Merge branch '25301-git-2.11-force-push-bug' into 'master'

changelogs/unreleased/25301-git-2-11-force-push-bug.yml

+---
+title: Accept environment variables from the `pre-receive` script
+merge_request: 7967
+author: 

lib/api/helpers/internal_helpers.rb

@@ -52,6 +52,14 @@ module API
           :push_code
         ]
       end
+
+      def parse_allowed_environment_variables
+        return if params[:env].blank?
+
+        JSON.parse(params[:env])
+
+      rescue JSON::ParserError
+      end
     end
   end
 end

lib/api/internal.rb

@@ -32,7 +32,11 @@ module API
           if wiki?
             Gitlab::GitAccessWiki.new(actor, project, protocol, authentication_abilities: ssh_authentication_abilities)
           else
-            Gitlab::GitAccess.new(actor, project, protocol, authentication_abilities: ssh_authentication_abilities)
+            Gitlab::GitAccess.new(actor,
+                                  project,
+                                  protocol,
+                                  authentication_abilities: ssh_authentication_abilities,
+                                  env: parse_allowed_environment_variables)
           end
 
         access_status = access.check(params[:action], params[:changes])

lib/gitlab/checks/change_access.rb

@@ -3,11 +3,12 @@ module Gitlab
     class ChangeAccess
       attr_reader :user_access, :project
 
-      def initialize(change, user_access:, project:)
+      def initialize(change, user_access:, project:, env: {})
         @oldrev, @newrev, @ref = change.values_at(:oldrev, :newrev, :ref)
         @branch_name = Gitlab::Git.branch_name(@ref)
         @user_access = user_access
         @project = project
+        @env = env
       end
 
       def exec
@@ -68,7 +69,7 @@ module Gitlab
       end
 
       def forced_push?
-        Gitlab::Checks::ForcePush.force_push?(@project, @oldrev, @newrev)
+        Gitlab::Checks::ForcePush.force_push?(@project, @oldrev, @newrev, env: @env)
       end
 
       def matching_merge_request?

lib/gitlab/checks/force_push.rb

 module Gitlab
   module Checks
     class ForcePush
-      def self.force_push?(project, oldrev, newrev)
+      def self.force_push?(project, oldrev, newrev, env: {})
         return false if project.empty_repo?
 
         # Created or deleted branch
         if Gitlab::Git.blank_ref?(oldrev) || Gitlab::Git.blank_ref?(newrev)
           false
         else
-          missed_ref, _ = Gitlab::Popen.popen(%W(#{Gitlab.config.git.bin_path} --git-dir=#{project.repository.path_to_repo} rev-list --max-count=1 #{oldrev} ^#{newrev}))
+          missed_ref, exit_status = Gitlab::Git::RevList.new(oldrev, newrev, project: project, env: env).execute
+
+          if exit_status == 0
             missed_ref.present?
+          else
+            raise "Got a non-zero exit code while calling out to `git rev-list` in the force-push check."
+          end
         end
       end
     end

lib/gitlab/git/rev_list.rb

+module Gitlab
+  module Git
+    class RevList
+      attr_reader :project, :env
+
+      ALLOWED_VARIABLES = %w[GIT_OBJECT_DIRECTORY GIT_ALTERNATE_OBJECT_DIRECTORIES].freeze
+
+      def initialize(oldrev, newrev, project:, env: nil)
+        @project = project
+        @env = env.presence || {}
+        @args = [Gitlab.config.git.bin_path,
+                 "--git-dir=#{project.repository.path_to_repo}",
+                 "rev-list",
+                 "--max-count=1",
+                 oldrev,
+                 "^#{newrev}"]
+      end
+
+      def execute
+        Gitlab::Popen.popen(@args, nil, parse_environment_variables)
+      end
+
+      def valid?
+        environment_variables.all? do |(name, value)|
+          value.start_with?(project.repository.path_to_repo)
+        end
+      end
+
+      private
+
+      def parse_environment_variables
+        return {} unless valid?
+
+        environment_variables
+      end
+
+      def environment_variables
+        @environment_variables ||= env.slice(*ALLOWED_VARIABLES)
+      end
+    end
+  end
+end

lib/gitlab/git_access.rb

@@ -17,12 +17,13 @@ module Gitlab
 
     attr_reader :actor, :project, :protocol, :user_access, :authentication_abilities
 
-    def initialize(actor, project, protocol, authentication_abilities:)
+    def initialize(actor, project, protocol, authentication_abilities:, env: {})
       @actor    = actor
       @project  = project
       @protocol = protocol
       @authentication_abilities = authentication_abilities
       @user_access = UserAccess.new(user, project: project)
+      @env = env
     end
 
     def check(cmd, changes)
@@ -103,7 +104,7 @@ module Gitlab
     end
 
     def change_access_check(change)
-      Checks::ChangeAccess.new(change, user_access: user_access, project: project).exec
+      Checks::ChangeAccess.new(change, user_access: user_access, project: project, env: @env).exec
     end
 
     def protocol_allowed?

lib/gitlab/popen.rb

@@ -5,13 +5,13 @@ module Gitlab
   module Popen
     extend self
 
-    def popen(cmd, path = nil)
+    def popen(cmd, path = nil, vars = {})
       unless cmd.is_a?(Array)
         raise "System commands must be given as an array of strings"
       end
 
       path ||= Dir.pwd
-      vars = { "PWD" => path }
+      vars['PWD'] = path
       options = { chdir: path }
 
       unless File.directory?(path)

spec/lib/gitlab/checks/force_push_spec.rb

+require 'spec_helper'
+
+describe Gitlab::Checks::ChangeAccess, lib: true do
+  let(:project) { create(:project) }
+
+  context "exit code checking" do
+    it "does not raise a runtime error if the `popen` call to git returns a zero exit code" do
+      allow(Gitlab::Popen).to receive(:popen).and_return(['normal output', 0])
+
+      expect { Gitlab::Checks::ForcePush.force_push?(project, 'oldrev', 'newrev') }.not_to raise_error
+    end
+
+    it "raises a runtime error if the `popen` call to git returns a non-zero exit code" do
+      allow(Gitlab::Popen).to receive(:popen).and_return(['error', 1])
+
+      expect { Gitlab::Checks::ForcePush.force_push?(project, 'oldrev', 'newrev') }.to raise_error(RuntimeError)
+    end
+  end
+end

spec/lib/gitlab/git/rev_list_spec.rb

+require 'spec_helper'
+
+describe Gitlab::Git::RevList, lib: true do
+  let(:project) { create(:project) }
+
+  context "validations" do
+    described_class::ALLOWED_VARIABLES.each do |var|
+      context var do
+        it "accepts values starting with the project repo path" do
+          env = { var => "#{project.repository.path_to_repo}/objects" }
+          rev_list = described_class.new('oldrev', 'newrev', project: project, env: env)
+
+          expect(rev_list).to be_valid
+        end
+
+        it "rejects values starting not with the project repo path" do
+          env = { var => "/some/other/path" }
+          rev_list = described_class.new('oldrev', 'newrev', project: project, env: env)
+
+          expect(rev_list).not_to be_valid
+        end
+
+        it "rejects values containing the project repo path but not starting with it" do
+          env = { var => "/some/other/path/#{project.repository.path_to_repo}" }
+          rev_list = described_class.new('oldrev', 'newrev', project: project, env: env)
+
+          expect(rev_list).not_to be_valid
+        end
+      end
+    end
+  end
+
+  context "#execute" do
+    let(:env) { { "GIT_OBJECT_DIRECTORY" => project.repository.path_to_repo } }
+    let(:rev_list) { Gitlab::Git::RevList.new('oldrev', 'newrev', project: project, env: env) }
+
+    it "calls out to `popen` without environment variables if the record is invalid" do
+      allow(rev_list).to receive(:valid?).and_return(false)
+
+      expect(Open3).to receive(:popen3).with(hash_excluding(env), any_args)
+
+      rev_list.execute
+    end
+
+    it "calls out to `popen` with environment variables if the record is valid" do
+      allow(rev_list).to receive(:valid?).and_return(true)
+
+      expect(Open3).to receive(:popen3).with(hash_including(env), any_args)
+
+      rev_list.execute
+    end
+  end
+end