From 4e7bc74874564852990663e39773183c07b5ca22 Mon Sep 17 00:00:00 2001
From: Rick Olson <technoweenie@gmail.com>
Date: Fri, 25 Sep 2015 15:39:02 -0600
Subject: [PATCH] Better handling for tiny files below the blob size threshold
 that contain 'git-lfs'

---
 lfs/errors.go       | 32 ++++++++++++++++++++++++++++++++
 lfs/pointer.go      |  8 +++++++-
 lfs/pointer_test.go | 13 +++++++++++++
 test/test-pull.sh   |  3 ---
 test/test-smudge.sh |  1 +
 5 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/lfs/errors.go b/lfs/errors.go
index dd89a6cf..86e6a203 100644
--- a/lfs/errors.go
+++ b/lfs/errors.go
@@ -162,6 +162,19 @@ func IsNotAPointerError(err error) bool {
 	return false
 }
 
+// IsBadPointerKeyError indicates that the parsed data has an invalid key.
+func IsBadPointerKeyError(err error) bool {
+	if e, ok := err.(interface {
+		BadPointerKeyError() bool
+	}); ok {
+		return e.BadPointerKeyError()
+	}
+	if e, ok := err.(errorWrapper); ok {
+		return IsBadPointerKeyError(e.InnerError())
+	}
+	return false
+}
+
 // IsDownloadDeclinedError indicates that the smudge operation should not download.
 // TODO: I don't really like using errors to control that flow, it should be refactored.
 func IsDownloadDeclinedError(err error) bool {
@@ -483,6 +496,25 @@ func newNotAPointerError(err error) error {
 	return notAPointerError{newWrappedError(err, "Not a valid Git LFS pointer file.")}
 }
 
+type badPointerKeyError struct {
+	Expected string
+	Actual   string
+	errorWrapper
+}
+
+func (e badPointerKeyError) InnerError() error {
+	return e.errorWrapper
+}
+
+func (e badPointerKeyError) BadPointerKeyError() bool {
+	return true
+}
+
+func newBadPointerKeyError(expected, actual string) error {
+	err := fmt.Errorf("Error parsing LFS Pointer. Expected key %s, got %s", expected, actual)
+	return badPointerKeyError{expected, actual, newWrappedError(err, "")}
+}
+
 // Definitions for IsDownloadDeclinedError()
 
 type downloadDeclinedError struct {
diff --git a/lfs/pointer.go b/lfs/pointer.go
index 1b129d68..400a9097 100644
--- a/lfs/pointer.go
+++ b/lfs/pointer.go
@@ -131,6 +131,12 @@ func verifyVersion(version string) error {
 func decodeKV(data []byte) (*Pointer, error) {
 	kvps, exts, err := decodeKVData(data)
 	if err != nil {
+		if IsBadPointerKeyError(err) {
+			badErr := err.(badPointerKeyError)
+			if badErr.Expected == "version" {
+				return nil, newNotAPointerError(err)
+			}
+		}
 		return nil, err
 	}
 
@@ -252,7 +258,7 @@ func decodeKVData(data []byte) (kvps map[string]string, exts map[string]string,
 
 		if expected := pointerKeys[line]; key != expected {
 			if !extRE.Match([]byte(key)) {
-				err = fmt.Errorf("Expected key %s, got %s", expected, key)
+				err = newBadPointerKeyError(expected, key)
 				return
 			}
 			if exts == nil {
diff --git a/lfs/pointer_test.go b/lfs/pointer_test.go
index 862fb0f5..7873b4b4 100644
--- a/lfs/pointer_test.go
+++ b/lfs/pointer_test.go
@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"bytes"
 	"io"
+	"reflect"
 	"strings"
 	"testing"
 
@@ -60,6 +61,18 @@ func assertLine(t *testing.T, r *bufio.Reader, expected string) {
 	assert.Equal(t, expected, actual)
 }
 
+func TestDecodeTinyFile(t *testing.T) {
+	ex := "this is not a git-lfs file!"
+	p, err := DecodePointer(bytes.NewBufferString(ex))
+	if p != nil {
+		t.Errorf("pointer was decoded: %v", p)
+	}
+
+	if !IsNotAPointerError(err) {
+		t.Errorf("error is not a NotAPointerError: %s: '%v'", reflect.TypeOf(err), err)
+	}
+}
+
 func TestDecode(t *testing.T) {
 	ex := `version https://git-lfs.github.com/spec/v1
 oid sha256:4d7a214614ab2935c943f9e0ff69d22eadbb8f32b1258daaa5e2ca24d17e2393
diff --git a/test/test-pull.sh b/test/test-pull.sh
index 66ae31f9..af22b152 100755
--- a/test/test-pull.sh
+++ b/test/test-pull.sh
@@ -69,7 +69,6 @@ begin_test "pull"
   git lfs pull
   [ "a" = "$(cat a.dat)" ]
 
-
   # Test include / exclude filters supplied in gitconfig
   rm -rf .git/lfs/objects
   git config "lfs.fetchinclude" "a*"
@@ -91,8 +90,6 @@ begin_test "pull"
   rm -rf .git/lfs/objects
   git lfs pull --exclude="a*"
   refute_local_object "$contents_oid"
-
-
 )
 end_test
 
diff --git a/test/test-smudge.sh b/test/test-smudge.sh
index 04ab1497..56f3e323 100755
--- a/test/test-smudge.sh
+++ b/test/test-smudge.sh
@@ -44,6 +44,7 @@ begin_test "smudge with invalid pointer"
 
   cd repo
   [ "wat" = "$(echo "wat" | git lfs smudge)" ]
+  [ "not a git-lfs file" = "$(echo "wat" | git lfs smudge)" ]
 )
 end_test