Do something more expected with new file permissions.

Instead of inheriting the permissions from the tmp directory, new files should
have permissions that reflect the defaults on the system taking umask into
account.

It seems that (unix) permissions of 666 - umask are as close to a standard as
anything [1] and that 'touch' uses this. On Windows it seems sensible to just
use 644 directly [2].

[1] http://unix.stackexchange.com/a/102080
[2] http://ruby-doc.org/core-1.9.3/File.html

lib/zip/file.rb

@@ -71,11 +71,12 @@ module Zip
       case
       when !buffer && ::File.size?(file_name)
         @create = nil
-        @exist_file_perms = ::File.stat(file_name).mode
+        @file_permissions = ::File.stat(file_name).mode
         ::File.open(name, 'rb') do |f|
           read_from_stream(f)
         end
       when create
+        @file_permissions = create_file_permissions
         @entry_set = EntrySet.new
       else
         raise Error, "File #{file_name} not found"
@@ -405,7 +406,7 @@ module Zip
       tmpfile.close
       if yield tmp_filename
         ::File.rename(tmp_filename, name)
-        ::File.chmod(@exist_file_perms, name) if defined?(@exist_file_perms)
+        ::File.chmod(@file_permissions, name) if defined?(@file_permissions)
       end
     ensure
       tmpfile.unlink if tmpfile
@@ -416,6 +417,10 @@ module Zip
       temp_file.binmode
       temp_file
     end
+
+    def create_file_permissions
+      ::Zip::RUNNING_ON_WINDOWS ? 0644 : 0666 - ::File.umask
+    end
   end
 end
 

test/file_permissions_test.rb

@@ -0,0 +1,69 @@
+require 'test_helper'
+
+class FilePermissionsTest < MiniTest::Test
+
+  FILENAME = File.join(File.dirname(__FILE__), "umask.zip")
+
+  def teardown
+    ::File.unlink(FILENAME)
+  end
+
+  if ::Zip::RUNNING_ON_WINDOWS
+    # Windows tests
+
+    DEFAULT_PERMS = 0644
+
+    def test_windows_perms
+      create_file
+
+      assert_equal DEFAULT_PERMS, ::File.stat(FILENAME).mode
+    end
+
+  else
+    # Unix tests
+
+    DEFAULT_PERMS = 0100666
+
+    def test_current_umask
+      umask = DEFAULT_PERMS - ::File.umask
+      create_file
+
+      assert_equal umask, ::File.stat(FILENAME).mode
+    end
+
+    def test_umask_000
+      set_umask(0000) do
+        create_file
+      end
+
+      assert_equal DEFAULT_PERMS, ::File.stat(FILENAME).mode
+    end
+
+    def test_umask_066
+      umask = 0066
+      set_umask(umask) do
+        create_file
+      end
+
+      assert_equal((DEFAULT_PERMS - umask), ::File.stat(FILENAME).mode)
+    end
+
+  end
+
+  def create_file
+    ::Zip::File.open(FILENAME, ::Zip::File::CREATE) do |zip|
+      zip.comment = "test"
+    end
+  end
+
+  # If anything goes wrong, make sure the umask is restored.
+  def set_umask(umask, &block)
+    begin
+      saved_umask = ::File.umask(umask)
+      yield
+    ensure
+      ::File.umask(saved_umask)
+    end
+  end
+
+end