Detect if file that appears to be text in the first 1024 bytes is actually binary afer loading all datadm-blob-binaryness-change

3 files changed, 22 insertions, 13 deletions

diff --git a/app/models/blob.rb b/app/models/blob.rb
index 3869e79ba75..954d4e4d779 100644
--- a/app/models/blob.rb
+++ b/app/models/blob.rb
@@ -191,9 +191,12 @@ class Blob < SimpleDelegator
     rendered_as_text? && rich_viewer
   end
 
+  def expanded?
+    !!@expanded
+  end
+
   def expand!
-    simple_viewer&.expanded = true
-    rich_viewer&.expanded = true
+    @expanded = true
   end
 
   private
diff --git a/app/models/blob_viewer/base.rb b/app/models/blob_viewer/base.rb
index d2aa33d994e..35965d01692 100644
--- a/app/models/blob_viewer/base.rb
+++ b/app/models/blob_viewer/base.rb
@@ -6,15 +6,15 @@ module BlobViewer
 
     self.loading_partial_name = 'loading'
 
-    delegate :partial_path, :loading_partial_path, :rich?, :simple?, :text?, :binary?, to: :class
+    delegate :partial_path, :loading_partial_path, :rich?, :simple?, :load_async?, :text?, :binary?, to: :class
 
     attr_reader :blob
-    attr_accessor :expanded
 
     delegate :project, to: :blob
 
     def initialize(blob)
       @blob = blob
+      @initially_binary = blob.binary?
     end
 
     def self.partial_path
@@ -57,14 +57,10 @@ module BlobViewer
       false
     end
 
-    def load_async?
-      self.class.load_async? && render_error.nil?
-    end
-
     def collapsed?
       return @collapsed if defined?(@collapsed)
 
-      @collapsed = !expanded && collapse_limit && blob.raw_size > collapse_limit
+      @collapsed = !blob.expanded? && collapse_limit && blob.raw_size > collapse_limit
     end
 
     def too_large?
@@ -73,6 +69,10 @@ module BlobViewer
       @too_large = size_limit && blob.raw_size > size_limit
     end
 
+    def binary_detected_after_load?
+      !@initially_binary && blob.binary?
+    end
+
     # This method is used on the server side to check whether we can attempt to
     # render the blob at all. Human-readable error messages are found in the
     # `BlobHelper#blob_render_error_reason` helper.
diff --git a/app/views/projects/blob/_viewer.html.haml b/app/views/projects/blob/_viewer.html.haml
index 4252f27d007..013f1c267c8 100644
--- a/app/views/projects/blob/_viewer.html.haml
+++ b/app/views/projects/blob/_viewer.html.haml
@@ -1,13 +1,19 @@
 - hidden = local_assigns.fetch(:hidden, false)
 - render_error = viewer.render_error
-- load_async = local_assigns.fetch(:load_async, viewer.load_async?)
+- load_async = local_assigns.fetch(:load_async, viewer.load_async? && render_error.nil?)
 
 - viewer_url = local_assigns.fetch(:viewer_url) { url_for(params.merge(viewer: viewer.type, format: :json)) } if load_async
 .blob-viewer{ data: { type: viewer.type, url: viewer_url }, class: ('hidden' if hidden) }
-  - if load_async
-    = render viewer.loading_partial_path, viewer: viewer
-  - elsif render_error
+  - if render_error
     = render 'projects/blob/render_error', viewer: viewer
+  - elsif load_async
+    = render viewer.loading_partial_path, viewer: viewer
   - else
     - viewer.prepare!
+
+    -# In the rare case where the first kilobyte of the file looks like text,
+    -# but the file turns out to actually be binary after loading all data,
+    -# we fall back on the binary Download viewer.
+    - viewer = BlobViewer::Download.new(viewer.blob) if viewer.binary_detected_after_load?
+
     = render viewer.partial_path, viewer: viewer