1 files changed, 50 insertions, 0 deletions
diff --git a/file/file.go b/file/file.go
index f8fa2839..16067161 100644
--- a/file/file.go
+++ b/file/file.go
@@ -3,6 +3,8 @@ package file
 import (
 	"io/ioutil"
 	"os"
+	"path/filepath"
+	"strings"
 
 	"github.com/pkg/errors"
 
@@ -43,3 +45,51 @@ func ReadDir(path string) ([]string, error) {
 	}
 	return nil, errors.New("file is not a directory")
 }
+
+// Write a
+func Write(filename string, content []byte) error {
+	err := assertPathInWD(filename)
+	if err != nil {
+		return errors.Wrapf(err, "failed to open %s", filename)
+	}
+
+	fi, err := os.Stat(filename)
+	if err != nil && !os.IsNotExist(err) {
+		return errors.Wrapf(err, "failed to stat %s", filename)
+	}
+	mode := os.FileMode(0644)
+	if fi != nil {
+		mode = fi.Mode()
+	}
+	inFile, err := fs.OpenFile(filename, os.O_RDWR|os.O_CREATE, mode)
+	if err != nil {
+		return errors.Wrapf(err, "failed to open %s", filename)
+	}
+	n, err := inFile.Write(content)
+	if err != nil {
+		return errors.Wrapf(err, "failed to write %s", filename)
+	}
+	if n != len(content) {
+		return errors.Wrapf(err, "short write on %s (%d bytes)", filename, n)
+	}
+	return nil
+}
+
+func assertPathInWD(filename string) error {
+	wd, err := os.Getwd()
+	if err != nil {
+		return err
+	}
+	f, err := filepath.Abs(filename)
+	if err != nil {
+		return err
+	}
+	r, err := filepath.Rel(wd, f)
+	if err != nil {
+		return err
+	}
+	if strings.HasPrefix(r, "..") {
+		return errors.Errorf("path %s not contained by working directory %s (rel: %s)", filename, wd, r)
+	}
+	return nil
+}