Class: Cfg2asm::CFG::Disassembler

Inherits:
Object
  • Object
show all
Defined in:
lib/cfg2asm/cfg/disassembler.rb

Overview

Disassemble and print comments from cfg files

Instance Method Summary collapse

Constructor Details

#initialize(out) ⇒ Disassembler

Returns a new instance of Disassembler.



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# File 'lib/cfg2asm/cfg/disassembler.rb', line 7

def initialize(out)
  @out = out
end

Instance Method Details

#disassemble(nmethod, print_comments) ⇒ Object 



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# File 'lib/cfg2asm/cfg/disassembler.rb', line 11

def disassemble(nmethod, print_comments)
  require_crabstone

  comments = nmethod.comments
  comments_n = 0

  case [nmethod.code.arch, nmethod.code.arch_width]
  when %w[AMD64 64]
    crabstone_arch = [Crabstone::ARCH_X86, Crabstone::MODE_64]
  when %w[aarch64 64]
    crabstone_arch = [Crabstone::ARCH_ARM64, Crabstone::MODE_ARM]
  else
    raise "Unknown architecture #{nmethod.code.arch} and bit width #{nmethod.code.arch_width}"
  end

  cs = Crabstone::Disassembler.new(*crabstone_arch)
  begin
    cs.disasm(nmethod.code.code, nmethod.code.base).each do |i|
      if print_comments
        # Print comments associated to the instruction.
        last_comment = i.address + i.bytes.length - nmethod.code.base
        while comments_n < comments.length && comments[comments_n].offset < last_comment
          if comments[comments_n].offset == -1
            @out.printf("\t\t\t\t;%<comment>s\n", comment: comments[comments_n].comment)
          else
            @out.printf(
              "\t\t\t\t;Comment %<loc>i:\t%<comment>s\n",
              loc: comments[comments_n].offset,
              comment: comments[comments_n].comment
            )
          end
          comments_n += 1
        end
      end

      # Print the instruction.
      @out.printf(
        "\t0x%<address>x:\t%<instruction>s\t%<details>s\n",
        address: i.address,
        instruction: i.mnemonic,
        details: i.op_str
      )
    end
  rescue StandardError => e
    raise "Disassembly error: #{e.message}"
  ensure
    cs.close
  end
end

#require_crabstone ⇒ Object 



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# File 'lib/cfg2asm/cfg/disassembler.rb', line 61

def require_crabstone
  require 'crabstone'
rescue LoadError => e
  if $DEBUG
    raise e
  else
    raise 'Could not load Capstone - is it installed?'
  end
end