CHEF-5322: Add utility for validating Windows paths

1 files changed, 94 insertions, 0 deletions

diff --git a/lib/chef/util/path_helper.rb b/lib/chef/util/path_helper.rb
new file mode 100644
index 0000000000..534a9087ae
--- /dev/null
+++ b/lib/chef/util/path_helper.rb
@@ -0,0 +1,94 @@
+#
+# Author:: Bryan McLellan <btm@loftninjas.org>
+# Copyright:: Copyright (c) 2014 Chef Software, Inc.
+# License:: Apache License, Version 2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+require 'chef/platform'
+require 'chef/exceptions'
+
+class Chef
+  class Util
+    class PathHelper
+      # Maximum characters in a standard Windows path (260 including drive letter and NUL)
+      WIN_MAX_PATH = 259
+
+      def self.validate_path(path)
+        if Chef::Platform.windows?
+          unless printable?(path)
+            msg = "Path '#{path}' contains non-printable characters. Check that backslashes are escaped with another backslash (e.g. C:\\\\Windows) in double-quoted strings."
+            Chef::Log.error(msg)
+            raise Chef::Exceptions::ValidationFailed, msg
+          end
+            
+          if windows_max_length_exceeded?(path)
+            Chef::Log.debug("Path '#{path}' is longer than #{WIN_MAX_PATH}, prefixing with'\\\\?\\'")
+            path.insert(0, "\\\\?\\")
+          end
+        end
+
+        path
+      end
+
+      def self.windows_max_length_exceeded?(path)
+        # Check to see if paths without the \\?\ prefix are over the maximum allowed length for the Windows API
+        # http://msdn.microsoft.com/en-us/library/windows/desktop/aa365247%28v=vs.85%29.aspx
+        unless path =~ /^\\\\?\\/
+          if path.length > WIN_MAX_PATH
+            return true
+          end
+        end
+        
+        false
+      end
+
+      def self.printable?(string)
+        # returns true if string is free of non-printable characters (escape sequences)
+        # this returns false for whitespace escape sequences as well, e.g. \n\t
+        if string =~ /[^[:print:]]/
+          false
+        else
+          true
+        end
+      end
+
+      # Produces a comparable path.
+      def self.canonical_path(path, add_prefix=true)
+        # Rather than find an equivalent for File.absolute_path on 1.8.7, just bail out
+        raise NotImplementedError, "This feature is not supported on Ruby versions < 1.9" if RUBY_VERSION.to_f < 1.9
+
+        # First remove extra separators and resolve any relative paths
+        abs_path = File.absolute_path(path)
+
+        if Chef::Platform.windows?
+          # Add the \\?\ API prefix on Windows unless add_prefix is false
+          # Downcase on Windows where paths are still case-insensitive
+          abs_path.gsub!(::File::SEPARATOR, ::File::ALT_SEPARATOR)
+          if add_prefix && abs_path !~ /^\\\\?\\/
+            abs_path.insert(0, "\\\\?\\")
+          end
+
+          abs_path.downcase!
+        end
+
+        abs_path
+      end
+
+      def self.paths_eql?(path1, path2)
+        canonical_path(path1) == canonical_path(path2)
+      end
+    end
+  end
+end