Add Seek

unarr.go

@@ -144,12 +144,32 @@ func (a *Archive) Read(b []byte) (n int, err error) {
 	return
 }
 
+// Seek moves the read offset pointer interpreted according to whence.
+//
+// Returns the new offset.
+func (a *Archive) Seek(offset int64, whence int) (int64, error) {
+	r := bool(C.ar_seek(a.stream, C.off64_t(offset), C.int(whence)))
+	if !r {
+		return 0, errors.New("unarr: Seek failed")
+	}
+
+	return int64(C.ar_tell(a.stream)), nil
+}
+
+// Close closes the underlying unarr archive
+func (a *Archive) Close() (err error) {
+	C.ar_close_archive(a.archive)
+	C.ar_close(a.stream)
+
+	return
+}
+
 // Size returns the total size of uncompressed data of the current entry
 func (a *Archive) Size() int {
 	return int(C.ar_entry_get_size(a.archive))
 }
 
-// Offset returns the stream offset of the current entry
+// Offset returns the stream offset of the current entry, for use with EntryAt
 func (a *Archive) Offset() int64 {
 	return int64(C.ar_entry_get_offset(a.archive))
 }
@@ -165,14 +185,6 @@ func (a *Archive) ModTime() time.Time {
 	return time.Unix((filetime/10000000)-11644473600, 0)
 }
 
-// Close closes the underlying unarr archive
-func (a *Archive) Close() (err error) {
-	C.ar_close_archive(a.archive)
-	C.ar_close(a.stream)
-
-	return
-}
-
 // ReadAll reads current entry and returns data
 func (a *Archive) ReadAll() ([]byte, error) {
 	size := a.Size()

unarr_test.go

@@ -150,6 +150,40 @@ func TestRead(t *testing.T) {
 	}
 }
 
+func TestSeek(t *testing.T) {
+	for _, e := range exts {
+		a, err := NewArchive(filepath.Join("testdata", "test."+e))
+		if err != nil {
+			t.Error(err)
+		}
+
+		off, err := a.Seek(3, 0)
+		if err != nil {
+			t.Error(err)
+		}
+
+		if off != 3 {
+			t.Error("Seek failed")
+		}
+
+		a.Close()
+	}
+}
+
+func TestClose(t *testing.T) {
+	for _, e := range exts {
+		a, err := NewArchive(filepath.Join("testdata", "test."+e))
+		if err != nil {
+			t.Error(err)
+		}
+
+		err = a.Close()
+		if err != nil {
+			t.Error(err)
+		}
+	}
+}
+
 func TestSize(t *testing.T) {
 	for _, f := range files {
 		a, err := NewArchive(filepath.Join("testdata", f))
@@ -231,20 +265,6 @@ func TestModTime(t *testing.T) {
 	}
 }
 
-func TestClose(t *testing.T) {
-	for _, e := range exts {
-		a, err := NewArchive(filepath.Join("testdata", "test."+e))
-		if err != nil {
-			t.Error(err)
-		}
-
-		err = a.Close()
-		if err != nil {
-			t.Error(err)
-		}
-	}
-}
-
 func TestReadAll(t *testing.T) {
 	for _, e := range exts {
 		a, err := NewArchive(filepath.Join("testdata", "test."+e))