# db_env_set_func_read

`

###

    #include <db.h>

    int
    db_env_set_func_read(ssize_t (*func_read)(int fd, void *buf, size_t nbytes));

# Description

Replace Berkeley DB calls to the IEEE/ANSI Std 1003.1 (POSIX) read interface with func_read, which must conform to the standard interface.

The db_env_set_func_read method configures all operations performed by a process and all of its threads of control, not operations confined to a single database environment.

Although the db_env_set_func_read interface may be called at any time during the life of the application, it should normally be called before making calls to the db_env_create or db_create methods.

The db_env_set_func_read method returns a non-zero error value on failure and 0 on success.

# Errors

The db_env_set_func_read method may fail and return a non-zero error for the following conditions:

EINVAL
  An invalid flag value or parameter was specified.

The db_env_set_func_read method may fail and return a non-zero error for errors specified for other Berkeley DB and C library or system functions. If a catastrophic error has occurred, the db_env_set_func_read method may fail and return DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.

# See Also

Run-time configuration`

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