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Forcing the Write of DOS File Access Buffers

IP.com Disclosure Number: IPCOM000038846D
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Nyfeler, JA: AUTHOR

Abstract

A method is described for dynamically writing information in any personal computer (PC) disk operating system (DOS) file access buffer. As an application executes, it may have multiple files open and employed. Reads and writes to the files are handled by employing access buffers for each file. An access buffer may be written to several times before it physically sends the information to the actual device. This can be a problem if the precise status of the device is requested. For example, if an exact file size is requested of a file already open and under the control of an application, it is very likely the size will not reflect any changes made to it since it was opened when the program commenced operation. One way to insure that the DOS file access buffers were written out to disk is to close and reopen each file.

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Forcing the Write of DOS File Access Buffers

A method is described for dynamically writing information in any personal computer (PC) disk operating system (DOS) file access buffer. As an application executes, it may have multiple files open and employed. Reads and writes to the files are handled by employing access buffers for each file. An access buffer may be written to several times before it physically sends the information to the actual device. This can be a problem if the precise status of the device is requested. For example, if an exact file size is requested of a file already open and under the control of an application, it is very likely the size will not reflect any changes made to it since it was opened when the program commenced operation. One way to insure that the DOS file access buffers were written out to disk is to close and reopen each file. This would fix the problem, but significant operating system overhead would be incurred. A better approach is to use the DOS function calls "Find First" and "Find Next". Whenever these function calls are invoked, DOS writes out any information that is still in the buffers. The system overhead is minimal as only the information in the buffers is involved and no reopening of the file must take place. The advantage of this method is that little system resource is involved to insure the integrity of the information. The application can be sure that the file access buffers have been transferred to the physical m...