mirror of
https://github.com/token2/snapd.git
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94 lines
2.7 KiB
Go
94 lines
2.7 KiB
Go
// -*- Mode: Go; indent-tabs-mode: t -*-
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/*
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* Copyright (C) 2019 Canonical Ltd
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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 version 3 as
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* published by the Free Software Foundation.
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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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*/
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package gadget
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import (
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"fmt"
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"path/filepath"
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"github.com/snapcore/snapd/dirs"
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"github.com/snapcore/snapd/logger"
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"github.com/snapcore/snapd/osutil"
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"github.com/snapcore/snapd/osutil/disks"
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)
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var evalSymlinks = filepath.EvalSymlinks
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// FindDeviceForStructure attempts to find an existing block device matching
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// given volume structure, by inspecting its name and, optionally, the
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// filesystem label. Assumes that the host's udev has set up device symlinks
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// correctly.
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func FindDeviceForStructure(vs *VolumeStructure) (string, error) {
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var candidates []string
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if vs.Name != "" {
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byPartlabel := filepath.Join(dirs.GlobalRootDir, "/dev/disk/by-partlabel/", disks.BlkIDEncodeLabel(vs.Name))
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candidates = append(candidates, byPartlabel)
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}
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if vs.HasFilesystem() {
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fsLabel := vs.Label
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if fsLabel == "" && vs.Name != "" {
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// when image is built and the structure has no
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// filesystem label, the structure name will be used by
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// default as the label
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fsLabel = vs.Name
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}
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if fsLabel != "" {
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candLabel, err := disks.CandidateByLabelPath(fsLabel)
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if err == nil {
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candidates = append(candidates, candLabel)
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} else {
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logger.Debugf("no by-label candidate for %q: %v", fsLabel, err)
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}
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}
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}
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var found string
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var match string
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for _, candidate := range candidates {
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if !osutil.FileExists(candidate) {
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continue
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}
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if !osutil.IsSymlink(candidate) {
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// /dev/disk/by-label/* and /dev/disk/by-partlabel/* are
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// expected to be symlink
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return "", fmt.Errorf("candidate %v is not a symlink", candidate)
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}
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target, err := evalSymlinks(candidate)
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if err != nil {
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return "", fmt.Errorf("cannot read device link: %v", err)
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}
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if found != "" && target != found {
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// partition and filesystem label links point to
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// different devices
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return "", fmt.Errorf("conflicting device match, %q points to %q, previous match %q points to %q",
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candidate, target, match, found)
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}
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found = target
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match = candidate
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}
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if found == "" {
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return "", ErrDeviceNotFound
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}
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return found, nil
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}
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