Don't hang when reading an invalid rvalue (#77)

Fixes #76

cmd/tomll/main.go

@@ -0,0 +1,61 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+
+	"github.com/pelletier/go-toml"
+)
+
+func main() {
+	flag.Usage = func() {
+		fmt.Fprintln(os.Stderr, `tomll can be used in two ways:
+Writing to STDIN and reading from STDOUT:
+  cat file.toml | tomll > file.toml
+
+Reading and updating a list of files:
+  tomll a.toml b.toml c.toml
+
+When given a list of files, tomll will modify all files in place without asking.
+`)
+	}
+	flag.Parse()
+	// read from stdin and print to stdout
+	if flag.NArg() == 0 {
+		s, err := lintReader(os.Stdin)
+		if err != nil {
+			io.WriteString(os.Stderr, err.Error())
+			os.Exit(-1)
+		}
+		io.WriteString(os.Stdout, s)
+	} else {
+		// otherwise modify a list of files
+		for _, filename := range flag.Args() {
+			s, err := lintFile(filename)
+			if err != nil {
+				io.WriteString(os.Stderr, err.Error())
+				os.Exit(-1)
+			}
+			ioutil.WriteFile(filename, []byte(s), 0644)
+		}
+	}
+}
+
+func lintFile(filename string) (string, error) {
+	tree, err := toml.LoadFile(filename)
+	if err != nil {
+		return "", err
+	}
+	return tree.String(), nil
+}
+
+func lintReader(r io.Reader) (string, error) {
+	tree, err := toml.LoadReader(r)
+	if err != nil {
+		return "", err
+	}
+	return tree.String(), nil
+}

lexer.go

@@ -234,6 +234,7 @@ func (l *tomlLexer) lexRvalue() tomlLexStateFn {
 			return l.lexKey
 		}
 
+		return l.errorf("no value can start with %c", next)
 	}
 
 	l.emit(tokenEOF)

lexer_test.go

@@ -692,3 +692,17 @@ func TestInvalidFloat(t *testing.T) {
 		token{Position{1, 7}, tokenEOF, ""},
 	})
 }
+
+func TestLexUnknownRvalue(t *testing.T) {
+	testFlow(t, `a = !b`, []token{
+		token{Position{1, 1}, tokenKey, "a"},
+		token{Position{1, 3}, tokenEqual, "="},
+		token{Position{1, 5}, tokenError, "no value can start with !"},
+	})
+
+	testFlow(t, `a = \b`, []token{
+		token{Position{1, 1}, tokenKey, "a"},
+		token{Position{1, 3}, tokenEqual, "="},
+		token{Position{1, 5}, tokenError, `no value can start with \`},
+	})
+}

parser_test.go

@@ -299,6 +299,18 @@ func TestArrayNestedStrings(t *testing.T) {
 	})
 }
 
+func TestParseUnknownRvalue(t *testing.T) {
+	_, err := Load("a = !bssss")
+	if err == nil {
+		t.Error("Expecting a parse error")
+	}
+
+	_, err = Load("a = /b")
+	if err == nil {
+		t.Error("Expecting a parse error")
+	}
+}
+
 func TestMissingValue(t *testing.T) {
 	_, err := Load("a = ")
 	if err.Error() != "(1, 5): expecting a value" {

tomltree_conversions.go

@@ -108,9 +108,14 @@ func (t *TomlTree) toToml(indent, keyspace string) string {
 	return result
 }
 
+// ToString is an alias for String
+func (t *TomlTree) ToString() string {
+	return t.String()
+}
+
 // ToString generates a human-readable representation of the current tree.
 // Output spans multiple lines, and is suitable for ingest by a TOML parser
-func (t *TomlTree) ToString() string {
+func (t *TomlTree) String() string {
 	return t.toToml("", "")
 }