1 /* $NetBSD: apropos-utils.c,v 1.3 2012/04/07 10:44:58 apb Exp $ */ 2 /*- 3 * Copyright (c) 2011 Abhinav Upadhyay <er.abhinav.upadhyay@gmail.com> 4 * All rights reserved. 5 * 6 * This code was developed as part of Google's Summer of Code 2011 program. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in 16 * the documentation and/or other materials provided with the 17 * distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 22 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 23 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 24 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 25 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 26 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 27 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 28 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 29 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #include <sys/cdefs.h> 34 __RCSID("$NetBSD: apropos-utils.c,v 1.3 2012/04/07 10:44:58 apb Exp $"); 35 36 #include <sys/stat.h> 37 38 #include <assert.h> 39 #include <ctype.h> 40 #include <err.h> 41 #include <math.h> 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include <string.h> 45 #include <util.h> 46 #include <zlib.h> 47 48 #include "apropos-utils.h" 49 #include "mandoc.h" 50 #include "sqlite3.h" 51 52 typedef struct orig_callback_data { 53 void *data; 54 int (*callback) (void *, const char *, const char *, const char *, 55 const char *, size_t); 56 } orig_callback_data; 57 58 typedef struct inverse_document_frequency { 59 double value; 60 int status; 61 } inverse_document_frequency; 62 63 /* weights for individual columns */ 64 static const double col_weights[] = { 65 2.0, // NAME 66 2.00, // Name-description 67 0.55, // DESCRIPTION 68 0.10, // LIBRARY 69 0.001, //RETURN VALUES 70 0.20, //ENVIRONMENT 71 0.01, //FILES 72 0.001, //EXIT STATUS 73 2.00, //DIAGNOSTICS 74 0.05, //ERRORS 75 0.00, //md5_hash 76 1.00 //machine 77 }; 78 79 /* 80 * lower -- 81 * Converts the string str to lower case 82 */ 83 char * 84 lower(char *str) 85 { 86 assert(str); 87 int i = 0; 88 char c; 89 while (str[i] != '\0') { 90 c = tolower((unsigned char) str[i]); 91 str[i++] = c; 92 } 93 return str; 94 } 95 96 /* 97 * concat-- 98 * Utility function. Concatenates together: dst, a space character and src. 99 * dst + " " + src 100 */ 101 void 102 concat(char **dst, const char *src) 103 { 104 concat2(dst, src, strlen(src)); 105 } 106 107 void 108 concat2(char **dst, const char *src, size_t srclen) 109 { 110 size_t total_len, dst_len; 111 assert(src != NULL); 112 113 /* If destination buffer dst is NULL, then simply strdup the source buffer */ 114 if (*dst == NULL) { 115 *dst = estrdup(src); 116 return; 117 } 118 119 dst_len = strlen(*dst); 120 /* 121 * NUL Byte and separator space 122 */ 123 total_len = dst_len + srclen + 2; 124 125 *dst = erealloc(*dst, total_len); 126 127 /* Append a space at the end of dst */ 128 (*dst)[dst_len++] = ' '; 129 130 /* Now, copy src at the end of dst */ 131 memcpy(*dst + dst_len, src, srclen + 1); 132 } 133 134 void 135 close_db(sqlite3 *db) 136 { 137 sqlite3_close(db); 138 sqlite3_shutdown(); 139 } 140 141 /* 142 * create_db -- 143 * Creates the database schema. 144 */ 145 static int 146 create_db(sqlite3 *db) 147 { 148 const char *sqlstr = NULL; 149 char *schemasql; 150 char *errmsg = NULL; 151 152 /*------------------------ Create the tables------------------------------*/ 153 154 #if NOTYET 155 sqlite3_exec(db, "PRAGMA journal_mode = WAL", NULL, NULL, NULL); 156 #else 157 sqlite3_exec(db, "PRAGMA journal_mode = DELETE", NULL, NULL, NULL); 158 #endif 159 160 schemasql = sqlite3_mprintf("PRAGMA user_version = %d", 161 APROPOS_SCHEMA_VERSION); 162 sqlite3_exec(db, schemasql, NULL, NULL, &errmsg); 163 if (errmsg != NULL) 164 goto out; 165 sqlite3_free(schemasql); 166 167 sqlstr = "CREATE VIRTUAL TABLE mandb USING fts4(section, name, " 168 "name_desc, desc, lib, return_vals, env, files, " 169 "exit_status, diagnostics, errors, md5_hash UNIQUE, machine, " 170 "compress=zip, uncompress=unzip, tokenize=porter); " //mandb 171 "CREATE TABLE IF NOT EXISTS mandb_meta(device, inode, mtime, " 172 "file UNIQUE, md5_hash UNIQUE, id INTEGER PRIMARY KEY); " 173 //mandb_meta 174 "CREATE TABLE IF NOT EXISTS mandb_links(link, target, section, " 175 "machine); "; //mandb_links 176 177 sqlite3_exec(db, sqlstr, NULL, NULL, &errmsg); 178 if (errmsg != NULL) 179 goto out; 180 181 sqlstr = "CREATE INDEX IF NOT EXISTS index_mandb_links ON mandb_links " 182 "(link); " 183 "CREATE INDEX IF NOT EXISTS index_mandb_meta_dev ON mandb_meta " 184 "(device, inode)"; 185 sqlite3_exec(db, sqlstr, NULL, NULL, &errmsg); 186 if (errmsg != NULL) 187 goto out; 188 return 0; 189 190 out: 191 warnx("%s", errmsg); 192 free(errmsg); 193 sqlite3_close(db); 194 sqlite3_shutdown(); 195 return -1; 196 } 197 198 /* 199 * zip -- 200 * User defined Sqlite function to compress the FTS table 201 */ 202 static void 203 zip(sqlite3_context *pctx, int nval, sqlite3_value **apval) 204 { 205 int nin; 206 long int nout; 207 const unsigned char * inbuf; 208 unsigned char *outbuf; 209 210 assert(nval == 1); 211 nin = sqlite3_value_bytes(apval[0]); 212 inbuf = (const unsigned char *) sqlite3_value_blob(apval[0]); 213 nout = nin + 13 + (nin + 999) / 1000; 214 outbuf = emalloc(nout); 215 compress(outbuf, (unsigned long *) &nout, inbuf, nin); 216 sqlite3_result_blob(pctx, outbuf, nout, free); 217 } 218 219 /* 220 * unzip -- 221 * User defined Sqlite function to uncompress the FTS table. 222 */ 223 static void 224 unzip(sqlite3_context *pctx, int nval, sqlite3_value **apval) 225 { 226 unsigned int rc; 227 unsigned char *outbuf; 228 z_stream stream; 229 230 assert(nval == 1); 231 stream.next_in = __UNCONST(sqlite3_value_blob(apval[0])); 232 stream.avail_in = sqlite3_value_bytes(apval[0]); 233 stream.avail_out = stream.avail_in * 2 + 100; 234 stream.next_out = outbuf = emalloc(stream.avail_out); 235 stream.zalloc = NULL; 236 stream.zfree = NULL; 237 238 if (inflateInit(&stream) != Z_OK) { 239 free(outbuf); 240 return; 241 } 242 243 while ((rc = inflate(&stream, Z_SYNC_FLUSH)) != Z_STREAM_END) { 244 if (rc != Z_OK || 245 (stream.avail_out != 0 && stream.avail_in == 0)) { 246 free(outbuf); 247 return; 248 } 249 outbuf = erealloc(outbuf, stream.total_out * 2); 250 stream.next_out = outbuf + stream.total_out; 251 stream.avail_out = stream.total_out; 252 } 253 if (inflateEnd(&stream) != Z_OK) { 254 free(outbuf); 255 return; 256 } 257 outbuf = erealloc(outbuf, stream.total_out); 258 sqlite3_result_text(pctx, (const char *) outbuf, stream.total_out, free); 259 } 260 261 /* init_db -- 262 * Prepare the database. Register the compress/uncompress functions and the 263 * stopword tokenizer. 264 * db_flag specifies the mode in which to open the database. 3 options are 265 * available: 266 * 1. DB_READONLY: Open in READONLY mode. An error if db does not exist. 267 * 2. DB_READWRITE: Open in read-write mode. An error if db does not exist. 268 * 3. DB_CREATE: Open in read-write mode. It will try to create the db if 269 * it does not exist already. 270 * RETURN VALUES: 271 * The function will return NULL in case the db does not exist and DB_CREATE 272 * was not specified. And in case DB_CREATE was specified and yet NULL is 273 * returned, then there was some other error. 274 * In normal cases the function should return a handle to the db. 275 */ 276 sqlite3 * 277 init_db(int db_flag) 278 { 279 sqlite3 *db = NULL; 280 sqlite3_stmt *stmt; 281 struct stat sb; 282 int rc; 283 int create_db_flag = 0; 284 285 /* Check if the database exists or not */ 286 if (!(stat(DBPATH, &sb) == 0 && S_ISREG(sb.st_mode))) { 287 /* Database does not exist, check if DB_CREATE was specified, and set 288 * flag to create the database schema 289 */ 290 if (db_flag != (MANDB_CREATE)) { 291 warnx("Missing apropos database. " 292 "Please run makemandb to create it."); 293 return NULL; 294 } 295 create_db_flag = 1; 296 } 297 298 /* Now initialize the database connection */ 299 sqlite3_initialize(); 300 rc = sqlite3_open_v2(DBPATH, &db, db_flag, NULL); 301 302 if (rc != SQLITE_OK) { 303 warnx("%s", sqlite3_errmsg(db)); 304 sqlite3_shutdown(); 305 return NULL; 306 } 307 308 if (create_db_flag && create_db(db) < 0) { 309 warnx("%s", "Unable to create database schema"); 310 goto error; 311 } 312 313 rc = sqlite3_prepare_v2(db, "PRAGMA user_version", -1, &stmt, NULL); 314 if (rc != SQLITE_OK) { 315 warnx("Unable to query schema version: %s", 316 sqlite3_errmsg(db)); 317 goto error; 318 } 319 if (sqlite3_step(stmt) != SQLITE_ROW) { 320 sqlite3_finalize(stmt); 321 warnx("Unable to query schema version: %s", 322 sqlite3_errmsg(db)); 323 goto error; 324 } 325 if (sqlite3_column_int(stmt, 0) != APROPOS_SCHEMA_VERSION) { 326 sqlite3_finalize(stmt); 327 warnx("Incorrect schema version found. " 328 "Please run makemandb -f."); 329 goto error; 330 } 331 sqlite3_finalize(stmt); 332 333 sqlite3_extended_result_codes(db, 1); 334 335 /* Register the zip and unzip functions for FTS compression */ 336 rc = sqlite3_create_function(db, "zip", 1, SQLITE_ANY, NULL, zip, NULL, NULL); 337 if (rc != SQLITE_OK) { 338 warnx("Unable to register function: compress: %s", 339 sqlite3_errmsg(db)); 340 goto error; 341 } 342 343 rc = sqlite3_create_function(db, "unzip", 1, SQLITE_ANY, NULL, 344 unzip, NULL, NULL); 345 if (rc != SQLITE_OK) { 346 warnx("Unable to register function: uncompress: %s", 347 sqlite3_errmsg(db)); 348 goto error; 349 } 350 return db; 351 error: 352 sqlite3_close(db); 353 sqlite3_shutdown(); 354 return NULL; 355 } 356 357 /* 358 * rank_func -- 359 * Sqlite user defined function for ranking the documents. 360 * For each phrase of the query, it computes the tf and idf and adds them over. 361 * It computes the final rank, by multiplying tf and idf together. 362 * Weight of term t for document d = (term frequency of t in d * 363 * inverse document frequency of t) 364 * 365 * Term Frequency of term t in document d = Number of times t occurs in d / 366 * Number of times t appears in all 367 * documents 368 * 369 * Inverse document frequency of t = log(Total number of documents / 370 * Number of documents in which t occurs) 371 */ 372 static void 373 rank_func(sqlite3_context *pctx, int nval, sqlite3_value **apval) 374 { 375 inverse_document_frequency *idf = sqlite3_user_data(pctx); 376 double tf = 0.0; 377 const unsigned int *matchinfo; 378 int ncol; 379 int nphrase; 380 int iphrase; 381 int ndoc; 382 int doclen = 0; 383 const double k = 3.75; 384 /* Check that the number of arguments passed to this function is correct. */ 385 assert(nval == 1); 386 387 matchinfo = (const unsigned int *) sqlite3_value_blob(apval[0]); 388 nphrase = matchinfo[0]; 389 ncol = matchinfo[1]; 390 ndoc = matchinfo[2 + 3 * ncol * nphrase + ncol]; 391 for (iphrase = 0; iphrase < nphrase; iphrase++) { 392 int icol; 393 const unsigned int *phraseinfo = &matchinfo[2 + ncol+ iphrase * ncol * 3]; 394 for(icol = 1; icol < ncol; icol++) { 395 396 /* nhitcount: number of times the current phrase occurs in the current 397 * column in the current document. 398 * nglobalhitcount: number of times current phrase occurs in the current 399 * column in all documents. 400 * ndocshitcount: number of documents in which the current phrase 401 * occurs in the current column at least once. 402 */ 403 int nhitcount = phraseinfo[3 * icol]; 404 int nglobalhitcount = phraseinfo[3 * icol + 1]; 405 int ndocshitcount = phraseinfo[3 * icol + 2]; 406 doclen = matchinfo[2 + icol ]; 407 double weight = col_weights[icol - 1]; 408 if (idf->status == 0 && ndocshitcount) 409 idf->value += log(((double)ndoc / ndocshitcount))* weight; 410 411 /* Dividing the tf by document length to normalize the effect of 412 * longer documents. 413 */ 414 if (nglobalhitcount > 0 && nhitcount) 415 tf += (((double)nhitcount * weight) / (nglobalhitcount * doclen)); 416 } 417 } 418 idf->status = 1; 419 420 /* Final score = (tf * idf)/ ( k + tf) 421 * Dividing by k+ tf further normalizes the weight leading to better 422 * results. 423 * The value of k is experimental 424 */ 425 double score = (tf * idf->value/ ( k + tf)) ; 426 sqlite3_result_double(pctx, score); 427 return; 428 } 429 430 /* 431 * run_query -- 432 * Performs the searches for the keywords entered by the user. 433 * The 2nd param: snippet_args is an array of strings providing values for the 434 * last three parameters to the snippet function of sqlite. (Look at the docs). 435 * The 3rd param: args contains rest of the search parameters. Look at 436 * arpopos-utils.h for the description of individual fields. 437 * 438 */ 439 int 440 run_query(sqlite3 *db, const char *snippet_args[3], query_args *args) 441 { 442 const char *default_snippet_args[3]; 443 char *section_clause = NULL; 444 char *limit_clause = NULL; 445 char *machine_clause = NULL; 446 char *query; 447 const char *section; 448 char *name; 449 const char *name_desc; 450 const char *machine; 451 const char *snippet; 452 char *m = NULL; 453 int rc; 454 inverse_document_frequency idf = {0, 0}; 455 sqlite3_stmt *stmt; 456 457 if (args->machine) 458 easprintf(&machine_clause, "AND machine = \'%s\' ", args->machine); 459 460 /* Register the rank function */ 461 rc = sqlite3_create_function(db, "rank_func", 1, SQLITE_ANY, (void *)&idf, 462 rank_func, NULL, NULL); 463 if (rc != SQLITE_OK) { 464 warnx("Unable to register the ranking function: %s", 465 sqlite3_errmsg(db)); 466 sqlite3_close(db); 467 sqlite3_shutdown(); 468 exit(EXIT_FAILURE); 469 } 470 471 /* We want to build a query of the form: "select x,y,z from mandb where 472 * mandb match :query [AND (section LIKE '1' OR section LIKE '2' OR...)] 473 * ORDER BY rank DESC..." 474 * NOTES: 1. The portion in square brackets is optional, it will be there 475 * only if the user has specified an option on the command line to search in 476 * one or more specific sections. 477 * 2. I am using LIKE operator because '=' or IN operators do not seem to be 478 * working with the compression option enabled. 479 */ 480 481 if (args->sec_nums) { 482 char *temp; 483 int i; 484 485 for (i = 0; i < SECMAX; i++) { 486 if (args->sec_nums[i] == 0) 487 continue; 488 easprintf(&temp, " OR section = \'%d\'", i + 1); 489 if (section_clause) { 490 concat(§ion_clause, temp); 491 free(temp); 492 } else { 493 section_clause = temp; 494 } 495 } 496 if (section_clause) { 497 /* 498 * At least one section requested, add glue for query. 499 */ 500 temp = section_clause; 501 /* Skip " OR " before first term. */ 502 easprintf(§ion_clause, " AND (%s)", temp + 4); 503 free(temp); 504 } 505 } 506 if (args->nrec >= 0) { 507 /* Use the provided number of records and offset */ 508 easprintf(&limit_clause, " LIMIT %d OFFSET %d", 509 args->nrec, args->offset); 510 } 511 512 if (snippet_args == NULL) { 513 default_snippet_args[0] = ""; 514 default_snippet_args[1] = ""; 515 default_snippet_args[2] = "..."; 516 snippet_args = default_snippet_args; 517 } 518 query = sqlite3_mprintf("SELECT section, name, name_desc, machine," 519 " snippet(mandb, %Q, %Q, %Q, -1, 40 )," 520 " rank_func(matchinfo(mandb, \"pclxn\")) AS rank" 521 " FROM mandb" 522 " WHERE mandb MATCH %Q %s " 523 "%s" 524 " ORDER BY rank DESC" 525 "%s", 526 snippet_args[0], snippet_args[1], snippet_args[2], args->search_str, 527 machine_clause ? machine_clause : "", 528 section_clause ? section_clause : "", 529 limit_clause ? limit_clause : ""); 530 531 free(machine_clause); 532 free(section_clause); 533 free(limit_clause); 534 535 if (query == NULL) { 536 *args->errmsg = estrdup("malloc failed"); 537 return -1; 538 } 539 rc = sqlite3_prepare_v2(db, query, -1, &stmt, NULL); 540 if (rc == SQLITE_IOERR) { 541 warnx("Corrupt database. Please rerun makemandb"); 542 sqlite3_free(query); 543 return -1; 544 } else if (rc != SQLITE_OK) { 545 warnx("%s", sqlite3_errmsg(db)); 546 sqlite3_free(query); 547 return -1; 548 } 549 550 while (sqlite3_step(stmt) == SQLITE_ROW) { 551 section = (const char *) sqlite3_column_text(stmt, 0); 552 name_desc = (const char *) sqlite3_column_text(stmt, 2); 553 machine = (const char *) sqlite3_column_text(stmt, 3); 554 snippet = (const char *) sqlite3_column_text(stmt, 4); 555 if (machine && machine[0]) { 556 m = estrdup(machine); 557 easprintf(&name, "%s/%s", lower(m), 558 sqlite3_column_text(stmt, 1)); 559 free(m); 560 } else { 561 name = estrdup((const char *) sqlite3_column_text(stmt, 1)); 562 } 563 564 (args->callback)(args->callback_data, section, name, name_desc, snippet, 565 strlen(snippet)); 566 567 free(name); 568 } 569 570 sqlite3_finalize(stmt); 571 sqlite3_free(query); 572 return *(args->errmsg) == NULL ? 0 : -1; 573 } 574 575 /* 576 * callback_html -- 577 * Callback function for run_query_html. It builds the html output and then 578 * calls the actual user supplied callback function. 579 */ 580 static int 581 callback_html(void *data, const char *section, const char *name, 582 const char *name_desc, const char *snippet, size_t snippet_length) 583 { 584 const char *temp = snippet; 585 int i = 0; 586 size_t sz = 0; 587 int count = 0; 588 struct orig_callback_data *orig_data = (struct orig_callback_data *) data; 589 int (*callback) (void *, const char *, const char *, const char *, 590 const char *, size_t) = orig_data->callback; 591 592 /* First scan the snippet to find out the number of occurrences of {'>', '<' 593 * '"', '&'}. 594 * Then allocate a new buffer with sufficient space to be able to store the 595 * quoted versions of the special characters {>, <, ", &}. 596 * Copy over the characters from the original snippet to this buffer while 597 * replacing the special characters with their quoted versions. 598 */ 599 600 while (*temp) { 601 sz = strcspn(temp, "<>\"&\002\003"); 602 temp += sz + 1; 603 count++; 604 } 605 size_t qsnippet_length = snippet_length + count * 5; 606 char *qsnippet = emalloc(qsnippet_length + 1); 607 sz = 0; 608 while (*snippet) { 609 sz = strcspn(snippet, "<>\"&\002\003"); 610 if (sz) { 611 memcpy(&qsnippet[i], snippet, sz); 612 snippet += sz; 613 i += sz; 614 } 615 616 switch (*snippet++) { 617 case '<': 618 memcpy(&qsnippet[i], "<", 4); 619 i += 4; 620 break; 621 case '>': 622 memcpy(&qsnippet[i], ">", 4); 623 i += 4; 624 break; 625 case '\"': 626 memcpy(&qsnippet[i], """, 6); 627 i += 6; 628 break; 629 case '&': 630 /* Don't perform the quoting if this & is part of an mdoc escape 631 * sequence, e.g. \& 632 */ 633 if (i && *(snippet - 2) != '\\') { 634 memcpy(&qsnippet[i], "&", 5); 635 i += 5; 636 } else { 637 qsnippet[i++] = '&'; 638 } 639 break; 640 case '\002': 641 memcpy(&qsnippet[i], "<b>", 3); 642 i += 3; 643 break; 644 case '\003': 645 memcpy(&qsnippet[i], "</b>", 4); 646 i += 4; 647 break; 648 default: 649 break; 650 } 651 } 652 qsnippet[++i] = 0; 653 (*callback)(orig_data->data, section, name, name_desc, 654 (const char *)qsnippet, qsnippet_length); 655 free(qsnippet); 656 return 0; 657 } 658 659 /* 660 * run_query_html -- 661 * Utility function to output query result in HTML format. 662 * It internally calls run_query only, but it first passes the output to it's 663 * own custom callback function, which preprocess the snippet for quoting 664 * inline HTML fragments. 665 * After that it delegates the call the actual user supplied callback function. 666 */ 667 int 668 run_query_html(sqlite3 *db, query_args *args) 669 { 670 struct orig_callback_data orig_data; 671 orig_data.callback = args->callback; 672 orig_data.data = args->callback_data; 673 const char *snippet_args[] = {"\002", "\003", "..."}; 674 args->callback = &callback_html; 675 args->callback_data = (void *) &orig_data; 676 return run_query(db, snippet_args, args); 677 } 678 679 /* 680 * callback_pager -- 681 * A callback similar to callback_html. It overstrikes the matching text in 682 * the snippet so that it appears emboldened when viewed using a pager like 683 * more or less. 684 */ 685 static int 686 callback_pager(void *data, const char *section, const char *name, 687 const char *name_desc, const char *snippet, size_t snippet_length) 688 { 689 struct orig_callback_data *orig_data = (struct orig_callback_data *) data; 690 char *psnippet; 691 const char *temp = snippet; 692 int count = 0; 693 int i = 0; 694 size_t sz = 0; 695 size_t psnippet_length; 696 697 /* Count the number of bytes of matching text. For each of these bytes we 698 * will use 2 extra bytes to overstrike it so that it appears bold when 699 * viewed using a pager. 700 */ 701 while (*temp) { 702 sz = strcspn(temp, "\002\003"); 703 temp += sz; 704 if (*temp == '\003') { 705 count += 2 * (sz); 706 } 707 temp++; 708 } 709 710 psnippet_length = snippet_length + count; 711 psnippet = emalloc(psnippet_length + 1); 712 713 /* Copy the bytes from snippet to psnippet: 714 * 1. Copy the bytes before \002 as it is. 715 * 2. The bytes after \002 need to be overstriked till we encounter \003. 716 * 3. To overstrike a byte 'A' we need to write 'A\bA' 717 */ 718 while (*snippet) { 719 sz = strcspn(snippet, "\002"); 720 memcpy(&psnippet[i], snippet, sz); 721 snippet += sz; 722 i += sz; 723 724 /* Don't change this. Advancing the pointer without reading the byte 725 * is causing strange behavior. 726 */ 727 if (*snippet == '\002') 728 snippet++; 729 while (*snippet && *snippet != '\003') { 730 psnippet[i++] = *snippet; 731 psnippet[i++] = '\b'; 732 psnippet[i++] = *snippet++; 733 } 734 if (*snippet) 735 snippet++; 736 } 737 738 psnippet[i] = 0; 739 (orig_data->callback)(orig_data->data, section, name, name_desc, psnippet, 740 psnippet_length); 741 free(psnippet); 742 return 0; 743 } 744 745 /* 746 * run_query_pager -- 747 * Utility function similar to run_query_html. This function tries to 748 * pre-process the result assuming it will be piped to a pager. 749 * For this purpose it first calls it's own callback function callback_pager 750 * which then delegates the call to the user supplied callback. 751 */ 752 int run_query_pager(sqlite3 *db, query_args *args) 753 { 754 struct orig_callback_data orig_data; 755 orig_data.callback = args->callback; 756 orig_data.data = args->callback_data; 757 const char *snippet_args[] = {"\002", "\003", "..."}; 758 args->callback = &callback_pager; 759 args->callback_data = (void *) &orig_data; 760 return run_query(db, snippet_args, args); 761 } 762