apropos_db.c

   1 /*      $Id: apropos_db.c,v 1.29 2012/03/23 05:07:35 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         { UINT64_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                         uint64_t *, recno_t *, 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.lorder = 4321;
 157         info.flags = R_DUP;
 158
 159         db = dbopen(MANDOC_DB, O_RDONLY, 0, DB_BTREE, &info);
 160         if (NULL != db)
 161                 return(db);
 162
 163         return(NULL);
 164 }
 165
 166 /*
 167  * Read a keyword from the database and normalise it.
 168  * Return 0 if the database is insane, else 1.
 169  */
 170 static int
 171 btree_read(const DBT *k, const DBT *v, const struct mchars *mc,
 172                 uint64_t *mask, recno_t *rec, char **buf)
 173 {
 174         uint64_t         vbuf[2];
 175
 176         /* Are our sizes sane? */
 177         if (k->size < 2 || sizeof(vbuf) != 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         norm_string((const char *)k->data, mc, buf);
 185         memcpy(vbuf, v->data, v->size);
 186         *mask = betoh64(vbuf[0]);
 187         *rec  = betoh64(vbuf[1]);
 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         int              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((size_t)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         char             type;
 369
 370 #define INDEX_BREAD(_dst) \
 371         do { \
 372                 if (NULL == (np = memchr(cp, '\0', left))) \
 373                         return(0); \
 374                 norm_string(cp, mc, &(_dst)); \
 375                 left -= (np - cp) + 1; \
 376                 cp = np + 1; \
 377         } while (/* CONSTCOND */ 0)
 378
 379         if (0 == (left = val->size))
 380                 return(0);
 381
 382         cp = val->data;
 383         assert(sizeof(recno_t) == key->size);
 384         memcpy(&rec->res.rec, key->data, key->size);
 385         rec->res.volume = index;
 386
 387         if ('d' == (type = *cp++))
 388                 rec->res.type = RESTYPE_MDOC;
 389         else if ('a' == type)
 390                 rec->res.type = RESTYPE_MAN;
 391         else if ('c' == type)
 392                 rec->res.type = RESTYPE_CAT;
 393         else
 394                 return(0);
 395
 396         left--;
 397         INDEX_BREAD(rec->res.file);
 398         INDEX_BREAD(rec->res.cat);
 399         INDEX_BREAD(rec->res.title);
 400         INDEX_BREAD(rec->res.arch);
 401         INDEX_BREAD(rec->res.desc);
 402         return(1);
 403 }
 404
 405 /*
 406  * Search mandocdb databases in paths for expression "expr".
 407  * Filter out by "opts".
 408  * Call "res" with the results, which may be zero.
 409  * Return 0 if there was a database error, else return 1.
 410  */
 411 int
 412 apropos_search(int pathsz, char **paths, const struct opts *opts,
 413                 const struct expr *expr, size_t terms, void *arg,
 414                 void (*res)(struct res *, size_t, void *))
 415 {
 416         struct rectree   tree;
 417         struct mchars   *mc;
 418         struct res      *ress;
 419         int              i, mlen, rc;
 420
 421         memset(&tree, 0, sizeof(struct rectree));
 422
 423         rc = 0;
 424         mc = mchars_alloc();
 425
 426         /*
 427          * Main loop.  Change into the directory containing manpage
 428          * databases.  Run our expession over each database in the set.
 429          */
 430
 431         for (i = 0; i < pathsz; i++) {
 432                 if (chdir(paths[i]))
 433                         continue;
 434                 if ( ! single_search(&tree, opts, expr, terms, mc, i))
 435                         goto out;
 436         }
 437
 438         /*
 439          * Count matching files, transfer to a "clean" array, then feed
 440          * them to the output handler.
 441          */
 442
 443         for (mlen = i = 0; i < tree.len; i++)
 444                 if (tree.node[i].matched)
 445                         mlen++;
 446
 447         ress = mandoc_malloc(mlen * sizeof(struct res));
 448
 449         for (mlen = i = 0; i < tree.len; i++)
 450                 if (tree.node[i].matched)
 451                         memcpy(&ress[mlen++], &tree.node[i].res,
 452                                         sizeof(struct res));
 453
 454         (*res)(ress, mlen, arg);
 455         free(ress);
 456
 457         rc = 1;
 458 out:
 459         for (i = 0; i < tree.len; i++)
 460                 recfree(&tree.node[i]);
 461
 462         free(tree.node);
 463         mchars_free(mc);
 464         return(rc);
 465 }
 466
 467 static int
 468 single_search(struct rectree *tree, const struct opts *opts,
 469                 const struct expr *expr, size_t terms,
 470                 struct mchars *mc, int vol)
 471 {
 472         int              root, leaf, ch;
 473         DBT              key, val;
 474         DB              *btree, *idx;
 475         char            *buf;
 476         struct rec      *rs;
 477         struct rec       r;
 478         uint64_t         mask;
 479         recno_t          rec;
 480
 481         root    = -1;
 482         leaf    = -1;
 483         btree   = NULL;
 484         idx     = NULL;
 485         buf     = NULL;
 486         rs      = tree->node;
 487
 488         memset(&r, 0, sizeof(struct rec));
 489
 490         if (NULL == (btree = btree_open()))
 491                 return(1);
 492
 493         if (NULL == (idx = index_open())) {
 494                 (*btree->close)(btree);
 495                 return(1);
 496         }
 497
 498         while (0 == (ch = (*btree->seq)(btree, &key, &val, R_NEXT))) {
 499                 if ( ! btree_read(&key, &val, mc, &mask, &rec, &buf))
 500                         break;
 501
 502                 /*
 503                  * See if this keyword record matches any of the
 504                  * expressions we have stored.
 505                  */
 506                 if ( ! exprmark(expr, buf, mask, NULL))
 507                         continue;
 508
 509                 /*
 510                  * O(log n) scan for prior records.  Since a record
 511                  * number is unbounded, this has decent performance over
 512                  * a complex hash function.
 513                  */
 514
 515                 for (leaf = root; leaf >= 0; )
 516                         if (rec > rs[leaf].res.rec &&
 517                                         rs[leaf].rhs >= 0)
 518                                 leaf = rs[leaf].rhs;
 519                         else if (rec < rs[leaf].res.rec &&
 520                                         rs[leaf].lhs >= 0)
 521                                 leaf = rs[leaf].lhs;
 522                         else
 523                                 break;
 524
 525                 /*
 526                  * If we find a record, see if it has already evaluated
 527                  * to true.  If it has, great, just keep going.  If not,
 528                  * try to evaluate it now and continue anyway.
 529                  */
 530
 531                 if (leaf >= 0 && rs[leaf].res.rec == rec) {
 532                         if (0 == rs[leaf].matched)
 533                                 exprexec(expr, buf, mask, &rs[leaf]);
 534                         continue;
 535                 }
 536
 537                 /*
 538                  * We have a new file to examine.
 539                  * Extract the manpage's metadata from the index
 540                  * database, then begin partial evaluation.
 541                  */
 542
 543                 key.data = &rec;
 544                 key.size = sizeof(recno_t);
 545
 546                 if (0 != (*idx->get)(idx, &key, &val, 0))
 547                         break;
 548
 549                 r.lhs = r.rhs = -1;
 550                 if ( ! index_read(&key, &val, vol, mc, &r))
 551                         break;
 552
 553                 /* XXX: this should be elsewhere, I guess? */
 554
 555                 if (opts->cat && strcasecmp(opts->cat, r.res.cat))
 556                         continue;
 557
 558                 if (opts->arch && *r.res.arch)
 559                         if (strcasecmp(opts->arch, r.res.arch))
 560                                 continue;
 561
 562                 tree->node = rs = mandoc_realloc
 563                         (rs, (tree->len + 1) * sizeof(struct rec));
 564
 565                 memcpy(&rs[tree->len], &r, sizeof(struct rec));
 566                 memset(&r, 0, sizeof(struct rec));
 567                 rs[tree->len].matches =
 568                         mandoc_calloc(terms, sizeof(int));
 569
 570                 exprexec(expr, buf, mask, &rs[tree->len]);
 571
 572                 /* Append to our tree. */
 573
 574                 if (leaf >= 0) {
 575                         if (rec > rs[leaf].res.rec)
 576                                 rs[leaf].rhs = tree->len;
 577                         else
 578                                 rs[leaf].lhs = tree->len;
 579                 } else
 580                         root = tree->len;
 581
 582                 tree->len++;
 583         }
 584
 585         (*btree->close)(btree);
 586         (*idx->close)(idx);
 587
 588         free(buf);
 589         recfree(&r);
 590         return(1 == ch);
 591 }
 592
 593 static void
 594 recfree(struct rec *rec)
 595 {
 596
 597         free(rec->res.file);
 598         free(rec->res.cat);
 599         free(rec->res.title);
 600         free(rec->res.arch);
 601         free(rec->res.desc);
 602
 603         free(rec->matches);
 604 }
 605
 606 /*
 607  * Compile a list of straight-up terms.
 608  * The arguments are re-written into ~[[:<:]]term[[:>:]], or "term"
 609  * surrounded by word boundaries, then pumped through exprterm().
 610  * Terms are case-insensitive.
 611  * This emulates whatis(1) behaviour.
 612  */
 613 struct expr *
 614 termcomp(int argc, char *argv[], size_t *tt)
 615 {
 616         char            *buf;
 617         int              pos;
 618         struct expr     *e, *next;
 619         size_t           sz;
 620
 621         buf = NULL;
 622         e = NULL;
 623         *tt = 0;
 624
 625         for (pos = argc - 1; pos >= 0; pos--) {
 626                 sz = strlen(argv[pos]) + 18;
 627                 buf = mandoc_realloc(buf, sz);
 628                 strlcpy(buf, "Nm~[[:<:]]", sz);
 629                 strlcat(buf, argv[pos], sz);
 630                 strlcat(buf, "[[:>:]]", sz);
 631                 if (NULL == (next = exprterm(buf, 0))) {
 632                         free(buf);
 633                         exprfree(e);
 634                         return(NULL);
 635                 }
 636                 next->next = e;
 637                 e = next;
 638                 (*tt)++;
 639         }
 640
 641         free(buf);
 642         return(e);
 643 }
 644
 645 /*
 646  * Compile a sequence of logical expressions.
 647  * See apropos.1 for a grammar of this sequence.
 648  */
 649 struct expr *
 650 exprcomp(int argc, char *argv[], size_t *tt)
 651 {
 652         int              pos, lvl;
 653         struct expr     *e;
 654
 655         pos = lvl = 0;
 656         *tt = 0;
 657
 658         e = exprexpr(argc, argv, &pos, &lvl, tt);
 659
 660         if (0 == lvl && pos >= argc)
 661                 return(e);
 662
 663         exprfree(e);
 664         return(NULL);
 665 }
 666
 667 /*
 668  * Compile an array of tokens into an expression.
 669  * An informal expression grammar is defined in apropos(1).
 670  * Return NULL if we fail doing so.  All memory will be cleaned up.
 671  * Return the root of the expression sequence if alright.
 672  */
 673 static struct expr *
 674 exprexpr(int argc, char *argv[], int *pos, int *lvl, size_t *tt)
 675 {
 676         struct expr     *e, *first, *next;
 677         int              log;
 678
 679         first = next = NULL;
 680
 681         for ( ; *pos < argc; (*pos)++) {
 682                 e = next;
 683
 684                 /*
 685                  * Close out a subexpression.
 686                  */
 687
 688                 if (NULL != e && 0 == strcmp(")", argv[*pos])) {
 689                         if (--(*lvl) < 0)
 690                                 goto err;
 691                         break;
 692                 }
 693
 694                 /*
 695                  * Small note: if we're just starting, don't let "-a"
 696                  * and "-o" be considered logical operators: they're
 697                  * just tokens unless pairwise joining, in which case we
 698                  * record their existence (or assume "OR").
 699                  */
 700                 log = 0;
 701
 702                 if (NULL != e && 0 == strcmp("-a", argv[*pos]))
 703                         log = 1;
 704                 else if (NULL != e && 0 == strcmp("-o", argv[*pos]))
 705                         log = 2;
 706
 707                 if (log > 0 && ++(*pos) >= argc)
 708                         goto err;
 709
 710                 /*
 711                  * Now we parse the term part.  This can begin with
 712                  * "-i", in which case the expression is case
 713                  * insensitive.
 714                  */
 715
 716                 if (0 == strcmp("(", argv[*pos])) {
 717                         ++(*pos);
 718                         ++(*lvl);
 719                         next = mandoc_calloc(1, sizeof(struct expr));
 720                         next->subexpr = exprexpr(argc, argv, pos, lvl, tt);
 721                         if (NULL == next->subexpr) {
 722                                 free(next);
 723                                 next = NULL;
 724                         }
 725                 } else if (0 == strcmp("-i", argv[*pos])) {
 726                         if (++(*pos) >= argc)
 727                                 goto err;
 728                         next = exprterm(argv[*pos], 0);
 729                 } else
 730                         next = exprterm(argv[*pos], 1);
 731
 732                 if (NULL == next)
 733                         goto err;
 734
 735                 next->and = log == 1;
 736                 next->index = (int)(*tt)++;
 737
 738                 /* Append to our chain of expressions. */
 739
 740                 if (NULL == first) {
 741                         assert(NULL == e);
 742                         first = next;
 743                 } else {
 744                         assert(NULL != e);
 745                         e->next = next;
 746                 }
 747         }
 748
 749         return(first);
 750 err:
 751         exprfree(first);
 752         return(NULL);
 753 }
 754
 755 /*
 756  * Parse a terminal expression with the grammar as defined in
 757  * apropos(1).
 758  * Return NULL if we fail the parse.
 759  */
 760 static struct expr *
 761 exprterm(char *buf, int cs)
 762 {
 763         struct expr      e;
 764         struct expr     *p;
 765         char            *key;
 766         int              i;
 767
 768         memset(&e, 0, sizeof(struct expr));
 769
 770         /* Choose regex or substring match. */
 771
 772         if (NULL == (e.v = strpbrk(buf, "=~"))) {
 773                 e.regex = 0;
 774                 e.v = buf;
 775         } else {
 776                 e.regex = '~' == *e.v;
 777                 *e.v++ = '\0';
 778         }
 779
 780         /* Determine the record types to search for. */
 781
 782         e.mask = 0;
 783         if (buf < e.v) {
 784                 while (NULL != (key = strsep(&buf, ","))) {
 785                         i = 0;
 786                         while (types[i].mask &&
 787                                         strcmp(types[i].name, key))
 788                                 i++;
 789                         e.mask |= types[i].mask;
 790                 }
 791         }
 792         if (0 == e.mask)
 793                 e.mask = TYPE_Nm | TYPE_Nd;
 794
 795         if (e.regex) {
 796                 i = REG_EXTENDED | REG_NOSUB | (cs ? 0 : REG_ICASE);
 797                 if (regcomp(&e.re, e.v, i))
 798                         return(NULL);
 799         }
 800
 801         e.v = mandoc_strdup(e.v);
 802
 803         p = mandoc_calloc(1, sizeof(struct expr));
 804         memcpy(p, &e, sizeof(struct expr));
 805         return(p);
 806 }
 807
 808 void
 809 exprfree(struct expr *p)
 810 {
 811         struct expr     *pp;
 812
 813         while (NULL != p) {
 814                 if (p->subexpr)
 815                         exprfree(p->subexpr);
 816                 if (p->regex)
 817                         regfree(&p->re);
 818                 free(p->v);
 819                 pp = p->next;
 820                 free(p);
 821                 p = pp;
 822         }
 823 }
 824
 825 static int
 826 exprmark(const struct expr *p, const char *cp,
 827                 uint64_t mask, int *ms)
 828 {
 829
 830         for ( ; p; p = p->next) {
 831                 if (p->subexpr) {
 832                         if (exprmark(p->subexpr, cp, mask, ms))
 833                                 return(1);
 834                         continue;
 835                 } else if ( ! (mask & p->mask))
 836                         continue;
 837
 838                 if (p->regex) {
 839                         if (regexec(&p->re, cp, 0, NULL, 0))
 840                                 continue;
 841                 } else if (NULL == strcasestr(cp, p->v))
 842                         continue;
 843
 844                 if (NULL == ms)
 845                         return(1);
 846                 else
 847                         ms[p->index] = 1;
 848         }
 849
 850         return(0);
 851 }
 852
 853 static int
 854 expreval(const struct expr *p, int *ms)
 855 {
 856         int              match;
 857
 858         /*
 859          * AND has precedence over OR.  Analysis is left-right, though
 860          * it doesn't matter because there are no side-effects.
 861          * Thus, step through pairwise ANDs and accumulate their Boolean
 862          * evaluation.  If we encounter a single true AND collection or
 863          * standalone term, the whole expression is true (by definition
 864          * of OR).
 865          */
 866
 867         for (match = 0; p && ! match; p = p->next) {
 868                 /* Evaluate a subexpression, if applicable. */
 869                 if (p->subexpr && ! ms[p->index])
 870                         ms[p->index] = expreval(p->subexpr, ms);
 871
 872                 match = ms[p->index];
 873                 for ( ; p->next && p->next->and; p = p->next) {
 874                         /* Evaluate a subexpression, if applicable. */
 875                         if (p->next->subexpr && ! ms[p->next->index])
 876                                 ms[p->next->index] =
 877                                         expreval(p->next->subexpr, ms);
 878                         match = match && ms[p->next->index];
 879                 }
 880         }
 881
 882         return(match);
 883 }
 884
 885 /*
 886  * First, update the array of terms for which this expression evaluates
 887  * to true.
 888  * Second, logically evaluate all terms over the updated array of truth
 889  * values.
 890  * If this evaluates to true, mark the expression as satisfied.
 891  */
 892 static void
 893 exprexec(const struct expr *e, const char *cp,
 894                 uint64_t mask, struct rec *r)
 895 {
 896
 897         assert(0 == r->matched);
 898         exprmark(e, cp, mask, r->matches);
 899         r->matched = expreval(e, r->matches);
 900 }