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-rw-r--r--db.c436
1 files changed, 436 insertions, 0 deletions
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+/* $Id$ */
+/*
+ * Copyright (c) 2011 Kristaps Dzonsons <kristaps@bsd.lv>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+#include <assert.h>
+#include <fcntl.h>
+#include <regex.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <string.h>
+
+#ifdef __linux__
+# include <db_185.h>
+#else
+# include <db.h>
+#endif
+
+#include "apropos.h"
+#include "mandoc.h"
+
+static DB *btree_open(void);
+static int btree_read(const DBT *, const struct mchars *, char **);
+static DB *index_open(void);
+static int index_read(const DBT *, const DBT *,
+ const struct mchars *, struct rec *);
+static void norm_string(const char *,
+ const struct mchars *, char **);
+static size_t norm_utf8(unsigned int, char[7]);
+
+/*
+ * Open the keyword mandoc-db database.
+ */
+static DB *
+btree_open(void)
+{
+ BTREEINFO info;
+ DB *db;
+
+ memset(&info, 0, sizeof(BTREEINFO));
+ info.flags = R_DUP;
+
+ db = dbopen("mandoc.db", O_RDONLY, 0, DB_BTREE, &info);
+ if (NULL != db)
+ return(db);
+
+ return(NULL);
+}
+
+/*
+ * Read a keyword from the database and normalise it.
+ * Return 0 if the database is insane, else 1.
+ */
+static int
+btree_read(const DBT *v, const struct mchars *mc, char **buf)
+{
+
+ /* Sanity: are we nil-terminated? */
+
+ assert(v->size > 0);
+ if ('\0' != ((char *)v->data)[(int)v->size - 1])
+ return(0);
+
+ norm_string((char *)v->data, mc, buf);
+ return(1);
+}
+
+/*
+ * Take a Unicode codepoint and produce its UTF-8 encoding.
+ * This isn't the best way to do this, but it works.
+ * The magic numbers are from the UTF-8 packaging.
+ * They're not as scary as they seem: read the UTF-8 spec for details.
+ */
+static size_t
+norm_utf8(unsigned int cp, char out[7])
+{
+ size_t rc;
+
+ rc = 0;
+
+ if (cp <= 0x0000007F) {
+ rc = 1;
+ out[0] = (char)cp;
+ } else if (cp <= 0x000007FF) {
+ rc = 2;
+ out[0] = (cp >> 6 & 31) | 192;
+ out[1] = (cp & 63) | 128;
+ } else if (cp <= 0x0000FFFF) {
+ rc = 3;
+ out[0] = (cp >> 12 & 15) | 224;
+ out[1] = (cp >> 6 & 63) | 128;
+ out[2] = (cp & 63) | 128;
+ } else if (cp <= 0x001FFFFF) {
+ rc = 4;
+ out[0] = (cp >> 18 & 7) | 240;
+ out[1] = (cp >> 12 & 63) | 128;
+ out[2] = (cp >> 6 & 63) | 128;
+ out[3] = (cp & 63) | 128;
+ } else if (cp <= 0x03FFFFFF) {
+ rc = 5;
+ out[0] = (cp >> 24 & 3) | 248;
+ out[1] = (cp >> 18 & 63) | 128;
+ out[2] = (cp >> 12 & 63) | 128;
+ out[3] = (cp >> 6 & 63) | 128;
+ out[4] = (cp & 63) | 128;
+ } else if (cp <= 0x7FFFFFFF) {
+ rc = 6;
+ out[0] = (cp >> 30 & 1) | 252;
+ out[1] = (cp >> 24 & 63) | 128;
+ out[2] = (cp >> 18 & 63) | 128;
+ out[3] = (cp >> 12 & 63) | 128;
+ out[4] = (cp >> 6 & 63) | 128;
+ out[5] = (cp & 63) | 128;
+ } else
+ return(0);
+
+ out[rc] = '\0';
+ return(rc);
+}
+
+/*
+ * Normalise strings from the index and database.
+ * These strings are escaped as defined by mandoc_char(7) along with
+ * other goop in mandoc.h (e.g., soft hyphens).
+ * This function normalises these into a nice UTF-8 string.
+ * Returns 0 if the database is fucked.
+ */
+static void
+norm_string(const char *val, const struct mchars *mc, char **buf)
+{
+ size_t sz, bsz;
+ char utfbuf[7];
+ const char *seq, *cpp;
+ int len, u, pos;
+ enum mandoc_esc esc;
+ static const char res[] = { '\\', '\t',
+ ASCII_NBRSP, ASCII_HYPH, '\0' };
+
+ /* Pre-allocate by the length of the input */
+
+ bsz = strlen(val) + 1;
+ *buf = mandoc_realloc(*buf, bsz);
+ pos = 0;
+
+ while ('\0' != *val) {
+ /*
+ * Halt on the first escape sequence.
+ * This also halts on the end of string, in which case
+ * we just copy, fallthrough, and exit the loop.
+ */
+ if ((sz = strcspn(val, res)) > 0) {
+ memcpy(&(*buf)[pos], val, sz);
+ pos += (int)sz;
+ val += (int)sz;
+ }
+
+ if (ASCII_HYPH == *val) {
+ (*buf)[pos++] = '-';
+ val++;
+ continue;
+ } else if ('\t' == *val || ASCII_NBRSP == *val) {
+ (*buf)[pos++] = ' ';
+ val++;
+ continue;
+ } else if ('\\' != *val)
+ break;
+
+ /* Read past the slash. */
+
+ val++;
+ u = 0;
+
+ /*
+ * Parse the escape sequence and see if it's a
+ * predefined character or special character.
+ */
+
+ esc = mandoc_escape(&val, &seq, &len);
+ if (ESCAPE_ERROR == esc)
+ break;
+
+ /*
+ * XXX - this just does UTF-8, but we need to know
+ * beforehand whether we should do text substitution.
+ */
+
+ switch (esc) {
+ case (ESCAPE_SPECIAL):
+ if (0 != (u = mchars_spec2cp(mc, seq, len)))
+ break;
+ /* FALLTHROUGH */
+ default:
+ continue;
+ }
+
+ /*
+ * If we have a Unicode codepoint, try to convert that
+ * to a UTF-8 byte string.
+ */
+
+ cpp = utfbuf;
+ if (0 == (sz = norm_utf8(u, utfbuf)))
+ continue;
+
+ /* Copy the rendered glyph into the stream. */
+
+ sz = strlen(cpp);
+ bsz += sz;
+
+ *buf = mandoc_realloc(*buf, bsz);
+
+ memcpy(&(*buf)[pos], cpp, sz);
+ pos += (int)sz;
+ }
+
+ (*buf)[pos] = '\0';
+}
+
+/*
+ * Open the filename-index mandoc-db database.
+ * Returns NULL if opening failed.
+ */
+static DB *
+index_open(void)
+{
+ DB *db;
+
+ db = dbopen("mandoc.index", O_RDONLY, 0, DB_RECNO, NULL);
+ if (NULL != db)
+ return(db);
+
+ return(NULL);
+}
+
+/*
+ * Safely unpack from an index file record into the structure.
+ * Returns 1 if an entry was unpacked, 0 if the database is insane.
+ */
+static int
+index_read(const DBT *key, const DBT *val,
+ const struct mchars *mc, struct rec *rec)
+{
+ size_t left;
+ char *np, *cp;
+
+#define INDEX_BREAD(_dst) \
+ do { \
+ if (NULL == (np = memchr(cp, '\0', left))) \
+ return(0); \
+ norm_string(cp, mc, &(_dst)); \
+ left -= (np - cp) + 1; \
+ cp = np + 1; \
+ } while (/* CONSTCOND */ 0)
+
+ left = val->size;
+ cp = (char *)val->data;
+
+ rec->rec = *(recno_t *)key->data;
+
+ INDEX_BREAD(rec->file);
+ INDEX_BREAD(rec->cat);
+ INDEX_BREAD(rec->title);
+ INDEX_BREAD(rec->arch);
+ INDEX_BREAD(rec->desc);
+ return(1);
+}
+
+/*
+ * Search the mandocdb database for the regular expression "q".
+ * Filter out by "opts".
+ * Call "res" with the results, which may be zero.
+ */
+void
+apropos_search(const struct opts *opts, const char *q, void *arg,
+ void (*res)(struct rec *, size_t, void *))
+{
+ int i, len, root, leaf;
+ regex_t reg;
+ DBT key, val;
+ DB *btree, *idx;
+ struct mchars *mc;
+ int ch;
+ char *buf;
+ recno_t rec;
+ struct rec *recs;
+ struct rec srec;
+
+ root = -1;
+ leaf = -1;
+ btree = NULL;
+ idx = NULL;
+ mc = NULL;
+ buf = NULL;
+ recs = NULL;
+ len = 0;
+
+ memset(&srec, 0, sizeof(struct rec));
+
+ if (NULL != q && '\0' == *q)
+ q = NULL;
+
+ ch = REG_EXTENDED | REG_NOSUB |
+ (OPTS_INSENS & opts->flags ? REG_ICASE : 0);
+
+ /* XXX: error out with bad regexp? */
+
+ if (NULL == q || regcomp(&reg, q, ch)) {
+ (*res)(NULL, 0, arg);
+ return;
+ }
+
+ mc = mchars_alloc();
+
+ /* XXX: return fact that we've errored? */
+
+ if (NULL == (btree = btree_open()))
+ goto out;
+ if (NULL == (idx = index_open()))
+ goto out;
+
+ while (0 == (ch = (*btree->seq)(btree, &key, &val, R_NEXT))) {
+ /*
+ * Low-water mark for key and value.
+ * The key must have something in it, and the value must
+ * have the correct tags/recno mix.
+ */
+ if (key.size < 2 || 8 != val.size)
+ break;
+
+ if ( ! (*(int32_t *)val.data & opts->types))
+ continue;
+
+ if ( ! btree_read(&key, mc, &buf))
+ break;
+ if (regexec(&reg, buf, 0, NULL, 0))
+ continue;
+
+ memcpy(&rec, val.data + 4, sizeof(recno_t));
+
+ /*
+ * O(log n) scan for prior records. Since a record
+ * number is unbounded, this has decent performance over
+ * a complex hash function.
+ */
+
+ for (leaf = root; leaf >= 0; )
+ if (rec > recs[leaf].rec && recs[leaf].rhs >= 0)
+ leaf = recs[leaf].rhs;
+ else if (rec < recs[leaf].rec && recs[leaf].lhs >= 0)
+ leaf = recs[leaf].lhs;
+ else
+ break;
+
+ if (leaf >= 0 && recs[leaf].rec == rec)
+ continue;
+
+ /*
+ * Now we actually extract the manpage's metadata from
+ * the index database.
+ */
+
+ key.data = &rec;
+ key.size = sizeof(recno_t);
+
+ if (0 != (*idx->get)(idx, &key, &val, 0))
+ break;
+
+ srec.lhs = srec.rhs = -1;
+ if ( ! index_read(&key, &val, mc, &srec))
+ break;
+
+ if (opts->cat && strcasecmp(opts->cat, srec.cat))
+ continue;
+ if (opts->arch && strcasecmp(opts->arch, srec.arch))
+ continue;
+
+ recs = mandoc_realloc
+ (recs, (len + 1) * sizeof(struct rec));
+
+ memcpy(&recs[len], &srec, sizeof(struct rec));
+
+ /* Append to our tree. */
+
+ if (leaf >= 0) {
+ if (rec > recs[leaf].rec)
+ recs[leaf].rhs = len;
+ else
+ recs[leaf].lhs = len;
+ } else
+ root = len;
+
+ memset(&srec, 0, sizeof(struct rec));
+ len++;
+ }
+
+ if (1 == ch)
+ (*res)(recs, len, arg);
+
+ /* XXX: else? corrupt database error? */
+out:
+ for (i = 0; i < len; i++) {
+ free(recs[i].file);
+ free(recs[i].cat);
+ free(recs[i].title);
+ free(recs[i].arch);
+ free(recs[i].desc);
+ }
+
+ free(srec.file);
+ free(srec.cat);
+ free(srec.title);
+ free(srec.arch);
+ free(srec.desc);
+
+ if (mc)
+ mchars_free(mc);
+ if (btree)
+ (*btree->close)(btree);
+ if (idx)
+ (*idx->close)(idx);
+
+ free(buf);
+ free(recs);
+ regfree(&reg);
+}