Merge pull request #8504 from chrisroberts/fix/win-unc-paths

Do not prefix Windows paths if UNC prefix already exists

lib/vagrant/util/platform.rb

@@ -188,11 +188,16 @@ module Vagrant
         def windows_unc_path(path)
           path = path.gsub("/", "\\")
 
-          # If the path is just a drive letter, then return that as-is
-          return path + "\\" if path =~ /^[a-zA-Z]:\\?$/
-
           # Convert to UNC path
-          "\\\\?\\" + path.gsub("/", "\\")
+          if path =~ /^[a-zA-Z]:\\?$/
+            # If the path is just a drive letter, then return that as-is
+            path + "\\"
+          elsif path.start_with?("\\\\")
+            # If the path already starts with `\\` assume UNC and return as-is
+            path
+          else
+            "\\\\?\\" + path.gsub("/", "\\")
+          end
         end
 
         # Returns a boolean noting whether the terminal supports color.

test/unit/vagrant/util/platform_test.rb

@@ -55,5 +55,13 @@ describe Vagrant::Util::Platform do
     it "correctly converts a path" do
       expect(described_class.windows_unc_path("c:/foo").to_s).to eql("\\\\?\\c:\\foo")
     end
+
+    context "when given a UNC path" do
+      let(:unc_path){ "\\\\srvname\\path" }
+
+      it "should not modify the path" do
+        expect(described_class.windows_unc_path(unc_path).to_s).to eql(unc_path)
+      end
+    end
   end
 end