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Improved Static Resolution of Dynamic Class Loading in Java

Improved Static Resolution of Dynamic Class Loading in Java . Jason Sawin, Atanas Rountev Ohio State University Work supported by NSF. Dynamic Class Loading. Dynamic Class Loading Ability to install classes at run time . String className = “foo.bar.clazz”; .....

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Improved Static Resolution of Dynamic Class Loading in Java

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  1. Improved Static Resolution of Dynamic Class Loading in Java Jason Sawin, Atanas Rountev Ohio State University Work supported by NSF

  2. Dynamic Class Loading • Dynamic Class Loading • Ability to install classes at run time String className = “foo.bar.clazz”; ..... Class c = Class.forName(className); Object h = c.newInstance(); .....

  3. Class Loading and Static Analysis • In the general case it is impossible to statically determine the affects of dynamic class loading • Static Analysis Approaches • Ignore it • Overly conservative • Query the user • Utilize casting information • String analysis

  4. Problems with Modern Approaches • Problem: string analysis only considers purely static string values • Many uses of dynamic class loading will rely on string values which are not hard coded into applications • Insight: hybrid (static/dynamic) analysis can increase information being considered • Increases precision • Loss of global soundness • Problem: state-of-the-art string analysis is not powerful enough to precisely model all language features • Insight: generalization can be made to improve the precision of string analysis

  5. Hybrid Generalization • Extended Java String Analyzer (JSA) • During the static string analysis, dynamically gather information about the values of system environment variables • Inject this information at environment variable entry points • System.getProperty(String propName) • Utilize JSA to resolve propName

  6. Increasing the Precision of JSA • Field Generalization: JSA provides no treatment for fields • We provide a context-insensitive treatment for certain fields • Type Generalization: String is a subclass of Object • Use type inferencing analysis to determine objects of static type Object which are actually objects of type String • Needed for the up and down casting of objects between String and Object

  7. Study of Java 1.4 Libraries

  8. Summary of Initial Study • Our approach increases by a factor of 2.6 the ability of a state-of-the-art string analysis to resolve instances of dynamic class loading • Results are sound for the values of environment variables observed at analysis time • Gathering environment information maybe a useful technique for a wide range of static analyses

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