Class: Gem::Package

Inherits:
Object
  • Object
show all
Includes:
UserInteraction
Defined in:
lib/rubygems/package.rb

Overview

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

Direct Known Subclasses

Old

Defined Under Namespace

Classes: DigestIO, Error, FileSource, FormatError, IOSource, NonSeekableIO, Old, PathError, Source, SymlinkError, TarHeader, TarInvalidError, TarReader, TarWriter, TooLongFileName

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from UserInteraction

#alert, #alert_error, #alert_warning, #ask, #ask_for_password, #ask_yes_no, #choose_from_list, #say, #terminate_interaction, #verbose

Methods included from DefaultUserInteraction

ui, #ui, ui=, #ui=, use_ui, #use_ui

Methods included from Text

#clean_text, #format_text, #levenshtein_distance, #min3, #truncate_text

Constructor Details

#initialize(gem, security_policy) ⇒ Package

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



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# File 'lib/rubygems/package.rb', line 195

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

Instance Attribute Details

#build_time ⇒ Object

:nodoc:



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# File 'lib/rubygems/package.rb', line 91

def build_time
  @build_time
end

#checksums ⇒ Object (readonly)

Checksums for the contents of the package



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# File 'lib/rubygems/package.rb', line 96

def checksums
  @checksums
end

#data_mode ⇒ Object

Permission for other files



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# File 'lib/rubygems/package.rb', line 129

def data_mode
  @data_mode
end

#dir_mode ⇒ Object

Permission for directories



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# File 'lib/rubygems/package.rb', line 121

def dir_mode
  @dir_mode
end

#files ⇒ Object (readonly)

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



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# File 'lib/rubygems/package.rb', line 102

def files
  @files
end

#gem ⇒ Object (readonly)

Reference to the gem being packaged.



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# File 'lib/rubygems/package.rb', line 107

def gem
  @gem
end

#prog_mode ⇒ Object

Permission for program files



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# File 'lib/rubygems/package.rb', line 125

def prog_mode
  @prog_mode
end

#security_policy ⇒ Object

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



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# File 'lib/rubygems/package.rb', line 112

def security_policy
  @security_policy
end

#spec ⇒ Object

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.



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# File 'lib/rubygems/package.rb', line 595

def spec
  verify unless @spec

  @spec
end

Class Method Details

.build(spec, skip_validation = false, strict_validation = false, file_name = nil) ⇒ Object 



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# File 'lib/rubygems/package.rb', line 131

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) ⇒ Object

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.



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# File 'lib/rubygems/package.rb', line 148

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
end

.raw_spec(path, security_policy = nil) ⇒ Object

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



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# File 'lib/rubygems/package.rb', line 171

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

Instance Method Details

#add_checksums(tar) ⇒ Object

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



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# File 'lib/rubygems/package.rb', line 221

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

#add_contents(tar) ⇒ Object

Adds the files listed in the packages’s Gem::Specification to data.tar.gz and adds this file to the tar.



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# File 'lib/rubygems/package.rb', line 243

def add_contents(tar) # :nodoc:
  digests = tar.add_file_signed "data.tar.gz", 0o444, @signer do |io|
    gzip_to io do |gz_io|
      Gem::Package::TarWriter.new gz_io do |data_tar|
        add_files data_tar
      end
    end
  end

  @checksums["data.tar.gz"] = digests
end

#add_files(tar) ⇒ Object

Adds files included the package’s Gem::Specification to the tar file



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# File 'lib/rubygems/package.rb', line 258

def add_files(tar) # :nodoc:
  @spec.files.each do |file|
    stat = File.lstat file

    if stat.symlink?
      tar.add_symlink file, File.readlink(file), stat.mode
    end

    next unless stat.file?

    tar.add_file_simple file, stat.mode, stat.size do |dst_io|
      File.open file, "rb" do |src_io|
        copy_stream(src_io, dst_io)
      end
    end
  end
end

#add_metadata(tar) ⇒ Object

Adds the package’s Gem::Specification to the tar file



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# File 'lib/rubygems/package.rb', line 279

def add_metadata(tar) # :nodoc:
  digests = tar.add_file_signed "metadata.gz", 0o444, @signer do |io|
    gzip_to io do |gz_io|
      gz_io.write @spec.to_yaml
    end
  end

  @checksums["metadata.gz"] = digests
end

#build(skip_validation = false, strict_validation = false) ⇒ Object

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



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# File 'lib/rubygems/package.rb', line 292

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

#contents ⇒ Object

A list of file names contained in this gem



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# File 'lib/rubygems/package.rb', line 326

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

#copy_stream(src, dst) ⇒ Object

:nodoc:



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# File 'lib/rubygems/package.rb', line 718

def copy_stream(src, dst) # :nodoc:
  dst.write src.read
end

#copy_to(path) ⇒ Object

Copies this package to path (if possible)



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# File 'lib/rubygems/package.rb', line 214

def copy_to(path)
  FileUtils.cp @gem.path, path unless File.exist? path
end

#digest(entry) ⇒ Object

Creates a digest of the TarEntry entry from the digest algorithm set by the security policy.



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# File 'lib/rubygems/package.rb', line 356

def digest(entry) # :nodoc:
  algorithms = if @checksums
    @checksums.to_h {|algorithm, _| [algorithm, Gem::Security.create_digest(algorithm)] }
  elsif Gem::Security::DIGEST_NAME
    { Gem::Security::DIGEST_NAME => Gem::Security.create_digest(Gem::Security::DIGEST_NAME) }
  end

  return @digests if algorithms.nil? || algorithms.empty?

  buf = String.new(capacity: 16_384, encoding: Encoding::BINARY)
  until entry.eof?
    entry.readpartial(16_384, buf)
    algorithms.each_value {|digester| digester << buf }
  end
  entry.rewind

  algorithms.each do |algorithm, digester|
    @digests[algorithm][entry.full_name] = digester
  end

  @digests
end

#extract_files(destination_dir, pattern = "*") ⇒ Object

Extracts the files in this package into destination_dir

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



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# File 'lib/rubygems/package.rb', line 385

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

#extract_tar_gz(io, destination_dir, pattern = "*") ⇒ Object

Extracts all the files in the gzipped tar archive io into destination_dir.

If an entry in the archive contains a relative path above destination_dir or an absolute path is encountered an exception is raised.

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



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# File 'lib/rubygems/package.rb', line 416

def extract_tar_gz(io, destination_dir, pattern = "*") # :nodoc:
  destination_dir = File.realpath(destination_dir)

  directories = []
  symlinks = []

  open_tar_gz io do |tar|
    tar.each do |entry|
      full_name = entry.full_name
      next unless File.fnmatch pattern, full_name, File::FNM_DOTMATCH

      destination = install_location full_name, destination_dir

      if entry.symlink?
        link_target = entry.header.linkname
        real_destination = link_target.start_with?("/") ? link_target : File.expand_path(link_target, File.dirname(destination))

        raise Gem::Package::SymlinkError.new(full_name, real_destination, destination_dir) unless
          normalize_path(real_destination).start_with? normalize_path(destination_dir + "/")

        symlinks << [full_name, link_target, destination, real_destination]
      end

      FileUtils.rm_rf destination

      mkdir =
        if entry.directory?
          destination
        else
          File.dirname destination
        end

      unless directories.include?(mkdir)
        FileUtils.mkdir_p mkdir, mode: dir_mode ? 0o755 : (entry.header.mode if entry.directory?)
        directories << mkdir
      end

      if entry.file?
        File.open(destination, "wb") {|out| copy_stream(entry, out) }
        FileUtils.chmod file_mode(entry.header.mode) & ~File.umask, destination
      end

      verbose destination
    end
  end

  symlinks.each do |name, target, destination, real_destination|
    if File.exist?(real_destination)
      File.symlink(target, destination)
    else
      alert_warning "#{@spec.full_name} ships with a dangling symlink named #{name} pointing to missing #{target} file. Ignoring"
    end
  end

  if dir_mode
    File.chmod(dir_mode, *directories)
  end
end

#file_mode(mode) ⇒ Object

:nodoc:



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# File 'lib/rubygems/package.rb', line 475

def file_mode(mode) # :nodoc:
  ((mode & 0o111).zero? ? data_mode : prog_mode) ||
    # If we're not using one of the default modes, then we're going to fall
    # back to the mode from the tarball. In this case we need to mask it down
    # to fit into 2^16 bits (the maximum value for a mode in CRuby since it
    # gets put into an unsigned short).
    (mode & ((1 << 16) - 1))
end

#gzip_to(io) ⇒ Object

Gzips content written to gz_io to io. – Also sets the gzip modification time to the package build time to ease testing.



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# File 'lib/rubygems/package.rb', line 490

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

#install_location(filename, destination_dir) ⇒ Object

Returns the full path for installing filename.

If filename is not inside destination_dir an exception is raised.

Raises:



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# File 'lib/rubygems/package.rb', line 504

def install_location(filename, destination_dir) # :nodoc:
  raise Gem::Package::PathError.new(filename, destination_dir) if
    filename.start_with? "/"

  destination_dir = File.realpath(destination_dir)
  destination = File.expand_path(filename, destination_dir)

  raise Gem::Package::PathError.new(destination, destination_dir) unless
    normalize_path(destination).start_with? normalize_path(destination_dir + "/")

  destination
end

#limit_read(io, name, limit) ⇒ Object

Raises:



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# File 'lib/rubygems/package.rb', line 727

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

#load_spec(entry) ⇒ Object

Loads a Gem::Specification from the TarEntry entry



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# File 'lib/rubygems/package.rb', line 528

def load_spec(entry) # :nodoc:
  limit = 10 * 1024 * 1024
  case entry.full_name
  when "metadata" then
    @spec = Gem::Specification.from_yaml limit_read(entry, "metadata", limit)
  when "metadata.gz" then
    Zlib::GzipReader.wrap(entry, external_encoding: Encoding::UTF_8) do |gzio|
      @spec = Gem::Specification.from_yaml limit_read(gzio, "metadata.gz", limit)
    end
  end
end

#normalize_path(pathname) ⇒ Object 



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# File 'lib/rubygems/package.rb', line 517

def normalize_path(pathname)
  if Gem.win_platform?
    pathname.downcase
  else
    pathname
  end
end

#open_tar_gz(io) ⇒ Object

Opens io as a gzipped tar archive



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# File 'lib/rubygems/package.rb', line 543

def open_tar_gz(io) # :nodoc:
  Zlib::GzipReader.wrap io do |gzio|
    tar = Gem::Package::TarReader.new gzio

    yield tar
  end
end

#read_checksums(gem) ⇒ Object

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



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# File 'lib/rubygems/package.rb', line 554

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

#setup_signer(signer_options: {}) ⇒ Object

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



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# File 'lib/rubygems/package.rb', line 568

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

#verify ⇒ Object

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



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# File 'lib/rubygems/package.rb', line 611

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

#verify_checksums(digests, checksums) ⇒ Object

Verifies the checksums against the digests. This check is not cryptographically secure. Missing checksums are ignored.



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# File 'lib/rubygems/package.rb', line 642

def verify_checksums(digests, checksums) # :nodoc:
  return unless checksums

  checksums.sort.each do |algorithm, gem_digests|
    gem_digests.sort.each do |file_name, gem_hexdigest|
      computed_digest = digests[algorithm][file_name]

      unless computed_digest.hexdigest == gem_hexdigest
        raise Gem::Package::FormatError.new \
          "#{algorithm} checksum mismatch for #{file_name}", @gem
      end
    end
  end
end

#verify_entry(entry) ⇒ Object

Verifies entry in a .gem file.



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# File 'lib/rubygems/package.rb', line 660

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

#verify_files(gem) ⇒ Object

Verifies the files of the gem



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# File 'lib/rubygems/package.rb', line 686

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

#verify_gz(entry) ⇒ Object

Verifies that entry is a valid gzipped file.



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# File 'lib/rubygems/package.rb', line 708

def verify_gz(entry) # :nodoc:
  Zlib::GzipReader.wrap entry do |gzio|
    # TODO: read into a buffer once zlib supports it
    gzio.read 16_384 until gzio.eof? # gzip checksum verification
  end
rescue Zlib::GzipFile::Error => e
  raise Gem::Package::FormatError.new(e.message, entry.full_name)
end