Revert "Refactor module-detection to use go/build instead of static file"

This reverts commit c23f7a1066.

The package-path will be a build-path rather than a source-path, and any
assets being referred to will not be found.

v2/common/testing_common.go

@@ -1,10 +1,9 @@
 package exifcommon
 
 import (
+	"os"
 	"path"
 
-	"go/build"
-
 	"encoding/binary"
 	"io/ioutil"
 
@@ -24,32 +23,63 @@ var (
 	TestDefaultByteOrder = binary.BigEndian
 )
 
-// GetModuleRootPath returns our source-path when running from source during
-// tests.
 func GetModuleRootPath() string {
-	p, err := build.Default.Import(
-		"github.com/dsoprea/go-exif/v2",
-		build.Default.GOPATH,
-		build.FindOnly)
+	if moduleRootPath != "" {
+		return moduleRootPath
+	}
 
+	moduleRootPath := os.Getenv("EXIF_MODULE_ROOT_PATH")
+	if moduleRootPath != "" {
+		return moduleRootPath
+	}
+
+	currentWd, err := os.Getwd()
 	log.PanicIf(err)
 
-	packagePath := p.Dir
-	return packagePath
+	currentPath := currentWd
+	visited := make([]string, 0)
+
+	for {
+		tryStampFilepath := path.Join(currentPath, ".MODULE_ROOT")
+
+		_, err := os.Stat(tryStampFilepath)
+		if err != nil && os.IsNotExist(err) != true {
+			log.Panic(err)
+		} else if err == nil {
+			break
+		}
+
+		visited = append(visited, tryStampFilepath)
+
+		currentPath = path.Dir(currentPath)
+		if currentPath == "/" {
+			log.Panicf("could not find module-root: %v", visited)
+		}
+	}
+
+	return currentPath
 }
 
 func getTestAssetsPath() string {
-	moduleRootPath := GetModuleRootPath()
-	assetsPath := path.Join(moduleRootPath, "assets")
+	if assetsPath == "" {
+		moduleRootPath := GetModuleRootPath()
+		assetsPath = path.Join(moduleRootPath, "assets")
+	}
 
 	return assetsPath
 }
 
 func getTestImageFilepath() string {
-	return path.Join(assetsPath, "NDM_8901.jpg")
+	if testImageFilepath == "" {
+		assetsPath := getTestAssetsPath()
+		testImageFilepath = path.Join(assetsPath, "NDM_8901.jpg")
+	}
+
+	return testImageFilepath
 }
 
 func getTestExifData() []byte {
+	assetsPath := getTestAssetsPath()
 	filepath := path.Join(assetsPath, "NDM_8901.jpg.exif")
 
 	var err error
@@ -59,7 +89,3 @@ func getTestExifData() []byte {
 
 	return testExifData
 }
-
-func init() {
-	assetsPath = getTestAssetsPath()
-}

v2/exif.go

@@ -173,7 +173,7 @@ func ParseExifHeader(data []byte) (eh ExifHeader, err error) {
 	//      CIPA DC-008-2016; JEITA CP-3451D
 	//      -> http://www.cipa.jp/std/documents/e/DC-008-Translation-2016-E.pdf
 
-	if len(data) < ExifSignatureLength {
+	if len(data) < 8 {
 		exifLogger.Warningf(nil, "Not enough data for EXIF header: (%d)", len(data))
 		return eh, ErrNoExif
 	}

v2/testing_common.go

@@ -13,7 +13,10 @@ import (
 )
 
 var (
-	assetsPath   = ""
+	assetsPath           = ""
+	testImageFilepath    = ""
+	testGpsImageFilepath = ""
+
 	testExifData = make([]byte, 0)
 )
 
@@ -157,18 +160,25 @@ func validateExifSimpleTestIb(exifData []byte, t *testing.T) {
 }
 
 func getTestAssetsPath() string {
-	moduleRootPath := exifcommon.GetModuleRootPath()
-	assetsPath := path.Join(moduleRootPath, "assets")
+	if assetsPath == "" {
+		moduleRootPath := exifcommon.GetModuleRootPath()
+		assetsPath = path.Join(moduleRootPath, "assets")
+	}
 
 	return assetsPath
 }
 
 func getTestImageFilepath() string {
-	testImageFilepath := path.Join(assetsPath, "NDM_8901.jpg")
+	if testImageFilepath == "" {
+		assetsPath := getTestAssetsPath()
+		testImageFilepath = path.Join(assetsPath, "NDM_8901.jpg")
+	}
+
 	return testImageFilepath
 }
 
 func getTestExifData() []byte {
+	assetsPath := getTestAssetsPath()
 	filepath := path.Join(assetsPath, "NDM_8901.jpg.exif")
 
 	var err error
@@ -180,10 +190,10 @@ func getTestExifData() []byte {
 }
 
 func getTestGpsImageFilepath() string {
-	testGpsImageFilepath := path.Join(assetsPath, "gps.jpg")
+	if testGpsImageFilepath == "" {
+		assetsPath := getTestAssetsPath()
+		testGpsImageFilepath = path.Join(assetsPath, "gps.jpg")
+	}
+
 	return testGpsImageFilepath
 }
-
-func init() {
-	assetsPath = getTestAssetsPath()
-}