Emulated read-write disk drive using a protected medium
First Claim
1. A method of emulating a computer storage device having read and write capabilities using a protected media having read-only access, comprising:
- providing a computer storage device image file on said protected media, said image file including at least one file having a file access attribute;
providing a written disk sector database;
intercepting file access requests from the operating system of said computer; and
for write requests to read-write files, directing the write data to said written disk sector database;
for read requests to files, providing data from said written disk sector database if said file has previously been written, and providing data from a corresponding file on said protected media if said file has not previously been written; and
for write requests, delete requests, or requests to change file access attributes to read-only files, failing said requests.
1 Assignment
0 Petitions
Accused Products
Abstract
A read-write hard disk drive is emulated using a hard disk drive image file on a protected medium such as a CD-ROM, a written disk sector database, and file system filters. A file system filter intercepts file I/O requests from the operating system. Initial read requests are serviced from the hard disk drive image file. Write operations are directed to a database, such as in RAM. Subsequent read requests for previously written data are serviced from the database. Another file system filter monitors attempts to alter the file access attributes, and prevents pre-existing read-only files on the emulated drive from being written or deleted. The maximum size of the written disk sector database is the sum of sectors on the hard disk drive image file allocated to read-write files and free space. The emulated read-write hard disk drive allows for the execution of programs requiring a read-write native media.
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Citations
15 Claims
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1. A method of emulating a computer storage device having read and write capabilities using a protected media having read-only access, comprising:
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providing a computer storage device image file on said protected media, said image file including at least one file having a file access attribute;
providing a written disk sector database;
intercepting file access requests from the operating system of said computer; and
for write requests to read-write files, directing the write data to said written disk sector database;
for read requests to files, providing data from said written disk sector database if said file has previously been written, and providing data from a corresponding file on said protected media if said file has not previously been written; and
for write requests, delete requests, or requests to change file access attributes to read-only files, failing said requests. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An emulated mass storage device for a computer, comprising:
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a computer storage device image file on a protected medium operative to supply data from read-only files, data from the initial state of read-write files, and free space for said emulated mass storage device; and
a written disk sector database operative to store data written to read-write files and free space on said emulated mass storage device, and operative to supply data previously written to read-write files on said emulated mass storage device, said written disk sector database constrained in size to the total number of sectors allocated to read-write files and free space on said computer storage device image file, without reallocating any storage among said sectors. - View Dependent Claims (8, 9, 10, 11)
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12. A computer, comprising:
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an operating system; and
an emulated mass storage device comprising;
a computer storage device image file on a protected medium, said image file including data organized into a plurality of files, each file having an access attribute;
a fixed-size, non-reallocating written disk sector database operative to store data written to said emulated mass storage device; and
a file system filter operative to intercept file access requests from said operating system and to service said requests via said written disk sector database and said computer storage device image file, said file system filter enforcing said access attributes by failing requests to write, delete, or change the access attributes of read-only files. - View Dependent Claims (13, 14, 15)
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Specification