Class: MachO::LoadCommands::LoadCommand

Inherits:
MachOStructure show all
Defined in:
lib/macho/load_commands.rb

Overview

The top-level Mach-O load command structure.

This is the most generic load command -- only the type ID and size are represented. Used when a more specific class isn't available or isn't implemented.

Defined Under Namespace

Classes: LCStr, SerializationContext

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from MachOStructure

bytesize, format, #initialize

Constructor Details

This class inherits a constructor from MachO::MachOStructure

Class Method Details

.create(cmd_sym, *args) ⇒ Object

Creates a new (viewless) command corresponding to the symbol provided

Parameters:

  • cmd_sym (Symbol) —

    the symbol of the load command being created

  • args (Array) —

    the arguments for the load command being created

Raises:



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# File 'lib/macho/load_commands.rb', line 241

def self.create(cmd_sym, *args)
  raise LoadCommandNotCreatableError, cmd_sym unless CREATABLE_LOAD_COMMANDS.include?(cmd_sym)

  klass = LoadCommands.const_get LC_STRUCTURES[cmd_sym]
  cmd = LOAD_COMMAND_CONSTANTS[cmd_sym]

  # cmd will be filled in, view and cmdsize will be left unpopulated
  klass_arity = klass.min_args - 3

  # macOS 15 introduces a new dylib load command that adds a flags field to the end.
  # It uses the same commands with it dynamically being created if the dylib has a flags field
  if klass == DylibUseCommand && (args[1] != DYLIB_USE_MARKER || args.size <= DylibCommand.min_args - 3)
    klass = DylibCommand
    klass_arity = klass.min_args - 3
  end

  raise LoadCommandCreationArityError.new(cmd_sym, klass_arity, args.size) if klass_arity > args.size

  klass.new(nil, cmd, nil, *args)
end

.new_from_bin(view) ⇒ LoadCommand

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Instantiates a new LoadCommand given a view into its origin Mach-O

Parameters:

Returns:



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# File 'lib/macho/load_commands.rb', line 231

def self.new_from_bin(view)
  bin = view.raw_data.slice(view.offset, bytesize)
  format = Utils.specialize_format(self.format, view.endianness)

  new(view, *bin.unpack(format))
end

Instance Method Details

#cmd ⇒ Integer

Returns the load command's type ID.

Returns:

  • (Integer) —

    the load command's type ID



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# File 'lib/macho/load_commands.rb', line 222

field :cmd, :uint32

#cmdsize ⇒ Integer

Returns the size of the load command, in bytes.

Returns:

  • (Integer) —

    the size of the load command, in bytes



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# File 'lib/macho/load_commands.rb', line 225

field :cmdsize, :uint32

#offset ⇒ Integer

Deprecated.

use #view instead

Returns the load command's offset in the source file.

Returns:

  • (Integer) —

    the load command's offset in the source file



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# File 'lib/macho/load_commands.rb', line 281

def offset
  view.offset
end

#serializable? ⇒ Boolean

Returns whether the load command can be serialized.

Returns:

  • (Boolean) —

    whether the load command can be serialized



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# File 'lib/macho/load_commands.rb', line 263

def serializable?
  CREATABLE_LOAD_COMMANDS.include?(LOAD_COMMANDS[cmd])
end

#serialize(context) ⇒ String?

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns the serialized fields of the load command, or nil if the load command can't be serialized.

Parameters:

Returns:

  • (String, nil) —

    the serialized fields of the load command, or nil if the load command can't be serialized

Raises:



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# File 'lib/macho/load_commands.rb', line 272

def serialize(context)
  raise LoadCommandNotSerializableError, LOAD_COMMANDS[cmd] unless serializable?

  format = Utils.specialize_format(self.class.format, context.endianness)
  [cmd, self.class.bytesize].pack(format)
end

#to_h ⇒ Hash

Note:

Children should override this to include additional information.

Returns a hash representation of this load command.

Returns:

  • (Hash) —

    a hash representation of this load command



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# File 'lib/macho/load_commands.rb', line 301

def to_h
  {
    "view" => view.to_h,
    "cmd" => cmd,
    "cmdsize" => cmdsize,
    "type" => type,
  }.merge super
end

#to_s ⇒ String

Returns a string representation of the load command's identifying number.

Returns:

  • (String) —

    a string representation of the load command's identifying number



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# File 'lib/macho/load_commands.rb', line 295

def to_s
  type.to_s
end

#type ⇒ Symbol? Also known as: to_sym

Returns a symbol representation of the load command's type ID, or nil if the ID doesn't correspond to a known load command class.

Returns:

  • (Symbol, nil) —

    a symbol representation of the load command's type ID, or nil if the ID doesn't correspond to a known load command class



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# File 'lib/macho/load_commands.rb', line 287

def type
  LOAD_COMMANDS[cmd]
end

#view ⇒ MachO::MachOView?

Returns the raw view associated with the load command, or nil if the load command was created via create.

Returns:

  • (MachO::MachOView, nil) —

    the raw view associated with the load command, or nil if the load command was created via create.



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# File 'lib/macho/load_commands.rb', line 219

field :view, :view