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, 222 insertions, 0 deletions

diff --git a/pkg/sentry/fs/ext/disklayout/inode_test.go b/pkg/sentry/fs/ext/disklayout/inode_test.go
new file mode 100644
index 000000000..9cae9e4f0
--- /dev/null
+++ b/pkg/sentry/fs/ext/disklayout/inode_test.go
@@ -0,0 +1,222 @@
+// 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 (
+	"fmt"
+	"strconv"
+	"testing"
+
+	"gvisor.dev/gvisor/pkg/sentry/kernel/time"
+)
+
+// TestInodeSize tests that the inode structs are of the correct size.
+func TestInodeSize(t *testing.T) {
+	assertSize(t, InodeOld{}, oldInodeSize)
+
+	// This was updated from 156 bytes to 160 bytes in Oct 2015.
+	assertSize(t, InodeNew{}, 160)
+}
+
+// TestTimestampSeconds tests that the seconds part of [a/c/m] timestamps in
+// ext4 inode structs are decoded correctly.
+//
+// These tests are derived from the table under https://www.kernel.org/doc/html/latest/filesystems/ext4/dynamic.html#inode-timestamps.
+func TestTimestampSeconds(t *testing.T) {
+	type timestampTest struct {
+		// msbSet tells if the most significant bit of InodeOld.[X]TimeRaw is set.
+		// If this is set then the 32-bit time is negative.
+		msbSet bool
+
+		// lowerBound tells if we should take the lowest possible value of
+		// InodeOld.[X]TimeRaw while satisfying test.msbSet condition. If set to
+		// false it tells to take the highest possible value.
+		lowerBound bool
+
+		// extraBits is InodeNew.[X]TimeExtra.
+		extraBits uint32
+
+		// want is the kernel time struct that is expected.
+		want time.Time
+	}
+
+	tests := []timestampTest{
+		// 1901-12-13
+		{
+			msbSet:     true,
+			lowerBound: true,
+			extraBits:  0,
+			want:       time.FromUnix(int64(-0x80000000), 0),
+		},
+
+		// 1969-12-31
+		{
+			msbSet:     true,
+			lowerBound: false,
+			extraBits:  0,
+			want:       time.FromUnix(int64(-1), 0),
+		},
+
+		// 1970-01-01
+		{
+			msbSet:     false,
+			lowerBound: true,
+			extraBits:  0,
+			want:       time.FromUnix(int64(0), 0),
+		},
+
+		// 2038-01-19
+		{
+			msbSet:     false,
+			lowerBound: false,
+			extraBits:  0,
+			want:       time.FromUnix(int64(0x7fffffff), 0),
+		},
+
+		// 2038-01-19
+		{
+			msbSet:     true,
+			lowerBound: true,
+			extraBits:  1,
+			want:       time.FromUnix(int64(0x80000000), 0),
+		},
+
+		// 2106-02-07
+		{
+			msbSet:     true,
+			lowerBound: false,
+			extraBits:  1,
+			want:       time.FromUnix(int64(0xffffffff), 0),
+		},
+
+		// 2106-02-07
+		{
+			msbSet:     false,
+			lowerBound: true,
+			extraBits:  1,
+			want:       time.FromUnix(int64(0x100000000), 0),
+		},
+
+		// 2174-02-25
+		{
+			msbSet:     false,
+			lowerBound: false,
+			extraBits:  1,
+			want:       time.FromUnix(int64(0x17fffffff), 0),
+		},
+
+		// 2174-02-25
+		{
+			msbSet:     true,
+			lowerBound: true,
+			extraBits:  2,
+			want:       time.FromUnix(int64(0x180000000), 0),
+		},
+
+		// 2242-03-16
+		{
+			msbSet:     true,
+			lowerBound: false,
+			extraBits:  2,
+			want:       time.FromUnix(int64(0x1ffffffff), 0),
+		},
+
+		// 2242-03-16
+		{
+			msbSet:     false,
+			lowerBound: true,
+			extraBits:  2,
+			want:       time.FromUnix(int64(0x200000000), 0),
+		},
+
+		// 2310-04-04
+		{
+			msbSet:     false,
+			lowerBound: false,
+			extraBits:  2,
+			want:       time.FromUnix(int64(0x27fffffff), 0),
+		},
+
+		// 2310-04-04
+		{
+			msbSet:     true,
+			lowerBound: true,
+			extraBits:  3,
+			want:       time.FromUnix(int64(0x280000000), 0),
+		},
+
+		// 2378-04-22
+		{
+			msbSet:     true,
+			lowerBound: false,
+			extraBits:  3,
+			want:       time.FromUnix(int64(0x2ffffffff), 0),
+		},
+
+		// 2378-04-22
+		{
+			msbSet:     false,
+			lowerBound: true,
+			extraBits:  3,
+			want:       time.FromUnix(int64(0x300000000), 0),
+		},
+
+		// 2446-05-10
+		{
+			msbSet:     false,
+			lowerBound: false,
+			extraBits:  3,
+			want:       time.FromUnix(int64(0x37fffffff), 0),
+		},
+	}
+
+	lowerMSB0 := int32(0)           // binary: 00000000 00000000 00000000 00000000
+	upperMSB0 := int32(0x7fffffff)  // binary: 01111111 11111111 11111111 11111111
+	lowerMSB1 := int32(-0x80000000) // binary: 10000000 00000000 00000000 00000000
+	upperMSB1 := int32(-1)          // binary: 11111111 11111111 11111111 11111111
+
+	get32BitTime := func(test timestampTest) int32 {
+		if test.msbSet {
+			if test.lowerBound {
+				return lowerMSB1
+			}
+
+			return upperMSB1
+		}
+
+		if test.lowerBound {
+			return lowerMSB0
+		}
+
+		return upperMSB0
+	}
+
+	getTestName := func(test timestampTest) string {
+		return fmt.Sprintf(
+			"Tests time decoding with epoch bits 0b%s and 32-bit raw time: MSB set=%t, lower bound=%t",
+			strconv.FormatInt(int64(test.extraBits), 2),
+			test.msbSet,
+			test.lowerBound,
+		)
+	}
+
+	for _, test := range tests {
+		t.Run(getTestName(test), func(t *testing.T) {
+			if got := fromExtraTime(get32BitTime(test), test.extraBits); got != test.want {
+				t.Errorf("Expected: %v, Got: %v", test.want, got)
+			}
+		})
+	}
+}