Chapter 7 File Manager Functions
fNotFound	The file could not be found.
fNoPerm	Access denied (file/directory/disk is locked/protected).
fIsOpen	File is open or directory is not empty.
fIOErr	Unspecified I/O error occurred.

Locking a File Range

FLockOrUnlockRange

syntax	MgErr	FLockOrUnlockRange(fd, mode, offset,
		count, lock);

FLockOrUnlockRange locks or unlocks a section of a file.

Parameter	Type	Description
fd	File	File descriptor associated with the file.
mode	int32	Position in the file relative to which
		FLockOrUnlockRange determines the first byte
		to lock or unlock.
		If mode is fStart, the first byte to lock or unlock
		is located offset bytes from the start of the file
		(offset must be greater than or equal to 0).
		If mode is fCurrent, the first byte to lock or
		unlock is located offset bytes from the current
		position mark (offset can be positive, 0, or
		negative).
		If mode is fEnd, the first byte to lock or unlock is
		located offset bytes from the end of the file (offset
		must be less that or equal to 0).
offset	int32	The position of the first byte to lock or unlock. The
		position is the number of bytes from the beginning
		of the file, the current position mark, or the end of
		the file, as determined by mode.
count	int32	Number of bytes to lock or unlock starting at the
		location specified by mode and offset.
lock	Bool32	A boolean that specifies whether
		FLockOrUnlockRange locks or unlocks a range
		of bytes. If lock is TRUE this functions locks a
		range; if FALSE the function unlocks a range.

National Instruments Corporation

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LabVIEW Code Interface Reference Manual