Class: ElfUtils::Section::DebugInfo::Die

Inherits:
Object
  • Object
show all
Defined in:
lib/elf_utils/section/debug_info/die.rb

Defined Under Namespace

Classes: Base

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(cu:, offset:, tag:, children:, abbrev:, attrs: nil, buf: nil) ⇒ Die

Returns a new instance of Die.



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# File 'lib/elf_utils/section/debug_info/die.rb', line 5

def initialize(cu:, offset:, tag:, children:, abbrev:, attrs: nil, buf: nil)
  @cu = cu
  @offset = offset
  @tag = tag
  @children = children ? [] : false
  @abbrev = abbrev
  @unpacked_attrs = attrs
  @buf = buf
end

Instance Attribute Details

#abbrev ⇒ Object (readonly)

Returns the value of attribute abbrev.



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# File 'lib/elf_utils/section/debug_info/die.rb', line 14

def abbrev
  @abbrev
end

#cu ⇒ Object (readonly)

Returns the value of attribute cu.



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# File 'lib/elf_utils/section/debug_info/die.rb', line 14

def cu
  @cu
end

#offset ⇒ Object (readonly)

Returns the value of attribute offset.



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# File 'lib/elf_utils/section/debug_info/die.rb', line 14

def offset
  @offset
end

#tag ⇒ Object (readonly)

Returns the value of attribute tag.



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# File 'lib/elf_utils/section/debug_info/die.rb', line 14

def tag
  @tag
end

Instance Method Details

#[](name) ⇒ Object 



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# File 'lib/elf_utils/section/debug_info/die.rb', line 89

def [](name)
  @attrs ||= parse_attrs
  @attrs[name]
end

#[]=(name, value) ⇒ Object 



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# File 'lib/elf_utils/section/debug_info/die.rb', line 94

def []=(name, value)
  @attrs ||= parse_attrs
  @attrs[name] = value
end

#add_child(child) ⇒ Object

Raises:



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# File 'lib/elf_utils/section/debug_info/die.rb', line 65

def add_child(child)
  raise Error, "This DIE cannot have children" unless @children
  @children << child
  self
end

#addr_ranges ⇒ Object 



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# File 'lib/elf_utils/section/debug_info/die.rb', line 112

def addr_ranges
  @attrs ||= parse_attrs
  @addr_ranges ||=
    if (low = @attrs[:low_pc]) && (high = @attrs[:high_pc])
      [low..(high - 1)]
    elsif @attrs[:ranges]
      @cu.file.section(".debug_ranges")
        .get(offset: @attrs[:ranges], base: @attrs[:low] || 0)
    end
end

#attrs ⇒ Object 



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# File 'lib/elf_utils/section/debug_info/die.rb', line 99

def attrs
  @attrs ||= parse_attrs
  @attrs.keys
end

#children ⇒ Object 



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# File 'lib/elf_utils/section/debug_info/die.rb', line 57

def children
  @children || []
end

#children? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/elf_utils/section/debug_info/die.rb', line 53

def children?
  @children != false
end

#ctype ⇒ Object 



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# File 'lib/elf_utils/section/debug_info/die.rb', line 226

def ctype
  return unless type?
  return @ctype if @ctype

  @attrs ||= parse_attrs

  @ctype = case tag
  when :base_type
    signed = !@attrs[:encoding].to_s.include?("unsigned")
    int_type(size: @attrs[:byte_size], signed:)
  when :typedef
    @attrs[:type].ctype
  when :const_type, :volatile_type
    # const void has no equivalent ctype... maybe empty struct?
    @attrs[:type]&.ctype
  when :pointer_type, :subroutine_type
    @cu.addr_type
  when :array_type
    # subrange_len may return nil for variable-length arrays
    sizes = children
      .select { |c| c.tag == :subrange_type }
      .map { |c| c.subrange_len }

    # if we have a signed char array, we'll use a string to hold it
    inner_type = @attrs[:type].ctype
    if inner_type.is_a?(CTypes::Int) &&
        inner_type.size == 1 &&
        inner_type.signed?
      inner_type = CTypes::String.new(size: sizes.pop)
    end

    sizes.reverse_each do |size|
      inner_type = CTypes::Array.new(type: inner_type, size:)
    end

    inner_type
  when :structure_type
    offset = 0
    struct = CTypes::Struct.builder
      .name(self[:name])
      .endian(@endian ||= @cu.file.endian)
    bitfield = nil

    (@children || []).each do |child|
      next unless child.tag == :member

      name = child[:name]&.to_sym
      type = child[:type].ctype
      loc = child[:data_member_location] || 0
      if loc.is_a?(Types::Dwarf::Expression)
        child[:data_member_location] = loc =
          loc.evaluate(addr_type: @cu.addr_type)[0]
      end
      delta = loc - offset

      # add any bitfield if we're moving past it
      if bitfield && delta >= 0
        struct.attribute bitfield.build
        bitfield = nil
      end

      # handle any padding we need to do
      struct.pad delta if delta > 0

      # check for v2, v3 bitfield
      if (bits = child[:bit_size]) && (bit_offset = child[:bit_offset])
        bitfield ||= CTypes::Bitfield.builder.endian(@endian)

        # convert the left-hand offset to a right-hand offset when we're
        # on a little-endian system
        if CTypes.host_endian == :little
          bit_offset = child[:byte_size] * 8 - bit_offset - bits
        end

        bitfield.field(name,
          offset: bit_offset,
          bits: bits,
          signed: type.signed?)

      # v4, v5 bitfield
      elsif (bits = child[:bit_size]) &&
          (bit_offset = child[:data_bit_offset])

        bitfield ||= CTypes::Bitfield.builder.endian(@endian)

        # If the endian of the type doesn't match the host-endian, we
        # need to flip the offset
        if @endian != CTypes.host_endian
          bit_offset = self[:byte_size] * 8 - bit_offset - bits
        end

        bitfield.field(name,
          offset: bit_offset,
          bits: bits,
          signed: type.signed?)

      # not a bitfield
      elsif name.nil?
        # handle unnamed field
        struct.attribute type

        # must be a named field
      else
        struct.attribute name, type
      end
      offset = loc + type.size
    end

    # if there's tail padding to fit a specific alignment, add it here
    tail = self[:byte_size] - offset
    struct.pad(tail) if tail > 0

    # ensure we include the bitfield if it was the last element
    struct.attribute(bitfield.build) if bitfield

    struct.build
  when :union_type
    union = CTypes::Union.builder
      .name(self[:name])
      .endian(@endian ||= @cu.file.endian)
    (@children || []).each do |child|
      next unless child.tag == :member

      name = child[:name]
      type = child[:type].ctype
      if name
        union.member name.to_sym, type
      else
        union.member type
      end
    end

    union.build
  when :enumeration_type
    type = int_type(size: @attrs[:byte_size], signed: false)

    values = {}
    @children.each do |child|
      values[child[:name].downcase.to_sym] = child[:const_value]
    end

    CTypes::Enum.new(type.with_endian(@cu.file.endian), values)
  when :subrange_type
    return
  else
    raise Error, "unsupported DIE: %p" % [self]
  end
end

#has_addr?(addr) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/elf_utils/section/debug_info/die.rb', line 123

def has_addr?(addr)
  case tag
  when :subprogram
    addr_ranges&.any? { |r| r.include?(addr) }
  when :variable
    type = self[:type].ctype
    [location...location + type.size]
  else
    false
  end
end

#has_attr?(attr) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/elf_utils/section/debug_info/die.rb', line 61

def has_attr?(attr)
  @attrs ? @attrs.has_key?(attr) : @abbrev.attrs.has_key?(attr)
end

#location ⇒ Object

return the value of DW_AT_location



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# File 'lib/elf_utils/section/debug_info/die.rb', line 166

def location
  value = self[:location]

  if value.is_a?(Types::Dwarf::Expression)
    value = value.evaluate(addr_type: cu.addr_type, stack: [])[-1]
  end
  value
end

#pretty_print(q) ⇒ Object 



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# File 'lib/elf_utils/section/debug_info/die.rb', line 16

def pretty_print(q)
  q.group(4,
    "<%p 0x%08x: DW_TAG_%s (%d children)" %
      [self.class, @offset, @tag, @children ? @children.size : 0],
    ">") do
    q.text("\n" + " " * q.indent)
    q.group_sub do
      attrs = if @attrs
        @attrs.map do |name, value|
          ["DW_AT_%-15s  " % [name], value]
        end
      elsif @unpacked_attrs
        @unpacked_attrs.map do |name, form, value|
          ["DW_AT_%-15s  [DW_FORM_%s] " % [name, form], value]
        end
      end

      if attrs
        q.seplist(attrs) do |label, value|
          q.group(4, label) do
            case value
            when self.class
              q.text("<%p 0x%08x: DW_TAG_%s ...>" %
                     [self.class, value.offset, value.tag])
            else
              q.pp(value)
            end
          end
        end
      else
        q.group(1, "abbrev=") { q.pp(@abbrev) }
      end
    end
  end
end

#raw_attr(key) ⇒ Object

get the unprocessed value for an attribute

Raises:



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# File 'lib/elf_utils/section/debug_info/die.rb', line 105

def raw_attr(key)
  unpacked_attrs.each do |name, _, value|
    return value if name == key
  end
  raise Error, "no attribute %p found in DIE: %p" % [key, self]
end

#subrange_len ⇒ Object

return the number of elements in the subrange



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# File 'lib/elf_utils/section/debug_info/die.rb', line 136

def subrange_len
  @attrs ||= parse_attrs

  raise "not a subrange DIE: %p" % [self] unless @tag == :subrange_type
  count = @attrs[:count]
  case count
  when Integer
    return count
  when Section::DebugInfo::Die
    # return a size of nil for variable-length array
    return nil if count.tag == :variable
    raise ElfUtils::Error, "unexpected DIE type in subrange[:count]: %p" %
      [count] 
  when nil
    # fall through when there is no count attribute
  else
    raise ElfUtils::Error, "unexpected value in subrange[:count]: %p" %
      [count]
  end

  # upper bound may be DW_TAG_variable, so special handling
  if (upper_bound = @attrs[:upper_bound])
    return @attrs[:upper_bound] + 1 if upper_bound.is_a?(Integer)
  end

  # XXX we'll need to do some work to support flexible array members
  0
end

#type? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/elf_utils/section/debug_info/die.rb', line 71

def type?
  @is_a_type ||= case @tag
  when :base_type,
        :typedef,
        :volatile_type,
        :const_type,
        :pointer_type,
        :array_type,
        :union_type,
        :enumeration_type,
        :structure_type,
        :subroutine_type
    true
  else
    false
  end
end

#type_name ⇒ Object 



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# File 'lib/elf_utils/section/debug_info/die.rb', line 175

def type_name
  return nil unless type?

  @type_name ||= begin
    @attrs ||= parse_attrs

    case @tag
    when :base_type, :typedef
      @attrs[:name]
    when :volatile_type
      "volatile #{@attrs[:type]&.type_name || "void"}"
    when :const_type
      "const #{@attrs[:type]&.type_name || "void"}"
    when :array_type
      buf = "#{@attrs[:type]&.type_name}"
      sizes = children.each do |child|
          next unless child.tag == :subrange_type

          # subrange_len may return nil for variable-length arrays
          len = child.subrange_len
          if len
            buf << "[%d]" % len
          else
            buf << "[]"
          end
        end
      buf
    when :pointer_type
      inner = @attrs[:type]&.type_name || "void"
      if inner.end_with?("*")
        "#{inner}*"
      else
        "#{inner} *"
      end
    when :structure_type
      name = @attrs[:name] || ("anon_%x" % @offset)
      "struct #{name}"
    when :union_type
      name = @attrs[:name] || ("anon_%x" % @offset)
      "union #{name}"
    when :enumeration_type
      name = @attrs[:name] || ("anon_%x" % @offset)
      "enum #{name}"
    when :subrange_type, :subroutine_type
      return
    else
      raise Error, "unsupported DIE: %p" % [self]
    end
  end
end