core: can't add boxes from network shares [GH-3279]

CHANGELOG.md

@@ -13,6 +13,7 @@ BUG FIXES:
       fail [GH-3391]
   - core: `vagrant` on Windows cmd.exe doesn't always exit with exit
       code zero. [GH-3420]
+  - core: Adding a box from a network share has nice error on Windows. [GH-3279]
   - commands/package: Nice error if includes contain symlinks. [GH-3200]
   - commands/rsync-auto: Don't crash if the machine can't be communicated
       to. [GH-3419]

lib/vagrant/action/builtin/box_add.rb

@@ -41,6 +41,12 @@ module Vagrant
             # Expand the path and try to use that, if possible
             p = File.expand_path(URI.unescape(u.gsub(/^file:\/\//, "")))
             p = Util::Platform.cygwin_windows_path(p)
+
+            # If this is a network share on Windows then show the user an error
+            if Util::Platform.windows? && (p.start_with?("//") || p.start_with?("\\\\"))
+              raise Errors::BoxUrlIsNetworkShare, url: p
+            end
+
             next "file://#{URI.escape(p.gsub("\\", "/"))}" if File.file?(p)
 
             u

lib/vagrant/errors.rb

@@ -232,6 +232,10 @@ module Vagrant
       error_key(:box_update_no_metadata)
     end
 
+    class BoxUrlIsNetworkShare < VagrantError
+      error_key(:box_url_is_network_share)
+    end
+
     class BoxVerificationFailed < VagrantError
       error_key(:failed, "vagrant.actions.box.verify")
     end

templates/locales/en.yml

@@ -495,6 +495,13 @@ en:
         directly instead of from a box catalog. Vagrant can only
         check the versions of boxes that were added from a catalog
         such as from the public Vagrant Server.
+      box_url_is_network_share: |-
+        You specified a network share path as a path to add a box. Vagrant
+        current doesn't support network share URLs. Please copy the file
+        from the network share to your local machine, then add it from
+        there.
+
+        URL: %{url}
       bundler_disabled: |-
         Vagrant's built-in bundler management mechanism is disabled because
         Vagrant is running in an external bundler environment. In these