FGyama

FGyama, or Flow Graph yama is a static source code analyzer that extracts an interprocedural dataflow graph from Java source code. It's designed to be scalable so that it can be applied to a large code base.

What It Does

Input

public class Hello {
    public static void main(String[] args) {
        String name = args[0];
        System.out.println("Hello, "+name);
    }
}

Output (SVG)

Output (XML)

<?xml version="1.0" encoding="UTF-8"?><fgyama>
  <class extends="Ljava/lang/Object;" name="LHello;" path="/home/euske/work/r/fgyama/tests/Hello.java">
    <method id="LHello;.&lt;clinit&gt;()V" name="&lt;clinit&gt;" style="initializer">
      <ast end="141" start="0" type="55"/>
      <scope name="LHello;.&lt;clinit&gt;"/>
    </method>
    <method id="LHello;.main([Ljava/lang/String;)V" name="main" style="static">
      <ast end="139" start="25" type="31"/>
      <scope name="LHello;.:main:25:139">
        <node id="M2_main_N1" kind="input" ref="#arg0" type="[Ljava/lang/String;">
          <ast end="62" start="49" type="44"/>
        </node>
        <node id="M2_main_N2" kind="assign_var" ref="$LHello;.:main:25:139/$args" type="[Ljava/lang/String;">
          <ast end="62" start="49" type="44"/>
          <accept src="M2_main_N1"/>
        </node>
        <node id="M2_main_N3" kind="input" ref="#this" type="LHello;"/>
        <node id="M2_main_N4" kind="input" ref="%Ljava/lang/String;" type="Ljava/lang/String;"/>
        <node id="M2_main_N5" kind="input" ref="@Ljava/lang/System;/.out" type="Ljava/io/PrintStream;"/>
        <scope name="LHello;.:main:25:139.:B:64:139">
          <node id="M2_main_N6" kind="ref_var" ref="$LHello;.:main:25:139/$args" type="[Ljava/lang/String;">
            <ast end="85" start="81" type="42"/>
            <accept src="M2_main_N2"/>
          </node>
          <node data="0" id="M2_main_N7" kind="value" type="I">
            <ast end="87" start="86" type="34"/>
          </node>
          <node id="M2_main_N8" kind="ref_array" ref="%Ljava/lang/String;" type="Ljava/lang/String;">
            <ast end="88" start="81" type="2"/>
            <accept label="array" src="M2_main_N6"/>
            <accept label="index" src="M2_main_N7"/>
            <accept src="M2_main_N4"/>
          </node>
          <node id="M2_main_N9" kind="assign_var" ref="$LHello;.:main:25:139.:B:64:139/$name" type="Ljava/lang/String;">
            <ast end="88" start="74" type="59"/>
            <accept src="M2_main_N8"/>
          </node>
          <node id="M2_main_N10" kind="ref_field" ref="@Ljava/lang/System;/.out" type="Ljava/io/PrintStream;">
            <ast end="108" start="98" type="40"/>
            <accept src="M2_main_N5"/>
          </node>
          <node data="Hello, " id="M2_main_N11" kind="value" type="Ljava/lang/String;">
            <ast end="126" start="117" type="45"/>
          </node>
          <node id="M2_main_N12" kind="ref_var" ref="$LHello;.:main:25:139.:B:64:139/$name" type="Ljava/lang/String;">
            <ast end="131" start="127" type="42"/>
            <accept src="M2_main_N9"/>
          </node>
          <node data="+" id="M2_main_N13" kind="op_infix" type="Ljava/lang/String;">
            <ast end="131" start="117" type="27"/>
            <accept label="L" src="M2_main_N11"/>
            <accept label="R" src="M2_main_N12"/>
          </node>
          <node data="Ljava/io/PrintStream;.println(Ljava/lang/String;)V" id="M2_main_N14" kind="call" type="V">
            <ast end="132" start="98" type="32"/>
            <accept label="#this" src="M2_main_N10"/>
            <accept label="#arg0" src="M2_main_N13"/>
          </node>
          <node id="M2_main_N15" kind="receive" type="V">
            <ast end="132" start="98" type="32"/>
            <accept src="M2_main_N14"/>
          </node>
        </scope>
      </scope>
    </method>
  </class>
</fgyama>

Node types (kinds):

Basic Operations

Kind	Data	Input(s)
value	Actual value
valueset	Value count	value0, value1, ...
op_assign	Assignment operator	L, R
op_prefix	Prefix operator	(default)
op_infix	Infix operator	L, R
op_postfix	Postfix operator	(default)
op_typecast	Casting type	(default)
op_typecheck	Checking type	(default)
op_iter		(default)
ref_var		(default)
ref_array		(default), array, index
ref_field		(default), obj
assign_var		(default)
assign_array		(default), array, index
assign_field		(default), obj

Function Call

Kind	Data	Input(s)
call	Method IDs	@type, #arg0, ..., #bypass, .field, %type
new	Method ID	@type, #arg0, ..., #bypass, .field, %type
input
output		(default)
return		(default)
receive		(default), Fields
throw		!type
catch		exc0, ...
catchjoin		!type

Control Flow

Kind	Data	Input(s)
join		cond, true, false
begin	Loop ID	init, cont
end	Loop ID	(default), cond, _repeat
repeat	Loop ID	(default), _end
case	Label count	(default), match0, ...

How to Build

Prerequisites

• Java/Maven
• Eclipse JDT (automatically downloaded)
• Graphviz http://graphviz.org/

Compiling

$ mvn clean package

Testing

$ mvn exec:java -Dexec.args="./tests/Hello.java" > Hello.graph
or
$ ./tools/java2df.sh ./tests/Hello.java > Hello.graph
then
$ python tools/graph2gv.py Hello.graph | dot -Tsvg > Hello.svg

How to Use

XmlExporter exporter = new XmlExporter(System.out);
Java2DF converter = new Java2DF();
converter.loadDefaults();       // Load the standard classes.
converter.loadJarFile("path/to/my.jar");        // Add a jar.
converter.addSourceFile("path/to/Hello.java");  // Add a source code.
// Perform analysis for every user-defined class.
for (DFSourceKlass klass : converter.getSourceKlasses()) {
    converter.analyzeKlass(exporter, klass);
}
exporter.close();

Options

• -v: increases verbosity.
• -i filelist: takes a filename list.
• -o output: specifies the output file.
• -C classpath: add a jar file / directory to the classpath.
• -S: strict mode. (stops at a first error)
• -F: pretty printing XML.

Development

Coding style

(c-add-style "me"
         '("Java"
           (c-offsets-alist . (
                               (arglist-cont . c-lineup-argcont)
                               (arglist-intro . +)
                               ))
           ))

TODOs

• Handle consecutive SwitchCases.
• Correct local scope handling.
• Java language spec.: https://docs.oracle.com/javase/specs/
• Moar unittests.