Chapter 7 File Manager Functions

Path Data Type

The file manager defines the Path data type for use in describing paths to files and directories. The data structure for the Path data type is private. You use file manager routines to create and manipulate

Paths.

Permissions

The file manager uses the int32 data type to describe permissions for files and directories. The manager uses only the least significant nine bits of the int32.

On a UNIX computer, the nine bits of permissions correspond exactly to nine UNIX permission bits governing read, write, and execute permissions for user, group, and others. Permission bits on a UNIX system are represented in the following illustration.

	user group others
permission	} } }
	r w x r w x r w x

bit 31 8 7 6 5 4 3 2 1 0

r - read permission w - write permission

x - execute permission

On the PC, permissions are ignored for directories. For files, only bit 7 (the UNIX user write permission bit) is used. If this bit is clear, the file is read-only. Otherwise, you can write to the file.

On the Macintosh, all nine bits are used for directories (folders). The bits which control read, write, and execute permissions, respectively, on a UNIX system are used to control See Files, Make Changes, and See Folders access rights, respectively, on the Macintosh. For files, only bit 7 (the UNIX user write permission bit) is used. If this bit is clear, the file is locked. Otherwise, the file is not locked.

Volume Information Record

The volume information record is:

National Instruments Corporation

7-3

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