support filesystem magic for linux

fs/magic_linux.go

@@ -0,0 +1,123 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+/*
+Copyright 2013-2018 Docker, Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+	https://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Original source: https://github.com/moby/moby/blob/v26.0.0/daemon/graphdriver/driver_linux.go
+
+package fs
+
+import (
+	"path/filepath"
+	"syscall"
+)
+
+// Magic unsigned id of the filesystem in use.
+type Magic uint32
+
+const (
+	// MagicUnsupported is a predefined constant value other than a valid filesystem id.
+	MagicUnsupported = Magic(0x00000000)
+)
+
+const (
+	// MagicAufs filesystem id for Aufs
+	MagicAufs = Magic(0x61756673)
+	// MagicBtrfs filesystem id for Btrfs
+	MagicBtrfs = Magic(0x9123683E)
+	// MagicCramfs filesystem id for Cramfs
+	MagicCramfs = Magic(0x28cd3d45)
+	// MagicEcryptfs filesystem id for eCryptfs
+	MagicEcryptfs = Magic(0xf15f)
+	// MagicExtfs filesystem id for Extfs
+	MagicExtfs = Magic(0x0000EF53)
+	// MagicF2fs filesystem id for F2fs
+	MagicF2fs = Magic(0xF2F52010)
+	// MagicGPFS filesystem id for GPFS
+	MagicGPFS = Magic(0x47504653)
+	// MagicJffs2Fs filesystem if for Jffs2Fs
+	MagicJffs2Fs = Magic(0x000072b6)
+	// MagicJfs filesystem id for Jfs
+	MagicJfs = Magic(0x3153464a)
+	// MagicNfsFs filesystem id for NfsFs
+	MagicNfsFs = Magic(0x00006969)
+	// MagicRAMFs filesystem id for RamFs
+	MagicRAMFs = Magic(0x858458f6)
+	// MagicReiserFs filesystem id for ReiserFs
+	MagicReiserFs = Magic(0x52654973)
+	// MagicSmbFs filesystem id for SmbFs
+	MagicSmbFs = Magic(0x0000517B)
+	// MagicSquashFs filesystem id for SquashFs
+	MagicSquashFs = Magic(0x73717368)
+	// MagicTmpFs filesystem id for TmpFs
+	MagicTmpFs = Magic(0x01021994)
+	// MagicVxFS filesystem id for VxFs
+	MagicVxFS = Magic(0xa501fcf5)
+	// MagicXfs filesystem id for Xfs
+	MagicXfs = Magic(0x58465342)
+	// MagicZfs filesystem id for Zfs
+	MagicZfs = Magic(0x2fc12fc1)
+	// MagicOverlay filesystem id for overlay
+	MagicOverlay = Magic(0x794C7630)
+)
+
+var (
+	// FsNames maps filesystem id to name of the filesystem.
+	FsNames = map[Magic]string{
+		MagicAufs:        "aufs",
+		MagicBtrfs:       "btrfs",
+		MagicCramfs:      "cramfs",
+		MagicExtfs:       "extfs",
+		MagicF2fs:        "f2fs",
+		MagicGPFS:        "gpfs",
+		MagicJffs2Fs:     "jffs2",
+		MagicJfs:         "jfs",
+		MagicNfsFs:       "nfs",
+		MagicOverlay:     "overlayfs",
+		MagicRAMFs:       "ramfs",
+		MagicReiserFs:    "reiserfs",
+		MagicSmbFs:       "smb",
+		MagicSquashFs:    "squashfs",
+		MagicTmpFs:       "tmpfs",
+		MagicUnsupported: "unsupported",
+		MagicVxFS:        "vxfs",
+		MagicXfs:         "xfs",
+		MagicZfs:         "zfs",
+	}
+)
+
+// GetMagic returns the filesystem id given the path.
+func GetMagic(rootpath string) (Magic, error) {
+	var buf syscall.Statfs_t
+	if err := syscall.Statfs(filepath.Dir(rootpath), &buf); err != nil {
+		return 0, err
+	}
+	return Magic(buf.Type), nil
+}