# DbEnv::log_file

`

###

    #include <db_cxx.h>

    int
    DbEnv::log_file(const DbLsn *lsn, char *namep, size_t len);

# Description

The DbEnv::log_file method maps DbLsn objects to file names, copying the name of the file containing the record named by lsn into the memory location referenced by namep.

The len argument is the length of the namep buffer in bytes. If namep is too short to hold the file name, DbEnv::log_file will return ENOMEM. (Log file names are normally quite short, on the order of 10 characters.)

This mapping of DbLsn objects to files is needed for database administration. For example, a transaction manager typically records the earliest DbLsn needed for restart, and the database administrator may want to archive log files to tape when they contain only DbLsn entries before the earliest one needed for restart.

The DbEnv::log_file method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success.

# Errors

The DbEnv::log_file method may fail and throw an exception or return a non-zero error for the following conditions:

ENOMEM
  The supplied buffer was too small to hold the log file name.

The DbEnv::log_file method may fail and throw an exception or return a non-zero error for errors specified for other Berkeley DB and C library or system methods. If a catastrophic error has occurred, the DbEnv::log_file method may fail and either return DB_RUNRECOVERY or throw an exception encapsulating DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.

### Class

DbEnv

# See Also

DbEnv::set_lg_bsize, DbEnv::set_lg_max, DbEnv::log_archive, DbEnv::log_compare, DbEnv::log_file, DbEnv::log_flush, DbEnv::log_get, DbEnv::log_put, DbEnv::log_register, DbEnv::log_stat and DbEnv::log_unregister.`

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