# db_env_set_func_unmap

`

###

    #include <db.h>

    int
    db_env_set_func_unmap(int (*func_unmap)(void *addr, size_t len));

# Description

The Berkeley DB library requires the ability to unmap a file or shared memory region from memory. The func_unmap argument must conform to the following interface:

>     int unmap(void *addr, size_t len);

The addr argument is the argument returned by the db_env_set_func_map function when the file or region was mapped into memory, and the len argument is the same as the len argument specified to the db_env_set_func_map function when the file or region was mapped into memory.

The func_unmap function must return the value of errno on failure and 0 on success.

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

While the db_env_set_func_unmap 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_unmap function returns a non-zero error value on failure and 0 on success.

# Errors

EINVAL
  An invalid flag value or parameter was specified.

# 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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