Class: SeccompTools::Asm::Compiler

Inherits:
Object
  • Object
show all
Defined in:
lib/seccomp-tools/asm/compiler.rb

Overview

Compile seccomp rules.

Instance Method Summary collapse

Constructor Details

#initialize(arch) ⇒ Compiler

Instantiate a SeccompTools::Asm::Compiler object.

Parameters:

  • arch (Symbol) —

    Architecture.



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# File 'lib/seccomp-tools/asm/compiler.rb', line 17

def initialize(arch)
  @arch = arch
  @insts = []
  @labels = {}
  @insts_linenum = {}
  @input = []
end

Instance Method Details

#compile! ⇒ Array<SeccompTools::BPF>

Compiles the processed instructions.

Returns:

Raises:

  • (ArgumentError) —

    Raises the error found during compilation.



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# File 'lib/seccomp-tools/asm/compiler.rb', line 66

def compile!
  @insts.map.with_index do |inst, idx|
    @line = idx
    case inst.first
    when :assign then compile_assign(inst[1], inst[2])
    when :alu then compile_alu(inst[1], inst[2])
    when :ret then compile_ret(inst[1])
    when :cmp then compile_cmp(inst[1], inst[2], inst[3], inst[4])
    when :jmp_abs then compile_jmp_abs(inst[1])
    end
  end
rescue ArgumentError => e
  invalid(@insts_linenum[@line], e.message)
end

#process(line) ⇒ void

This method returns an undefined value.

Before compile assembly codes, process each lines.

With this we can support label in seccomp rules.

Parameters:

  • line (String) —

    One line of seccomp rule.



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# File 'lib/seccomp-tools/asm/compiler.rb', line 31

def process(line)
  @input << line.strip
  line = remove_comment(line)
  @token = Tokenizer.new(line)
  return if line.empty?

  begin
    res = case line
          when /\?/ then cmp
          when /^#{Tokenizer::LABEL_REGEXP}:/ then define_label
          when /^return/ then ret
          when /^A\s*=\s*-A/ then alu_neg
          when /^(A|X)\s*=[^=]/ then assign
          when /^mem\[\d+\]\s*=\s*(A|X)/ then store
          when /^A\s*.{1,2}=/ then alu
          when /^(goto|jmp|jump)/ then jmp_abs
          end
  rescue ArgumentError => e
    invalid(@input.size - 1, e.message)
  end
  invalid(@input.size - 1) if res.nil?
  if res.first == :label
    @labels[res.last] = @insts.size
  else
    @insts << res
    @insts_linenum[@insts.size - 1] = @input.size - 1
  end
end