1 files changed, 75 insertions, 0 deletions
diff --git a/rrdformat/errors_binary.go b/rrdformat/errors_binary.go
new file mode 100644
index 0000000..7329927
--- /dev/null
+++ b/rrdformat/errors_binary.go
@@ -0,0 +1,75 @@
+package rrdformat
+
+import (
+	"fmt"
+	"io"
+)
+
+type BinaryError struct {
+	msg    string
+	ctxPos int
+	ctxDat []byte
+	ctxEOF bool
+}
+
+func newBinError(msg string, ctxFile []byte, ctxStart, ctxLen int) error {
+	if ctxStart+ctxLen > len(ctxFile) {
+		ctxLen = len(ctxFile) - ctxStart
+	}
+	return BinaryError{
+		msg:    msg,
+		ctxPos: ctxStart,
+		ctxDat: ctxFile[ctxStart : ctxStart+ctxLen],
+		ctxEOF: ctxStart+ctxLen == len(ctxFile),
+	}
+}
+
+func (e BinaryError) Error() string {
+	return "invalid RRD: " + e.msg
+}
+
+var cAsciiEscapes = map[byte]byte{
+	0x00: '0',
+	0x07: 'a',
+	0x08: 'b',
+	0x09: 't',
+	0x0A: 'n',
+	0x0B: 'v',
+	0x0C: 'f',
+	0x0D: 'r',
+}
+
+func (e BinaryError) Format(s fmt.State, verb rune) {
+	switch verb {
+	case 'v':
+		io.WriteString(s, e.Error())
+		if s.Flag('+') {
+			fmt.Fprintf(s, "\n\tat byte %d:", e.ctxPos)
+			io.WriteString(s, "\n\t\tascii:")
+			for _, byte := range e.ctxDat {
+				if ' ' <= byte && byte <= '~' {
+					fmt.Fprintf(s, "  %c", byte)
+				} else if c, ok := cAsciiEscapes[byte]; ok {
+					fmt.Fprintf(s, " \\%c", c)
+				} else {
+					io.WriteString(s, " ??")
+				}
+			}
+			if e.ctxEOF {
+				io.WriteString(s, " <EOF>")
+			}
+			io.WriteString(s, "\n\t\thex  :")
+			for _, byte := range e.ctxDat {
+				fmt.Fprintf(s, " %02x", byte)
+			}
+			if e.ctxEOF {
+				io.WriteString(s, " <EOF>")
+			}
+			io.WriteString(s, "\n")
+		}
+	case 's':
+		io.WriteString(s, e.Error())
+	case 'q':
+		fmt.Fprintf(s, "%q", e.Error())
+	}
+}