1 files changed, 35 insertions, 12 deletions

diff --git a/lib/tmpdir.rb b/lib/tmpdir.rb
index 70bd010de5..f78fd721b7 100644
--- a/lib/tmpdir.rb
+++ b/lib/tmpdir.rb
@@ -16,15 +16,14 @@ class Dir
   # Class variables are inaccessible from non-main Ractor.
   # And instance variables too, in Ruby 3.0.
 
-  # System-wide temporary directory path
-  SYSTMPDIR = (defined?(Etc.systmpdir) ? Etc.systmpdir.freeze : '/tmp')
-  private_constant :SYSTMPDIR
-
   ##
   # Returns the operating system's temporary file path.
+  #
+  #   require 'tmpdir'
+  #   Dir.tmpdir # => "/tmp"
 
   def self.tmpdir
-    ['TMPDIR', 'TMP', 'TEMP', ['system temporary path', SYSTMPDIR], ['/tmp']*2, ['.']*2].find do |name, dir|
+    Tmpname::TMPDIR_CANDIDATES.find do |name, dir|
       unless dir
         next if !(dir = ENV[name] rescue next) or dir.empty?
       end
@@ -33,7 +32,9 @@ class Dir
       case
       when !stat.directory?
         warn "#{name} is not a directory: #{dir}"
-      when !stat.writable?
+      when !File.writable?(dir)
+        # We call File.writable?, not stat.writable?, because you can't tell if a dir is actually
+        # writable just from stat; OS mechanisms other than user/group/world bits can affect this.
         warn "#{name} is not writable: #{dir}"
       when stat.world_writable? && !stat.sticky?
         warn "#{name} is world-writable: #{dir}"
@@ -45,6 +46,11 @@ class Dir
 
   # Dir.mktmpdir creates a temporary directory.
   #
+  #   require 'tmpdir'
+  #   Dir.mktmpdir {|dir|
+  #     # use the directory
+  #   }
+  #
   # The directory is created with 0700 permission.
   # Application should not change the permission to make the temporary directory accessible from other users.
   #
@@ -88,20 +94,21 @@ class Dir
   #    FileUtils.remove_entry dir
   #  end
   #
-  def self.mktmpdir(prefix_suffix=nil, *rest, **options)
+  def self.mktmpdir(prefix_suffix=nil, *rest, **options, &block)
     base = nil
     path = Tmpname.create(prefix_suffix || "d", *rest, **options) {|path, _, _, d|
       base = d
       mkdir(path, 0700)
     }
-    if block_given?
+    if block
       begin
         yield path.dup
       ensure
         unless base
-          stat = File.stat(File.dirname(path))
+          base = File.dirname(path)
+          stat = File.stat(base)
           if stat.world_writable? and !stat.sticky?
-            raise ArgumentError, "parent directory is world writable but not sticky"
+            raise ArgumentError, "parent directory is world writable but not sticky: #{base}"
           end
         end
         FileUtils.remove_entry path
@@ -115,6 +122,18 @@ class Dir
   module Tmpname # :nodoc:
     module_function
 
+    # System-wide temporary directory path
+    systmpdir = (defined?(Etc.systmpdir) ? Etc.systmpdir.freeze : '/tmp')
+
+    # Temporary directory candidates consisting of environment variable
+    # names or description and path pairs.
+    TMPDIR_CANDIDATES = [
+      'TMPDIR', 'TMP', 'TEMP',
+      ['system temporary path', systmpdir],
+      %w[/tmp /tmp],
+      %w[. .],
+    ].each(&:freeze).freeze
+
     def tmpdir
       Dir.tmpdir
     end
@@ -138,8 +157,12 @@ class Dir
 
     # Generates and yields random names to create a temporary name
     def create(basename, tmpdir=nil, max_try: nil, **opts)
-      origdir = tmpdir
-      tmpdir ||= tmpdir()
+      if tmpdir
+        origdir = tmpdir = File.path(tmpdir)
+        raise ArgumentError, "empty parent path" if tmpdir.empty?
+      else
+        tmpdir = tmpdir()
+      end
       n = nil
       prefix, suffix = basename
       prefix = (String.try_convert(prefix) or