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# class Gem::Package

Example using a `Gem::Package`

Builds a .gem file given a `Gem::Specification`. A .gem file is a tarball which contains a data.tar.gz, metadata.gz, checksums.yaml.gz and possibly signatures.

    require 'rubygems'
    require 'rubygems/package'

    spec = Gem::Specification.new do |s|
      s.summary = "Ruby based make-like utility."
      s.name = 'rake'
      s.version = PKG_VERSION
      s.requirements << 'none'
      s.files = PKG_FILES
      s.description = <<-EOF
    Rake is a Make-like program implemented in Ruby. Tasks
    and dependencies are specified in standard Ruby syntax.
      EOF
    end

    Gem::Package.build spec

Reads a .gem file.

    require 'rubygems'
    require 'rubygems/package'

    the_gem = Gem::Package.new(path_to_dot_gem)
    the_gem.contents # get the files in the gem
    the_gem.extract_files destination_directory # extract the gem into a directory
    the_gem.spec # get the spec out of the gem
    the_gem.verify # check the gem is OK (contains valid gem specification, contains a not corrupt contents archive)

`files` are the files in the .gem tar file, not the Ruby files in the gem `extract_files` and `contents` automatically call `verify`

### Attributes

checksums [R]

Checksums for the contents of the package

data_mode [RW]

Permission for other files

dir_mode [RW]

Permission for directories

files [R]

The files in this package. This is not the contents of the gem, just the files in the top-level container.

gem [R]

Reference to the gem being packaged.

prog_mode [RW]

Permission for program files

security_policy [RW]

The security policy used for verifying the contents of this package.

spec [W]

Sets the `Gem::Specification` to use to build this package.

### Public Class Methods

build (spec, skip_validation = false, strict_validation = false, file_name = nil)
Source

    # File lib/rubygems/package.rb, line 132
    def self.build(spec, skip_validation = false, strict_validation = false, file_name = nil)
      gem_file = file_name || spec.file_name

      package = new gem_file
      package.spec = spec
      package.build skip_validation, strict_validation

      gem_file
    end

new (gem, security_policy = nil)
Source

    # File lib/rubygems/package.rb, line 149
    def self.new(gem, security_policy = nil)
      gem = if gem.is_a?(Gem::Package::Source)
        gem
      elsif gem.respond_to? :read
        Gem::Package::IOSource.new gem
      else
        Gem::Package::FileSource.new gem
      end

      return super unless self == Gem::Package
      return super unless gem.present?

      return super unless gem.start
      return super unless gem.start.include? "MD5SUM ="

      Gem::Package::Old.new gem, security_policy
    end

Creates a new `Gem::Package` for the file at `gem`. `gem` can also be provided as an `IO` object.

If `gem` is an existing file in the old format a `Gem::Package::Old` will be returned.

Calls superclass method `BasicObject::new`
raw_spec (path, security_policy = nil)
Source

    # File lib/rubygems/package.rb, line 172
    def self.raw_spec(path, security_policy = nil)
      format = new(path, security_policy)
      spec = format.spec

      metadata = nil

      File.open path, Gem.binary_mode do |io|
        tar = Gem::Package::TarReader.new io
        tar.each_entry do |entry|
          case entry.full_name
          when "metadata" then
            metadata = entry.read
          when "metadata.gz" then
            metadata = Gem::Util.gunzip entry.read
          end
        end
      end

      [spec, metadata]
    end

Extracts the `Gem::Specification` and raw metadata from the .gem file at `path`.

### Public Instance Methods

add_checksums (tar)
Source

    # File lib/rubygems/package.rb, line 222
    def add_checksums(tar)
      Gem.load_yaml

      checksums_by_algorithm = Hash.new {|h, algorithm| h[algorithm] = {} }

      @checksums.each do |name, digests|
        digests.each do |algorithm, digest|
          checksums_by_algorithm[algorithm][name] = digest.hexdigest
        end
      end

      tar.add_file_signed "checksums.yaml.gz", 0o444, @signer do |io|
        gzip_to io do |gz_io|
          Psych.dump checksums_by_algorithm, gz_io
        end
      end
    end

Adds a checksum for each entry in the gem to checksums.yaml.gz.

build (skip_validation = false, strict_validation = false)
Source

    # File lib/rubygems/package.rb, line 293
      def build(skip_validation = false, strict_validation = false)
        raise ArgumentError, "skip_validation = true and strict_validation = true are incompatible" if skip_validation && strict_validation

        Gem.load_yaml

        @spec.validate true, strict_validation unless skip_validation

        setup_signer(
          signer_options: {
            expiration_length_days: Gem.configuration.cert_expiration_length_days,
          }
        )

        @gem.with_write_io do |gem_io|
          Gem::Package::TarWriter.new gem_io do |gem|
            add_metadata gem
            add_contents gem
            add_checksums gem
          end
        end

        say <<-EOM
      Successfully built RubyGem
      Name: #{@spec.name}
      Version: #{@spec.version}
      File: #{File.basename @gem.path}
    EOM
      ensure
        @signer = nil
      end

Builds this package based on the specification set by `spec=`

contents ()
Source

    # File lib/rubygems/package.rb, line 327
    def contents
      return @contents if @contents

      verify unless @spec

      @contents = []

      @gem.with_read_io do |io|
        gem_tar = Gem::Package::TarReader.new io

        gem_tar.each do |entry|
          next unless entry.full_name == "data.tar.gz"

          open_tar_gz entry do |pkg_tar|
            pkg_tar.each do |contents_entry|
              @contents << contents_entry.full_name
            end
          end

          return @contents
        end
      end
    rescue Zlib::GzipFile::Error, EOFError, Gem::Package::TarInvalidError => e
      raise Gem::Package::FormatError.new e.message, @gem
    end

A list of file names contained in this gem

copy_to (path)
Source

    # File lib/rubygems/package.rb, line 215
    def copy_to(path)
      FileUtils.cp @gem.path, path unless File.exist? path
    end

Copies this package to `path` (if possible)

extract_files (destination_dir, pattern = "*")
Source

    # File lib/rubygems/package.rb, line 386
    def extract_files(destination_dir, pattern = "*")
      verify unless @spec

      FileUtils.mkdir_p destination_dir, mode: dir_mode && 0o755

      @gem.with_read_io do |io|
        reader = Gem::Package::TarReader.new io

        reader.each do |entry|
          next unless entry.full_name == "data.tar.gz"

          extract_tar_gz entry, destination_dir, pattern

          break # ignore further entries
        end
      end
    rescue Zlib::GzipFile::Error, EOFError, Gem::Package::TarInvalidError => e
      raise Gem::Package::FormatError.new e.message, @gem
    end

Extracts the files in this package into `destination_dir`

If `pattern` is specified, only entries matching that glob will be extracted.

gzip_to (io) { |gz_io| ... }
Source

    # File lib/rubygems/package.rb, line 500
    def gzip_to(io) # :yields: gz_io
      gz_io = Zlib::GzipWriter.new io, Zlib::BEST_COMPRESSION
      gz_io.mtime = @build_time

      yield gz_io
    ensure
      gz_io.close
    end

Gzips content written to `gz_io` to `io`.

read_checksums (gem)
Source

    # File lib/rubygems/package.rb, line 575
    def read_checksums(gem)
      Gem.load_yaml

      @checksums = gem.seek "checksums.yaml.gz" do |entry|
        Zlib::GzipReader.wrap entry do |gz_io|
          Gem::SafeYAML.safe_load limit_read(gz_io, "checksums.yaml.gz", 10 * 1024 * 1024)
        end
      end
    end

Reads and loads checksums.yaml.gz from the tar file `gem`

setup_signer (signer_options: {})
Source

    # File lib/rubygems/package.rb, line 589
    def setup_signer(signer_options: {})
      passphrase = ENV["GEM_PRIVATE_KEY_PASSPHRASE"]
      if @spec.signing_key
        @signer =
          Gem::Security::Signer.new(
            @spec.signing_key,
            @spec.cert_chain,
            passphrase,
            signer_options
          )

        @spec.signing_key = nil
        @spec.cert_chain = @signer.cert_chain.map(&:to_s)
      else
        @signer = Gem::Security::Signer.new nil, nil, passphrase
        @spec.cert_chain = @signer.cert_chain.map(&:to_pem) if
          @signer.cert_chain
      end
    end

Prepares the gem for signing and checksum generation. If a signing certificate and key are not present only checksum generation is set up.

spec ()
Source

    # File lib/rubygems/package.rb, line 616
    def spec
      verify unless @spec

      @spec
    end

The spec for this gem.

If this is a package for a built gem the spec is loaded from the gem and returned. If this is a package for a gem being built the provided spec is returned.

verify ()
Source

    # File lib/rubygems/package.rb, line 632
    def verify
      @files     = []
      @spec      = nil

      @gem.with_read_io do |io|
        Gem::Package::TarReader.new io do |reader|
          read_checksums reader

          verify_files reader
        end
      end

      verify_checksums @digests, @checksums

      @security_policy&.verify_signatures @spec, @digests, @signatures

      true
    rescue Gem::Security::Exception
      @spec = nil
      @files = []
      raise
    rescue Errno::ENOENT => e
      raise Gem::Package::FormatError.new e.message
    rescue Zlib::GzipFile::Error, EOFError, Gem::Package::TarInvalidError => e
      raise Gem::Package::FormatError.new e.message, @gem
    end

Verifies that this gem:

- Contains a valid gem specification

- Contains a contents archive

- The contents archive is not corrupt

After verification the gem specification from the gem is available from `spec`

### Protected Instance Methods

initialize (gem, security_policy)
Source

    # File lib/rubygems/package.rb, line 196
    def initialize(gem, security_policy) # :notnew:
      require "zlib"

      @gem = gem

      @build_time      = Gem.source_date_epoch
      @checksums       = {}
      @contents        = nil
      @digests         = Hash.new {|h, algorithm| h[algorithm] = {} }
      @files           = nil
      @security_policy = security_policy
      @signatures      = {}
      @signer          = nil
      @spec            = nil
    end

Creates a new package that will read or write to the file `gem`.

### Private Instance Methods

create_symlink (old_name, new_name)
Source

    # File lib/rubygems/package.rb, line 759
    def create_symlink(old_name, new_name)
      File.symlink(old_name, new_name)
    rescue Errno::EACCES
      from = File.expand_path(old_name, File.dirname(new_name))
      FileUtils.cp_r(from, new_name)
    end

Create a symlink and fallback to copy the file or directory on Windows, where symlink creation needs special privileges in form of the Developer Mode.

limit_read (io, name, limit)
Source

    # File lib/rubygems/package.rb, line 750
    def limit_read(io, name, limit)
      bytes = io.read(limit + 1)
      raise Gem::Package::FormatError, "#{name} is too big (over #{limit} bytes)" if bytes.size > limit
      bytes
    end

verify_entry (entry)
Source

    # File lib/rubygems/package.rb, line 683
    def verify_entry(entry)
      file_name = entry.full_name
      @files << file_name

      case file_name
      when /\.sig$/ then
        @signatures[$`] = limit_read(entry, file_name, 1024 * 1024) if @security_policy
        return
      else
        digest entry
      end

      case file_name
      when "metadata", "metadata.gz" then
        load_spec entry
      when "data.tar.gz" then
        verify_gz entry
      end
    rescue StandardError
      warn "Exception while verifying #{@gem.path}"
      raise
    end

Verifies `entry` in a .gem file.

verify_files (gem)
Source

    # File lib/rubygems/package.rb, line 709
    def verify_files(gem)
      gem.each do |entry|
        verify_entry entry
      end

      unless @spec
        raise Gem::Package::FormatError.new "package metadata is missing", @gem
      end

      unless @files.include? "data.tar.gz"
        raise Gem::Package::FormatError.new \
          "package content (data.tar.gz) is missing", @gem
      end

      if (duplicates = @files.group_by {|f| f }.select {|_k,v| v.size > 1 }.map(&:first)) && duplicates.any?
        raise Gem::Security::Exception, "duplicate files in the package: (#{duplicates.map(&:inspect).join(", ")})"
      end
    end

Verifies the files of the `gem`