Fix a few bugs found while fuzzing (#1308)

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

2 files changed, 11 insertions, 2 deletions

diff --git a/strings/strings.go b/strings/strings.go
index fd8e6000..d822a57d 100644
--- a/strings/strings.go
+++ b/strings/strings.go
@@ -9,14 +9,19 @@ import (
 	"github.com/Masterminds/goutils"
 )
 
-// Indent - indent each line of the string with the given indent string
+// Indent - indent each line of the string with the given indent string.
+// Any indent characters are permitted, except for '\n'.
+//
+// TODO: return an error if the indent string contains '\n' instead of
+// succeeding
 func Indent(width int, indent, s string) string {
-	if width == 0 {
+	if width <= 0 || strings.Contains(indent, "\n") {
 		return s
 	}
 	if width > 1 {
 		indent = strings.Repeat(indent, width)
 	}
+
 	var res []byte
 	bol := true
 	for i := 0; i < len(s); i++ {
diff --git a/strings/strings_test.go b/strings/strings_test.go
index eba33183..e79614f9 100644
--- a/strings/strings_test.go
+++ b/strings/strings_test.go
@@ -11,11 +11,15 @@ func TestIndent(t *testing.T) {
 	actual := "hello\nworld\n!"
 	expected := "  hello\n  world\n  !"
 	assert.Equal(t, actual, Indent(0, "  ", actual))
+	assert.Equal(t, actual, Indent(-1, "  ", actual))
 	assert.Equal(t, expected, Indent(1, "  ", actual))
 	assert.Equal(t, "\n", Indent(1, "  ", "\n"))
 	assert.Equal(t, "  foo\n", Indent(1, "  ", "foo\n"))
 	assert.Equal(t, "   foo", Indent(1, "   ", "foo"))
 	assert.Equal(t, "   foo", Indent(3, " ", "foo"))
+
+	// indenting with newline is not permitted
+	assert.Equal(t, "foo", Indent(3, "\n", "foo"))
 }
 
 func TestTrunc(t *testing.T) {