into the stream. */
 329
 330                 sz = strlen(cpp);
 331                 bsz += sz;
 332
 333                 *buf = mandoc_realloc(*buf, bsz);
 334
 335                 memcpy(&(*buf)[pos], cpp, sz);
 336                 pos += (int)sz;
 337         }
 338
 339         (*buf)[pos] = '\0';
 340 }
 341
 342 /*
 343  * Open the filename-index mandoc-db database.
 344  * Returns NULL if opening failed.
 345  */
 346 static DB *
 347 index_open(void)
 348 {
 349         DB              *db;
 350
 351         db = dbopen(MANDOC_IDX, O_RDONLY, 0, DB_RECNO, NULL);
 352         if (NULL != db)
 353                 return(db);
 354
 355         return(NULL);
 356 }
 357
 358 /*
 359  * Safely unpack from an index file record into the structure.
 360  * Returns 1 if an entry was unpacked, 0 if the database is insane.
 361  */
 362 static int
 363 index_read(const DBT *key, const DBT *val, int index,
 364                 const struct mchars *mc, struct rec *rec)
 365 {
 366         size_t           left;
 367         char            *np, *cp;
 368
 369 #define INDEX_BREAD(_dst) \
 370         do { \
 371                 if (NULL == (np = memchr(cp, '\0', left))) \
 372                         return(0); \
 373                 norm_string(cp, mc, &(_dst)); \
 374                 left -= (np - cp) + 1; \
 375                 cp = np + 1; \
 376         } while (/* CONSTCOND */ 0)
 377
 378         left = val->size;
 379         cp = (char *)val->data;
 380
 381         rec->res.rec = *(recno_t *)key->data;
 382         rec->res.volume = index;
 383
 384         INDEX_BREAD(rec->res.type);
 385         INDEX_BREAD(rec->res.file);
 386         INDEX_BREAD(rec->res.cat);
 387         INDEX_BREAD(rec->res.title);
 388         INDEX_BREAD(rec->res.arch);
 389         INDEX_BREAD(rec->res.desc);
 390         return(1);
 391 }
 392
 393 /*
 394  * Search mandocdb databases in paths for expression "expr".
 395  * Filter out by "opts".
 396  * Call "res" with the results, which may be zero.
 397  * Return 0 if there was a database error, else return 1.
 398  */
 399 int
 400 apropos_search(int pathsz, char **paths, const struct opts *opts,
 401                 const struct expr *expr, size_t terms, void *arg,
 402                 void (*res)(struct res *, size_t, void *))
 403 {
 404         struct rectree   tree;
 405         struct mchars   *mc;
 406         struct res      *ress;
 407         int              i, mlen, rc;
 408
 409         memset(&tree, 0, sizeof(struct rectree));
 410
 411         rc = 0;
 412         mc = mchars_alloc();
 413
 414         /*
 415          * Main loop.  Change into the directory containing manpage
 416          * databases.  Run our expession over each database in the set.
 417          */
 418
 419         for (i = 0; i < pathsz; i++) {
 420                 if (chdir(paths[i]))
 421                         continue;
 422                 if ( ! single_search(&tree, opts, expr, terms, mc, i))
 423                         goto out;
 424         }
 425
 426         /*
 427          * Count matching files, transfer to a "clean" array, then feed
 428          * them to the output handler.
 429          */
 430
 431         for (mlen = i = 0; i < tree.len; i++)
 432                 if (tree.node[i].matched)
 433                         mlen++;
 434
 435         ress = mandoc_malloc(mlen * sizeof(struct res));
 436
 437         for (mlen = i = 0; i < tree.len; i++)
 438                 if (tree.node[i].matched)
 439                         memcpy(&ress[mlen++], &tree.node[i].res,
 440                                         sizeof(struct res));
 441
 442         (*res)(ress, mlen, arg);
 443         free(ress);
 444
 445         rc = 1;
 446 out:
 447         for (i = 0; i < tree.len; i++)
 448                 recfree(&tree.node[i]);
 449
 450         free(tree.node);
 451         mchars_free(mc);
 452         return(rc);
 453 }
 454
 455 static int
 456 single_search(struct rectree *tree, const struct opts *opts,
 457                 const struct expr *expr, size_t terms,
 458                 struct mchars *mc, int vol)
 459 {
 460         int              root, leaf, ch;
 461         DBT              key, val;
 462         DB              *btree, *idx;
 463         char            *buf;
 464         struct rec      *rs;
 465         struct rec       r;
 466         struct db_val    vb;
 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 rec));
 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, &vb, &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, vb.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 (vb.rec > rs[leaf].res.rec &&
 504                                         rs[leaf].rhs >= 0)
 505                                 leaf = rs[leaf].rhs;
 506                         else if (vb.rec < rs[leaf].res.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].res.rec == vb.rec) {
 519                         if (0 == rs[leaf].matched)
 520                                 exprexec(expr, buf, vb.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 = &vb.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.res.cat))
 543                         continue;
 544                 if (opts->arch && strcasecmp(opts->arch, r.res.arch))
 545                         continue;
 546
 547                 tree->node = rs = mandoc_realloc
 548                         (rs, (tree->len + 1) * sizeof(struct rec));
 549
 550                 memcpy(&rs[tree->len], &r, sizeof(struct rec));
 551                 rs[tree->len].matches =
 552                         mandoc_calloc(terms, sizeof(int));
 553
 554                 exprexec(expr, buf, vb.mask, &rs[tree->len]);
 555
 556                 /* Append to our tree. */
 557
 558                 if (leaf >= 0) {
 559                         if (vb.rec > rs[leaf].res.rec)
 560                                 rs[leaf].rhs = tree->len;
 561                         else
 562                                 rs[leaf].lhs = tree->len;
 563                 } else
 564                         root = tree->len;
 565
 566                 memset(&r, 0, sizeof(struct rec));
 567                 tree->len++;
 568         }
 569
 570         (*btree->close)(btree);
 571         (*idx->close)(idx);
 572
 573         free(buf);
 574         return(1 == ch);
 575 }
 576
 577 static void
 578 recfree(struct rec *rec)
 579 {
 580
 581         free(rec->res.type);
 582         free(rec->res.file);
 583         free(rec->res.cat);
 584         free(rec->res.title);
 585         free(rec->res.arch);
 586         free(rec->res.desc);
 587
 588         free(rec->matches);
 589 }
 590
 591 /*
 592  * Compile a list of straight-up terms.
 593  * The arguments are re-written into ~[[:<:]]term[[:>:]], or "term"
 594  * surrounded by word boundaries, then pumped through exprterm().
 595  * Terms are case-insensitive.
 596  * This emulates whatis(1) behaviour.
 597  */
 598 struct expr *
 599 termcomp(int argc, char *argv[], size_t *tt)
 600 {
 601         char            *buf;
 602         int              pos;
 603         struct expr     *e, *next;
 604         size_t           sz;
 605
 606         buf = NULL;
 607         e = NULL;
 608         *tt = 0;
 609
 610         for (pos = argc - 1; pos >= 0; pos--) {
 611                 sz = strlen(argv[pos]) + 18;
 612                 buf = mandoc_realloc(buf, sz);
 613                 strlcpy(buf, "Nm~[[:<:]]", sz);
 614                 strlcat(buf, argv[pos], sz);
 615                 strlcat(buf, "[[:>:]]", sz);
 616                 if (NULL == (next = exprterm(buf, 0))) {
 617                         free(buf);
 618                         exprfree(e);
 619                         return(NULL);
 620                 }
 621                 next->next = e;
 622                 e = next;
 623                 (*tt)++;
 624         }
 625
 626         free(buf);
 627         return(e);
 628 }
 629
 630 /*
 631  * Compile a sequence of logical expressions.
 632  * See apropos.1 for a grammar of this sequence.
 633  */
 634 struct expr *
 635 exprcomp(int argc, char *argv[], size_t *tt)
 636 {
 637         int              pos, lvl;
 638         struct expr     *e;
 639
 640         pos = lvl = 0;
 641         *tt = 0;
 642
 643         e = exprexpr(argc, argv, &pos, &lvl, tt);
 644
 645         if (0 == lvl && pos >= argc)
 646                 return(e);
 647
 648         exprfree(e);
 649         return(NULL);
 650 }
 651
 652 /*
 653  * Compile an array of tokens into an expression.
 654  * An informal expression grammar is defined in apropos(1).
 655  * Return NULL if we fail doing so.  All memory will be cleaned up.
 656  * Return the root of the expression sequence if alright.
 657  */
 658 static struct expr *
 659 exprexpr(int argc, char *argv[], int *pos, int *lvl, size_t *tt)
 660 {
 661         struct expr     *e, *first, *next;
 662         int              log;
 663
 664         first = next = NULL;
 665
 666         for ( ; *pos < argc; (*pos)++) {
 667                 e = next;
 668
 669                 /*
 670                  * Close out a subexpression.
 671                  */
 672
 673                 if (NULL != e && 0 == strcmp(")", argv[*pos])) {
 674                         if (--(*lvl) < 0)
 675                                 goto err;
 676                         break;
 677                 }
 678
 679                 /*
 680                  * Small note: if we're just starting, don't let "-a"
 681                  * and "-o" be considered logical operators: they're
 682                  * just tokens unless pairwise joining, in which case we
 683                  * record their existence (or assume "OR").
 684                  */
 685                 log = 0;
 686
 687                 if (NULL != e && 0 == strcmp("-a", argv[*pos]))
 688                         log = 1;
 689                 else if (NULL != e && 0 == strcmp("-o", argv[*pos]))
 690                         log = 2;
 691
 692                 if (log > 0 && ++(*pos) >= argc)
 693                         goto err;
 694
 695                 /*
 696                  * Now we parse the term part.  This can begin with
 697                  * "-i", in which case the expression is case
 698                  * insensitive.
 699                  */
 700
 701                 if (0 == strcmp("(", argv[*pos])) {
 702                         ++(*pos);
 703                         ++(*lvl);
 704                         next = mandoc_calloc(1, sizeof(struct expr));
 705                         next->subexpr = exprexpr(argc, argv, pos, lvl, tt);
 706                         if (NULL == next->subexpr) {
 707                                 free(next);
 708                                 next = NULL;
 709                         }
 710                 } else if (0 == strcmp("-i", argv[*pos])) {
 711                         if (++(*pos) >= argc)
 712                                 goto err;
 713                         next = exprterm(argv[*pos], 0);
 714                 } else
 715                         next = exprterm(argv[*pos], 1);
 716
 717                 if (NULL == next)
 718                         goto err;
 719
 720                 next->and = log == 1;
 721                 next->index = (int)(*tt)++;
 722
 723                 /* Append to our chain of expressions. */
 724
 725                 if (NULL == first) {
 726                         assert(NULL == e);
 727                         first = next;
 728                 } else {
 729                         assert(NULL != e);
 730                         e->next = next;
 731                 }
 732         }
 733
 734         return(first);
 735 err:
 736         exprfree(first);
 737         return(NULL);
 738 }
 739
 740 /*
 741  * Parse a terminal expression with the grammar as defined in
 742  * apropos(1).
 743  * Return NULL if we fail the parse.
 744  */
 745 static struct expr *
 746 exprterm(char *buf, int cs)
 747 {
 748         struct expr      e;
 749         struct expr     *p;
 750         char            *key;
 751         int              i;
 752
 753         memset(&e, 0, sizeof(struct expr));
 754
 755         /* Choose regex or substring match. */
 756
 757         if (NULL == (e.v = strpbrk(buf, "=~"))) {
 758                 e.regex = 0;
 759                 e.v = buf;
 760         } else {
 761                 e.regex = '~' == *e.v;
 762                 *e.v++ = '\0';
 763         }
 764
 765         /* Determine the record types to search for. */
 766
 767         e.mask = 0;
 768         if (buf < e.v) {
 769                 while (NULL != (key = strsep(&buf, ","))) {
 770                         i = 0;
 771                         while (types[i].mask &&
 772                                         strcmp(types[i].name, key))
 773                                 i++;
 774                         e.mask |= types[i].mask;
 775                 }
 776         }
 777         if (0 == e.mask)
 778                 e.mask = TYPE_Nm | TYPE_Nd;
 779
 780         if (e.regex) {
 781                 i = REG_EXTENDED | REG_NOSUB | (cs ? 0 : REG_ICASE);
 782                 if (regcomp(&e.re, e.v, i))
 783                         return(NULL);
 784         }
 785
 786         e.v = mandoc_strdup(e.v);
 787
 788         p = mandoc_calloc(1, sizeof(struct expr));
 789         memcpy(p, &e, sizeof(struct expr));
 790         return(p);
 791 }
 792
 793 void
 794 exprfree(struct expr *p)
 795 {
 796         struct expr     *pp;
 797
 798         while (NULL != p) {
 799                 if (p->subexpr)
 800                         exprfree(p->subexpr);
 801                 if (p->regex)
 802                         regfree(&p->re);
 803                 free(p->v);
 804                 pp = p->next;
 805                 free(p);
 806                 p = pp;
 807         }
 808 }
 809
 810 static int
 811 exprmark(const struct expr *p, const char *cp,
 812                 uint64_t mask, int *ms)
 813 {
 814
 815         for ( ; p; p = p->next) {
 816                 if (p->subexpr) {
 817                         if (exprmark(p->subexpr, cp, mask, ms))
 818                                 return(1);
 819                         continue;
 820                 } else if ( ! (mask & p->mask))
 821                         continue;
 822
 823                 if (p->regex) {
 824                         if (regexec(&p->re, cp, 0, NULL, 0))
 825                                 continue;
 826                 } else if (NULL == strcasestr(cp, p->v))
 827                         continue;
 828
 829                 if (NULL == ms)
 830                         return(1);
 831                 else
 832                         ms[p->index] = 1;
 833         }
 834
 835         return(0);
 836 }
 837
 838 static int
 839 expreval(const struct expr *p, int *ms)
 840 {
 841         int              match;
 842
 843         /*
 844          * AND has precedence over OR.  Analysis is left-right, though
 845          * it doesn't matter because there are no side-effects.
 846          * Thus, step through pairwise ANDs and accumulate their Boolean
 847          * evaluation.  If we encounter a single true AND collection or
 848          * standalone term, the whole expression is true (by definition
 849          * of OR).
 850          */
 851
 852         for (match = 0; p && ! match; p = p->next) {
 853                 /* Evaluate a subexpression, if applicable. */
 854                 if (p->subexpr && ! ms[p->index])
 855                         ms[p->index] = expreval(p->subexpr, ms);
 856
 857                 match = ms[p->index];
 858                 for ( ; p->next && p->next->and; p = p->next) {
 859                         /* Evaluate a subexpression, if applicable. */
 860                         if (p->next->subexpr && ! ms[p->next->index])
 861                                 ms[p->next->index] =
 862                                         expreval(p->next->subexpr, ms);
 863                         match = match && ms[p->next->index];
 864                 }
 865         }
 866
 867         return(match);
 868 }
 869
 870 /*
 871  * First, update the array of terms for which this expression evaluates
 872  * to true.
 873  * Second, logically evaluate all terms over the updated array of truth
 874  * values.
 875  * If this evaluates to true, mark the expression as satisfied.
 876  */
 877 static void
 878 exprexec(const struct expr *e, const char *cp,
 879                 uint64_t mask, struct rec *r)
 880 {
 881
 882         assert(0 == r->matched);
 883         exprmark(e, cp, mask, r->matches);
 884         r->matched = expreval(e, r->matches);
 885 }