[PATCH] udev - udevinfo with device chain walk

udevinfo is now capable to print "all" attributes along the device chain
of a sysfs device. Just like udev itself it walks the chain upwards and
prints all usable attributes in the udev key format.
So it should be easy to find unique attributes to compose a rule.

All multiline attribute values and values containing non printable
characters are skipped now. I hope nothing useful gets lost with this :)

NOTE:
  The BUS value corresponding with the attributes is printed for every
  device. Don't specify BUS= in a rule and mix SYSFS_attributes from
  different busses, the rule can't match.

./udevinfo /sys/block/sda/sda1

device '/sys/block/sda/sda1' has major:minor 8:1
  looking at class device '/sys/block/sda/sda1':
    SYSFS_dev="8:1"
    SYSFS_start="32"
    SYSFS_size="160"
    SYSFS_stat="       0        0        0        0"

follow the class device's "device"
  looking at the device chain at '/sys/devices/pci0000:00/0000:00:1d.0/usb1/1-1/1-1.3/1-1.3:1.0/host32/32:0:0:0':
    BUS="scsi"
    ID="32:0:0:0"
    SYSFS_detach_state="0"
    SYSFS_type="0"
    SYSFS_model="USB 2 HS-CF"
    SYSFS_vendor="SMSC    "
    SYSFS_max_sectors="240"
    SYSFS_device_blocked="0"
    SYSFS_queue_depth="1"
    SYSFS_scsi_level="3"
    SYSFS_rev="1.25"
    SYSFS_online="1"

  looking at the device chain at '/sys/devices/pci0000:00/0000:00:1d.0/usb1/1-1/1-1.3/1-1.3:1.0/host32':
    BUS=""
    ID="host32"
    SYSFS_detach_state="0"

  looking at the device chain at '/sys/devices/pci0000:00/0000:00:1d.0/usb1/1-1/1-1.3/1-1.3:1.0':
    BUS="usb"
    ID="1-1.3:1.0"
    SYSFS_detach_state="0"
    SYSFS_bInterfaceNumber="00"
    SYSFS_bAlternateSetting=" 0"
    SYSFS_bNumEndpoints="02"
    SYSFS_bInterfaceClass="08"
    SYSFS_bInterfaceSubClass="06"
    SYSFS_bInterfaceProtocol="50"
    SYSFS_iInterface="00"

  looking at the device chain at '/sys/devices/pci0000:00/0000:00:1d.0/usb1/1-1/1-1.3':
    BUS="usb"
    ID="1-1.3"
    SYSFS_detach_state="0"
    SYSFS_bNumConfigurations="1"
    SYSFS_bNumInterfaces=" 1"
    SYSFS_bConfigurationValue="1"
    SYSFS_bmAttributes="80"
    SYSFS_bMaxPower=" 96mA"
    SYSFS_idVendor="0424"
    SYSFS_idProduct="20fc"
    SYSFS_bcdDevice="0125"
    SYSFS_bDeviceClass="00"
    SYSFS_bDeviceSubClass="00"
    SYSFS_bDeviceProtocol="00"
    SYSFS_speed="12"
    SYSFS_manufacturer="SMSC"
    SYSFS_product="USB 2 Flash Media Device"
    SYSFS_serial="0305037000C2"

  looking at the device chain at '/sys/devices/pci0000:00/0000:00:1d.0/usb1/1-1':
    BUS="usb"
    ID="1-1"
    SYSFS_detach_state="0"
    SYSFS_bNumConfigurations="1"
    SYSFS_bNumInterfaces=" 1"
    SYSFS_bConfigurationValue="1"
    SYSFS_bmAttributes="e0"
    SYSFS_bMaxPower=" 64mA"
    SYSFS_idVendor="03eb"
    SYSFS_idProduct="3301"
    SYSFS_bcdDevice="0300"
    SYSFS_bDeviceClass="09"
    SYSFS_bDeviceSubClass="00"
    SYSFS_bDeviceProtocol="00"
    SYSFS_speed="12"
    SYSFS_product="Standard USB Hub"

  looking at the device chain at '/sys/devices/pci0000:00/0000:00:1d.0/usb1':
    BUS="usb"
    ID="usb1"
    SYSFS_detach_state="0"
    SYSFS_bNumConfigurations="1"
    SYSFS_bNumInterfaces=" 1"
    SYSFS_bConfigurationValue="1"
    SYSFS_bmAttributes="40"
    SYSFS_bMaxPower="  0mA"
    SYSFS_idVendor="0000"
    SYSFS_idProduct="0000"
    SYSFS_bcdDevice="0206"
    SYSFS_bDeviceClass="09"
    SYSFS_bDeviceSubClass="00"
    SYSFS_bDeviceProtocol="00"
    SYSFS_speed="12"
    SYSFS_manufacturer="Linux 2.6.2-rc1-p4 uhci_hcd"
    SYSFS_product="UHCI Host Controller"
    SYSFS_serial="0000:00:1d.0"

  looking at the device chain at '/sys/devices/pci0000:00/0000:00:1d.0':
    BUS="pci"
    ID="0000:00:1d.0"
    SYSFS_detach_state="0"
    SYSFS_vendor="0x8086"
    SYSFS_device="0x2482"
    SYSFS_subsystem_vendor="0x1014"
    SYSFS_subsystem_device="0x0220"
    SYSFS_class="0x0c0300"
    SYSFS_irq="9"

  looking at the device chain at '/sys/devices/pci0000:00':
    BUS=""
    ID="pci0000:00"
    SYSFS_detach_state="0"