1 files changed, 36 insertions, 4 deletions

diff --git a/lib/gitlab/gitaly_client/operation_service.rb b/lib/gitlab/gitaly_client/operation_service.rb
index 4637bf2e3ff..d575c0f470d 100644
--- a/lib/gitlab/gitaly_client/operation_service.rb
+++ b/lib/gitlab/gitaly_client/operation_service.rb
@@ -101,6 +101,16 @@ module Gitlab
         if pre_receive_error = response.pre_receive_error.presence
           raise Gitlab::Git::PreReceiveError, pre_receive_error
         end
+      rescue GRPC::BadStatus => e
+        detailed_error = decode_detailed_error(e)
+
+        case detailed_error&.error
+        when :custom_hook
+          raise Gitlab::Git::PreReceiveError.new(custom_hook_error_message(detailed_error.custom_hook),
+                                                 fallback_message: e.details)
+        else
+          raise
+        end
       end
 
       def user_merge_to_ref(user, source_sha:, branch:, target_ref:, message:, first_parent_ref:, allow_conflicts: false)
@@ -163,6 +173,9 @@ module Gitlab
           access_check_error = detailed_error.access_check
           # These messages were returned from internal/allowed API calls
           raise Gitlab::Git::PreReceiveError.new(fallback_message: access_check_error.error_message)
+        when :custom_hook
+          raise Gitlab::Git::PreReceiveError.new(custom_hook_error_message(detailed_error.custom_hook),
+                                                 fallback_message: e.details)
         when :reference_update
           # We simply ignore any reference update errors which are typically an
           # indicator of multiple RPC calls trying to update the same reference
@@ -299,10 +312,6 @@ module Gitlab
           timeout: GitalyClient.long_timeout
         )
 
-        if response.git_error.presence
-          raise Gitlab::Git::Repository::GitError, response.git_error
-        end
-
         response.squash_sha
       rescue GRPC::BadStatus => e
         detailed_error = decode_detailed_error(e)
@@ -464,6 +473,21 @@ module Gitlab
         )
 
         handle_cherry_pick_or_revert_response(response)
+      rescue GRPC::BadStatus => e
+        detailed_error = decode_detailed_error(e)
+
+        case detailed_error&.error
+        when :access_check
+          access_check_error = detailed_error.access_check
+          # These messages were returned from internal/allowed API calls
+          raise Gitlab::Git::PreReceiveError.new(fallback_message: access_check_error.error_message)
+        when :cherry_pick_conflict
+          raise Gitlab::Git::Repository::CreateTreeError, 'CONFLICT'
+        when :target_branch_diverged
+          raise Gitlab::Git::CommitError, 'branch diverged'
+        else
+          raise e
+        end
       end
 
       def handle_cherry_pick_or_revert_response(response)
@@ -526,6 +550,14 @@ module Gitlab
         # Error Class might not be known to ruby yet
         nil
       end
+
+      def custom_hook_error_message(custom_hook_error)
+        # Custom hooks may return messages via either stdout or stderr which have a specific prefix. If
+        # that prefix is present we'll want to print the hook's output, otherwise we'll want to print the
+        # Gitaly error as a fallback.
+        custom_hook_output = custom_hook_error.stderr.presence || custom_hook_error.stdout
+        EncodingHelper.encode!(custom_hook_output)
+      end
     end
   end
 end