Allow browsing branches that end with '.atom'

We need to do two things to support this:

1. Simplify the regex capture in the routing for the CommitsController
   to not exclude the '.atom' suffix. That's a perfectly valid git
   branch name, so we shouldn't blow up if we get it.
2. Because Rails now can't automatically detect the request format, add
   some code to do so in `ExtractPath` when there is no path. This means
   that, given branches 'foo' and 'foo.atom', the Atom feed for the
   former is unroutable. To fix this: don't do that! Give the branches
   different names!

1 files changed, 31 insertions, 2 deletions

diff --git a/lib/extracts_path.rb b/lib/extracts_path.rb
index a4558d157c0..e4d996a3fb6 100644
--- a/lib/extracts_path.rb
+++ b/lib/extracts_path.rb
@@ -52,8 +52,7 @@ module ExtractsPath
       # Append a trailing slash if we only get a ref and no file path
       id += '/' unless id.ends_with?('/')
 
-      valid_refs = @project.repository.ref_names
-      valid_refs.select! { |v| id.start_with?("#{v}/") }
+      valid_refs = ref_names.select { |v| id.start_with?("#{v}/") }
 
       if valid_refs.length == 0
         # No exact ref match, so just try our best
@@ -74,6 +73,19 @@ module ExtractsPath
     pair
   end
 
+  # If we have an ID of 'foo.atom', and the controller provides Atom and HTML
+  # formats, then we have to check if the request was for the Atom version of
+  # the ID without the '.atom' suffix, or the HTML version of the ID including
+  # the suffix. We only check this if the version including the suffix doesn't
+  # match, so it is possible to create a branch which has an unroutable Atom
+  # feed.
+  def extract_ref_without_atom(id)
+    id_without_atom = id.sub(/\.atom$/, '')
+    valid_refs = ref_names.select { |v| "#{id_without_atom}/".start_with?("#{v}/") }
+
+    valid_refs.max_by(&:length)
+  end
+
   # Assigns common instance variables for views working with Git tree-ish objects
   #
   # Assignments are:
@@ -86,6 +98,10 @@ module ExtractsPath
   # If the :id parameter appears to be requesting a specific response format,
   # that will be handled as well.
   #
+  # If there is no path and the ref doesn't exist in the repo, try to resolve
+  # the ref without an '.atom' suffix. If _that_ ref is found, set the request's
+  # format to Atom manually.
+  #
   # Automatically renders `not_found!` if a valid tree path could not be
   # resolved (e.g., when a user inserts an invalid path or ref).
   def assign_ref_vars
@@ -103,6 +119,13 @@ module ExtractsPath
       @commit = @repo.commit(@options[:extended_sha1])
     end
 
+    if @path.empty? && !@commit
+      @id = @ref = extract_ref_without_atom(@id)
+      @commit = @repo.commit(@ref)
+
+      request.format = :atom if @commit
+    end
+
     raise InvalidPathError unless @commit
 
     @hex_path = Digest::SHA1.hexdigest(@path)
@@ -125,4 +148,10 @@ module ExtractsPath
     id += "/" + params[:path] unless params[:path].blank?
     id
   end
+
+  def ref_names
+    return [] unless @project
+
+    @ref_names ||= @project.repository.ref_names
+  end
 end