Exit Program for Open Directory (QHFOPNDR) API

Before applications can use the Open Directory (QHFOPNDR) API with your file system, you must:

1. Write an exit program that performs the open directory operation on behalf of the API. For a detailed description of the API and its calling parameters, see Open Directory (QHFOPNDR) 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 QHFOPNDR 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 (OPNDR)

INPUT; CHAR(5)

The abbreviation for the operation being performed (OPNDR).

File system job handle

INPUT; CHAR(16)

The work area or job identifier used by the file system.

Reserved

INPUT; CHAR(20)

Reserved for future use. This parameter is set to blanks.

Except as noted, the following parameters are the same as the parameters for the API.

Open directory handle

OUTPUT; CHAR(16)

Path name

INPUT; CHAR(*)

The API removes the file system name before passing the path name to the exit program.

Path name length

INPUT; BINARY(4)

Open information

INPUT; CHAR(6)

The exit program can ignore character 2, which describes the type of open operation to perform. This field is used by HFS support during job cleanup if the job ends before the file is closed.

Attribute selection table

INPUT; CHAR(*)

Length of the attribute selection table

INPUT; BINARY(4)

API Functions

The QHFOPNDR API performs the standard functions described in Standard HFS API Functions. The API does not validate the attribute selection table in any way.

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:

• Verifies that all directories in the path exist.
  
  
• If the last element of the path name is a specific name, opens that specific directory.
  
  
• If the last element of the path name is a generic name:
  
  
  • Opens the directory specified as the next-to-last element.
    
    
  • Interprets the generic name so that only directory entries that match it are available for subsequent read operations.
    
    
• Validates the attribute selection table.
  
  
• Locks the directory and its attributes according to the specified lock mode.
  
  
• Associates the attribute selection table with the open directory so that subsequent read operations using the QHFRDDR API return only the attributes selected when the directory was opened.

Error Messages for Exit Program Use

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