Workaround for ARM Upgrades from RHEL8 to RHEL9.5+

Address issue with ARM system upgrades from RHEL 8 to RHEL 9.5+ caused
by GRUB bootloader incompatibility with newer kernels. When attempting
to load the RHEL 9.5+ kernel using the RHEL 8 bootloader, the upgrade
process halts due to a boot crash.

JIRA: 41193

repos/system_upgrade/common/libraries/grub.py

@@ -1,10 +1,207 @@
 import os
+import re
 
 from leapp.exceptions import StopActorExecution
 from leapp.libraries.common import mdraid
 from leapp.libraries.stdlib import api, CalledProcessError, run
 from leapp.utils.deprecation import deprecated
 
+EFI_MOUNTPOINT = '/boot/efi/'
+"""The path to the required mountpoint for ESP."""
+
+GRUB2_BIOS_ENTRYPOINT = '/boot/grub2'
+"""The entrypoint path of the BIOS GRUB2"""
+
+GRUB2_BIOS_ENV_FILE = os.path.join(GRUB2_BIOS_ENTRYPOINT, 'grubenv')
+"""The path to the env file for GRUB2 in BIOS"""
+
+
+def canonical_path_to_efi_format(canonical_path):
+    r"""Transform the canonical path to the UEFI format.
+
+    e.g. /boot/efi/EFI/redhat/shimx64.efi -> \EFI\redhat\shimx64.efi
+    (just single backslash; so the string needs to be put into apostrophes
+    when used for /usr/sbin/efibootmgr cmd)
+
+    The path has to start with /boot/efi otherwise the path is invalid for UEFI.
+    """
+
+    # We want to keep the last "/" of the EFI_MOUNTPOINT
+    return canonical_path.replace(EFI_MOUNTPOINT[:-1], "").replace("/", "\\")
+
+
+class EFIBootLoader:
+    """
+    Representation of an UEFI boot loader entry.
+    """
+
+    def __init__(self, boot_number, label, active, efi_bin_source):
+        self.boot_number = boot_number
+        """Expected string, e.g. '0001'. """
+
+        self.label = label
+        """Label of the UEFI entry. E.g. 'Redhat'"""
+
+        self.active = active
+        """True when the UEFI entry is active (asterisk is present next to the boot number)"""
+
+        self.efi_bin_source = efi_bin_source
+        """Source of the UEFI binary.
+
+        It could contain various values, e.g.:
+            FvVol(7cb8bdc9-f8eb-4f34-aaea-3ee4af6516a1)/FvFile(462caa21-7614-4503-836e-8ab6f4662331)
+            HD(1,GPT,28c77f6b-3cd0-4b22-985f-c99903835d79,0x800,0x12c000)/File(\\EFI\\redhat\\shimx64.efi)
+            PciRoot(0x0)/Pci(0x2,0x3)/Pci(0x0,0x0)N.....YM....R,Y.
+        """
+
+    def __eq__(self, other):
+        return all(
+            [
+                self.boot_number == other.boot_number,
+                self.label == other.label,
+                self.active == other.active,
+                self.efi_bin_source == other.efi_bin_source,
+            ]
+        )
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
+    def __repr__(self):
+        return 'EFIBootLoader({boot_number}, {label}, {active}, {efi_bin_source})'.format(
+            boot_number=repr(self.boot_number),
+            label=repr(self.label),
+            active=repr(self.active),
+            efi_bin_source=repr(self.efi_bin_source)
+        )
+
+    def is_referring_to_file(self):
+        """Return True when the boot source is a file.
+
+        Some sources could refer e.g. to PXE boot. Return true if the source
+        refers to a file ("ends with /File(...path...)")
+
+        Does not matter whether the file exists or not.
+        """
+        return '/File(\\' in self.efi_bin_source
+
+    @staticmethod
+    def _efi_path_to_canonical(efi_path):
+        return os.path.join(EFI_MOUNTPOINT, efi_path.replace("\\", "/").lstrip("/"))
+
+    def get_canonical_path(self):
+        """Return expected canonical path for the referred UEFI bin or None.
+
+        Return None in case the entry is not referring to any UEFI bin
+        (e.g. when it refers to a PXE boot).
+        """
+        if not self.is_referring_to_file():
+            return None
+        match = re.search(r'/File\((?P<path>\\.*)\)$', self.efi_bin_source)
+        return EFIBootLoader._efi_path_to_canonical(match.groups('path')[0])
+
+
+class EFIBootInfo:
+    """
+    Data about the current UEFI boot configuration.
+
+    Raise StopActorExecution when:
+        - unable to obtain info about the UEFI configuration.
+        - BIOS is detected.
+        - ESP is not mounted where expected.
+    """
+
+    def __init__(self):
+        if not is_efi():
+            raise StopActorExecution('Unable to collect data about UEFI on a BIOS system.')
+        try:
+            result = run(['/usr/sbin/efibootmgr', '-v'])
+        except CalledProcessError:
+            raise StopActorExecution('Unable to get information about UEFI boot entries.')
+
+        bootmgr_output = result['stdout']
+
+        self.current_bootnum = None
+        """The boot number (str) of the current boot."""
+        self.next_bootnum = None
+        """The boot number (str) of the next boot."""
+        self.boot_order = tuple()
+        """The tuple of the UEFI boot loader entries in the boot order."""
+        self.entries = {}
+        """The UEFI boot loader entries {'boot_number': EFIBootLoader}"""
+
+        self._parse_efi_boot_entries(bootmgr_output)
+        self._parse_current_bootnum(bootmgr_output)
+        self._parse_next_bootnum(bootmgr_output)
+        self._parse_boot_order(bootmgr_output)
+        self._print_loaded_info()
+
+    def _parse_efi_boot_entries(self, bootmgr_output):
+        """
+        Return dict of UEFI boot loader entries: {"<boot_number>": EFIBootLoader}
+        """
+
+        self.entries = {}
+        regexp_entry = re.compile(
+            r"^Boot(?P<bootnum>[a-zA-Z0-9]+)(?P<active>\*?)\s*(?P<label>.*?)\t(?P<bin_source>.*)$"
+        )
+
+        for line in bootmgr_output.splitlines():
+            match = regexp_entry.match(line)
+            if not match:
+                continue
+
+            self.entries[match.group('bootnum')] = EFIBootLoader(
+                boot_number=match.group('bootnum'),
+                label=match.group('label'),
+                active='*' in match.group('active'),
+                efi_bin_source=match.group('bin_source'),
+            )
+
+        if not self.entries:
+            # it's not expected that no entry exists
+            raise StopActorExecution('UEFI: Unable to detect any UEFI bootloader entry.')
+
+    def _parse_key_value(self, bootmgr_output, key):
+        # e.g.: <key>: <value>
+        for line in bootmgr_output.splitlines():
+            if line.startswith(key + ':'):
+                return line.split(':')[1].strip()
+
+        return None
+
+    def _parse_current_bootnum(self, bootmgr_output):
+        # e.g.: BootCurrent: 0002
+        self.current_bootnum = self._parse_key_value(bootmgr_output, 'BootCurrent')
+
+        if self.current_bootnum is None:
+            raise StopActorExecution('UEFI: Unable to detect current boot number.')
+
+    def _parse_next_bootnum(self, bootmgr_output):
+        # e.g.: BootNext: 0002
+        self.next_bootnum = self._parse_key_value(bootmgr_output, 'BootNext')
+
+        if self.current_bootnum is None:
+            raise StopActorExecution('UEFI: Unable to detect next boot number.')
+
+    def _parse_boot_order(self, bootmgr_output):
+        # e.g.:  BootOrder: 0001,0002,0000,0003
+        for line in bootmgr_output.splitlines():
+            if line.startswith('BootOrder:'):
+                self.boot_order = tuple(line.split(':')[1].strip().split(','))
+                return
+
+        raise StopActorExecution('UEFI: Unable to detect current boot order.')
+
+    def _print_loaded_info(self):
+        msg = 'Bootloader setup:'
+        msg += '\nCurrent boot: %s' % self.current_bootnum
+        msg += '\nBoot order: %s\nBoot entries:' % ', '.join(self.boot_order)
+        for bootnum, entry in self.entries.items():
+            msg += '\n- %s: %s' % (bootnum, entry.label.rstrip())
+
+        api.current_logger().debug(msg)
+
 
 def has_grub(blk_dev):
     """
@@ -33,39 +230,126 @@ def blk_dev_from_partition(partition):
     try:
         result = run(['lsblk', '-spnlo', 'name', partition])
     except CalledProcessError:
-        api.current_logger().warning(
-            'Could not get parent device of {} partition'.format(partition)
-        )
-        raise StopActorExecution()  # TODO: return some meaningful value/error
+        msg = 'Could not get parent device of {} partition'.format(partition)
+        api.current_logger().warning(msg)
+        raise StopActorExecution(msg)
+
     # lsblk "-s" option prints dependencies in inverse order, so the parent device will always
     # be the last or the only device.
     # Command result example:
     # 'result', {'signal': 0, 'pid': 3872, 'exit_code': 0, 'stderr': u'', 'stdout': u'/dev/vda1\n/dev/vda\n'}
     return result['stdout'].strip().split()[-1]
 
 
+def _get_partition(directory):
+    """
+    Get partition name of `directory`.
+    """
+
+    try:
+        result = run(['grub2-probe', '--target=device', directory])
+    except CalledProcessError:
+        msg = 'Could not get name of underlying {} partition'.format(directory)
+        api.current_logger().warning(msg)
+        raise StopActorExecution(msg)
+    except OSError:
+        msg = ('Could not get name of underlying {} partition:'
+               ' grub2-probe is missing.'
+               ' Possibly called on system that does not use GRUB2?').format(directory)
+        api.current_logger().warning(msg)
+        raise StopActorExecution(msg)
+
+    partition = result['stdout'].strip()
+    api.current_logger().info('{} is on {}'.format(directory, partition))
+
+    return partition
+
+
 def get_boot_partition():
     """
     Get /boot partition name.
     """
+
+    return _get_partition('/boot')
+
+
+def is_efi():
+    """
+    Return True if UEFI is used.
+
+    NOTE(pstodulk): the check doesn't have to be valid for hybrid boot (e.g. AWS, Azure, ..)
+    """
+
+    return os.path.exists("/sys/firmware/efi")
+
+
+def get_efi_partition():
+    """
+    Return the EFI System Partition (ESP).
+
+    Raise StopActorExecution when:
+        - UEFI is not detected,
+        - ESP is not mounted where expected,
+        - the partition can't be obtained from GRUB.
+    """
+
+    if not is_efi():
+        raise StopActorExecution('Unable to get ESP when BIOS is used.')
+
+    if not os.path.exists(EFI_MOUNTPOINT) or not os.path.ismount(EFI_MOUNTPOINT):
+        raise StopActorExecution(
+            'The UEFI has been detected but the ESP is not mounted in /boot/efi as required.'
+        )
+
+    return _get_partition('/boot/efi/')
+
+
+def get_blk_device(device):
+    """
+    Get the block device.
+
+    In case of the block device itself (e.g. /dev/sda), return just the block
+    device. In case of a partition, return its block device:
+        /dev/sda  -> /dev/sda
+        /dev/sda1 -> /dev/sda
+
+    Raise CalledProcessError when unable to get the block device.
+    """
+
     try:
-        # call grub2-probe to identify /boot partition
-        result = run(['grub2-probe', '--target=device', '/boot'])
+        result = run(['lsblk', '-spnlo', 'name', device])
     except CalledProcessError:
-        api.current_logger().warning(
-            'Could not get name of underlying /boot partition'
-        )
-        raise StopActorExecution()  # TODO: return some meaningful value/error
-    except OSError:
-        api.current_logger().warning(
-            'Could not get name of underlying /boot partition:'
-            ' grub2-probe is missing.'
-            ' Possibly called on system that does not use GRUB2?'
+        raise StopActorExecution('Unable to get a block device for {}'.format(device))
+
+    return result['stdout'].strip().splitlines()[-1].strip()
+
+
+def get_device_number(device):
+    """Get the partition number of a particular device.
+
+    This method will use `blkid` to determinate what is the partition number
+    related to a particular device.
+
+    :param device: The device to be analyzed.
+    :type device: str
+    :return: The device partition number.
+    :rtype: int
+    """
+
+    try:
+        result = run(
+            ['/usr/sbin/blkid', '-p', '-s', 'PART_ENTRY_NUMBER', device],
         )
-        raise StopActorExecution()  # TODO: return some meaningful value/error
-    boot_partition = result['stdout'].strip()
-    api.current_logger().info('/boot is on {}'.format(boot_partition))
-    return boot_partition
+        output = result['stdout'].strip()
+    except CalledProcessError:
+        raise StopActorExecution('Unable to get information about the {} device'.format(device))
+
+    if not output:
+        raise StopActorExecution('The {} device has no PART_ENTRY_NUMBER'.format(device))
+
+    partition_number = output.split('PART_ENTRY_NUMBER=')[-1].replace('"', '')
+
+    return int(partition_number)
 
 
 def get_grub_devices():
@@ -94,6 +378,12 @@ def get_grub_devices():
     return have_grub
 
 
+def get_efi_device():
+    """Get the block device on which GRUB is installed."""
+
+    return get_blk_device(get_efi_partition())
+
+
 @deprecated(since='2023-06-23', message='This function has been replaced by get_grub_devices')
 def get_grub_device():
     """