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DBM(3) FreeBSD Library Functions Manual DBM(3)
NAME
dbm_clearerr, dbm_close, dbm_delete, dbm_dirfno, dbm_error, dbm_fetch,
dbm_firstkey, dbm_nextkey, dbm_open, dbm_store - database access
functions
SYNOPSIS
#include <fcntl.h>
#include <ndbm.h>
DBM *
dbm_open(const char *base, int flags, mode_t mode);
void
dbm_close(DBM *db);
int
dbm_store(DBM *db, datum key, datum data, int flags);
datum
dbm_fetch(DBM *db, datum key);
int
dbm_delete(DBM *db, datum key);
datum
dbm_firstkey(DBM *db);
datum
dbm_nextkey(DBM *db);
int
dbm_error(DBM *db);
int
dbm_clearerr(DBM *db);
int
dbm_dirfno(DBM *db);
DESCRIPTION
Database access functions. These functions are implemented using
dbopen(3) with a hash(3) database.
datum is declared in <ndbm.h>:
typedef struct {
void *dptr;
int dsize;
} datum;
The dbm_open(base, flags, mode) function opens or creates a database.
The base argument is the basename of the file containing the database;
the actual database has a .db suffix. I.e., if base is
"/home/me/mystuff" then the actual database is in the file
/home/me/mystuff.db. The flags and mode arguments are passed to open(2).
(O_RDWR | O_CREAT) is a typical value for flags; 0660 is a typical value
for mode. O_WRONLY is not allowed in flags. The pointer returned by
in the database. The flags argument is either DBM_INSERT or DBM_REPLACE.
If flags is DBM_INSERT and the database already contains an entry for
key, that entry is not replaced. Otherwise the entry is replaced or
inserted. The dbm_store() function normally returns zero but returns 1
if the entry could not be inserted (because flags is DBM_INSERT, and an
entry with key already exists) or returns -1 and sets errno if there were
any errors.
The dbm_fetch(db, key) function returns NULL or the data corresponding to
key.
The dbm_delete(db, key) function deletes the entry for key. The
dbm_delete() function normally returns zero or returns -1 and sets errno
if there were any errors.
The dbm_firstkey(db) function returns the first key in the database. The
dbm_nextkey(db) function returns subsequent keys. The db_firstkey()
function must be called before dbm_nextkey(). The order in which keys
are returned is unspecified and may appear random. The dbm_nextkey()
function returns NULL after all keys have been returned.
The dbm_error(db) function returns the errno value of the most recent
error. The dbm_clearerr(db) function resets this value to 0 and returns
0.
The dbm_dirfno(db) function returns the file descriptor to the database.
SEE ALSO
open(2), dbopen(3), hash(3)
STANDARDS
These functions (except dbm_dirfno()) are included in the Version 2 of
the Single UNIX Specification ("SUSv2").
HISTORY
The functions dbminit(), fetch(), store(), delete(), firstkey(), and
nextkey() first appeared in Version 7 AT&T UNIX.
FreeBSD 14.0-RELEASE-p11 April 2, 2022 FreeBSD 14.0-RELEASE-p11