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/* $OpenBSD: dbm_map.c,v 1.1 2016/08/01 10:32:39 schwarze Exp $ */
/*
* Copyright (c) 2016 Ingo Schwarze <schwarze@openbsd.org>
*
* 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.
*
* Low-level routines for the map-based version
* of the mandoc database, for read-only access.
* The interface is defined in "dbm_map.h".
*/
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <endian.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <regex.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "mansearch.h"
#include "dbm_map.h"
#include "dbm.h"
static struct stat st;
static char *dbm_base;
static int ifd;
static int32_t max_offset;
/*
* Open a disk-based database for read-only access.
* Validate the file format as far as it is not mandoc-specific.
* Return 0 on success. Return -1 and set errno on failure.
*/
int
dbm_map(const char *fname)
{
int save_errno;
const int32_t *magic;
if ((ifd = open(fname, O_RDONLY)) == -1)
return -1;
if (fstat(ifd, &st) == -1)
goto fail;
if (st.st_size < 5) {
warnx("dbm_map(%s): File too short", fname);
errno = EFTYPE;
goto fail;
}
if (st.st_size > INT32_MAX) {
errno = EFBIG;
goto fail;
}
if ((dbm_base = mmap(NULL, st.st_size, PROT_READ, MAP_SHARED,
ifd, 0)) == MAP_FAILED)
goto fail;
magic = dbm_getint(0);
if (be32toh(*magic) != MANDOCDB_MAGIC) {
warnx("dbm_map(%s): Bad initial magic %x (expected %x)",
fname, be32toh(*magic), MANDOCDB_MAGIC);
errno = EFTYPE;
goto fail;
}
magic = dbm_getint(1);
if (be32toh(*magic) != MANDOCDB_VERSION) {
warnx("dbm_map(%s): Bad version number %d (expected %d)",
fname, be32toh(*magic), MANDOCDB_VERSION);
errno = EFTYPE;
goto fail;
}
max_offset = be32toh(*dbm_getint(3)) + sizeof(int32_t);
if (st.st_size != max_offset) {
warnx("dbm_map(%s): Inconsistent file size %llu (expected %d)",
fname, st.st_size, max_offset);
errno = EFTYPE;
goto fail;
}
if ((magic = dbm_get(*dbm_getint(3))) == NULL) {
errno = EFTYPE;
goto fail;
}
if (be32toh(*magic) != MANDOCDB_MAGIC) {
warnx("dbm_map(%s): Bad final magic %x (expected %x)",
fname, be32toh(*magic), MANDOCDB_MAGIC);
errno = EFTYPE;
goto fail;
}
return 0;
fail:
save_errno = errno;
close(ifd);
errno = save_errno;
return -1;
}
void
dbm_unmap(void)
{
if (munmap(dbm_base, st.st_size) == -1)
warn("dbm_unmap: munmap");
if (close(ifd) == -1)
warn("dbm_unmap: close");
dbm_base = (char *)-1;
}
/*
* Take a raw integer as it was read from the database.
* Interpret it as an offset into the database file
* and return a pointer to that place in the file.
*/
void *
dbm_get(int32_t offset)
{
offset = be32toh(offset);
if (offset < 0 || offset >= max_offset) {
warnx("dbm_get: Database corrupt: offset %d > %d",
offset, max_offset);
return NULL;
}
return dbm_base + offset;
}
/*
* Assume the database starts with some integers.
* Assume they are numbered starting from 0, increasing.
* Get a pointer to one with the number "offset".
*/
int32_t *
dbm_getint(int32_t offset)
{
return (int32_t *)dbm_base + offset;
}
/*
* The reverse of dbm_get().
* Take pointer into the database file
* and convert it to the raw integer
* that would be used to refer to that place in the file.
*/
int32_t
dbm_addr(const void *p)
{
return htobe32((char *)p - dbm_base);
}
int
dbm_match(const struct dbm_match *match, const char *str)
{
switch (match->type) {
case DBM_EXACT:
return strcmp(str, match->str) == 0;
case DBM_SUB:
return strcasestr(str, match->str) != NULL;
case DBM_REGEX:
return regexec(match->re, str, 0, NULL, 0) == 0;
default:
abort();
}
}
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