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Explanation Of Exclusive And Nonexclusive File Status On Open |
The information in this document applies to:
WordPerfect® 5.1 for DOS
Problem
When a document is retrieved into two document screens from a local drive in either WordPerfect 5.0, WordPerfect 5.1, or WordPerfect for Windows, both copies will be retrieved or opened as Read-Write (exclusive) unless SHARE.EXE is loaded. In another scenario, if a document is retrieved from a network drive, without SHARE loaded, the second copy will open as Read-Only (nonexclusive). This occurs if the program is run from either the local or network drive, and with or without the /NT-# switch making the program network-aware. This seems to be an inconsistency in the program. |
Answer:
The situations described above are normal. This is how the program works. WPCorp word processing programs rely on the operating system to determine how to display a file once it has been opened by a user. |
Details:
If the file is already in use, the lock on the file is nonexclusive (Read-Only). If the file is not in use, then the user retrieving the file has an exclusive lock (Read-Write). WP makes a DOS call on Interrupt 21h Function 3d to open a file as Read-Write (exclusive). If DOS returns 02h, the user will have the file in Read-Write (exclusive) status. If 002 is returned, the file is Read-Only (nonexclusive). NOTE: DOS will return 002 on files opened from local drives unless SHARE is loaded. SHARE.EXE was introduced with DOS 4.0 for optional file-sharing and file-locking routines for networking. It allows use of partitions greater than 32M. Some network operating systems, e.g., Artisoft's LANtastic network, require SHARE, which is used to lock files. Other applications like Borland's Paradox program also use SHARE. Once SHARE is installed, DOS will use the code loaded by SHARE to validate all Read and Write requests from any program. When network drives are present, some of the calls DOS makes are on or to network drives. In this case WP relies on the network operating system to initiate these Read/Write/Open requests. One of the criteria that a Network Operating System has to meet in order to be considered "supported" by WPCorp is that it has file-locking capabilities. |
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