From 58762e6f2bd9a6e42933aafbfc073de28c9918d2 Mon Sep 17 00:00:00 2001
From: Petr Stodulka <pstodulk@redhat.com>
Date: Fri, 31 Jul 2020 14:47:57 +0200
Subject: [PATCH] Fix detection of the grub configuration path

Previos solution was still buggy. Discussed with the bootloader team,
the solution has been updated for redhat-upgrade-tool (not for boom!).
When the redhat-upgrade-tool is executed, only one configuration file
will remain.
---
 redhat_upgrade_tool/__init__.py            | 45 ++++++++++++++++++++--
 redhat_upgrade_tool/rollback/bootloader.py | 43 +++++++++++++--------
 2 files changed, 69 insertions(+), 19 deletions(-)

diff --git a/redhat_upgrade_tool/__init__.py b/redhat_upgrade_tool/__init__.py
index 1e0b1b3..9e1fecd 100644
--- a/redhat_upgrade_tool/__init__.py
+++ b/redhat_upgrade_tool/__init__.py
@@ -67,8 +67,47 @@ rhel_gpgkey_path = 'file:///etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release'
 preupgrade_dir = "/root/preupgrade"
 preupgrade_script_path = os.path.join(preupgrade_dir, 'preupgrade-scripts')
 release_version_file = os.path.join(preupgrade_dir, preupgrade_script_path, 'release_version')
-grub_conf_file = "/boot/grub/grub.conf"
-if not os.path.exists(grub_conf_file):
-    grub_conf_file = "/boot/efi/EFI/redhat/grub.conf"
+
+def detect_grub_conf():
+    """
+    Detect the right path of the grub configuration file and shot the another
+    one if exist.
+
+    This is really needed.
+    """
+    _BIOS_GRUB_CONF_PATH = "/boot/grub/grub.conf"
+    _EFI_GRUB_CONF_PATH = "/boot/efi/EFI/redhat/grub.conf"
+
+    # regarding https://access.redhat.com/solutions/3781221 - this should
+    # be enough for RHEL 6
+    if os.path.exists("/sys/firmware/efi"):
+        # we should be on EFI
+        grub_conf_file = _EFI_GRUB_CONF_PATH
+        _non_grub_file = _BIOS_GRUB_CONF_PATH
+    else:
+        # we are on BIOS
+        grub_conf_file = _BIOS_GRUB_CONF_PATH
+        _non_grub_file = _EFI_GRUB_CONF_PATH
+    if not os.path.exists(grub_conf_file) or not os.path.getsize(grub_conf_file):
+        # that's fatal error. It shouldn't happened
+        raise Exception(
+            "The expected grub configuration file doesn't exist or it is empty: %s" % grub_conf_file)
+
+    if os.path.exists(_non_grub_file):
+        # it's wrong that both files exist, if it's empty, remove it,
+        # otherwise rename it
+        if not os.path.getsize(_non_grub_file):
+            # Note: this is typical case after IPU 6 -> 7 for EFI
+            # remove the empty file
+            os.remove(_non_grub_file)
+        else:
+            # this is really weird when it happens
+            print "WARNING: Detected two grub configuration files, but only one can exist"
+            print "WARNING: Moving {fname} to {fname}.preupg_rollback_backup".format(fname=_non_grub_file)
+            shutil.move(_non_grub_file, "{}.preupg_rollback_backup".format(_non_grub_file))
+    return grub_conf_file
+
+
+grub_conf_file = detect_grub_conf()
 
 MIN_AVAIL_BYTES_FOR_BOOT = 50 * 2**20  # 50 MiB
diff --git a/redhat_upgrade_tool/rollback/bootloader.py b/redhat_upgrade_tool/rollback/bootloader.py
index aff23f4..2f605ff 100644
--- a/redhat_upgrade_tool/rollback/bootloader.py
+++ b/redhat_upgrade_tool/rollback/bootloader.py
@@ -15,23 +15,34 @@ try:
 except ImportError:
     _BIOS_GRUB_CONF_PATH = "/boot/grub/grub.conf"
     _EFI_GRUB_CONF_PATH = "/boot/efi/EFI/redhat/grub.conf"
-    grub_conf_file = _BIOS_GRUB_CONF_PATH
-    if not os.path.exists(grub_conf_file):
+
+    # regarding https://access.redhat.com/solutions/3781221 - this should
+    # be enough for RHEL 6
+    if os.path.exists("/sys/firmware/efi"):
+        # we should be on EFI
         grub_conf_file = _EFI_GRUB_CONF_PATH
-    elif os.path.exists(_EFI_GRUB_CONF_PATH):
-        if not os.path.getsize(grub_conf_file):
-            # it can happen that both files (usually on EFI systems) exists,
-            # but the BIOS one is empty in such a case
-            os.remove(grub_conf_file)
-            grub_conf_file = _EFI_GRUB_CONF_PATH
-        elif os.path.exists("/sys/firmware/efi"):
-            # ok, the 'bios' file is not empty
-            # rather move it instead of real remove, as this is weird
-            shutil.move(grub_conf_file, "{}.preupg_rollback_backup".format(grub_conf_file))
-            grub_conf_file = _EFI_GRUB_CONF_PATH
-        # else:
-        # regarding https://access.redhat.com/solutions/3781221 - we can consider
-        # the system is booted in BIOS mode; do nothing
+        _non_grub_file = _BIOS_GRUB_CONF_PATH
+    else:
+        # we are on BIOS
+        grub_conf_file = _BIOS_GRUB_CONF_PATH
+        _non_grub_file = _EFI_GRUB_CONF_PATH
+    if not os.path.exists(grub_conf_file) or not os.path.getsize(grub_conf_file):
+        # that's fatal error. It shouldn't happened
+        raise Exception(
+            "The expected grub configuration file doesn't exist or it is empty: %s" % grub_conf_file)
+
+    if os.path.exists(_non_grub_file):
+        # it's wrong that both files exist, if it's empty, remove it,
+        # otherwise rename it
+        if not os.path.getsize(_non_grub_file):
+            # Note: this is typical case after IPU 6 -> 7 for EFI
+            # remove the empty file
+            os.remove(_non_grub_file)
+        else:
+            # this is really weird when it happens
+            print "WARNING: Detected two grub configuration files, but only one can exist"
+            print "WARNING: Moving {fname} to {fname}.preupg_rollback_backup".format(fname=_non_grub_file)
+            shutil.move(_non_grub_file, "{}.preupg_rollback_backup".format(_non_grub_file))
 
     def check_call(*popenargs, **kwargs):
         retcode = call(*popenargs, **kwargs)
-- 
2.25.4