Analysis of the effect of program execution of calling components with data variable checkpointing and resource allocation analysis

• US 6,154,876 A
• Filed: 07/30/1997
• Issued: 11/28/2000
• Est. Priority Date: 08/10/1994
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Intrinsa Corp. (Microsoft Corporation)
• Inventors: Bush, William R., Pincus, Jonathan D., Haley, Matthew A.
• Primary Examiner(s): Hafiz, Tariq R.
• Assistant Examiner(s): INGBERG, TODD D
• Application Number:
  US08/903,512
• Time in Patent Office: 1,217 Days
• Field of Search: 395/701, 395/704, 395/500, 717/4, 717/9
• US Class Current: 717/133
• CPC Class Codes: G06F 11/366 using diagnostics G06F11/0703 takes precedence

Abstract

An error detection mechanism for detecting programming errors in a computer program. A component of the computer program, e.g., a procedure or function of the computer program, is analyzed to determine the effect of the component on resources used by the computer program. A component is analyzed by traversing the computer instructions, i.e., statements, of the component and tracking the state of resources used by the component as affected by the statements of the component. Each resource has a prescribed behavior represented by a number of states and transition between states. Violations in the prescribed behavior of a resource resulting from an emulated execution of the statements of the component are detected and reported as programming errors. Resources used by two or more components are modelled by modelling externals of the components. The effect of execution of a component on externals and resources of the component is determined by traversing one or more possible control flow paths through the component and tracking the use of each external and resource by each statement of each control flow path. Once the effect of execution of a component on externals and resources of the component is determined, a model of the component is created and used to model externals and resources of other components which invoke the modelled component.

Claims

1. A method for analyzing the effect of execution of a calling component of a computer program on an item of the calling component, the method comprising:

determining that the calling component includes a call to a called component, of which the item is an external; and

determining, from a component model which describes effects of execution of the called component on one or more externals of the called component, the effect of execution of the called component on the item, said component model specifying operations applied to said one or more externals and corresponding state changes produced in said one or more externals, wherein said component model automatically analyzes each possible control flow path through said called component

wherein determining the effect of execution of the called component on the item includes;

determining whether the item is checked for validity before being used by the called component;

determining whether the called component allocates and frees the item; and

determining a state of a resource associated with the item.

2. The method of claim 1 wherein the item has a state;

and

further wherein the step of determining the effect of execution of the called component on the item comprises determining a change in the state of the item prescribed by the called component.

3. The method of claim 2 wherein the called component prescribes a change in the state of the item by specifying one or more operations to be applied to the state of the item.

4. The method of claim 2 further comprising:

determining that the called component prescribes a transition in the state of the item from a valid state to an invalid state.

5. The method of claim 2 further comprising:

determining that the called component prescribes a transition in the state of the item other than a transition from a first valid state to a second valid state.