ext: boilerplate code.

Renamed ext4 to ext since we are targeting ext(2/3/4).
Removed fs.go since we are targeting VFS2.
Added ext.go with filesystem struct.

PiperOrigin-RevId: 257689775

1 files changed, 117 insertions, 0 deletions

diff --git a/pkg/sentry/fs/ext/disklayout/inode_old.go b/pkg/sentry/fs/ext/disklayout/inode_old.go
new file mode 100644
index 000000000..dc4c9d8e4
--- /dev/null
+++ b/pkg/sentry/fs/ext/disklayout/inode_old.go
@@ -0,0 +1,117 @@
+// Copyright 2019 The gVisor 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.
+
+package disklayout
+
+import (
+	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
+	"gvisor.dev/gvisor/pkg/sentry/kernel/time"
+)
+
+const (
+	// oldInodeSize is the inode size in ext2/ext3.
+	oldInodeSize = 128
+)
+
+// InodeOld implements Inode interface. It emulates ext2/ext3 inode struct.
+// Inode struct size and record size are both 128 bytes for this.
+//
+// All fields representing time are in seconds since the epoch. Which means that
+// they will overflow in January 2038.
+type InodeOld struct {
+	ModeRaw uint16
+	UIDLo   uint16
+	SizeLo  uint32
+
+	// The time fields are signed integers because they could be negative to
+	// represent time before the epoch.
+	AccessTimeRaw       int32
+	ChangeTimeRaw       int32
+	ModificationTimeRaw int32
+	DeletionTimeRaw     int32
+
+	GIDLo         uint16
+	LinksCountRaw uint16
+	BlocksCountLo uint32
+	FlagsRaw      uint32
+	VersionLo     uint32 // This is OS dependent.
+	BlocksRaw     [60]byte
+	Generation    uint32
+	FileACLLo     uint32
+	SizeHi        uint32
+	ObsoFaddr     uint32
+
+	// OS dependent fields have been inlined here.
+	BlocksCountHi uint16
+	FileACLHi     uint16
+	UIDHi         uint16
+	GIDHi         uint16
+	ChecksumLo    uint16
+	_             uint16
+}
+
+// Compiles only if InodeOld implements Inode.
+var _ Inode = (*InodeOld)(nil)
+
+// Mode implements Inode.Mode.
+func (in *InodeOld) Mode() linux.FileMode { return linux.FileMode(in.ModeRaw) }
+
+// UID implements Inode.UID.
+func (in *InodeOld) UID() auth.KUID {
+	return auth.KUID((uint32(in.UIDHi) << 16) | uint32(in.UIDLo))
+}
+
+// GID implements Inode.GID.
+func (in *InodeOld) GID() auth.KGID {
+	return auth.KGID((uint32(in.GIDHi) << 16) | uint32(in.GIDLo))
+}
+
+// Size implements Inode.Size.
+func (in *InodeOld) Size() uint64 {
+	// In ext2/ext3, in.SizeHi did not exist, it was instead named in.DirACL.
+	return uint64(in.SizeLo)
+}
+
+// InodeSize implements Inode.InodeSize.
+func (in *InodeOld) InodeSize() uint16 { return oldInodeSize }
+
+// AccessTime implements Inode.AccessTime.
+func (in *InodeOld) AccessTime() time.Time {
+	return time.FromUnix(int64(in.AccessTimeRaw), 0)
+}
+
+// ChangeTime implements Inode.ChangeTime.
+func (in *InodeOld) ChangeTime() time.Time {
+	return time.FromUnix(int64(in.ChangeTimeRaw), 0)
+}
+
+// ModificationTime implements Inode.ModificationTime.
+func (in *InodeOld) ModificationTime() time.Time {
+	return time.FromUnix(int64(in.ModificationTimeRaw), 0)
+}
+
+// DeletionTime implements Inode.DeletionTime.
+func (in *InodeOld) DeletionTime() time.Time {
+	return time.FromUnix(int64(in.DeletionTimeRaw), 0)
+}
+
+// LinksCount implements Inode.LinksCount.
+func (in *InodeOld) LinksCount() uint16 { return in.LinksCountRaw }
+
+// Flags implements Inode.Flags.
+func (in *InodeOld) Flags() InodeFlags { return InodeFlagsFromInt(in.FlagsRaw) }
+
+// Blocks implements Inode.Blocks.
+func (in *InodeOld) Blocks() [60]byte { return in.BlocksRaw }