1/*	$Id: dbm_map.c,v 1.8 2017/02/17 14:43:54 schwarze Exp $ */
2/*
3 * Copyright (c) 2016 Ingo Schwarze <schwarze@openbsd.org>
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 *
17 * Low-level routines for the map-based version
18 * of the mandoc database, for read-only access.
19 * The interface is defined in "dbm_map.h".
20 */
21#include "config.h"
22
23#include <sys/mman.h>
24#include <sys/stat.h>
25#include <sys/types.h>
26
27#if HAVE_ENDIAN
28#include <endian.h>
29#elif HAVE_SYS_ENDIAN
30#include <sys/endian.h>
31#elif HAVE_NTOHL
32#include <arpa/inet.h>
33#endif
34#if HAVE_ERR
35#include <err.h>
36#endif
37#include <errno.h>
38#include <fcntl.h>
39#include <regex.h>
40#include <stdint.h>
41#include <stdlib.h>
42#include <string.h>
43#include <unistd.h>
44
45#include "mansearch.h"
46#include "dbm_map.h"
47#include "dbm.h"
48
49static struct stat	 st;
50static char		*dbm_base;
51static int		 ifd;
52static int32_t		 max_offset;
53
54/*
55 * Open a disk-based database for read-only access.
56 * Validate the file format as far as it is not mandoc-specific.
57 * Return 0 on success.  Return -1 and set errno on failure.
58 */
59int
60dbm_map(const char *fname)
61{
62	int		 save_errno;
63	const int32_t	*magic;
64
65	if ((ifd = open(fname, O_RDONLY)) == -1)
66		return -1;
67	if (fstat(ifd, &st) == -1)
68		goto fail;
69	if (st.st_size < 5) {
70		warnx("dbm_map(%s): File too short", fname);
71		errno = EFTYPE;
72		goto fail;
73	}
74	if (st.st_size > INT32_MAX) {
75		errno = EFBIG;
76		goto fail;
77	}
78	if ((dbm_base = mmap(NULL, st.st_size, PROT_READ, MAP_SHARED,
79	    ifd, 0)) == MAP_FAILED)
80		goto fail;
81	magic = dbm_getint(0);
82	if (be32toh(*magic) != MANDOCDB_MAGIC) {
83		if (strncmp(dbm_base, "SQLite format 3", 15))
84			warnx("dbm_map(%s): "
85			    "Bad initial magic %x (expected %x)",
86			    fname, be32toh(*magic), MANDOCDB_MAGIC);
87		else
88			warnx("dbm_map(%s): "
89			    "Obsolete format based on SQLite 3",
90			    fname);
91		errno = EFTYPE;
92		goto fail;
93	}
94	magic = dbm_getint(1);
95	if (be32toh(*magic) != MANDOCDB_VERSION) {
96		warnx("dbm_map(%s): Bad version number %d (expected %d)",
97		    fname, be32toh(*magic), MANDOCDB_VERSION);
98		errno = EFTYPE;
99		goto fail;
100	}
101	max_offset = be32toh(*dbm_getint(3)) + sizeof(int32_t);
102	if (st.st_size != max_offset) {
103		warnx("dbm_map(%s): Inconsistent file size %lld (expected %d)",
104		    fname, (long long)st.st_size, max_offset);
105		errno = EFTYPE;
106		goto fail;
107	}
108	if ((magic = dbm_get(*dbm_getint(3))) == NULL) {
109		errno = EFTYPE;
110		goto fail;
111	}
112	if (be32toh(*magic) != MANDOCDB_MAGIC) {
113		warnx("dbm_map(%s): Bad final magic %x (expected %x)",
114		    fname, be32toh(*magic), MANDOCDB_MAGIC);
115		errno = EFTYPE;
116		goto fail;
117	}
118	return 0;
119
120fail:
121	save_errno = errno;
122	close(ifd);
123	errno = save_errno;
124	return -1;
125}
126
127void
128dbm_unmap(void)
129{
130	if (munmap(dbm_base, st.st_size) == -1)
131		warn("dbm_unmap: munmap");
132	if (close(ifd) == -1)
133		warn("dbm_unmap: close");
134	dbm_base = (char *)-1;
135}
136
137/*
138 * Take a raw integer as it was read from the database.
139 * Interpret it as an offset into the database file
140 * and return a pointer to that place in the file.
141 */
142void *
143dbm_get(int32_t offset)
144{
145	offset = be32toh(offset);
146	if (offset < 0) {
147		warnx("dbm_get: Database corrupt: offset %d", offset);
148		return NULL;
149	}
150	if (offset >= max_offset) {
151		warnx("dbm_get: Database corrupt: offset %d > %d",
152		    offset, max_offset);
153		return NULL;
154	}
155	return dbm_base + offset;
156}
157
158/*
159 * Assume the database starts with some integers.
160 * Assume they are numbered starting from 0, increasing.
161 * Get a pointer to one with the number "offset".
162 */
163int32_t *
164dbm_getint(int32_t offset)
165{
166	return (int32_t *)dbm_base + offset;
167}
168
169/*
170 * The reverse of dbm_get().
171 * Take pointer into the database file
172 * and convert it to the raw integer
173 * that would be used to refer to that place in the file.
174 */
175int32_t
176dbm_addr(const void *p)
177{
178	return htobe32((const char *)p - dbm_base);
179}
180
181int
182dbm_match(const struct dbm_match *match, const char *str)
183{
184	switch (match->type) {
185	case DBM_EXACT:
186		return strcmp(str, match->str) == 0;
187	case DBM_SUB:
188		return strcasestr(str, match->str) != NULL;
189	case DBM_REGEX:
190		return regexec(match->re, str, 0, NULL, 0) == 0;
191	default:
192		abort();
193	}
194}
195