Last modified: 26 April 2016
Name: H5Pget_efile_prefix
Signature:
  `ssize_t H5Pget_efile_prefix( hid_t dapl_id, const char *prefix, size_t size )`
Purpose:
  Retrieves the prefix for external raw data storage files as set in the dataset access property list.
Description:
  `H5Pget_efile_prefix` retrieves the file system path prefix for locating external files associated with a dataset that uses external storage. This will be the value set with `H5Pset_efile_prefix` or the HDF5 Library’s default.

  The value of `size` is the size in bytes of the prefix, including the `NULL` terminator. If the size is unknown, a preliminary `H5Pget_elink_prefix` call with the pointer `prefix` set to `NULL` will return the size of the prefix without the `NULL` terminator.

  The `prefix` buffer must be allocated by the caller. In a call that retrieves the actual prefix, that buffer must be of the size specified in `size`.

Note:
  See `H5Pset_efile_prefix` for a more complete description of file location behavior and for notes on the use of the `HDF5_EXTFILE_PREFIX` environment variable.
Parameters:

  `hid_t dapl_id` | `` | IN: Dataset access property list identifier
  `const char *prefix` | `` | IN/OUT: Dataset external storage prefix in UTF-8 or ASCII (Path and filename must be ASCII on Windows systems.)
  `size_t size` | `` | IN: Size of prefix buffer in bytes

Returns:
  Returns the size of `prefix` and the prefix string will be stored in `prefix` if successful.
  Otherwise returns a negative value and the contents of `prefix` will be undefined.
Fortran Interface:
  None
See Also:

`H5Pset_efile_prefix` `H5Pset_external`

History:

  Release | Change
  1.10.0 and 1.8.17 | C function introduced in these releases.