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// -*- Mode: Go; indent-tabs-mode: t -*-
/*
* Copyright (C) 2020 Canonical Ltd
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* 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 <http://www.gnu.org/licenses/>.
*
*/
package boot
import (
"fmt"
"strings"
"github.com/snapcore/snapd/bootloader/efi"
)
const (
// note the vendor ID 4a67b082-0a4c-41cf-b6c7-440b29bb8c4f is systemd, this
// variable is populated by shim
loaderDevicePartUUID = "LoaderDevicePartUUID-4a67b082-0a4c-41cf-b6c7-440b29bb8c4f"
)
// FindPartitionUUIDForBootedKernelDisk returns the partition uuid for the
// partition that the booted kernel is located on.
func FindPartitionUUIDForBootedKernelDisk() (string, error) {
// try efi variables first
partuuid, _, err := efi.ReadVarString(loaderDevicePartUUID)
if err == nil {
// the LoaderDevicePartUUID is in all caps, but lsblk,
// etc. use lower case so for consistency just make it
// lower case here too
return strings.ToLower(partuuid), nil
}
if err == efi.ErrNoEFISystem {
return "", err
}
// TODO:UC20: use the kernel command line parameter from the little kernel
// bootloader if we have a littlekernel bootloader
// TODO:UC20: add more fallbacks here, even on amd64, when we don't have efi
// i.e. on bios?
return "", fmt.Errorf("could not find partition uuid for booted kernel: %v", err)
}
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