Exit Program for Read Directory Entries (QHFRDDR) API

Before applications can use the Read Directory Entries (QHFRDDR) API with your file system, you must:

1. Write an exit program that performs the read directory entries operation on behalf of the API. For a detailed description of the API and its calling parameters, see Read Directory Entries (QHFRDDR) API.
   
   
2. Give the exit program's name when you register the file system with the Register File System (QHFRGFS) API.

After that, when an application calls the QHFRDDR API, the API calls your exit program and passes it the parameters specified by the application. Your exit program performs the work and returns any data to the API. The API passes the data back to the calling application.

Authorities and Locks

None.

Required Parameter Group

The following shows the input parameters that the API passes to your exit program and the output parameter that the exit program must pass back to the API:

Operation (RDDR)

INPUT; CHAR(5)

The abbreviation for the operation being performed (RDDR).

File system job handle

INPUT; CHAR(16)

The work area or job identifier for use by the file system.

The following parameters are the same as the parameters for the API.

Open directory handle

INPUT; CHAR(16)

Data buffer

OUTPUT; CHAR(*)

Data buffer length

INPUT; BINARY(4)

Number of directory entries to read

INPUT; BINARY(4)

Number of directory entries read

OUTPUT; BINARY(4)

Length of data returned

OUTPUT; BINARY(4)

API Functions

The QHFRDDR API performs the standard functions described in Standard HFS API Functions and one additional function. The API validates the open directory handle to ensure that the directory is open and the current user profile is the user that opened it.

Exit Program Requirements

You must create an exit program that performs the standard functions described in Standard HFS Exit Program Requirements and these additional functions:

• Retrieves the directory entry information. The file system should return only attributes selected with the attribute selection table when the directory was opened. The file system must build the table and set the number of directory entries actually read and the length of data returned.
  
  
• If a requested attribute is not associated with a directory entry, returns the attribute name and the length of the attribute value, which is zero.
  
  
• Increases the directory pointer value to reflect its new position after directory entries are read.

In addition, your file system's documentation should describe the order in which directory entries are returned (for example, alphabetic or last-used date).

Error Messages for Exit Program Use

This section lists the messages that the exit program can return to the API.