Fat parser should fail on file with 0 architectures

lib/macho/exceptions.rb

@@ -56,6 +56,13 @@ def initialize
  end
  end
 
+ # Raised when a a fat Mach-O file has zero architectures
+ class ZeroArchitectureError < NotAMachOError
+ def initialize
+ super "Fat file has zero internal architectures"
+ end
+ end
+
  # Raised when a fat binary is loaded with MachOFile.
  class FatBinaryError < MachOError
  def initialize

lib/macho/fat_file.rb

@@ -327,6 +327,8 @@ def to_h
  # @raise [MagicError] if the magic is not valid Mach-O magic
  # @raise [MachOBinaryError] if the magic is for a non-fat Mach-O file
  # @raise [JavaClassFileError] if the file is a Java classfile
+ # @raise [ZeroArchitectureError] if the file has no internal slices
+ # (i.e., nfat_arch == 0) and the permissive option is not set
  # @api private
  def populate_fat_header
  # the smallest fat Mach-O header is 8 bytes
@@ -346,6 +348,11 @@ def populate_fat_header
  # formats.
  raise JavaClassFileError if fh.nfat_arch > 30
 
+ # Rationale: fat Mach-0 files with no internal slices should
+ # return an error unless the permissive option is set.
+ permissive = options.fetch(:permissive, false)
+ raise ZeroArchitectureError if !permissive && fh.nfat_arch.zero?
+
  fh
  end
 

test/test_fat.rb

@@ -36,6 +36,14 @@ def test_java_classfile
  end
  end
 
+ def test_zero_arch_file
+ assert_raises MachO::ZeroArchitectureError do
+ MachO::FatFile.new("test/bin/llvm/macho-invalid-fat-header")
+ end
+
+ MachO::FatFile.new("test/bin/llvm/macho-invalid-fat-header", :permissive => true)
+ end
+
  def test_fat_header
  filenames = FAT_ARCH_PAIRS.map { |a| fixture(a, "hello.bin") }
 
@@ -518,7 +526,7 @@ def test_dylib_load_commands
  end
 
  def test_fail_loading_thin
- filename = fixture('x86_64', 'libhello.dylib')
+ filename = fixture("x86_64", "libhello.dylib")
 
  ex = assert_raises(MachO::MachOBinaryError) do
  MachO::FatFile.new_from_bin File.read(filename)