From 9ddb3b667ce1ed0a66c361ad6767ee72d952ad66 Mon Sep 17 00:00:00 2001
From: Yiran Wang <yiran@uber.com>
Date: Thu, 19 Sep 2019 21:07:41 -0700
Subject: [PATCH 1/3] Fix parsing panic if variables are not defined

---
 lib/parser/dockerfile/base.go      | 3 +++
 lib/parser/dockerfile/copy_test.go | 1 +
 lib/parser/dockerfile/from_test.go | 1 +
 3 files changed, 5 insertions(+)

diff --git a/lib/parser/dockerfile/base.go b/lib/parser/dockerfile/base.go
index 68682b59..83ccb161 100644
--- a/lib/parser/dockerfile/base.go
+++ b/lib/parser/dockerfile/base.go
@@ -70,6 +70,9 @@ func (d *baseDirective) replaceVars(vars map[string]string) error {
 	if err != nil {
 		return d.err(fmt.Errorf("Failed to replace variables in input: %s", err))
 	}
+	if len(replaced) == 0 {
+		return d.err(fmt.Errorf("Empty args after replacing variables: %s", err))
+	}
 	d.Args = replaced
 	return nil
 }
diff --git a/lib/parser/dockerfile/copy_test.go b/lib/parser/dockerfile/copy_test.go
index 01ebfbe8..c4869332 100644
--- a/lib/parser/dockerfile/copy_test.go
+++ b/lib/parser/dockerfile/copy_test.go
@@ -34,6 +34,7 @@ func TestNewCopyDirective(t *testing.T) {
 		chown     string
 	}{
 		{"missing args", false, "copy ", nil, "", "", ""},
+		{"missing args after replace", false, "copy \\", nil, "", "", ""},
 		{"shell single source", true, `copy src dst`, []string{"src"}, "dst", "", ""},
 		{"shell multi source", true, `copy src1 src2 dst`, []string{"src1", "src2"}, "dst", "", ""},
 		{"shell substitution", true, `copy src1 ${prefix}src2 dst$suffix`, []string{"src1", "test_src2"}, "dst_test", "", ""},
diff --git a/lib/parser/dockerfile/from_test.go b/lib/parser/dockerfile/from_test.go
index 0b78a2a7..75dd3d35 100644
--- a/lib/parser/dockerfile/from_test.go
+++ b/lib/parser/dockerfile/from_test.go
@@ -43,6 +43,7 @@ func TestNewFromDirective(t *testing.T) {
 		{"bad 'as'", false, "from test_image:trusty sa test_alias", "", ""},
 		{"substitution", true, "from ${prefix}image:trusty as alias$suffix", "test_image:trusty", "alias_test"},
 		{"bad substitution", false, "from ${prefiximage:trusty as alias$suffix", "", ""},
+		{"empty substitution", false, "from ${0:+0}", "test_image", ""},
 	}
 
 	for _, test := range tests {

From bd5bcb827a13ed3d3c8484f530e4c3390dd028f1 Mon Sep 17 00:00:00 2001
From: Yiran Wang <yiran@uber.com>
Date: Thu, 19 Sep 2019 21:14:42 -0700
Subject: [PATCH 2/3] fix

---
 lib/parser/dockerfile/base.go | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/parser/dockerfile/base.go b/lib/parser/dockerfile/base.go
index 83ccb161..a777d51c 100644
--- a/lib/parser/dockerfile/base.go
+++ b/lib/parser/dockerfile/base.go
@@ -15,6 +15,7 @@
 package dockerfile
 
 import (
+	"errors"
 	"fmt"
 	"regexp"
 	"strings"
@@ -71,7 +72,7 @@ func (d *baseDirective) replaceVars(vars map[string]string) error {
 		return d.err(fmt.Errorf("Failed to replace variables in input: %s", err))
 	}
 	if len(replaced) == 0 {
-		return d.err(fmt.Errorf("Empty args after replacing variables: %s", err))
+		return d.err(errors.New("Empty args after replacing variables: %s"))
 	}
 	d.Args = replaced
 	return nil

From c4b5232f2daebea63a8aa0f19c2057738e25182d Mon Sep 17 00:00:00 2001
From: Yiran Wang <yiran@uber.com>
Date: Thu, 19 Sep 2019 21:15:27 -0700
Subject: [PATCH 3/3] fix

---
 lib/parser/dockerfile/base.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/parser/dockerfile/base.go b/lib/parser/dockerfile/base.go
index a777d51c..cae09019 100644
--- a/lib/parser/dockerfile/base.go
+++ b/lib/parser/dockerfile/base.go
@@ -72,7 +72,7 @@ func (d *baseDirective) replaceVars(vars map[string]string) error {
 		return d.err(fmt.Errorf("Failed to replace variables in input: %s", err))
 	}
 	if len(replaced) == 0 {
-		return d.err(errors.New("Empty args after replacing variables: %s"))
+		return d.err(errors.New("Empty args after replacing variables"))
 	}
 	d.Args = replaced
 	return nil