wip - write in place

pkg/yqlib/write_in_place_handler.go

@@ -0,0 +1,55 @@
+package yqlib
+
+import (
+	"io/ioutil"
+	"os"
+)
+
+type WriteInPlaceHandler interface {
+	CreateTempFile() (*os.File, error)
+	FinishWriteInPlace(evaluatedSuccessfully bool)
+}
+
+type writeInPlaceHandler struct {
+	inputFilename string
+	tempFile      *os.File
+}
+
+func NewWriteInPlaceHandler(inputFile string) WriteInPlaceHandler {
+
+	return &writeInPlaceHandler{inputFile, nil}
+}
+
+func (w *writeInPlaceHandler) CreateTempFile() (*os.File, error) {
+	info, err := os.Stat(w.inputFilename)
+	if err != nil {
+		return nil, err
+	}
+	_, err = os.Stat(os.TempDir())
+	if os.IsNotExist(err) {
+		err = os.Mkdir(os.TempDir(), 0700)
+		if err != nil {
+			return nil, err
+		}
+	} else if err != nil {
+		return nil, err
+	}
+
+	file, err := ioutil.TempFile("", "temp")
+	if err != nil {
+		return nil, err
+	}
+
+	err = os.Chmod(file.Name(), info.Mode())
+	w.tempFile = file
+	return file, err
+}
+
+func (w *writeInPlaceHandler) FinishWriteInPlace(evaluatedSuccessfully bool) {
+	safelyCloseFile(w.tempFile)
+	if evaluatedSuccessfully {
+		safelyRenameFile(w.tempFile.Name(), w.inputFilename)
+	} else {
+		os.Remove(w.tempFile.Name())
+	}
+}