Data processing: software development – installation – and managem – Software program development tool – Translation of code
Reexamination Certificate
1998-09-24
2001-02-20
Powell, Mark R. (Department: 2762)
Data processing: software development, installation, and managem
Software program development tool
Translation of code
C717S152000, C714S038110, C709S241000, C713S152000
Reexamination Certificate
active
06192512
ABSTRACT:
FIELD OF THE INVENTION
This invention is generally directed to computer software and, in particular, to a class of computer programs known as interpreters.
BACKGROUND OF THE INVENTION
As data processing systems become more powerful, more complex, and more highly interconnected, interpreted languages of various kinds are growing in importance. In non-interpreted languages, source programs are converted into the machine language for some particular CPU, and then stored, transmitted and executed in machine-language form. Computer programs that perform this function are typically referred to as compilers.
However, when using a computer program known as an interpreter the source programs are stored, transmitted and executed in a higher-level language. The interpreter is required at execution time to read the source program and carry out the instructions that it contains.
Interpreted languages tend to execute slower than other types of languages. That is, an interpreted source program may execute more slowly than the same source program that has been previously compiled into the machine code of the host CPU. However, the use of interpreters provides several advantages, including an ability to execute the same program on many different CPUs and operating systems (as long as each CPU and operating system has an interpreter for the language).
Interpreters are often embedded inside application program subsystems. For example, one widely used word processing program contains an interpreter for a specific language in which the word processor macros are written. The LotusNotes™ product contains an interpreter for LotusScript™, one of the languages in which LotusNotes™ macros are written. Also, several Web browsers contain interpreters for Java™, a language in which programs of various kinds are written, and made available on the World Wide Web (WWW). In many cases, these application program subsystems include application programming interfaces (APIs) which allow other programs to interact with the application program subsystem. One common feature offered by many APIs is the ability for an external program to access, create and execute programs written in the application program subsystem's interpreted language.
There are various types of programs, including anti-virus programs and general security programs, which may need to examine interpreted programs designed for application program subsystems. For a variety of purposes, such an external program may need to determine at least a subset of the actions that a given interpreted-language program would take, if it were to be executed by the interpreter contained in some application subsystem. Since existing APIs do not provide powerful features to allow this determination, designers of these external programs are faced with the choice of either implementing at least a subset of the interpreters themselves, or not supporting detailed examination of programs written for these interpreters. The former course of action is difficult, as implementing an interpreter for a powerful macro language can be costly and time-consuming, and it is not easy to ensure that the implemented interpreter actually behaves as the real one would in all relevant cases. The latter course of action is dangerous, as it may lead to exposure to viruses or security attacks.
SUMMARY OF THE INVENTION
This invention is directed to software interpreters. Specifically, the teachings of this invention are directed to providing a software interpreter within an application subsystem, and includes a virtualized interface to external programs for the evaluation of their behavior within the subsystem.
For security, virus detection and other purposes, external programs may need to determine what a given program would do if executed under a given interpreter. With the proliferation of complex interpreted languages, it may not be feasible for each of these external programs to contain its own implementations of each interpreter. On the other hand, application programming interfaces (APIs) known in the art only allow external programs to request the interpreter to execute a program, and not to determine what the program would do it were to be executed. The present invention solves this problem by providing an interpreter with an API allowing access to a virtualized mode of the interpreter.
In a first aspect this invention provides a computer subsystem having an interpreter that supports one or more programming languages. The computer subsystem includes an application programming interface (API) through which an external program may request simulated execution of a given program, written in one of the supported languages, in a specific simulated environment. The computer subsystem may thus simulate execution of the given program that is passed to it, and return to the external program one or more indications of what actions the given program would have taken had it actually run in the application program subsystem environment.
A method is also provided for predicting the actions of a given program within an application program subsystem having an interpreter. The method includes steps of: (a) receiving an API call for prediction; (b) initializing a virtual environment based on a real environment; (c) initializing application state information; (d) interpreting instructions of the given program; and (e) altering the application state information and the virtual environment in response to the interpreting step.
A method is disclosed for exercising a macro with an application program subsystem, having a macro interpreter, so as to detect a presence of potential viral activity. The method includes the steps of: (a) making an API call with a program, the API call identifying the macro and specifying an initial virtual environment within which the macro is to be interpreted; (b) interpreting in turn individual instructions of the macro; (c) altering the virtual environment in response to interpreted instructions; and (d) notifying the program upon the occurrence of an alteration to the virtual environment that triggers a predetermined notification criterion. The step of notifying the program can also take place upon the occurrence of the interpretation of the macro triggering a predetermined termination criterion. The API call may further specify an initial virtual application state within which the macro is to be interpreted.
In accordance with a further aspect of this invention there is provided a system and a method for executing a macro with a data processing system. The method includes a first step of generating an application program interface (API) call for interpreting a macro of interest in a virtual environment so as to execute all or a part of the macro of interest in the virtual environment. The step of generating includes a step of defining the virtual environment, wherein the virtual environment is defined at least in part through the use of at least one callback function that is invoked upon an occurrence of a virtual execution of the macro satisfying a predetermined callback function invocation criterion. The step of generating further includes a step of initializing state information. A next step of the method interprets in turn individual instructions of the macro, and alters at least one of the state information and the virtual environment in response to interpreted instructions.
The predetermined callback function invocation criterion can be, by example, an interpreted macro instruction attempting to perform file I/O, or attempting to access memory, or attempting to access a predetermined portion of a mass memory device.
The virtual environment includes simulated physical and logical devices that are either all present as real physical and logical devices in the data processing system, or that are not all present as real physical and logical devices in the data processing system.
REFERENCES:
patent: 5440723 (1995-08-01), Arnold et al.
patent: 5452442 (1995-09-01), Kephart
patent: 5475843 (1995-12-01), Halviatti et al.
patent: 5485575 (1996-01-01), Chess et al.
patent:
Booker Kelvin E.
IBM Corporation
International Business Machines - Corporation
Ohlandt Greeley Ruggiero & Perle L.L.P.
Powell Mark R.
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