Call the Ghidra decompiler from the command line

GhidraDecompiler.java

// Copyright (C) 2019 Guillaume Valadon <[email protected]>
// This program is published under a GPLv2 license

/*
 * Decompile a function with Ghidra
 *
 * analyzeHeadless . Test.gpr -import $BINARY_NAME -postScript GhidraDecompiler.java $FUNCTION_ADDRESS -deleteProject -noanalysis
 *
*/

import ghidra.app.decompiler.ClangLine;
import ghidra.app.decompiler.DecompInterface;
import ghidra.app.decompiler.DecompileResults;
import ghidra.app.decompiler.DecompiledFunction;
import ghidra.app.decompiler.PrettyPrinter;
import ghidra.app.decompiler.component.DecompilerUtils;

import ghidra.app.util.headless.HeadlessScript;

import ghidra.program.model.address.Address;
import ghidra.program.model.listing.Function;
import ghidra.program.model.listing.FunctionIterator;
import ghidra.program.model.listing.Listing;
import ghidra.program.model.pcode.HighFunction;

import java.util.ArrayList;

public class GhidraDecompiler extends HeadlessScript {

  @Override
  public void run() throws Exception {

    // Stop after this headless script
    setHeadlessContinuationOption(HeadlessContinuationOption.ABORT);

    // Get the function address from the script arguments
    String[] args = getScriptArgs();
    println(String.format("Array length: %d", args.length)); // DEBUG

    if (args.length == 0) {
      System.err.println("Please specify a function address!");
      System.err.println("Note: use c0ffe instead of 0xcoffee");
      return;
    }

    int functionAddress;
    try {
      functionAddress = Integer.parseInt(args[0], 16);
    }
    catch (NumberFormatException e) {
      System.err.println(String.format("Invalid hex address: %s", args[0]));
      return;
    }
    println(String.format("Address: %x", functionAddress)); // DEBUG

    DecompInterface di = new DecompInterface();
    println("Simplification style: " + di.getSimplificationStyle()); // DEBUG
    println("Debug enables: " + di.debugEnabled());

    Function f = this.getFunction(functionAddress);
    if (f == null) {
      System.err.println(String.format("Function not found at 0x%x", functionAddress));
      return;
    }

    println(String.format("Decompiling %s() at 0x%x", f.getName(), functionAddress));

    println("Program: " + di.openProgram(f.getProgram())); // DEBUG

    // Decompile with a 5-seconds timeout
    DecompileResults dr = di.decompileFunction(f, 5, null);
    println("Decompilation completed: " + dr.decompileCompleted()); // DEBUG

    DecompiledFunction df = dr.getDecompiledFunction();
    println(df.getC());

    // Print lines prepend with addresses
    PrettyPrinter pp = new PrettyPrinter(f, dr.getCCodeMarkup());
    ArrayList<ClangLine> lines = pp.getLines();

    for (ClangLine line : lines) {
      long minAddress = Long.MAX_VALUE; 
      long maxAddress = 0; 
      for (int i = 0; i < line.getNumTokens(); i++) {
        if (line.getToken(i).getMinAddress() == null) {
          continue; 
        }
        long addr = line.getToken(i).getMinAddress().getOffset();
        minAddress = addr < minAddress ? addr : minAddress;
        maxAddress = addr > maxAddress ? addr : maxAddress;
      }
      if (maxAddress == 0) {
        println(String.format("                      - %s", line.toString()));
      } else {
        println(String.format("0x%-8x 0x%-8x - %s", minAddress, maxAddress, line.toString()));
      }
    }
  }

  protected Function getFunction(int address) {
    // Logic from https://github.com/cea-sec/Sibyl/blob/master/ext/ghidra/ExportFunction.java

    Listing listing = currentProgram.getListing();
    FunctionIterator iter = listing.getFunctions(true);
    while (iter.hasNext() && !monitor.isCancelled()) {
      Function f = iter.next();
      if (f.isExternal()) {
        continue;
      }

      Address entry = f.getEntryPoint();
      if (entry != null && entry.getOffset() == address) {
        return f;
      }
    }
    return null;
  }

}

Hello,
what kind of $FUNCTION_ADDRESS does it expect?

If I try the symbol table address of the C function the post scripts fails with NULL pointer exception ...

INFO GhidraDecompiler.java> Array length: 1 (GhidraScript) INFO GhidraDecompiler.java> Address: 8820cd0 (GhidraScript) INFO GhidraDecompiler.java> Simplification style: decompile (GhidraScript) INFO GhidraDecompiler.java> Debug enables: false (GhidraScript) ERROR REPORT SCRIPT ERROR: /app/Ghidra/ghidra_10.1.2_PUBLIC/custom/scripts/GhidraDecompiler.java : null (HeadlessAnalyzer) java.lang.NullPointerException at GhidraDecompiler.getFunction(GhidraDecompiler.java:103) at GhidraDecompiler.run(GhidraDecompiler.java:60) at ghidra.app.script.GhidraScript.executeNormal(GhidraScript.java:379) at ghidra.app.script.GhidraScript.doExecute(GhidraScript.java:234) at ghidra.app.script.GhidraScript.execute(GhidraScript.java:212) at ghidra.app.util.headless.HeadlessAnalyzer.runScript(HeadlessAnalyzer.java:576) at ghidra.app.util.headless.HeadlessAnalyzer.runScriptsList(HeadlessAnalyzer.java:909) at ghidra.app.util.headless.HeadlessAnalyzer.processWithImport(HeadlessAnalyzer.java:1778) at ghidra.app.util.headless.HeadlessAnalyzer.processLocal(HeadlessAnalyzer.java:445) at ghidra.app.util.headless.AnalyzeHeadless.launch(AnalyzeHeadless.java:121) at ghidra.GhidraLauncher.launch(GhidraLauncher.java:59) at ghidra.Ghidra.main(Ghidra.java:47)

Any ideas? Thank you