We can define Java semantics with the abstract machine ! The preprocessed program is a valid Java program, which uses a subset of the features of Java. A Simple Semantics and Static Analysis for Java Security Anindya Banerjee and David A. Naumann Stevens Institute of Technology, CS Report 2001-1 July 5, 2001 Abstract: Security in Java depends on an access control mechanism speci ed operationally in terms of … A static method M of class C is called like this C.M(A) and if within scope the M found in the definition of C is invoked with arguments A passed by value. [1] For compiled languages, static semantics essentially include those semantic rules that can be checked at compile time. We say that a method msig throws more speci_c exceptions in A than in B, if for each class E occurring in the throws clause of msig in A there exists a class F in the throws clause of msig in B such that E _h F. K-Java, the rst complete semantics of Java 1.4 Comprehensive test suite of 840 tests Completeness assessment of ASM-Java and JavaFAN using tests Application TLL model-checking of multithreaded programs Denis Bogd na³ , Grigore Ro³u ( University of Ia³i, University of Illinois at Urbana-Champaign) K-Java January 16, 2015 5 / 32 We are also aware of other related work, e.g. nitions – a static semantics and a dynamic semantics. –Differs from C in that it has a static semantics rule that disallows the implicit execution of more than one segment –Each selectable segment must end with an unconditional branch (goto or break) –Also, in C# the control expression and the case constants can be strings Specification. The output of the static semantics is a preprocessed Java program, which is passed as input to the dynamic semantics for execution. Java Virtual Machine implementation version which may be interpreted as a Runtime.Version: java.vm.vendor: Java Virtual Machine implementation vendor: java.vm.name: Java Virtual Machine implementation name: java.specification.version: Java Runtime Environment specification version, whose value is the feature element of the runtime version Static and Dynamic Semantics Syntax concerns the form of a valid program, while semantics concerns its meaning Static semantic The classes Ei must be subclasses of Throwable, i.e., Ei _h Throwable. Unit 1 syntax and symatics.docx - Discussion Unit 1 Explain what is meant by the syntax and the semantics of a programming language Give Java examples. A Simple Semantics and Static Analysis for Java Security Anindya Banerjee a;1 a Stevens Institute of Technology, Hoboken, NJ 07030 USA David A. Naumann b;2 b Stevens Institute of Technology, Hoboken, NJ 07030 USA Abstract Security in Java depends on an access control mechanism specied operationally in terms of run-time stack inspection. In your case, it is your collection instance that is read-only, not the class itself, so the function must be non-static. This thoroughly cross-reviewed state-of-the-art survey is devoted to the study of the syntax and semantics of Java from a formal-methods point of view. Nevertheless, it is a fully functional high-level programming language that can provide users with a wide range of functionality and versatility. Static modifier nFields that don’t belong to objects nClass and interface fields nState extension: – Class/interface entries – References l Runtime checks l Class or interface v.s. Method Summary Type: asType() If THIS is an entity that denotes a Type, the denoted type; otherwise null. The semantics is applied to model-check multi-threaded programs. –E.g., in After the function has been called, a and b return to their former values (unchanged!) One method of describing a static semantics is an attribute grammar which it is designed by Knuth in the year 1968a. Static is not about accessing the member fields or not. After static semantics checking succeeds, the AST is transformed once again, in the mini-java.code-gen namespace, this time into valid JVM bytecode. –in Java: K-Java was extensively tested with a test suite developed alongside the project, following the Test Driven Development methodology. Example 2 (on the next page) shows a simple class that represents a Person, declared and implemented as separate header (.h) and implementation (.cc) files in C++, and the corresponding single file required for Java. •C++ and Java use static scoping: –mapping from uses to declarations is made at compile time. the Alves-Foss book on Java semantics [7] and Diehl’s formalization of Java compilation [6] , … Instead, analyses expect their users to provide customization for web applications, which is a significant burden, virtually never overcome in practice. Static is really about class methods, for factories or utility functions. Parameter passing ! The semantics is applied to model-check multi-threaded programs. Dynamic •The term static used to indicate properties that the compiler can determine without considering any particular execution. precisely what the Java language does ! java.lang.String t sb tb “hello” java.lang.String “he” java.lang.StringBuffer s1 t1 “hello” java.lang.String “hello” cs205: engineering software 15 Java Semantics Question public class Strings {public static void test {String s = new String ("hello"); String t = new String … De_nition . public class Semantics extends Object. A Java interpreter of simple expressions A Java translator of simple expressions to Lisp Note: These slides cover Chapter 4 of the textbook upto and including Section 4.3 Static and Dynamic Semantics Syntax concerns the form of a valid program, while semantics concerns its meaning Static semantic rules are enforced by a compiler at compile time You are to implement a semantic or contextual analyser that checks that the program conforms to the source language’s context-sensitive constraints (i.e., static semantics) according to the VC Language Definition.This part of the compilation process is referred to as the semantic or contextual analysis. Syntatically valid structure does not imply it to be semantically valid. Sets the value of a variable to the newValue, with memory semantics of setting as if the variable was declared non-volatile and non-final.Commonly referred to as plain write access. For a complete semantics of Java we recommend the book ! Security in Java depends on an access control mechanism specified operationally in terms of run-time stack inspection. The preprocessed program is a valid Java program, which uses a subset of the features of Java. The output of the static semantics is a preprocessed Java program, which is passed as input to the dynamic semantics for execution. We give two examples to show how to give the semantics of Java concepts ! Java, undoubtedly, has its roots in embedded systems and the Web. The pre-processed program is a valid Java program, which uses a subset of the features of Java. In programming language theory, semantics is the field concerned with the rigorous mathematical study of the meaning of programming languages.It does so by evaluating the meaning of syntactically valid strings defined by a specific programming language, showing the computation involved. Static attributes in classes ! In order to maintain clarity while handling the great size of Java, the semantics was split into two separate definitions - A static semantics and a dynamic semantics. Most (but not all) of the semantics is straightforward ! The output of the static semantics is a preprocessed Java program, which is passed as input to the dynamic semantics for execution. •Static semantic analysis –Produces “decorated tree” with additional information attached –Detects & eliminates remaining static errors 10/6/06 Prof. Hilfinger, CS164 Lecture 15 11 Static vs. COMP3131/9102 – Assignment 4: Static Semantics (or Contextual Analysis) 1. Attribute grammar is a formal approach of static semantics for checking and describing the correctness of semantic rules in a program. For example, the sentence "egg reads books" is a valid sentence but it makes no sense. Valid Java .class files are output at the end of this process, which can be run using java. Static Semantics "static" here means "at compile time", as opposed to "dynamic", which means "at run time" in the context of an interpreted language, substitute "at definition time" and "at evaluation time" "semantics" here has little to do with meaning, … value semantics: variables are copied whenever they are assigned, passed as parameters, or returned.. Java uses value semantics for all primitive types (String, double, int, etc)reference semantics: variables actually store the address of another object in memory . The method signature is of the form (CT1 ct1, ..., CTn ctn, T newValue)void. This process was aided by the use of the robust ASM 5 library. If a method applies to instances of the class, it must not be static. This class defines names for certain data attributes that are commonly used within Cytoscape. –C++ uses the "most closely nested" rule •a use of variable x matches the declaration with the most closely enclosing scope. •a deeply nested variable x hides x declared in an outer region. A Java interpreter of simple expressions A Java translator of simple expressions to Lisp Note: Study Chapter 4 of the textbook upto and including Section 4.3. The Java Programming Language: Fundamental Syntax and Semantics This is a long document, for a single web page (about a dozen printed pages). Static Semantics • A global variable is a variable that can be used any where in a program • A local variable is only available within the block where it is declaredwhere it is declared • A block is a program construct that includes local declarations • An activation of a block is the time interval that the block is executed / Faculteit Wiskunde en Informatica 28-9-2011PAGE 12 The semantics is applied to model-check multi-threaded programs. Thus while our work concerns the dynamic semantics of Java bytecode, their work concerns its static semantics. The term syntax referes to grammatical structure whereas the term semantics refers to its meaning. Here is the list of the top 10 Static Code Analysis Tools for Java, C++, C# and Python: ... Apart from finding semantics and syntax error, this tool also lets users detect vulnerabilities in the code. In order that it not be any longer, it contains a number of links pointing to other pages where the more detailed information that would otherwise have to appear at that point can be found. It is about class semantics. Examples include checking that every identifier is declared before it is used (in languages that require… A static method of class C, invoked inside class C's definition can be written 'M(A)' and have the same effect. The constants defined here are provided to enable different modules to use the same name when referring to the same conceptual attribute. This tool is well integrated with many common IDE’s like Eclipse, Visual Studio, and Intellij IDEA. Sections 4.4 to 4.6 are not required. number of classes), and specifies that it is using namespace std, while the Java program imports java.io.*. Let A and B be classes or interfaces. The static semantics defines restrictions on the structure of valid texts that are hard or impossible to express in standard syntactic formalisms. Popular static analysis frameworks for Java provide no support for the lifecycle or injected semantics of enterprise applications. object Semantics …