1 files changed, 71 insertions, 0 deletions
diff --git a/lib/gitlab/ci/artifact_file_reader.rb b/lib/gitlab/ci/artifact_file_reader.rb
new file mode 100644
index 00000000000..c2d17cc176e
--- /dev/null
+++ b/lib/gitlab/ci/artifact_file_reader.rb
@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+# This class takes in input a Ci::Build object and an artifact path to read.
+# It downloads and extracts the artifacts archive, then returns the content
+# of the artifact, if found.
+module Gitlab
+  module Ci
+    class ArtifactFileReader
+      Error = Class.new(StandardError)
+
+      MAX_ARCHIVE_SIZE = 5.megabytes
+
+      def initialize(job)
+        @job = job
+
+        raise ArgumentError, 'Job does not have artifacts' unless @job.artifacts?
+
+        validate!
+      end
+
+      def read(path)
+        return unless job.artifacts_metadata
+
+        metadata_entry = job.artifacts_metadata_entry(path)
+
+        if metadata_entry.total_size > MAX_ARCHIVE_SIZE
+          raise Error, "Artifacts archive for job `#{job.name}` is too large: max #{max_archive_size_in_mb}"
+        end
+
+        read_zip_file!(path)
+      end
+
+      private
+
+      attr_reader :job
+
+      def validate!
+        if job.job_artifacts_archive.size > MAX_ARCHIVE_SIZE
+          raise Error, "Artifacts archive for job `#{job.name}` is too large: max #{max_archive_size_in_mb}"
+        end
+
+        unless job.artifacts_metadata?
+          raise Error, "Job `#{job.name}` has missing artifacts metadata and cannot be extracted!"
+        end
+      end
+
+      def read_zip_file!(file_path)
+        job.artifacts_file.use_file do |archive_path|
+          Zip::File.open(archive_path) do |zip_file|
+            entry = zip_file.find_entry(file_path)
+            unless entry
+              raise Error, "Path `#{file_path}` does not exist inside the `#{job.name}` artifacts archive!"
+            end
+
+            if entry.name_is_directory?
+              raise Error, "Path `#{file_path}` was expected to be a file but it was a directory!"
+            end
+
+            zip_file.get_input_stream(entry) do |is|
+              is.read
+            end
+          end
+        end
+      end
+
+      def max_archive_size_in_mb
+        ActiveSupport::NumberHelper.number_to_human_size(MAX_ARCHIVE_SIZE)
+      end
+    end
+  end
+end