Class: MachO::MachOFile

Inherits:
Object
  • Object
show all
Defined in:
lib/macho/file.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(filename) ⇒ MachOFile

Returns a new instance of MachOFile.

Raises:

  • (ArgumentError) 


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# File 'lib/macho/file.rb', line 5

def initialize(filename)
  raise ArgumentError.new("filename must be a String") unless filename.is_a? String

  @filename = filename
  @raw_data = open(@filename, "rb") { |f| f.read }
  @header = get_mach_header
  @load_commands = get_load_commands
end

Instance Attribute Details

#header ⇒ Object (readonly)

Returns the value of attribute header.



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# File 'lib/macho/file.rb', line 3

def header
  @header
end

#load_commands ⇒ Object (readonly)

Returns the value of attribute load_commands.



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# File 'lib/macho/file.rb', line 3

def load_commands
  @load_commands
end

Instance Method Details

#bundle? ⇒ Boolean

is the file a dynamically bound bundle?

Returns:

  • (Boolean) 


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# File 'lib/macho/file.rb', line 33

def bundle?
  header[:filetype] == MH_BUNDLE
end

#command(name) ⇒ Object Also known as: []

get load commands by name



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# File 'lib/macho/file.rb', line 77

def command(name)
  load_commands.select { |lc| lc.to_s == name }
end

#cpusubtype ⇒ Object

string representation of the header’s cpusubtype field



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# File 'lib/macho/file.rb', line 57

def cpusubtype
  CPU_SUBTYPES[header[:cpusubtype]]
end

#cputype ⇒ Object

string representation of the header’s cputype field



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# File 'lib/macho/file.rb', line 52

def cputype
  CPU_TYPES[header[:cputype]]
end

#dylib? ⇒ Boolean

is the file a dynamically bound shared object?

Returns:

  • (Boolean) 


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# File 'lib/macho/file.rb', line 28

def dylib?
  header[:filetype] == MH_DYLIB
end

#dylib_id ⇒ Object

get the file’s dylib id, if it is a dylib



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# File 'lib/macho/file.rb', line 93

def dylib_id
  if !dylib?
    return nil
  end

  dylib_id_cmd = command('LC_ID_DYLIB').first

  cmdsize = dylib_id_cmd.cmdsize
  offset = dylib_id_cmd.offset
  stroffset = dylib_id_cmd.name

  dylib_id = @raw_data.slice(offset + stroffset...offset + cmdsize).unpack("Z*").first

  dylib_id.delete("\x00")
end

#dylib_id=(new_id) ⇒ Object 



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# File 'lib/macho/file.rb', line 109

def dylib_id=(new_id)
  if !new_id.is_a?(String)
    raise ArgumentError.new("argument must be a String")
  end

  if !dylib?
    return nil
  end

  if magic32?
    cmd_round = 4
  else
    cmd_round = 8
  end

  new_sizeofcmds = header[:sizeofcmds]
  dylib_id_cmd = command('LC_ID_DYLIB').first
  old_id = dylib_id
  new_id = new_id.dup

  new_pad = Utils.round(new_id.size, cmd_round) - new_id.size
  old_pad = Utils.round(old_id.size, cmd_round) - old_id.size

  # pad the old and new IDs with null bytes to meet command bounds
  old_id << "\x00" * old_pad
  new_id << "\x00" * new_pad

  # calculate the new size of the DylibCommand and sizeofcmds in MH
  new_size = DylibCommand.bytesize + new_id.size
  new_sizeofcmds += new_size - dylib_id_cmd.cmdsize

  # calculate the low file offset (offset to first section data)
  low_fileoff = 2**64 # ULLONGMAX

  segments.each do |seg|
    sections(seg).each do |sect|
      if sect.size != 0 && !sect.flag?(S_ZEROFILL) &&
          !sect.flag?(S_THREAD_LOCAL_ZEROFILL) &&
          sect.offset < low_fileoff

        low_fileoff = sect.offset
      end
    end
  end

  if new_sizeofcmds + header.bytesize > low_fileoff
    raise HeaderPadError.new(@filename)
  end

  # update sizeofcmds in mach_header
  set_sizeofcmds(new_sizeofcmds)

  # update cmdsize in the dylib_command
  @raw_data[dylib_id_cmd.offset + 4, 4] = [new_size].pack("V")

  # delete the old id
  @raw_data.slice!(dylib_id_cmd.offset + dylib_id_cmd.name...dylib_id_cmd.offset + dylib_id_cmd.class.bytesize + old_id.size)

  # insert the new id
  @raw_data.insert(dylib_id_cmd.offset + dylib_id_cmd.name, new_id)

  # pad/unpad after new_sizeofcmds until offsets are corrected
  null_pad = old_id.size - new_id.size

  if null_pad < 0
    @raw_data.slice!(new_sizeofcmds + header.bytesize, null_pad.abs)
  else
    @raw_data.insert(new_sizeofcmds + header.bytesize, "\x00" * null_pad)
  end

  # synchronize fields with the raw data
  header = get_mach_header
  load_commands = get_load_commands
end

#executable? ⇒ Boolean

is the file executable?

Returns:

  • (Boolean) 


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# File 'lib/macho/file.rb', line 23

def executable?
  header[:filetype] == MH_EXECUTE
end

#filetype ⇒ Object

string representation of the header’s filetype field



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# File 'lib/macho/file.rb', line 47

def filetype
  MH_FILETYPES[header[:filetype]]
end

#flags ⇒ Object

various execution flags



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# File 'lib/macho/file.rb', line 72

def flags
  header[:flags]
end

#linked_dylibs ⇒ Object

get a list of dylib paths linked to this file



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# File 'lib/macho/file.rb', line 185

def linked_dylibs
  dylibs = []
  dylib_cmds = command('LC_LOAD_DYLIB')

  dylib_cmds.each do |dylib_cmd|
    cmdsize = dylib_cmd.cmdsize
    offset = dylib_cmd.offset
    stroffset = dylib_cmd.name

    dylib = @raw_data.slice(offset + stroffset...offset + cmdsize).unpack("Z*").first

    dylibs << dylib
  end

  dylibs
end

#magic ⇒ Object 



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# File 'lib/macho/file.rb', line 37

def magic
  header[:magic]
end

#magic32? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/macho/file.rb', line 14

def magic32?
  Utils.magic32?(header[:magic])
end

#magic64? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/macho/file.rb', line 18

def magic64?
  Utils.magic64?(header[:magic])
end

#magic_string ⇒ Object

string representation of the header’s magic bytes



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# File 'lib/macho/file.rb', line 42

def magic_string
  MH_MAGICS[header[:magic]]
end

#ncmds ⇒ Object

number of load commands in the header



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# File 'lib/macho/file.rb', line 62

def ncmds
  header[:ncmds]
end

#sections(segment) ⇒ Object

get all sections in a segment by name



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# File 'lib/macho/file.rb', line 203

def sections(segment)
  sections = []

  if !segment.is_a?(SegmentCommand) && !segment.is_a?(SegmentCommand64)
    raise ArgumentError.new("not a valid segment")
  end

  if segment.nsects.zero?
    return sections
  end

  offset = segment.offset + segment.class.bytesize

  segment.nsects.times do
    if segment.is_a? SegmentCommand
      sections << Section.new_from_bin(@raw_data.slice(offset, Section.bytesize))
      offset += Section.bytesize
    else
      sections << Section64.new_from_bin(@raw_data.slice(offset, Section64.bytesize))
      offset += Section64.bytesize
    end
  end

  sections
end

#segments ⇒ Object

get all segment commands



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# File 'lib/macho/file.rb', line 84

def segments
  if magic32?
    command("LC_SEGMENT")
  else
    command("LC_SEGMENT_64")
  end
end

#sizeofcmds ⇒ Object

size of all load commands



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# File 'lib/macho/file.rb', line 67

def sizeofcmds
  header[:sizeofcmds]
end

#write(filename) ⇒ Object 



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# File 'lib/macho/file.rb', line 229

def write(filename)
  File.open(filename, "wb") { |f| f.write(@raw_data) }
end

#write! ⇒ Object 



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# File 'lib/macho/file.rb', line 233

def write!
  File.open(@filename, "wb") { |f| f.write(@raw_data) }
end