DESCRIPTION
Database access functions. These functions are implemented using dbopen(3) with a hash(3) database.
.Vt datum is declared in
.In ndbm.h :
typedef struct {
char *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 dbm_open identifies the database and is the db argument to the other functions. The dbm_open function returns NULL and sets errno if there were any errors.
The dbm_close db function closes the database. The dbm_close function normally returns zero.
The dbm_store db key data flags function inserts or replaces an entry 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 but returns 1 if there was no entry with key in the database 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
