fix reading past 'endstream' token when parsing

reader.go

@@ -125,8 +125,8 @@ func (this *PdfReader) skipComments(r *bufio.Reader) error {
 	return nil
 }
 
-// Advance reader so that whitespace is ignored
-func (this *PdfReader) skipWhitespace(r *bufio.Reader) error {
+// Advance reader so that skipBytes are ignored
+func (this *PdfReader) skip(r *bufio.Reader, skipBytes []byte) error {
 	var err error
 	var b byte
 
@@ -139,12 +139,20 @@ func (this *PdfReader) skipWhitespace(r *bufio.Reader) error {
 			return errors.Wrap(err, "Failed to read byte")
 		}
 
-		if b == ' ' || b == '\n' || b == '\r' || b == '\t' {
+		skipFound := false
+		for _, skipByte := range skipBytes {
+			if skipByte == b {
+				skipFound = true
+				break
+			}
+		}
+
+		if skipFound {
 			continue
-		} else {
-			r.UnreadByte()
-			break
 		}
+
+		r.UnreadByte()
+		break
 	}
 
 	return nil
@@ -154,14 +162,15 @@ func (this *PdfReader) skipWhitespace(r *bufio.Reader) error {
 func (this *PdfReader) readToken(r *bufio.Reader) (string, error) {
 	var err error
 
+	var buffer bytes.Buffer
 	// If there is a token available on the stack, pop it out and return it.
 	if len(this.stack) > 0 {
 		var popped string
 		popped, this.stack = this.stack[len(this.stack)-1], this.stack[:len(this.stack)-1]
 		return popped, nil
 	}
 
-	err = this.skipWhitespace(r)
+	err = this.skip(r, whitespaceBytes())
 	if err != nil {
 		return "", errors.Wrap(err, "Failed to skip whitespace")
 	}
@@ -201,9 +210,7 @@ func (this *PdfReader) readToken(r *bufio.Reader) (string, error) {
 		return this.readToken(r)
 
 	default:
-		// FIXME this may not be performant to create new strings for each byte
-		// Is it probably better to create a buffer and then convert to a string at the end.
-		str := string(b)
+		buffer.WriteByte(b)
 
 	loop:
 		for {
@@ -216,10 +223,10 @@ func (this *PdfReader) readToken(r *bufio.Reader) (string, error) {
 				r.UnreadByte()
 				break loop
 			default:
-				str += string(b)
+				buffer.WriteByte(b)
 			}
 		}
-		return str, nil
+		return buffer.String(), nil
 	}
 
 	return "", nil
@@ -668,7 +675,8 @@ func (this *PdfReader) resolveObject(objSpec *PdfValue) (*PdfValue, error) {
 		if token == "stream" {
 			result.Type = PDF_TYPE_STREAM
 
-			err = this.skipWhitespace(r)
+			// we just want to skip until after first CRLF
+			err = this.skip(r, newlineBytes())
 			if err != nil {
 				return nil, errors.Wrap(err, "Failed to skip whitespace")
 			}
@@ -808,6 +816,7 @@ func (this *PdfReader) findXref() error {
 func (this *PdfReader) readXref() error {
 	var err error
 
+	whitespace := whitespaceBytes()
 	// Create new bufio.Reader
 	r := bufio.NewReader(this.f)
 
@@ -908,7 +917,7 @@ func (this *PdfReader) readXref() error {
 
 					startObject := index[0]
 
-					err = this.skipWhitespace(r)
+					err = this.skip(r, whitespace)
 					if err != nil {
 						return errors.Wrap(err, "Failed to skip whitespace")
 					}
@@ -939,7 +948,7 @@ func (this *PdfReader) readXref() error {
 						return errors.New("Expected next token to be: stream, got: " + t)
 					}
 
-					err = this.skipWhitespace(r)
+					err = this.skip(r, whitespace)
 					if err != nil {
 						return errors.Wrap(err, "Failed to skip whitespace")
 					}
@@ -1630,3 +1639,11 @@ func (this *PdfReader) read() error {
 
 	return nil
 }
+
+func whitespaceBytes() []byte {
+	return []byte{0x20, 0x0A, 0x0C, 0x0D, 0x09, 0x00}
+}
+
+func newlineBytes() []byte {
+	return []byte{'\r', '\n'}
+}