232 lines
8.7 KiB
Python
232 lines
8.7 KiB
Python
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#
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# edd.py
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# BIOS EDD data parsing functions
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#
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# Copyright (C) 2010 Red Hat, Inc. All rights reserved.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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#
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# Author(s): Hans de Goede <hdegoede@redhat.com>
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# Ales Kozumplik <akozumpl@redhat.com>
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#
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import glob
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import logging
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import os
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import re
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import struct
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log = logging.getLogger("storage")
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re_host_bus = re.compile(r'^PCI\s*(\S*)\s*channel: (\S*)\s*$')
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re_interface_scsi = re.compile(r'^SCSI\s*id: (\S*)\s*lun: (\S*)\s*$')
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re_interface_ata = re.compile(r'^ATA\s*device: (\S*)\s*$')
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class EddEntry(object):
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""" This object merely collects what the /sys/firmware/edd/* entries can
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provide.
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"""
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def __init__(self, sysfspath):
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self.type = None
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self.ata_device = None
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self.channel = None
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self.mbr_signature = None
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self.pci_dev = None
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self.scsi_id = None
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self.scsi_lun = None
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self.sectors = None
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self.load(sysfspath)
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def __str__(self):
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return \
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"\ttype: %(type)s, ata_device: %(ata_device)s\n" \
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"\tchannel: %(channel)s, mbr_signature: %(mbr_signature)s\n" \
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"\tpci_dev: %(pci_dev)s, scsi_id: %(scsi_id)s\n" \
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"\tscsi_lun: %(scsi_lun)s, sectors: %(sectors)s" % self.__dict__
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def _read_file(self, filename):
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contents = None
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if os.path.exists(filename):
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with open(filename) as f:
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contents = f.read().rstrip()
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return contents
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def load(self, sysfspath):
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interface = self._read_file(os.path.join(sysfspath, "interface"))
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if interface:
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self.type = interface.split()[0]
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if self.type == "SCSI":
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match = re_interface_scsi.match(interface)
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self.scsi_id = int(match.group(1))
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self.scsi_lun = int(match.group(2))
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elif self.type == "ATA":
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match = re_interface_ata.match(interface)
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self.ata_device = int(match.group(1))
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self.mbr_signature = self._read_file(
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os.path.join(sysfspath, "mbr_signature"))
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sectors = self._read_file(os.path.join(sysfspath, "sectors"))
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if sectors:
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self.sectors = int(sectors)
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hbus = self._read_file(os.path.join(sysfspath, "host_bus"))
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if hbus:
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match = re_host_bus.match(hbus)
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if match:
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self.pci_dev = match.group(1)
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self.channel = int(match.group(2))
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else:
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log.warning("edd: can not match host_bus: %s" % hbus)
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class EddMatcher(object):
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""" This object tries to match given entry to a disk device name.
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Assuming, heuristic analysis and guessing hapens here.
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"""
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def __init__(self, edd_entry):
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self.edd = edd_entry
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def devname_from_pci_dev(self):
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name = None
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if self.edd.type == "ATA" and \
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self.edd.channel is not None and \
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self.edd.ata_device is not None:
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path = "/sys/devices/pci0000:00/0000:%(pci_dev)s/host%(chan)d/"\
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"target%(chan)d:0:%(dev)d/%(chan)d:0:%(dev)d:0/block" % {
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'pci_dev' : self.edd.pci_dev,
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'chan' : self.edd.channel,
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'dev' : self.edd.ata_device
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}
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if os.path.isdir(path):
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block_entries = os.listdir(path)
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if len(block_entries) == 1:
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name = block_entries[0]
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else:
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log.warning("edd: directory does not exist: %s" % path)
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elif self.edd.type == "SCSI":
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pattern = "/sys/devices/pci0000:00/0000:%(pci_dev)s/virtio*/block" % \
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{'pci_dev' : self.edd.pci_dev}
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matching_paths = glob.glob(pattern)
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if len(matching_paths) != 1 or not os.path.exists(matching_paths[0]):
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return None
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block_entries = os.listdir(matching_paths[0])
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if len(block_entries) == 1:
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name = block_entries[0]
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return name
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def match_via_mbrsigs(self, mbr_dict):
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""" Try to match the edd entry based on its mbr signature.
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This will obviously fail for a fresh drive/image, but in extreme
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cases can also show false positives for randomly matching data.
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"""
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for (name, mbr_signature) in mbr_dict.items():
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if mbr_signature == self.edd.mbr_signature:
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return name
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return None
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def biosdev_to_edd_dir(biosdev):
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return "/sys/firmware/edd/int13_dev%x" % biosdev
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def collect_edd_data():
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edd_data_dict = {}
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# the hard drive numbering starts at 0x80 (128 decimal):
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for biosdev in range(0x80, 0x80+16):
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sysfspath = biosdev_to_edd_dir(biosdev)
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if not os.path.exists(sysfspath):
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break
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edd_data_dict[biosdev] = EddEntry(sysfspath)
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return edd_data_dict
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def collect_mbrs(devices):
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""" Read MBR signatures from devices.
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Returns a dict mapping device names to their MBR signatures. It is not
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guaranteed this will succeed, with a new disk for instance.
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"""
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mbr_dict = {}
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for dev in devices:
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try:
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fd = os.open(dev.path, os.O_RDONLY)
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# The signature is the unsigned integer at byte 440:
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os.lseek(fd, 440, 0)
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mbrsig = struct.unpack('I', os.read(fd, 4))
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os.close(fd)
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except OSError as e:
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log.warning("edd: error reading mbrsig from disk %s: %s" %
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(dev.name, str(e)))
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continue
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mbrsig_str = "0x%08x" % mbrsig
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# sanity check
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if mbrsig_str == '0x00000000':
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log.info("edd: MBR signature on %s is zero. new disk image?" % dev.name)
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continue
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else:
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for (dev_name, mbrsig_str_old) in mbr_dict.items():
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if mbrsig_str_old == mbrsig_str:
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log.error("edd: dupicite MBR signature %s for %s and %s" %
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(mbrsig_str, dev_name, dev.name))
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# this actually makes all the other data useless
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return {}
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# update the dictionary
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mbr_dict[dev.name] = mbrsig_str
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log.info("edd: collected mbr signatures: %s" % mbr_dict)
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return mbr_dict
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def get_edd_dict(devices):
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""" Generates the 'device name' -> 'edd number' mapping.
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The EDD kernel module that exposes /sys/firmware/edd is thoroughly
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broken, the information there is incomplete and sometimes downright
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wrong. So after we mine out all useful information that the files under
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/sys/firmware/edd/int13_*/ can provide, we resort to heuristics and
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guessing. Our first attempt is, by looking at the device type int
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'interface', attempting to map pci device number, channel number etc. to
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a sysfs path, check that the path really exists, then read the device
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name (e.g 'sda') from there. Should this fail we try to match contents
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of 'mbr_signature' to a real MBR signature found on the existing block
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devices.
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"""
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mbr_dict = collect_mbrs(devices)
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edd_entries_dict = collect_edd_data()
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global edd_dict
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for (edd_number, edd_entry) in edd_entries_dict.items():
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log.debug("edd: data extracted from 0x%x:\n%s" % (edd_number, edd_entry))
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matcher = EddMatcher(edd_entry)
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# first try to match through the pci dev etc.
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name = matcher.devname_from_pci_dev()
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# next try to compare mbr signatures
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if name:
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log.debug("edd: matched 0x%x to %s using pci_dev" % (edd_number, name))
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else:
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name = matcher.match_via_mbrsigs(mbr_dict)
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if name:
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log.info("edd: matched 0x%x to %s using MBR sig" % (edd_number, name))
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if name:
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old_edd_number = edd_dict.get(name)
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if old_edd_number:
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log.info("edd: both edd entries 0x%x and 0x%x seem to map to %s" %
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(old_edd_number, edd_number, name))
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# this means all the other data can be confused and useless
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return {}
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edd_dict[name] = edd_number
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continue
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log.error("edd: unable to match edd entry 0x%x" % edd_number)
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return edd_dict
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edd_dict = {}
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