From c1c5dca31cad917756d0f4da8f2fc3831305cd6a Mon Sep 17 00:00:00 2001
From: Johan Euphrosine <proppy@google.com>
Date: Fri, 16 May 2014 12:15:21 -0700
Subject: [PATCH 1/3] archive: simplify DetectCompression

Docker-DCO-1.1-Signed-off-by: Johan Euphrosine <proppy@google.com> (github: proppy)
Upstream-commit: 3118952e0a63b42b830fc846a56b891d14902976
Component: engine
---
 components/engine/archive/archive.go | 16 +---------------
 1 file changed, 1 insertion(+), 15 deletions(-)

diff --git a/components/engine/archive/archive.go b/components/engine/archive/archive.go
index 5d29ce8193..c72849097b 100644
--- a/components/engine/archive/archive.go
+++ b/components/engine/archive/archive.go
@@ -42,26 +42,12 @@ const (
 )
 
 func DetectCompression(source []byte) Compression {
-	sourceLen := len(source)
 	for compression, m := range map[Compression][]byte{
 		Bzip2: {0x42, 0x5A, 0x68},
 		Gzip:  {0x1F, 0x8B, 0x08},
 		Xz:    {0xFD, 0x37, 0x7A, 0x58, 0x5A, 0x00},
 	} {
-		fail := false
-		if len(m) > sourceLen {
-			utils.Debugf("Len too short")
-			continue
-		}
-		i := 0
-		for _, b := range m {
-			if b != source[i] {
-				fail = true
-				break
-			}
-			i++
-		}
-		if !fail {
+		if bytes.Compare(m, source[:len(m)]) == 0 {
 			return compression
 		}
 	}

From 1976c1713ab1680217fbf6a1567719ac584a1c9c Mon Sep 17 00:00:00 2001
From: Johan Euphrosine <proppy@google.com>
Date: Fri, 16 May 2014 12:47:50 -0700
Subject: [PATCH 2/3] archive: fix panic if len(source) < len(m)

Docker-DCO-1.1-Signed-off-by: Johan Euphrosine <proppy@google.com> (github: proppy)
Upstream-commit: 67ce59a806007cd28d96fd11208c4a113d1b92e0
Component: engine
---
 components/engine/archive/archive.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/components/engine/archive/archive.go b/components/engine/archive/archive.go
index c72849097b..1eda6c2de9 100644
--- a/components/engine/archive/archive.go
+++ b/components/engine/archive/archive.go
@@ -47,6 +47,10 @@ func DetectCompression(source []byte) Compression {
 		Gzip:  {0x1F, 0x8B, 0x08},
 		Xz:    {0xFD, 0x37, 0x7A, 0x58, 0x5A, 0x00},
 	} {
+		if len(source) < len(m) {
+			utils.Debugf("Len too short")
+			continue
+		}
 		if bytes.Compare(m, source[:len(m)]) == 0 {
 			return compression
 		}

From 25b0a0131ed255a034ed1c7c554db6251f7cc05c Mon Sep 17 00:00:00 2001
From: Johan Euphrosine <proppy@google.com>
Date: Fri, 16 May 2014 16:26:28 -0700
Subject: [PATCH 3/3] archive: add missing bytes package

Docker-DCO-1.1-Signed-off-by: Johan Euphrosine <proppy@google.com> (github: proppy)
Upstream-commit: 4a3aefbb5232433098c9d27423a10031eb17ff93
Component: engine
---
 components/engine/archive/archive.go | 1 +
 1 file changed, 1 insertion(+)

diff --git a/components/engine/archive/archive.go b/components/engine/archive/archive.go
index 1eda6c2de9..160ea0737e 100644
--- a/components/engine/archive/archive.go
+++ b/components/engine/archive/archive.go
@@ -2,6 +2,7 @@ package archive
 
 import (
 	"bufio"
+	"bytes"
 	"compress/bzip2"
 	"compress/gzip"
 	"errors"