1 files changed, 37 insertions, 16 deletions

diff --git a/lib/tmpdir.rb b/lib/tmpdir.rb
index bf7db5282a..fe3e0e19d1 100644
--- a/lib/tmpdir.rb
+++ b/lib/tmpdir.rb
@@ -13,15 +13,24 @@ end
 
 class Dir
 
-  @@systmpdir ||= defined?(Etc.systmpdir) ? Etc.systmpdir : '/tmp'
+  # 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
-    tmp = nil
-    ['TMPDIR', 'TMP', 'TEMP', ['system temporary path', @@systmpdir], ['/tmp']*2, ['.']*2].each do |name, dir = ENV[name]|
-      next if !dir
+    ['TMPDIR', 'TMP', 'TEMP', ['system temporary path', SYSTMPDIR], ['/tmp']*2, ['.']*2].find do |name, dir|
+      unless dir
+        next if !(dir = ENV[name] rescue next) or dir.empty?
+      end
       dir = File.expand_path(dir)
       stat = File.stat(dir) rescue next
       case
@@ -32,16 +41,18 @@ class Dir
       when stat.world_writable? && !stat.sticky?
         warn "#{name} is world-writable: #{dir}"
       else
-        tmp = dir
-        break
+        break dir
       end
-    end
-    raise ArgumentError, "could not find a temporary directory" unless tmp
-    tmp
+    end or raise ArgumentError, "could not find a temporary directory"
   end
 
   # 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.
   #
@@ -69,7 +80,7 @@ class Dir
   #
   #  Dir.mktmpdir {|dir|
   #    # use the directory...
-  #    open("#{dir}/foo", "w") { ... }
+  #    open("#{dir}/foo", "w") { something using the file }
   #  }
   #
   # If a block is not given,
@@ -79,7 +90,7 @@ class Dir
   #  dir = Dir.mktmpdir
   #  begin
   #    # use the directory...
-  #    open("#{dir}/foo", "w") { ... }
+  #    open("#{dir}/foo", "w") { something using the file }
   #  ensure
   #    # remove the directory.
   #    FileUtils.remove_entry dir
@@ -96,9 +107,10 @@ class Dir
         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
@@ -108,6 +120,7 @@ class Dir
     end
   end
 
+  # Temporary name generator
   module Tmpname # :nodoc:
     module_function
 
@@ -115,16 +128,24 @@ class Dir
       Dir.tmpdir
     end
 
+    # Unusable characters as path name
     UNUSABLE_CHARS = "^,-.0-9A-Z_a-z~"
 
-    class << (RANDOM = Random.new)
+    # Dedicated random number generator
+    RANDOM = Object.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)
+        (::Random.urandom(4).unpack1("L")%MAX).to_s(36)
       end
     end
+    RANDOM.freeze
     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()
@@ -146,7 +167,7 @@ class Dir
         n ||= 0
         n += 1
         retry if !max_try or n < max_try
-        raise "cannot generate temporary name using `#{basename}' under `#{tmpdir}'"
+        raise "cannot generate temporary name using '#{basename}' under '#{tmpdir}'"
       end
       path
     end