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