// SPDX-License-Identifier: BSD-3-Clause
//
// DecompileAt.java - Ghidra post-script: decompile the function containing a
// given file virtual address. Version-agnostic copy of the per-version
// helper used with ghidra_decompile_at.sh.
//
// Usage:
//   analyzeHeadless <proj> <name> -process <program> -readOnly -noanalysis \
//     -postScript DecompileAt.java <hex-vaddr> [outfile]
//
// If the address does not fall inside a known function, the script tries to
// disassemble at the address; if the target is outside any function body it
// prints a comment with the nearest preceding function instead of failing.

import ghidra.app.script.GhidraScript;
import ghidra.app.decompiler.DecompInterface;
import ghidra.app.decompiler.DecompileResults;
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 java.io.FileWriter;

public class DecompileAt extends GhidraScript {
    @Override
    public void run() throws Exception {
        String[] args = getScriptArgs();
        if (args.length < 1) {
            println("usage: DecompileAt.java <hex-vaddr> [outfile]");
            return;
        }
        long fileAddr = Long.parseUnsignedLong(args[0].replaceFirst("^0x", ""), 16);
        // Arguments are FILE virtual addresses (libcuda+0x...). Ghidra may have
        // loaded the program at a non-zero image base (0x100000 in this build),
        // so translate before resolving. If image base is 0 this is a no-op.
        long imageBase = currentProgram.getImageBase().getOffset();
        Address addr = toAddr(fileAddr + imageBase);
        long target = addr.getOffset();

        Function f = getFunctionContaining(addr);
        if (f == null) {
            Listing listing = currentProgram.getListing();
            FunctionIterator it = listing.getFunctions(addr, false);
            if (it.hasNext()) f = it.next();
        }
        if (f == null) {
            disassemble(addr);
            f = createFunction(addr, null);
        }
        StringBuilder sb = new StringBuilder();
        if (f == null) {
            sb.append("// no function at 0x").append(Long.toHexString(target)).append("\n");
        } else {
            DecompInterface dif = new DecompInterface();
            dif.toggleCCode(true);
            dif.toggleSyntaxTree(true);
            dif.openProgram(currentProgram);
            DecompileResults res = dif.decompileFunction(f, 300, monitor);
            sb.append("// function ").append(f.getName())
              .append(" at libcuda+0x")
              .append(Long.toHexString(f.getEntryPoint().getOffset() - imageBase))
              .append(" (program 0x").append(Long.toHexString(f.getEntryPoint().getOffset()))
              .append(", query file 0x").append(Long.toHexString(fileAddr)).append(")\n");
            if (res != null && res.decompileCompleted()) {
                sb.append("#include <stdint.h>\n")
                  .append("typedef unsigned char undefined1;\n")
                  .append("typedef unsigned short undefined2;\n")
                  .append("typedef unsigned int undefined4;\n")
                  .append("typedef unsigned long long undefined8;\n")
                  .append("typedef long long longlong;\n")
                  .append("typedef unsigned long long ulonglong;\n\n")
                  .append(res.getDecompiledFunction().getC());
            } else {
                sb.append("// decompilation failed\n");
            }
        }
        String text = sb.toString();
        if (args.length > 1) {
            try (FileWriter w = new FileWriter(args[1])) {
                w.write(text);
            }
        }
        println(text);
    }
}