diff options
Diffstat (limited to 'dbm_map.c')
| -rw-r--r-- | dbm_map.c | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/dbm_map.c b/dbm_map.c new file mode 100644 index 00000000..8d24832d --- /dev/null +++ b/dbm_map.c @@ -0,0 +1,174 @@ +/* $Id$ */ +/* + * 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(); + } +} |