From 4f0f038e0bfc54b4eb58b4958ec5661be5c1677f Mon Sep 17 00:00:00 2001
From: Jesse Hallam <jesse.hallam@gmail.com>
Date: Tue, 25 May 2021 22:00:57 -0300
Subject: [PATCH] MM-35945: handle lots of files in ExtractTarGz (#17669)

* MM-35945: handle lots of files in ExtractTarGz

`ExtractTarGz` can fail on archives with a largish number or files, complaining about too many open file handles. Clean up as we go to avoid this.

Fixes: https://mattermost.atlassian.net/browse/MM-35945

* use closure to allow defer
---
 app/extract_plugin_tar.go      | 18 +++++++++++++-----
 app/extract_plugin_tar_test.go | 18 ++++++++++++++++++
 2 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/app/extract_plugin_tar.go b/app/extract_plugin_tar.go
index b81a4552cb..65c8646a7e 100644
--- a/app/extract_plugin_tar.go
+++ b/app/extract_plugin_tar.go
@@ -68,12 +68,20 @@ func extractTarGz(gzipStream io.Reader, dst string) error {
 				return err
 			}
 
-			outFile, err := os.OpenFile(path, os.O_RDWR|os.O_CREATE|os.O_TRUNC, os.FileMode(header.Mode))
-			if err != nil {
-				return err
+			copyFile := func() error {
+				outFile, err := os.OpenFile(path, os.O_RDWR|os.O_CREATE|os.O_TRUNC, os.FileMode(header.Mode))
+				if err != nil {
+					return err
+				}
+				defer outFile.Close()
+				if _, err := io.Copy(outFile, tarReader); err != nil {
+					return err
+				}
+
+				return nil
 			}
-			defer outFile.Close()
-			if _, err := io.Copy(outFile, tarReader); err != nil {
+
+			if err := copyFile(); err != nil {
 				return err
 			}
 		}
diff --git a/app/extract_plugin_tar_test.go b/app/extract_plugin_tar_test.go
index 8fba0ef4d7..3cacff7272 100644
--- a/app/extract_plugin_tar_test.go
+++ b/app/extract_plugin_tar_test.go
@@ -72,6 +72,24 @@ func TestExtractTarGz(t *testing.T) {
 		require.Error(t, err)
 	})
 
+	t.Run("huge tar", func(t *testing.T) {
+		files := make([]*tar.Header, 0, 10000)
+		for i := 0; i < 10000; i++ {
+			files = append(files, &tar.Header{
+				Name:     fmt.Sprintf("%d.txt", i),
+				Typeflag: tar.TypeReg,
+			})
+		}
+
+		dst, err := ioutil.TempDir("", "TestExtractTarGz")
+		require.NoError(t, err)
+		defer os.RemoveAll(dst)
+
+		archive := makeArchive(t, files)
+		err = extractTarGz(&archive, dst)
+		require.NoError(t, err)
+	})
+
 	testCases := []struct {
 		Files         []*tar.Header
 		ExpectedError bool