From 9190e0b56accc0bc031f50465b85ac3d1c437b93 Mon Sep 17 00:00:00 2001
From: Barry Allard <barry.allard@gmail.com>
Date: Sun, 29 Jan 2023 21:14:44 -0600
Subject: [PATCH] Refactor

Includes and integrates
  - https://github.com/ruby/tmpdir/pull/9
  - https://github.com/ruby/tmpdir/pull/20
  - https://github.com/ruby/tmpdir/pull/21
  - https://github.com/ruby/tmpdir/pull/22
---
 lib/tmpdir.rb                         | 104 ++----------------------
 lib/tmpdir/insecure_world_writable.rb |  17 ++++
 lib/tmpdir/tmpname.rb                 | 113 ++++++++++++++++++++++++++
 test/test_tmpdir.rb                   |  22 +++++
 4 files changed, 157 insertions(+), 99 deletions(-)
 create mode 100644 lib/tmpdir/insecure_world_writable.rb
 create mode 100644 lib/tmpdir/tmpname.rb

diff --git a/lib/tmpdir.rb b/lib/tmpdir.rb
index 55920a4..b63a299 100644
--- a/lib/tmpdir.rb
+++ b/lib/tmpdir.rb
@@ -5,37 +5,14 @@
 # $Id$
 #
 
-require 'fileutils'
-begin
-  require 'etc.so'
-rescue LoadError # rescue LoadError for miniruby
-end
+require_relative './tmpdir/tmpname'
 
 class Dir
-
-  @@systmpdir ||= defined?(Etc.systmpdir) ? Etc.systmpdir : '/tmp'
-
   ##
   # Returns the operating system's temporary file path.
-
+  #
   def self.tmpdir
-    ['TMPDIR', 'TMP', 'TEMP', ['system temporary path', @@systmpdir], ['/tmp']*2, ['.']*2].find do |name, dir|
-      unless dir
-        next if !(dir = ENV[name]) or dir.empty?
-      end
-      dir = File.expand_path(dir)
-      stat = File.stat(dir) rescue next
-      case
-      when !stat.directory?
-        warn "#{name} is not a directory: #{dir}"
-      when !stat.writable?
-        warn "#{name} is not writable: #{dir}"
-      when stat.world_writable? && !stat.sticky?
-        warn "#{name} is world-writable: #{dir}"
-      else
-        break dir
-      end
-    end or raise ArgumentError, "could not find a temporary directory"
+    Dir::Tmpname.tmpdir
   end
 
   # Dir.mktmpdir creates a temporary directory.
@@ -83,78 +60,7 @@ def self.tmpdir
   #    FileUtils.remove_entry dir
   #  end
   #
-  def self.mktmpdir(prefix_suffix=nil, *rest, **options)
-    base = nil
-    path = Tmpname.create(prefix_suffix || "d", *rest, **options) {|path, _, _, d|
-      base = d
-      mkdir(path, 0700)
-    }
-    if block_given?
-      begin
-        yield path.dup
-      ensure
-        unless base
-          stat = File.stat(File.dirname(path))
-          if stat.world_writable? and !stat.sticky?
-            raise ArgumentError, "parent directory is world writable but not sticky"
-          end
-        end
-        FileUtils.remove_entry path
-      end
-    else
-      path
-    end
-  end
-
-  # Temporary name generator
-  module Tmpname # :nodoc:
-    module_function
-
-    def tmpdir
-      Dir.tmpdir
-    end
-
-    # Unusable characters as path name
-    UNUSABLE_CHARS = "^,-.0-9A-Z_a-z~"
-
-    # Dedicated random number generator
-    RANDOM = Random.new
-    class << RANDOM # :nodoc:
-      # Maximum random number
-      MAX = 36**6 # < 0x100000000
-
-      # Returns new random string upto 6 bytes
-      def next
-        rand(MAX).to_s(36)
-      end
-    end
-    private_constant :RANDOM
-
-    # Generates and yields random names to create a temporary name
-    def create(basename, tmpdir=nil, max_try: nil, **opts)
-      origdir = tmpdir
-      tmpdir ||= tmpdir()
-      n = nil
-      prefix, suffix = basename
-      prefix = (String.try_convert(prefix) or
-                raise ArgumentError, "unexpected prefix: #{prefix.inspect}")
-      prefix = prefix.delete(UNUSABLE_CHARS)
-      suffix &&= (String.try_convert(suffix) or
-                  raise ArgumentError, "unexpected suffix: #{suffix.inspect}")
-      suffix &&= suffix.delete(UNUSABLE_CHARS)
-      begin
-        t = Time.now.strftime("%Y%m%d")
-        path = "#{prefix}#{t}-#{$$}-#{RANDOM.next}"\
-               "#{n ? %[-#{n}] : ''}#{suffix||''}"
-        path = File.join(tmpdir, path)
-        yield(path, n, opts, origdir)
-      rescue Errno::EEXIST
-        n ||= 0
-        n += 1
-        retry if !max_try or n < max_try
-        raise "cannot generate temporary name using `#{basename}' under `#{tmpdir}'"
-      end
-      path
-    end
+  def self.mktmpdir(prefix_suffix=nil, *rest, **options, &block)
+    Dir::Tmpname.mktmpdir(prefix_suffix, *rest, **options, &block)
   end
 end
diff --git a/lib/tmpdir/insecure_world_writable.rb b/lib/tmpdir/insecure_world_writable.rb
new file mode 100644
index 0000000..609f021
--- /dev/null
+++ b/lib/tmpdir/insecure_world_writable.rb
@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+class Dir
+  module Tmpname
+    module InsecureWorldWritable
+      refine File::Stat do
+        def insecure_world_writable?
+          world_writable? && !sticky?
+        end
+
+        def not_insecure_world_writable?
+          !insecure_world_writable?
+        end
+      end
+    end
+  end
+end
diff --git a/lib/tmpdir/tmpname.rb b/lib/tmpdir/tmpname.rb
new file mode 100644
index 0000000..8fd944f
--- /dev/null
+++ b/lib/tmpdir/tmpname.rb
@@ -0,0 +1,113 @@
+# frozen_string_literal: true
+#
+# tmpdir - retrieve temporary directory path
+#
+# $Id$
+#
+
+require 'fileutils'
+begin
+  require 'etc.so'
+rescue LoadError # rescue LoadError for miniruby
+end
+require_relative './insecure_world_writable'
+
+class Dir
+  # Temporary name generator
+  module Tmpname # :nodoc:
+    using InsecureWorldWritable
+
+    module_function
+
+    SYSTMPDIR = Etc.systmpdir rescue '/tmp'
+    private_constant :SYSTMPDIR
+
+    TRY_ENVS = %w{TMPDIR TMP TEMP}.freeze
+    private_constant :TRY_ENVS
+
+    TRY_DIRS = [['system temporary path', SYSTMPDIR], ['/tmp']*2, ['.']*2].map(&:freeze).freeze
+    private_constant :TRY_DIRS
+
+    PERM_CHECKS = [
+      ['not a directory', :directory? ],
+      ['not writable'   , :writable?  ],
+      ['world-writable' , :not_insecure_world_writable? ]].map(&:freeze).freeze
+    private_constant :PERM_CHECKS
+
+    def tmpdir
+      TRY_ENVS.each { |env|       d = self.verify_permissions(env, ENV[env]); return d if d }
+      TRY_DIRS.each { |name, dir| d = self.verify_permissions(name, dir)    ; return d if d }
+      raise ArgumentError, 'could not find a temporary directory'
+    end
+
+    private_class_method def verify_permissions(name, dir)
+      return if dir.to_s.empty?
+      dir = File.expand_path(dir)
+      stat = File.stat(dir) rescue return
+      dir if PERM_CHECKS.all? { |msg, ok| stat.send(ok) or warn "#{name} is #{msg}: #{dir}" }
+    end
+
+    def mktmpdir(prefix_suffix = nil, *rest, **options, &block)
+      base = nil
+      path = self.create(prefix_suffix || 'd', *rest, **options) do |path, _, _, d|
+        base = d
+        Dir.mkdir(path, 0700)
+      end
+      if block_given?
+        self.mktmpdir_with_block(base, path, block)
+      else
+        path
+      end
+    end
+
+    private_class_method def mktmpdir_with_block(base, path, block)
+      block.call(path.dup)
+    ensure
+      if !base && File.stat(File.dirname(path))&.insecure_world_writable?
+        raise ArgumentError, 'parent directory is world writable but not sticky'
+      end
+      FileUtils.remove_entry path
+    end
+
+    # Unusable characters as path name
+    UNUSABLE_CHARS = '^,-.0-9A-Z_a-z~'
+
+    # Generates and yields random names to create a temporary name
+    def create(basename, tmpdir = nil, max_try: nil, **opts)
+      raise ArgumentError, "empty parent path" if tmpdir&.empty?
+      n = nil
+      begin
+        path = generate_path(basename, tmpdir, n)
+        path = File.join(tmpdir || self.tmpdir, path)
+        yield(path, n, opts, tmpdir)
+        path
+      rescue Errno::EEXIST
+        n ||= 0
+        retry if max_try&.>=(n += 1)
+        raise "cannot generate temporary name using `#{basename}' under `#{tmpdir}'"
+      end
+    end
+
+    private_class_method def generate_path(basename, tmpdir, n)
+      prefix, suffix = self.make_prefix_suffix(basename)
+      time = Time.now.strftime('%Y%m%d')
+      rnd = Random.bytes(4).unpack1('L').to_s(36)[0..5]
+      '%s%s-%d-%s%s%s' % [prefix, time, $$, rnd, n&.-@, suffix]
+    end
+
+    private_class_method def make_prefix_suffix(basename)
+      prefix, suffix = basename
+      prefix = self.make_str('prefix', prefix)
+      suffix &&= self.make_str('suffix', suffix)
+      [prefix, suffix]
+    end
+
+    private_class_method def make_str(msg, var)
+      if x = String.try_convert(var)
+        x.delete(UNUSABLE_CHARS)
+      else
+        raise ArgumentError, "unexpected #{msg}: #{var.inspect}"
+      end
+    end
+  end
+end
diff --git a/test/test_tmpdir.rb b/test/test_tmpdir.rb
index eada416..eae0610 100644
--- a/test/test_tmpdir.rb
+++ b/test/test_tmpdir.rb
@@ -104,6 +104,12 @@ def test_mktmpdir_traversal_array
     end
   end
 
+  def test_mktmpdir_not_empty_parent
+    assert_raise(ArgumentError) do
+      Dir.mktmpdir("foo", "")
+    end
+  end
+
   def assert_mktmpdir_traversal
     Dir.mktmpdir do |target|
       target = target.chomp('/') + '/'
@@ -115,4 +121,20 @@ def assert_mktmpdir_traversal
       end
     end
   end
+
+  def test_ractor
+    assert_ractor(<<~'end;', require: "tmpdir")
+      r = Ractor.new do
+        Dir.mktmpdir() do |d|
+          Ractor.yield d
+          Ractor.receive
+        end
+      end
+      dir = r.take
+      assert_file.directory? dir
+      r.send true
+      r.take
+      assert_file.not_exist? dir
+    end;
+  end
 end