Parsing and Validating File Designators

The FPARSE intrinsic parses and validates a file designator string to determine if it is syntactically correct. You can employ this intrinsic to check a formal file designator representing a file before attempting to open the file with HPFOPEN/FOPEN. MPE/iX file designators used for the file system and two user interface commands include a remote environment ID (envid). This allows the user to indicate that a file is to be accessed from a remote environment established by the user with the DSLINE or REMOTE HELLO command. FPARSE facilitates the changes required for the file designator extension. It provides the only location within MPE/iX where file designators are parsed and syntax is checked.

The following are examples of the items and the vectors array pair. The order of entries in the vectors array corresponds to the order of items in the items array. Each 32-bit entry in the vectors array returns the byte offset of the item in the first half-word, and the length in bytes of the item in the second half-word. However, the last entry of the vectors array has a different meaning from that of the other entries: the second half-word gives the total length of the file string, and the first half-word gives a system file code when applicable.

In Figure 3-3 “Illustration of FPARSE Usage” the file string is "FILENAME/LOCKWORD.GROUP.ACCOUNT:ANIMAL.INDDCL.HPBCG":

Figure 3-3 Illustration of FPARSE Usage

The items array, as illustrated above, can be listed in any order or can be left unspecified if not required.

In Figure 3-4 “Illustration of FPARSE Usage”, below, the file string is "*FILENAME:ANIMAL":

Figure 3-4 Illustration of FPARSE Usage

In Figure 3-5 “Illustration of FPARSE Usage”, below, the file string is "$OLDPASS":

Figure 3-5 Illustration of FPARSE Usage

Note that "$" is a special exception to the rules of file names and is considered part of the file name, unlike "*", which is not.