From a4b445d2e9d609c431e38297a60e8f338816e445 Mon Sep 17 00:00:00 2001
From: Michael Crosby <crosbymichael@gmail.com>
Date: Mon, 8 Dec 2014 15:04:34 -0800
Subject: [PATCH] Flush stdin from within chroot archive

This makes sure that we don't buffer in memory and that we also flush
stdin from diff as well as untar.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
Upstream-commit: d1535131d259bb8a980770d47c0865a1be4373e3
Component: engine
---
 components/engine/pkg/chrootarchive/archive.go   |  5 +----
 .../engine/pkg/chrootarchive/archive_test.go     | 16 ++++++++++++++++
 components/engine/pkg/chrootarchive/diff.go      |  1 +
 components/engine/pkg/chrootarchive/init.go      |  8 ++++++++
 4 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/components/engine/pkg/chrootarchive/archive.go b/components/engine/pkg/chrootarchive/archive.go
index 8d139fa857..2942d9d6c0 100644
--- a/components/engine/pkg/chrootarchive/archive.go
+++ b/components/engine/pkg/chrootarchive/archive.go
@@ -6,7 +6,6 @@ import (
 	"flag"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
 	"runtime"
 	"strings"
@@ -35,9 +34,7 @@ func untar() {
 		fatal(err)
 	}
 	// fully consume stdin in case it is zero padded
-	if _, err := ioutil.ReadAll(os.Stdin); err != nil {
-		fatal(err)
-	}
+	flush(os.Stdin)
 	os.Exit(0)
 }
 
diff --git a/components/engine/pkg/chrootarchive/archive_test.go b/components/engine/pkg/chrootarchive/archive_test.go
index 8477c0676f..0fe3d64f95 100644
--- a/components/engine/pkg/chrootarchive/archive_test.go
+++ b/components/engine/pkg/chrootarchive/archive_test.go
@@ -83,3 +83,19 @@ func TestChrootUntarEmptyArchiveFromSlowReader(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestChrootApplyEmptyArchiveFromSlowReader(t *testing.T) {
+	tmpdir, err := ioutil.TempDir("", "docker-TestChrootApplyEmptyArchiveFromSlowReader")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(tmpdir)
+	dest := filepath.Join(tmpdir, "dest")
+	if err := os.MkdirAll(dest, 0700); err != nil {
+		t.Fatal(err)
+	}
+	stream := &slowEmptyTarReader{size: 10240, chunkSize: 1024}
+	if err := ApplyLayer(dest, stream); err != nil {
+		t.Fatal(err)
+	}
+}
diff --git a/components/engine/pkg/chrootarchive/diff.go b/components/engine/pkg/chrootarchive/diff.go
index 2653aefe9d..f9f9b9d5e0 100644
--- a/components/engine/pkg/chrootarchive/diff.go
+++ b/components/engine/pkg/chrootarchive/diff.go
@@ -32,6 +32,7 @@ func applyLayer() {
 		fatal(err)
 	}
 	os.RemoveAll(tmpDir)
+	flush(os.Stdin)
 	os.Exit(0)
 }
 
diff --git a/components/engine/pkg/chrootarchive/init.go b/components/engine/pkg/chrootarchive/init.go
index b548e9fe72..4116026eff 100644
--- a/components/engine/pkg/chrootarchive/init.go
+++ b/components/engine/pkg/chrootarchive/init.go
@@ -2,6 +2,8 @@ package chrootarchive
 
 import (
 	"fmt"
+	"io"
+	"io/ioutil"
 	"os"
 
 	"github.com/docker/docker/pkg/reexec"
@@ -16,3 +18,9 @@ func fatal(err error) {
 	fmt.Fprint(os.Stderr, err)
 	os.Exit(1)
 }
+
+// flush consumes all the bytes from the reader discarding
+// any errors
+func flush(r io.Reader) {
+	io.Copy(ioutil.Discard, r)
+}