1 files changed, 179 insertions, 0 deletions
diff --git a/app/services/git_operation_service.rb b/app/services/git_operation_service.rb
new file mode 100644
index 00000000000..27bcc047601
--- /dev/null
+++ b/app/services/git_operation_service.rb
@@ -0,0 +1,179 @@
+class GitOperationService
+  attr_reader :user, :repository
+
+  def initialize(new_user, new_repository)
+    @user = new_user
+    @repository = new_repository
+  end
+
+  def add_branch(branch_name, newrev)
+    ref = Gitlab::Git::BRANCH_REF_PREFIX + branch_name
+    oldrev = Gitlab::Git::BLANK_SHA
+
+    update_ref_in_hooks(ref, newrev, oldrev)
+  end
+
+  def rm_branch(branch)
+    ref = Gitlab::Git::BRANCH_REF_PREFIX + branch.name
+    oldrev = branch.target
+    newrev = Gitlab::Git::BLANK_SHA
+
+    update_ref_in_hooks(ref, newrev, oldrev)
+  end
+
+  def add_tag(tag_name, newrev, options = {})
+    ref = Gitlab::Git::TAG_REF_PREFIX + tag_name
+    oldrev = Gitlab::Git::BLANK_SHA
+
+    with_hooks(ref, newrev, oldrev) do |service|
+      # We want to pass the OID of the tag object to the hooks. For an
+      # annotated tag we don't know that OID until after the tag object
+      # (raw_tag) is created in the repository. That is why we have to
+      # update the value after creating the tag object. Only the
+      # "post-receive" hook will receive the correct value in this case.
+      raw_tag = repository.rugged.tags.create(tag_name, newrev, options)
+      service.newrev = raw_tag.target_id
+    end
+  end
+
+  def rm_tag(tag)
+    ref = Gitlab::Git::TAG_REF_PREFIX + tag.name
+    oldrev = tag.target
+    newrev = Gitlab::Git::BLANK_SHA
+
+    update_ref_in_hooks(ref, newrev, oldrev) do
+      repository.rugged.tags.delete(tag_name)
+    end
+  end
+
+  # Whenever `start_branch_name` is passed, if `branch_name` doesn't exist,
+  # it would be created from `start_branch_name`.
+  # If `start_project` is passed, and the branch doesn't exist,
+  # it would try to find the commits from it instead of current repository.
+  def with_branch(
+    branch_name,
+    start_branch_name: nil,
+    start_project: repository.project,
+    &block)
+
+    check_with_branch_arguments!(
+      branch_name, start_branch_name, start_project)
+
+    update_branch_with_hooks(branch_name) do
+      repository.with_repo_branch_commit(
+        start_project.repository,
+        start_branch_name || branch_name,
+        &block)
+    end
+  end
+
+  private
+
+  def update_branch_with_hooks(branch_name)
+    update_autocrlf_option
+
+    was_empty = repository.empty?
+
+    # Make commit
+    newrev = yield
+
+    unless newrev
+      raise Repository::CommitError.new('Failed to create commit')
+    end
+
+    branch = repository.find_branch(branch_name)
+    oldrev = find_oldrev_from_branch(newrev, branch)
+
+    ref = Gitlab::Git::BRANCH_REF_PREFIX + branch_name
+    update_ref_in_hooks(ref, newrev, oldrev)
+
+    # If repo was empty expire cache
+    repository.after_create if was_empty
+    repository.after_create_branch if
+      was_empty || Gitlab::Git.blank_ref?(oldrev)
+
+    newrev
+  end
+
+  def find_oldrev_from_branch(newrev, branch)
+    return Gitlab::Git::BLANK_SHA unless branch
+
+    oldrev = branch.target
+
+    if oldrev == repository.rugged.merge_base(newrev, branch.target)
+      oldrev
+    else
+      raise Repository::CommitError.new('Branch diverged')
+    end
+  end
+
+  def update_ref_in_hooks(ref, newrev, oldrev)
+    with_hooks(ref, newrev, oldrev) do
+      update_ref(ref, newrev, oldrev)
+    end
+  end
+
+  def with_hooks(ref, newrev, oldrev)
+    GitHooksService.new.execute(
+      user,
+      repository.path_to_repo,
+      oldrev,
+      newrev,
+      ref) do |service|
+
+      yield(service)
+    end
+  end
+
+  def update_ref(ref, newrev, oldrev)
+    # We use 'git update-ref' because libgit2/rugged currently does not
+    # offer 'compare and swap' ref updates. Without compare-and-swap we can
+    # (and have!) accidentally reset the ref to an earlier state, clobbering
+    # commits. See also https://github.com/libgit2/libgit2/issues/1534.
+    command = %W[#{Gitlab.config.git.bin_path} update-ref --stdin -z]
+    _, status = Gitlab::Popen.popen(
+      command,
+      repository.path_to_repo) do |stdin|
+      stdin.write("update #{ref}\x00#{newrev}\x00#{oldrev}\x00")
+    end
+
+    unless status.zero?
+      raise Repository::CommitError.new(
+        "Could not update branch #{Gitlab::Git.branch_name(ref)}." \
+        " Please refresh and try again.")
+    end
+  end
+
+  def update_autocrlf_option
+    if repository.raw_repository.autocrlf != :input
+      repository.raw_repository.autocrlf = :input
+    end
+  end
+
+  def check_with_branch_arguments!(
+    branch_name, start_branch_name, start_project)
+    return if repository.branch_exists?(branch_name)
+
+    if repository.project != start_project
+      unless start_branch_name
+        raise ArgumentError,
+          'Should also pass :start_branch_name if' +
+          ' :start_project is different from current project'
+      end
+
+      unless start_project.repository.branch_exists?(start_branch_name)
+        raise ArgumentError,
+          "Cannot find branch #{branch_name} nor" \
+          " #{start_branch_name} from" \
+          " #{start_project.path_with_namespace}"
+      end
+    elsif start_branch_name
+      unless repository.branch_exists?(start_branch_name)
+        raise ArgumentError,
+          "Cannot find branch #{branch_name} nor" \
+          " #{start_branch_name} from" \
+          " #{repository.project.path_with_namespace}"
+      end
+    end
+  end
+end