Browse Prior Art Database

Inter-Threaded Protected File for Multi-Operational Personal Computers

IP.com Disclosure Number: IPCOM000113858D
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 75K

Publishing Venue

IBM

Related People

Christopher, K: AUTHOR [+2]

Abstract

Described is a software implementation that provides inter-threaded protected file handles within the scope of a multi-threaded task in a multi-tasking operating systems, as used in Personal Computers (PCs) running OS/2*. The implementation utilizes a digital signature concept to insure the validity of requests of operating system software.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Inter-Threaded Protected File for Multi-Operational Personal Computers

      Described is a software implementation that provides
inter-threaded protected file handles within the scope of a
multi-threaded task in a multi-tasking operating systems, as used in
Personal Computers (PCs) running OS/2*.  The implementation utilizes
a digital signature concept to insure the validity of requests of
operating system software.

      In prior art, a sub-system whose threads do a file Input/Output
(I/O) within the same task as the application can be susceptible to
file path corruption due to errors in the application thread.  Also,
corruption can occur while performing a file I/O with file handles
which are no longer owned by the sub-system.

      The concept described herein provides a means of protection so
as to eliminate file path corruption due to errors in the application
thread.  For example, in certain applications, when the user makes an
"open file" request by way of a DOS protection open, a 32-bit random
number, called a file handle lock ID, is returned.  On subsequent
file handle-based file system functions, the user is required to
return the file system lock identification (ID) received from the
"open-file" request.  Only upon successful verification of the file
handle lock ID on the DOS protect write is the write request allowed
to be performed.

      Protection is provided from the applications (API) using the
current unprotected API because they logically pass in a file handle
lock ID of zero.  This is then compared against the system's copy of
a lock ID for the respective file handle.  The implementation allows
for a subsystem to open a file, or gain access to any system resource
that will be manipulated through a process global handle, and to
protect the resource from other code running within the same process.
It is associated with a unique signature value that is assoc...