New file.Write function

Signed-off-by: Dave Henderson <dhenderson@gmail.com>

2 files changed, 115 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
+}
diff --git a/file/file_test.go b/file/file_test.go
index 144c67a5..47c0d542 100644
--- a/file/file_test.go
+++ b/file/file_test.go
@@ -1,8 +1,12 @@
 package file
 
 import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
 	"testing"
 
+	tfs "github.com/gotestyourself/gotestyourself/fs"
 	"github.com/spf13/afero"
 	"github.com/stretchr/testify/assert"
 )
@@ -41,3 +45,64 @@ func TestReadDir(t *testing.T) {
 	_, err = ReadDir("/tmp/foo")
 	assert.Error(t, err)
 }
+
+func TestWrite(t *testing.T) {
+	oldwd, _ := os.Getwd()
+	defer os.Chdir(oldwd)
+
+	rootDir := tfs.NewDir(t, "gomplate-test")
+	defer rootDir.Remove()
+
+	newwd := rootDir.Join("the", "path", "we", "want")
+	badwd := rootDir.Join("some", "other", "dir")
+	fs.MkdirAll(newwd, 0755)
+	fs.MkdirAll(badwd, 0755)
+	newwd, _ = filepath.EvalSymlinks(newwd)
+	badwd, _ = filepath.EvalSymlinks(badwd)
+
+	err := os.Chdir(newwd)
+	assert.NoError(t, err)
+
+	err = Write("/foo", []byte("Hello world"))
+	assert.Error(t, err)
+
+	rel, err := filepath.Rel(newwd, badwd)
+	assert.NoError(t, err)
+	err = Write(rel, []byte("Hello world"))
+	assert.Error(t, err)
+
+	foopath := filepath.Join(newwd, "foo")
+	err = Write(foopath, []byte("Hello world"))
+	assert.NoError(t, err)
+
+	out, err := ioutil.ReadFile(foopath)
+	assert.NoError(t, err)
+	assert.Equal(t, "Hello world", string(out))
+}
+
+func TestAssertPathInWD(t *testing.T) {
+	oldwd, _ := os.Getwd()
+	defer os.Chdir(oldwd)
+
+	err := assertPathInWD("/tmp")
+	assert.Error(t, err)
+
+	err = assertPathInWD(filepath.Join(oldwd, "subpath"))
+	assert.NoError(t, err)
+
+	err = assertPathInWD("subpath")
+	assert.NoError(t, err)
+
+	err = assertPathInWD("./subpath")
+	assert.NoError(t, err)
+
+	err = assertPathInWD(filepath.Join("..", "bogus"))
+	assert.Error(t, err)
+
+	err = assertPathInWD(filepath.Join("..", "..", "bogus"))
+	assert.Error(t, err)
+
+	base := filepath.Base(oldwd)
+	err = assertPathInWD(filepath.Join("..", base))
+	assert.NoError(t, err)
+}