Method zipFileHeaderLocation

cf/appfiles/zipper.go:202–242

(name string)

}

func (zipper ApplicationZipper) zipFileHeaderLocation(name string) (int64, error) {
	f, err := os.Open(name)
	if err != nil {
		return -1, err
	}

	defer f.Close()

	// zip file header signature, 0x04034b50, reversed due to little-endian byte order
	firstByte := byte(0x50)
	restBytes := []byte{0x4b, 0x03, 0x04}
	count := int64(-1)
	foundAt := int64(-1)

	reader := bufio.NewReader(f)

	keepGoing := true
	for keepGoing {
		count++

		b, err := reader.ReadByte()
		if err != nil {
			keepGoing = false
			break
		}

		if b == firstByte {
			nextBytes, err := reader.Peek(3)
			if err != nil {
				keepGoing = false
			}
			if bytes.Compare(nextBytes, restBytes) == 0 {
				foundAt = count
				keepGoing = false
				break
			}
		}
	}

	return foundAt, nil
}

func (zipper ApplicationZipper) isZipWithOffsetFileHeaderLocation(name string) bool {
	loc, err := zipper.zipFileHeaderLocation(name)