# db_env_set_func_read

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    #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 function with func_read, which must conform to the standard interface.

The db_env_set_func_read interface affects the entire application, not a single database or database environment.

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

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

# Errors

The db_env_set_func_read function 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 function 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 function may fail and return DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.

# See Also

db_env_set_func_close, db_env_set_func_dirfree, db_env_set_func_dirlist, db_env_set_func_exists, db_env_set_func_free, db_env_set_func_fsync, db_env_set_func_ioinfo, db_env_set_func_malloc, db_env_set_func_map, db_env_set_func_open, db_env_set_func_read, db_env_set_func_realloc, db_env_set_func_seek, db_env_set_func_sleep, db_env_set_func_unlink, db_env_set_func_unmap, db_env_set_func_write, and db_env_set_func_yield.`

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