From 704d91fc7c01241c6c4a8c841dc81344f81ae3bc Mon Sep 17 00:00:00 2001
From: Aleksa Sarai <asarai@suse.de>
Date: Sat, 12 Nov 2016 01:48:17 +1100
Subject: [PATCH] keywords: safely encode symlink keywords

symlink(2) is a very dumb syscall, and allows you to put any damn value
you please inside a symlink. In addition, spaces are valid path
characters which causes issues with keyword parsing. So use Vis() and
Unvis() to safely store an encoded version of the path.

This also adds a cli test for this behaviour.

Signed-off-by: Aleksa Sarai <asarai@suse.de>
---
 keywords.go      | 12 ++++++++++--
 tar.go           |  6 +++++-
 test/cli/0002.sh | 24 ++++++++++++++++++++++++
 3 files changed, 39 insertions(+), 3 deletions(-)
 create mode 100644 test/cli/0002.sh

diff --git a/keywords.go b/keywords.go
index 3faad1d..cfaadb0 100644
--- a/keywords.go
+++ b/keywords.go
@@ -297,7 +297,11 @@ var (
 	linkKeywordFunc = func(path string, info os.FileInfo, r io.Reader) (string, error) {
 		if sys, ok := info.Sys().(*tar.Header); ok {
 			if sys.Linkname != "" {
-				return fmt.Sprintf("link=%s", sys.Linkname), nil
+				linkname, err := Vis(sys.Linkname)
+				if err != nil {
+					return "", err
+				}
+				return fmt.Sprintf("link=%s", linkname), nil
 			}
 			return "", nil
 		}
@@ -307,7 +311,11 @@ var (
 			if err != nil {
 				return "", err
 			}
-			return fmt.Sprintf("link=%s", str), nil
+			linkname, err := Vis(str)
+			if err != nil {
+				return "", err
+			}
+			return fmt.Sprintf("link=%s", linkname), nil
 		}
 		return "", nil
 	}
diff --git a/tar.go b/tar.go
index 0225b8b..8b8b034 100644
--- a/tar.go
+++ b/tar.go
@@ -129,7 +129,11 @@ func (ts *tarStream) readHeaders() {
 				log.Println(err)
 				break
 			}
-			linkname := KeyVal(kv).Value()
+			linkname, err := Unvis(KeyVal(kv).Value())
+			if err != nil {
+				log.Println(err)
+				break
+			}
 			if _, ok := ts.hardlinks[linkname]; !ok {
 				ts.hardlinks[linkname] = []string{hdr.Name}
 			} else {
diff --git a/test/cli/0002.sh b/test/cli/0002.sh
new file mode 100644
index 0000000..5bf9a40
--- /dev/null
+++ b/test/cli/0002.sh
@@ -0,0 +1,24 @@
+#!/bin/bash
+set -e
+
+name=$(basename $0)
+root=$1
+gomtree=$(readlink -f ${root}/gomtree)
+t=$(mktemp -d /tmp/go-mtree.XXXXXX)
+
+echo "[${name}] Running in ${t}"
+# This test is for basic running check of manifest, and check against tar and file system
+#
+
+pushd ${root}
+
+# Create a symlink with spaces in the entries.
+mkdir ${t}/root
+ln -s "this is a dummy symlink" ${t}/root/link
+
+# Create manifest and check it against the same symlink.
+${gomtree} -K link,sha256digest -c -p ${t}/root > ${t}/root.mtree
+${gomtree} -K link,sha256digest -f ${t}/root.mtree -p ${t}/root
+
+popd
+rm -rf ${t}