Path variablizing layered system

• US 7,877,413 B1
• Filed: 01/03/2006
• Issued: 01/25/2011
• Est. Priority Date: 06/12/2002
• Status: Active Grant

• Current Assignee: CA, Inc. (d/b/a CA Technologies) (Broadcom, Inc.)
• Original Assignee: Symantec Corporation (NortonLifeLock Inc.)
• Inventors: Blaser, Jared, Cook, Randall
• Primary Examiner(s): Bullock, Jr.; Lewis A
• Assistant Examiner(s): WANG, JUE S
• Application Number:
  US11/324,572
• Time in Patent Office: 1,848 Days
• Field of Search: None
• US Class Current: 707/783
• CPC Class Codes: G06F 11/1415 at system level
• CPC Class Codes: G06F 9/545 where tasks reside in different layers, e.g. user- and kernel-space

Abstract

The inventions relate generally to layered computing systems that provide public access to the content of the layers. Also disclosed herein are prioritization schemes usable in a layered computing system, including prioritization by layer type, by assigned priority weights, by access type, by sub-layers and by read-write indicators. Processes may further be associated to layers from which they originate, and priority given to associated layers thereby. Association may also be provided for installer services, thereby depositing an applications updates into its layer. Layers may also contain file reference information including exclusion or inclusion entries indicating what files may be written thereto. Paths recorded in layers may also embed variables to true paths on a layered system. Detailed information on various example embodiments of the inventions are provided in the Detailed Description below, and the inventions are defined by the appended claims.

Claims

1. A layered computing system for accessing files in a base filesystem and a plurality of enabled layers, and to prioritize those accesses with respect to the enabled layers, the system further supporting variable indirection in object pathnames, said system comprising:

a processor;

data and program storage accessible by said processor, said storage comprising one or more data storage devices;

an operating system stored to said storage;

computer readable instructions located to said program storage, wherein said instructions are configured to be executed by said processor to perform the functions of;

(i) maintaining a set of named path variables each containing a path,

(ii) receiving from an application a request to perform a file, directory or registry operation, that request containing a path reference appropriate to a file system,

(iii) producing a set of variablized paths by evaluating the set of maintained path variables against the path reference of the request,

(iv) identifying a set of enabled layers,

(v) determining a priority for searching the enabled layers and a base filesystem,

(vi) performing a search for the file object corresponding to the file reference, the search performed in order of the determined priority, and for read requests the search is performed for layers by testing for the presence of one of the produced variablized paths for a file reference contained in the layer, the search being performed for base filesystems without referencing the variablized paths,

(vii) if, in performing the search, a file object having priority is found corresponding to the file reference in a layer, returning a virtual file handle to that virtual file object,

(viii) if, in performing the search, a file object having priority is found corresponding to the file reference in a base filesystem, returning a file handle to that base file object,

(ix) if, in performing the search, a file object is not found corresponding to the file reference, and if the request was not a write request, returning a result indicating that no file object corresponding to the file reference can be accessed, and

(x) if, in performing the search, a file object is not found corresponding to the file reference, and if the request was a write request, returning a virtual file handle or a base file handle to a new file object in the layer having priority.

2. A layered computing system according to claim 1 capable of variablizing file object paths, wherein a path reference appropriate to a file system of a request may be a path reference to a file or directory.

3. A layered computing system according to claim 1 capable of variablizing registry settings, wherein said instructions are further configured to perform the functions of:

(xi) detecting a request to set a registry entry destined for a layer,

(xii) for detected requests to set a registry entry to a layer, identifying the name of a path variable containing a path included in the value to be set in the registry entry,

(xiii) inserting the identified variable name into the value producing a variablized setting, and

(xiv) writing the variablized setting to the destination layer as a registry entry.

4. A layered computing system according to claim 1 maintaining system path variables for layers, wherein said instructions are further configured to perform the functions of:

(xi) setting path variables pertaining to the operation of the system as the system boots, and

(xii) setting a path variable to the path of a system directory.

5. A layered computing system according to claim 1 maintaining user path variables for layers, wherein said instructions are further configured to perform the functions of:

(xi) on user identification, setting path variables pertaining to the identified user,

(xii) setting a path variable to the path of a user directory, and

(xiii) on user logout, releasing the path variables pertaining to that user.

6. A layered computing system according to claim 5, wherein said instructions are further configured to perform the following functions:

(xiv) maintaining a set of user path variables for each user logged into said system,

(xv) identifying a user associated to the application requesting to perform a file, directory or registry operation, and

(xvi) when producing a set of variablized paths for a path reference of a request, applying only user paths of the user associated to the requesting process.

7. A set of non-transitory computer readable media containing computer instructions for accessing files in a base filesystem and a plurality of enabled layers, and to prioritize those accesses with respect to the enabled layers, and further to support variable indirection in object pathnames, the set of computer readable media comprising at least one medium upon which is stored the computer instructions executable by a computing system to achieve the functions of:

(i) maintaining a set of named path variables each containing a path,

(ii) receiving from an application a request to perform a file, directory or registry operation, that request containing a path reference appropriate to a file system,

(iii) producing a set of variablized paths by evaluating the set of maintained path variables against the path reference of the request,

(iv) identifying a set of enabled layers,

(v) determining a priority for searching the enabled layers and a base filesystem,

(vi) performing a search for the file object corresponding to the file reference, the search performed in order of the determined priority, and for read requests the search is performed for layers by testing for the presence of one of the produced variablized paths for a file reference contained in the layer, the search being performed for base filesystems without referencing the variablized paths,

(vii) if, in performing the search, a file object having priority is found corresponding to the file reference in a layer, returning a virtual file handle to that virtual file object,

(viii) if, in performing the search, a file object having priority is found corresponding to the file reference in a base filesystem, returning a file handle to that base file object,

(ix) if, in performing the search, a file object is not found corresponding to the file reference, and if the request was not a write request, returning a result indicating that no file object corresponding to the file reference can be accessed, and

(x) if, in performing the search, a file object is not found corresponding to the file reference, and if the request was a write request, returning a virtual file handle or a base file handle to a new file object in the layer having priority.

8. A set of non-transitory computer readable media according to claim 7 capable of variablizing file object paths, wherein a path reference appropriate to a file system of a request may be a path reference to a file or directory.

9. A set of non-transitory computer readable media according to claim 7 capable of variablizing registry settings, wherein said instructions are further configured to perform the functions of:

(xi) detecting a request to set a registry entry destined for a layer,

(xii) for detected requests to set a registry entry to a layer, identifying the name of a path variable containing a path included in the value to be set in the registry entry,

(xiii) inserting the identified variable name into the value producing a variablized setting, and

(xiv) writing the variablized setting to the destination layer as a registry entry.

10. A set of non-transitory computer readable media according to claim 7 maintaining system path variables for layers, wherein said instructions are further configured to perform the function of setting path variables pertaining to the operation of the system as the system boots.

11. A set of non-transitory computer readable media according to claim 10, wherein said instructions are further configured to set a path variable to the path of a system directory.

12. A set of non-transitory computer readable media according to claim 7 maintaining user path variables for layers, wherein said instructions are further configured to perform the functions of:

(xi) on user identification, setting path variables pertaining to the identified user, and

(xii) on user logout, releasing the path variables pertaining to that user.

13. A set of non-transitory computer readable media according to claim 12, wherein said instructions are further configured to set a path variable to the path of a user directory.

14. A method of accessing files in a base filesystem and a plurality of enabled layers, and to prioritize those accesses with respect to the enabled layers, and further to support variable indirection in object pathnames, the method comprising:

maintaining a set of named path variables each containing a path;

receiving from an application a request to perform a file, directory or registry operation, that request containing a path reference appropriate to a file system;

producing a set of variablized paths by evaluating the set of maintained path variables against the path reference of the request;

identifying a set of enabled layers;

determining a priority for searching the enabled layers and a base filesystem;

performing a search for the file object corresponding to the file reference, the search performed in order of the determined priority, and for read requests the search is performed for layers by testing for the presence of one of the produced variablized paths for a file reference contained in the layer, the search being performed for base filesystems without referencing the variablized paths;

if, in performing the search, a file object having priority is found corresponding to the file reference in a layer, returning a virtual file handle to that virtual file object;

if, in performing the search, a file object having priority is found corresponding to the file reference in a base filesystem, returning a file handle to that base file object;

if, in performing the search, a file object is not found corresponding to the file reference, and if the request was not a write request, returning a result indicating that no file object corresponding to the file reference can be accessed; and

if, in performing the search, a file object is not found corresponding to the file reference, and if the request was a write request, returning a virtual file handle or a base file handle to a new file object in the layer having priority.

15. A method according to claim 14 for variablizing file object paths, wherein a path reference appropriate to a file system of a request may be a path reference to a file or directory.

16. A method according to claim 14 for variablizing registry settings, wherein said method further comprises:

detecting a request to set a registry entry destined for a layer;

for detected requests to set a registry entry to a layer, identifying the name of a path variable containing a path included in the value to be set in the registry entry;

inserting the identified variable name into the value producing a variablized setting; and

writing the variablized setting to the destination layer as a registry entry.

17. A method according to claim 14 for maintaining system path variables for layers, said method further comprising setting path variables pertaining to the operation of the system as the system boots.

18. A method according to claim 17, further comprising setting a path variable to the path of a system directory.

19. A method according to claim 14 for maintaining user path variables for layers, said method further comprising:

on user identification, setting path variables pertaining to the identified user, including setting a path variable to the path of a user directory; and

on user logout, releasing the path variables pertaining to that user.