Make checksum func public (#252)

* make FileChecksum.Checksum public

* add FileChecksum.String func

* FileChecksum.Checksum: change var name `file` to `filePath` to avoid confusion

checksum.go

@@ -27,6 +27,13 @@ type FileChecksum struct {
 	Filename string
 }
 
+// String returns the hash type and the hash separated by a colon, for example:
+//  "md5:090992ba9fd140077b0661cb75f7ce13"
+//  "sha1:ebfb681885ddf1234c18094a45bbeafd91467911"
+func (c *FileChecksum) String() string {
+	return c.Type + ":" + hex.EncodeToString(c.Value)
+}
+
 // A ChecksumError is returned when a checksum differs
 type ChecksumError struct {
 	Hash     hash.Hash
@@ -48,10 +55,11 @@ func (cerr *ChecksumError) Error() string {
 	)
 }
 
-// checksum is a simple method to compute the checksum of a source file
-// and compare it to the given expected value.
-func (c *FileChecksum) checksum(source string) error {
-	f, err := os.Open(source)
+// Checksum computes the Checksum for filePath using the hashing algorithm from
+// c.Hash and compares it to c.Value. If those values differ a ChecksumError
+// will be returned.
+func (c *FileChecksum) Checksum(filePath string) error {
+	f, err := os.Open(filePath)
 	if err != nil {
 		return fmt.Errorf("Failed to open file for checksum: %s", err)
 	}
@@ -67,7 +75,7 @@ func (c *FileChecksum) checksum(source string) error {
 			Hash:     c.Hash,
 			Actual:   actual,
 			Expected: c.Value,
-			File:     source,
+			File:     filePath,
 		}
 	}
 

checksum_test.go

@@ -5,6 +5,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"strconv"
 	"testing"
 )
 
@@ -61,3 +62,38 @@ func TestClient_GetChecksum(t *testing.T) {
 		t.Fatalf("bad: expecting filename ./netboot/mini.iso but was: %s", file.Filename)
 	}
 }
+
+func TestFileChecksum_String(t *testing.T) {
+	type fields struct {
+		checksum string
+	}
+	wd, err := os.Getwd()
+	if err != nil {
+		t.Fatalf(err.Error())
+	}
+	tests := []struct {
+		fields fields
+		want   string
+	}{
+		{fields{"090992ba9fd140077b0661cb75f7ce13"}, "md5:090992ba9fd140077b0661cb75f7ce13"},
+		{fields{"ebfb681885ddf1234c18094a45bbeafd91467911"}, "sha1:ebfb681885ddf1234c18094a45bbeafd91467911"},
+		{fields{"sha256:ed363350696a726b7932db864dda019bd2017365c9e299627830f06954643f93"}, "sha256:ed363350696a726b7932db864dda019bd2017365c9e299627830f06954643f93"},
+		{fields{"file:" + filepath.Join(wd, fixtureDir, "checksum-file", "sha1.sum")}, "sha1:e2c7dc83ac8aa7f181314387f6dfb132cd117e3a"},
+	}
+
+	for i, tt := range tests {
+		t.Run(strconv.Itoa(i), func(t *testing.T) {
+			req := &Request{
+				Src: "http://example.dev?checksum=" + tt.fields.checksum,
+			}
+			c, err := DefaultClient.GetChecksum(context.TODO(), req)
+			if err != nil {
+				t.Fatalf("GetChecksum: %v", err)
+			}
+
+			if got := c.String(); got != tt.want {
+				t.Errorf("FileChecksum.String() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

client.go

@@ -181,7 +181,7 @@ func (c *Client) Get(ctx context.Context, req *Request) (*GetResult, error) {
 	if req.Mode == ModeFile {
 		getFile := true
 		if checksum != nil {
-			if err := checksum.checksum(req.Dst); err == nil {
+			if err := checksum.Checksum(req.Dst); err == nil {
 				// don't get the file if the checksum of dst is correct
 				getFile = false
 			}
@@ -193,7 +193,7 @@ func (c *Client) Get(ctx context.Context, req *Request) (*GetResult, error) {
 			}
 
 			if checksum != nil {
-				if err := checksum.checksum(req.Dst); err != nil {
+				if err := checksum.Checksum(req.Dst); err != nil {
 					return nil, err
 				}
 			}