Method and apparatus for modifying relocatable object code files and monitoring programs

• US 6,618,824 B1
• Filed: 11/04/1999
• Issued: 09/09/2003
• Est. Priority Date: 06/21/1991
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: Rational Software Limited (International Business Machines Corporation)
• Inventors: Hastings, Reed
• Primary Examiner(s): Baderman, Scott T.
• Application Number:
  US09/434,203
• Time in Patent Office: 1,405 Days
• Field of Search: 714/35, 717/162, 717/124, 712/226, 709/315, 709/331, 709/332
• US Class Current: 714/35
• CPC Class Codes: G06F 11/3624 by performing operations on the source code, e.g. via a compiler
• CPC Class Codes: G06F 11/3636 by tracing the execution of the program
• CPC Class Codes: G06F 11/3644 by instrumenting at runtime
• CPC Class Codes: G06F 8/447 Target code generation
• CPC Class Codes: G06F 8/54 Link editing before load time
• CPC Class Codes: G06F 8/71 Version control security arrangements therefor G06F21/57; Configuration management
• CPC Class Codes: G06F 9/44521 Dynamic linking or loading; Link editing at or after load time, e.g. Java class loading

Abstract

An object code expansion program inserts new instructions and data between preexisting instructions and date of an object code file; offsets are modified to reflect new positions of the preexisting instructions and data. For each item of preexisting object code (instructions or data), the following steps are performed: making a new code block comprising any desired new instructions and the item, and storing it as new object code; tracking the location of the item and the new code block within the new object code; and tracking items that contain inter-item offsets. Then, each inter-item offset is updated using the new location of the item or new code block, as required. Finally, offsets in symbol tables and relocation structures are updated with the new location of the item.

Claims

1. A computer program product stored on a computer readable medium that stores computer codes for equipping a computer program with an interceptor function for being executed in place of an intercepted function, said computer program having a plurality of object code files including a first object code file containing a definition of said intercepted function and a second object code file including a first structure identifying said intercepted function definition by an original intercepted function name, said computer program product comprising:

computer code that modifies said first structure to identify said intercepted function definition by a modified intercepted function name, whereby a modified second object code file is produced;

computer code that provides a third object code file containing a definition of said interceptor function and a second structure identifying said interceptor function definition by said original intercepted function name; and

computer code that links at least said modified first object code file, said second object code file and said third object code file to produce a modified computer program whereby a first call causes execution of said interceptor function.

2. The computer program product for equipping a computer program with an interceptor function for being executed in place of an intercepted function as recited in claim 1, further including computer code that examines said plurality of object code files to identify said first object code file, and wherein said computer code that modifies said second object code file is responsive to said computer code that examines said plurality of object code files.

3. The computer program product for equipping a computer program with an interceptor function for being executed in place of an intercepted function as recited in claim 1, wherein said computer code that modifies said first structure comprises computer code that transforms at least one character of said original intercepted function name.

4. The computer program product for equipping a computer program with an interceptor function for being executed in place of an intercepted function as recited in claim 3, wherein said computer code that modifies said first structure comprises computer code that changes case of at least one character of said original intercepted function name.

5. The computer program product for equipping a computer program with an interceptor function for being executed in place of an intercepted function as recited in claim 1, wherein said computer code that provides a third object code file containing a definition of said interceptor function comprises a call from said interceptor function to a function identified by said modified intercepted function name, whereby execution of said interceptor function results in execution of said intercepted function.