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
49 static struct stat st;
50 static char *dbm_base;
51 static int ifd;
52 static 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 */
59 int
dbm_map(const char * fname)60 dbm_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
120 fail:
121 save_errno = errno;
122 close(ifd);
123 errno = save_errno;
124 return -1;
125 }
126
127 void
dbm_unmap(void)128 dbm_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 */
142 void *
dbm_get(int32_t offset)143 dbm_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 */
163 int32_t *
dbm_getint(int32_t offset)164 dbm_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 */
175 int32_t
dbm_addr(const void * p)176 dbm_addr(const void *p)
177 {
178 return htobe32((const char *)p - dbm_base);
179 }
180
181 int
dbm_match(const struct dbm_match * match,const char * str)182 dbm_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