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TDB_FIRSTKEY

TDB_FIRSTKEY

Section: Linux Programmer's Manual (3) Updated: Aug 16, 2000
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NAME

tdb_firstkey - return the key of the first record in a tdb database tdb_nextkey - return the key of next record in the tdb database  

SYNOPSIS

#include <tdb.h>

TDB_DATA tdb_firstkey(TDB_CONTEXT *tdb);
TDB_DATA tdb_nextkey(TDB_CONTEXT *tdb, TDB_DATA prev_key);

 

DESCRIPTION

tdb_firstkey fetches the key of the first entry in the tdb database. tdb_nextkey fetches the key of the entry immediately after prev_key in the database.

The TDB_DATA structure returned by both these functions is defined as:

typedef struct {
        char *dptr;
        size_t dsize;
} TDB_DATA;

The order in which this traverses the database is its own internal hash order. Do not expect the keys to be in any recognizably sorted order.

These functions are reliable even if other writers are accessing the database (or you are replacing or deleting elements as you traverse), except in the case of nested tdb_firstkey or tdb_nextkey calls. For example, the following outer traversal may fail to traverse all the elements, or may even traverse elements twice if other processes are manipulating the database:

        TDB_DATA i, j;

        for (i = tdb_firstkey(tdb); i.dptr; i = tdb_nextkey(tdb, i)) {
                for (j = tdb_firstkey(tdb); j.dptr; j = tdb_nextkey(tdb, j)) {
                ...
                }
        }

If such behaviour is desired, use tdb_traverse instead.

 

RETURN VALUE

If the call succeeds, then a TDB_DATA structure is returned with the dptr structure filled in. If the call fails or you have reached the end of the database then dptr will be set to NULL.

NOTE: The caller is responsible for freeing the data pointed to by dptr  

AUTHORS

Software: Andrew Tridgell <tridge@linuxcare.com> and Luke Kenneth Casson Leighton Man page: Ben Woodard <ben@valinux.com>  

SEE ALSO

gdbm(3), tdb(3)


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
AUTHORS
SEE ALSO

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Time: 21:57:06 GMT, April 16, 2011