package contenthash

import (
	"context"
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"testing"
	"time"

	"github.com/containerd/containerd/content/local"
	ctdmetadata "github.com/containerd/containerd/metadata"
	"github.com/containerd/containerd/snapshots"
	"github.com/containerd/containerd/snapshots/native"
	"github.com/moby/buildkit/cache"
	"github.com/moby/buildkit/cache/metadata"
	"github.com/moby/buildkit/snapshot"
	containerdsnapshot "github.com/moby/buildkit/snapshot/containerd"
	"github.com/moby/buildkit/util/leaseutil"
	digest "github.com/opencontainers/go-digest"
	"github.com/pkg/errors"
	"github.com/stretchr/testify/require"
	"github.com/tonistiigi/fsutil"
	fstypes "github.com/tonistiigi/fsutil/types"
	bolt "go.etcd.io/bbolt"
)

const (
	dgstFileData0     = digest.Digest("sha256:cd8e75bca50f2d695f220d0cb0997d8ead387e4f926e8669a92d7f104cc9885b")
	dgstDirD0         = digest.Digest("sha256:d47454417d2c554067fbefe5f5719edc49f3cfe969c36b62e34a187a4da0cc9a")
	dgstDirD0Modified = digest.Digest("sha256:555ffa3028630d97ba37832b749eda85ab676fd64ffb629fbf0f4ec8c1e3bff1")
)

func TestChecksumSymlinkNoParentScan(t *testing.T) {
	t.Parallel()
	tmpdir, err := ioutil.TempDir("", "buildkit-state")
	require.NoError(t, err)
	defer os.RemoveAll(tmpdir)

	snapshotter, err := native.NewSnapshotter(filepath.Join(tmpdir, "snapshots"))
	require.NoError(t, err)
	cm, _ := setupCacheManager(t, tmpdir, "native", snapshotter)
	defer cm.Close()

	ch := []string{
		"ADD aa dir",
		"ADD aa/bb dir",
		"ADD aa/bb/cc dir",
		"ADD aa/bb/cc/dd file data0",
		"ADD aa/ln symlink /aa",
	}

	ref := createRef(t, cm, ch)

	cc, err := newCacheContext(ref.Metadata(), nil)
	require.NoError(t, err)

	dgst, err := cc.Checksum(context.TODO(), ref, "aa/ln/bb/cc/dd", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)
}

func TestChecksumHardlinks(t *testing.T) {
	t.Parallel()
	tmpdir, err := ioutil.TempDir("", "buildkit-state")
	require.NoError(t, err)
	defer os.RemoveAll(tmpdir)

	snapshotter, err := native.NewSnapshotter(filepath.Join(tmpdir, "snapshots"))
	require.NoError(t, err)
	cm, _ := setupCacheManager(t, tmpdir, "native", snapshotter)
	defer cm.Close()

	ch := []string{
		"ADD abc dir",
		"ADD abc/foo file data0",
		"ADD ln file >/abc/foo",
		"ADD ln2 file >/abc/foo",
	}

	ref := createRef(t, cm, ch)

	cc, err := newCacheContext(ref.Metadata(), nil)
	require.NoError(t, err)

	dgst, err := cc.Checksum(context.TODO(), ref, "abc/foo", false)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	dgst, err = cc.Checksum(context.TODO(), ref, "ln", false)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	dgst, err = cc.Checksum(context.TODO(), ref, "ln2", false)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	// validate same results with handleChange
	ref2 := createRef(t, cm, nil)

	cc2, err := newCacheContext(ref2.Metadata(), nil)
	require.NoError(t, err)

	err = emit(cc2.HandleChange, changeStream(ch))
	require.NoError(t, err)

	dgst, err = cc2.Checksum(context.TODO(), ref, "abc/foo", false)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	dgst, err = cc2.Checksum(context.TODO(), ref, "ln", false)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	dgst, err = cc2.Checksum(context.TODO(), ref, "ln2", false)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	// modify two of the links

	ch = []string{
		"ADD abc/foo file data1",
		"ADD ln file >/abc/foo",
	}

	cc2.linkMap = map[string][][]byte{}

	err = emit(cc2.HandleChange, changeStream(ch))
	require.NoError(t, err)

	data1Expected := "sha256:c2b5e234f5f38fc5864da7def04782f82501a40d46192e4207d5b3f0c3c4732b"

	dgst, err = cc2.Checksum(context.TODO(), ref, "abc/foo", false)
	require.NoError(t, err)
	require.Equal(t, data1Expected, string(dgst))

	dgst, err = cc2.Checksum(context.TODO(), ref, "ln", false)
	require.NoError(t, err)
	require.Equal(t, data1Expected, string(dgst))

	dgst, err = cc2.Checksum(context.TODO(), ref, "ln2", false)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)
}

func TestChecksumWildcard(t *testing.T) {
	t.Parallel()
	tmpdir, err := ioutil.TempDir("", "buildkit-state")
	require.NoError(t, err)
	defer os.RemoveAll(tmpdir)

	snapshotter, err := native.NewSnapshotter(filepath.Join(tmpdir, "snapshots"))
	require.NoError(t, err)
	cm, _ := setupCacheManager(t, tmpdir, "native", snapshotter)
	defer cm.Close()

	ch := []string{
		"ADD bar file data1",
		"ADD foo file data0",
		"ADD fox file data2",
		"ADD x dir",
		"ADD x/d0 dir",
		"ADD x/d0/abc file data0",
		"ADD x/d0/def symlink abc",
		"ADD x/d0/ghi symlink nosuchfile",
		"ADD y1 symlink foo",
		"ADD y2 symlink fox",
	}

	ref := createRef(t, cm, ch)

	cc, err := newCacheContext(ref.Metadata(), nil)
	require.NoError(t, err)

	dgst, err := cc.ChecksumWildcard(context.TODO(), ref, "f*o", false)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	expFoos := digest.Digest("sha256:c9f914ad7ad8fe6092ce67484b43ca39c2087aabf9e4a1b223249b0f8b09b9f2")

	dgst, err = cc.ChecksumWildcard(context.TODO(), ref, "f*", false)
	require.NoError(t, err)
	require.Equal(t, expFoos, dgst)

	dgst, err = cc.ChecksumWildcard(context.TODO(), ref, "x/d?", false)
	require.NoError(t, err)
	require.Equal(t, dgstDirD0, dgst)

	dgst, err = cc.ChecksumWildcard(context.TODO(), ref, "x/d?/def", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	dgst, err = cc.ChecksumWildcard(context.TODO(), ref, "y*", true)
	require.NoError(t, err)
	require.Equal(t, expFoos, dgst)

	err = ref.Release(context.TODO())
	require.NoError(t, err)
}

func TestChecksumWildcardWithBadMountable(t *testing.T) {
	t.Parallel()
	tmpdir, err := ioutil.TempDir("", "buildkit-state")
	require.NoError(t, err)
	defer os.RemoveAll(tmpdir)

	snapshotter, err := native.NewSnapshotter(filepath.Join(tmpdir, "snapshots"))
	require.NoError(t, err)
	cm, _ := setupCacheManager(t, tmpdir, "native", snapshotter)
	defer cm.Close()

	ref := createRef(t, cm, nil)

	cc, err := newCacheContext(ref.Metadata(), nil)
	require.NoError(t, err)

	_, err = cc.ChecksumWildcard(context.TODO(), newBadMountable(), "*", false)
	require.Error(t, err)
}

func TestSymlinksNoFollow(t *testing.T) {
	t.Parallel()
	tmpdir, err := ioutil.TempDir("", "buildkit-state")
	require.NoError(t, err)
	defer os.RemoveAll(tmpdir)

	snapshotter, err := native.NewSnapshotter(filepath.Join(tmpdir, "snapshots"))
	require.NoError(t, err)
	cm, _ := setupCacheManager(t, tmpdir, "native", snapshotter)
	defer cm.Close()

	ch := []string{
		"ADD target file data0",
		"ADD sym symlink target",
		"ADD sym2 symlink target2",
		"ADD foo dir",
		"ADD foo/ghi symlink target",
		"ADD y1 symlink foo/ghi",
	}

	ref := createRef(t, cm, ch)

	cc, err := newCacheContext(ref.Metadata(), nil)
	require.NoError(t, err)

	expectedSym := digest.Digest("sha256:a2ba571981f48ec34eb79c9a3ab091b6491e825c2f7e9914ea86e8e958be7fae")

	dgst, err := cc.ChecksumWildcard(context.TODO(), ref, "sym", false)
	require.NoError(t, err)
	require.Equal(t, expectedSym, dgst)

	dgst, err = cc.ChecksumWildcard(context.TODO(), ref, "sym2", false)
	require.NoError(t, err)
	require.NotEqual(t, expectedSym, dgst)

	dgst, err = cc.ChecksumWildcard(context.TODO(), ref, "foo/ghi", false)
	require.NoError(t, err)
	require.Equal(t, expectedSym, dgst)

	_, err = cc.ChecksumWildcard(context.TODO(), ref, "foo/ghi", true) // same because broken symlink
	require.Error(t, err)
	require.Equal(t, true, errors.Is(err, errNotFound))

	_, err = cc.ChecksumWildcard(context.TODO(), ref, "y1", true)
	require.Error(t, err)
	require.Equal(t, true, errors.Is(err, errNotFound))

	dgst, err = cc.Checksum(context.TODO(), ref, "sym", false)
	require.NoError(t, err)
	require.Equal(t, expectedSym, dgst)

	dgst, err = cc.Checksum(context.TODO(), ref, "foo/ghi", false)
	require.NoError(t, err)
	require.Equal(t, expectedSym, dgst)

	err = ref.Release(context.TODO())
	require.NoError(t, err)
}

func TestChecksumBasicFile(t *testing.T) {
	t.Parallel()
	tmpdir, err := ioutil.TempDir("", "buildkit-state")
	require.NoError(t, err)
	defer os.RemoveAll(tmpdir)

	snapshotter, err := native.NewSnapshotter(filepath.Join(tmpdir, "snapshots"))
	require.NoError(t, err)
	cm, _ := setupCacheManager(t, tmpdir, "native", snapshotter)
	defer cm.Close()

	ch := []string{
		"ADD foo file data0",
		"ADD bar file data1",
		"ADD d0 dir",
		"ADD d0/abc file data0",
		"ADD d0/def symlink abc",
		"ADD d0/ghi symlink nosuchfile",
	}

	ref := createRef(t, cm, ch)

	// for the digest values, the actual values are not important in development
	// phase but consistency is

	cc, err := newCacheContext(ref.Metadata(), nil)
	require.NoError(t, err)

	_, err = cc.Checksum(context.TODO(), ref, "nosuch", true)
	require.Error(t, err)

	dgst, err := cc.Checksum(context.TODO(), ref, "foo", true)
	require.NoError(t, err)

	require.Equal(t, dgstFileData0, dgst)

	// second file returns different hash
	dgst, err = cc.Checksum(context.TODO(), ref, "bar", true)
	require.NoError(t, err)

	require.Equal(t, digest.Digest("sha256:c2b5e234f5f38fc5864da7def04782f82501a40d46192e4207d5b3f0c3c4732b"), dgst)

	// same file inside a directory
	dgst, err = cc.Checksum(context.TODO(), ref, "d0/abc", true)
	require.NoError(t, err)

	require.Equal(t, dgstFileData0, dgst)

	// repeat because codepath is different
	dgst, err = cc.Checksum(context.TODO(), ref, "d0/abc", true)
	require.NoError(t, err)

	require.Equal(t, dgstFileData0, dgst)

	// symlink to the same file is followed, returns same hash
	dgst, err = cc.Checksum(context.TODO(), ref, "d0/def", true)
	require.NoError(t, err)

	require.Equal(t, dgstFileData0, dgst)

	_, err = cc.Checksum(context.TODO(), ref, "d0/ghi", true)
	require.Error(t, err)
	require.Equal(t, true, errors.Is(err, errNotFound))

	dgst, err = cc.Checksum(context.TODO(), ref, "/", true)
	require.NoError(t, err)

	require.Equal(t, digest.Digest("sha256:427c9cf9ae98c0f81fb57a3076b965c7c149b6b0a85625ad4e884236649a42c6"), dgst)

	dgst, err = cc.Checksum(context.TODO(), ref, "d0", true)
	require.NoError(t, err)

	require.Equal(t, dgstDirD0, dgst)

	err = ref.Release(context.TODO())
	require.NoError(t, err)

	// this is same directory as previous d0
	ch = []string{
		"ADD abc file data0",
		"ADD def symlink abc",
		"ADD ghi symlink nosuchfile",
	}

	ref = createRef(t, cm, ch)

	cc, err = newCacheContext(ref.Metadata(), nil)
	require.NoError(t, err)

	dgst, err = cc.Checksum(context.TODO(), ref, "/", true)
	require.NoError(t, err)

	require.Equal(t, dgstDirD0, dgst)

	err = ref.Release(context.TODO())
	require.NoError(t, err)

	// test that removing broken symlink changes hash even though symlink itself can't be checksummed
	ch = []string{
		"ADD abc file data0",
		"ADD def symlink abc",
	}

	ref = createRef(t, cm, ch)

	cc, err = newCacheContext(ref.Metadata(), nil)
	require.NoError(t, err)

	dgst, err = cc.Checksum(context.TODO(), ref, "/", true)
	require.NoError(t, err)

	require.Equal(t, dgstDirD0Modified, dgst)
	require.NotEqual(t, dgstDirD0, dgst)

	err = ref.Release(context.TODO())
	require.NoError(t, err)

	// test multiple scans, get checksum of nested file first

	ch = []string{
		"ADD abc dir",
		"ADD abc/aa dir",
		"ADD abc/aa/foo file data2",
		"ADD d0 dir",
		"ADD d0/abc file data0",
		"ADD d0/def symlink abc",
		"ADD d0/ghi symlink nosuchfile",
	}

	ref = createRef(t, cm, ch)

	cc, err = newCacheContext(ref.Metadata(), nil)
	require.NoError(t, err)

	dgst, err = cc.Checksum(context.TODO(), ref, "abc/aa/foo", true)
	require.NoError(t, err)

	require.Equal(t, digest.Digest("sha256:1c67653c3cf95b12a0014e2c4cd1d776b474b3218aee54155d6ae27b9b999c54"), dgst)
	require.NotEqual(t, dgstDirD0, dgst)

	// this will force rescan
	dgst, err = cc.Checksum(context.TODO(), ref, "d0", true)
	require.NoError(t, err)

	require.Equal(t, dgstDirD0, dgst)

	err = ref.Release(context.TODO())
	require.NoError(t, err)
}

func TestHandleChange(t *testing.T) {
	t.Parallel()
	tmpdir, err := ioutil.TempDir("", "buildkit-state")
	require.NoError(t, err)
	defer os.RemoveAll(tmpdir)

	snapshotter, err := native.NewSnapshotter(filepath.Join(tmpdir, "snapshots"))
	require.NoError(t, err)
	cm, _ := setupCacheManager(t, tmpdir, "native", snapshotter)
	defer cm.Close()

	ch := []string{
		"ADD foo file data0",
		"ADD bar file data1",
		"ADD d0 dir",
		"ADD d0/abc file data0",
		"ADD d0/def symlink abc",
		"ADD d0/ghi symlink nosuchfile",
	}

	ref := createRef(t, cm, nil)

	// for the digest values, the actual values are not important in development
	// phase but consistency is

	cc, err := newCacheContext(ref.Metadata(), nil)
	require.NoError(t, err)

	err = emit(cc.HandleChange, changeStream(ch))
	require.NoError(t, err)

	dgstFoo, err := cc.Checksum(context.TODO(), ref, "foo", true)
	require.NoError(t, err)

	require.Equal(t, dgstFileData0, dgstFoo)

	// symlink to the same file is followed, returns same hash
	dgst, err := cc.Checksum(context.TODO(), ref, "d0/def", true)
	require.NoError(t, err)

	require.Equal(t, dgstFoo, dgst)

	// symlink to the same file is followed, returns same hash
	dgst, err = cc.Checksum(context.TODO(), ref, "d0", true)
	require.NoError(t, err)

	require.Equal(t, dgstDirD0, dgst)

	ch = []string{
		"DEL d0/ghi file",
	}

	err = emit(cc.HandleChange, changeStream(ch))
	require.NoError(t, err)

	dgst, err = cc.Checksum(context.TODO(), ref, "d0", true)
	require.NoError(t, err)
	require.Equal(t, dgstDirD0Modified, dgst)

	ch = []string{
		"DEL d0 dir",
	}

	err = emit(cc.HandleChange, changeStream(ch))
	require.NoError(t, err)

	_, err = cc.Checksum(context.TODO(), ref, "d0", true)
	require.Error(t, err)
	require.Equal(t, true, errors.Is(err, errNotFound))

	_, err = cc.Checksum(context.TODO(), ref, "d0/abc", true)
	require.Error(t, err)
	require.Equal(t, true, errors.Is(err, errNotFound))

	err = ref.Release(context.TODO())
	require.NoError(t, err)
}

func TestHandleRecursiveDir(t *testing.T) {
	t.Parallel()
	tmpdir, err := ioutil.TempDir("", "buildkit-state")
	require.NoError(t, err)
	defer os.RemoveAll(tmpdir)

	snapshotter, err := native.NewSnapshotter(filepath.Join(tmpdir, "snapshots"))
	require.NoError(t, err)
	cm, _ := setupCacheManager(t, tmpdir, "native", snapshotter)
	defer cm.Close()

	ch := []string{
		"ADD d0 dir",
		"ADD d0/foo dir",
		"ADD d0/foo/bar dir",
		"ADD d0/foo/bar/foo file data0",
		"ADD d0/foo/bar/bar file data1",
		"ADD d1 dir",
		"ADD d1/foo file data0",
	}

	ref := createRef(t, cm, nil)

	cc, err := newCacheContext(ref.Metadata(), nil)
	require.NoError(t, err)

	err = emit(cc.HandleChange, changeStream(ch))
	require.NoError(t, err)

	dgst, err := cc.Checksum(context.TODO(), ref, "d0/foo/bar", true)
	require.NoError(t, err)

	ch = []string{
		"DEL d0 dir",
		"DEL d0/foo dir", // the differ can produce a record for subdir as well
		"ADD d1/bar file data1",
	}

	err = emit(cc.HandleChange, changeStream(ch))
	require.NoError(t, err)

	dgst2, err := cc.Checksum(context.TODO(), ref, "d1", true)
	require.NoError(t, err)
	require.Equal(t, dgst2, dgst)

	_, err = cc.Checksum(context.TODO(), ref, "", true)
	require.NoError(t, err)
}

func TestChecksumUnorderedFiles(t *testing.T) {
	t.Parallel()
	tmpdir, err := ioutil.TempDir("", "buildkit-state")
	require.NoError(t, err)
	defer os.RemoveAll(tmpdir)

	snapshotter, err := native.NewSnapshotter(filepath.Join(tmpdir, "snapshots"))
	require.NoError(t, err)
	cm, _ := setupCacheManager(t, tmpdir, "native", snapshotter)
	defer cm.Close()

	ch := []string{
		"ADD d0 dir",
		"ADD d0/foo dir",
		"ADD d0/foo/bar file data0",
		"ADD d0/foo-subdir dir",
		"ADD d0/foo.subdir file data1",
	}

	ref := createRef(t, cm, nil)

	cc, err := newCacheContext(ref.Metadata(), nil)
	require.NoError(t, err)

	err = emit(cc.HandleChange, changeStream(ch))
	require.NoError(t, err)

	dgst, err := cc.Checksum(context.TODO(), ref, "d0", true)
	require.NoError(t, err)

	require.Equal(t, dgst, digest.Digest("sha256:14276c302c940a80f82ca5477bf766c98a24702d6a9948ee71bb277cdad3ae05"))

	// check regression from earier version that didn't track some files
	ch = []string{
		"ADD d0 dir",
		"ADD d0/foo dir",
		"ADD d0/foo/bar file data0",
	}

	ref = createRef(t, cm, nil)

	cc, err = newCacheContext(ref.Metadata(), nil)
	require.NoError(t, err)

	err = emit(cc.HandleChange, changeStream(ch))
	require.NoError(t, err)

	dgst2, err := cc.Checksum(context.TODO(), ref, "d0", true)
	require.NoError(t, err)

	require.NotEqual(t, dgst, dgst2)
}

func TestSymlinkInPathScan(t *testing.T) {
	t.Parallel()
	tmpdir, err := ioutil.TempDir("", "buildkit-state")
	require.NoError(t, err)
	defer os.RemoveAll(tmpdir)

	snapshotter, err := native.NewSnapshotter(filepath.Join(tmpdir, "snapshots"))
	require.NoError(t, err)
	cm, _ := setupCacheManager(t, tmpdir, "native", snapshotter)
	defer cm.Close()

	ch := []string{
		"ADD d0 dir",
		"ADD d0/sub dir",
		"ADD d0/sub/foo file data0",
		"ADD d0/def symlink sub",
	}
	ref := createRef(t, cm, ch)

	dgst, err := Checksum(context.TODO(), ref, "d0/def/foo", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	dgst, err = Checksum(context.TODO(), ref, "d0/def/foo", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	err = ref.Release(context.TODO())
	require.NoError(t, err)
}

func TestSymlinkNeedsScan(t *testing.T) {
	t.Parallel()
	tmpdir, err := ioutil.TempDir("", "buildkit-state")
	require.NoError(t, err)
	defer os.RemoveAll(tmpdir)

	snapshotter, err := native.NewSnapshotter(filepath.Join(tmpdir, "snapshots"))
	require.NoError(t, err)
	cm, _ := setupCacheManager(t, tmpdir, "native", snapshotter)
	defer cm.Close()

	ch := []string{
		"ADD c0 dir",
		"ADD c0/sub dir",
		"ADD c0/sub/foo file data0",
		"ADD d0 dir",
		"ADD d0/d1 dir",
		"ADD d0/d1/def symlink ../../c0/sub",
	}
	ref := createRef(t, cm, ch)

	// scan the d0 path containing the symlink that doesn't get followed
	_, err = Checksum(context.TODO(), ref, "d0/d1", true)
	require.NoError(t, err)

	dgst, err := Checksum(context.TODO(), ref, "d0/d1/def/foo", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	err = ref.Release(context.TODO())
	require.NoError(t, err)
}

func TestSymlinkAbsDirSuffix(t *testing.T) {
	t.Parallel()
	tmpdir, err := ioutil.TempDir("", "buildkit-state")
	require.NoError(t, err)
	defer os.RemoveAll(tmpdir)

	snapshotter, err := native.NewSnapshotter(filepath.Join(tmpdir, "snapshots"))
	require.NoError(t, err)
	cm, _ := setupCacheManager(t, tmpdir, "native", snapshotter)
	defer cm.Close()

	ch := []string{
		"ADD c0 dir",
		"ADD c0/sub dir",
		"ADD c0/sub/foo file data0",
		"ADD link symlink /c0/sub/",
	}
	ref := createRef(t, cm, ch)

	dgst, err := Checksum(context.TODO(), ref, "link/foo", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	err = ref.Release(context.TODO())
	require.NoError(t, err)
}

func TestSymlinkThroughParent(t *testing.T) {
	t.Parallel()
	tmpdir, err := ioutil.TempDir("", "buildkit-state")
	require.NoError(t, err)
	defer os.RemoveAll(tmpdir)

	snapshotter, err := native.NewSnapshotter(filepath.Join(tmpdir, "snapshots"))
	require.NoError(t, err)
	cm, _ := setupCacheManager(t, tmpdir, "native", snapshotter)
	defer cm.Close()

	ch := []string{
		"ADD lib dir",
		"ADD lib/sub dir",
		"ADD lib/sub/foo file data0",
		"ADD lib/sub/link symlink ../../lib2",
		"ADD lib2 dir",
		"ADD lib2/sub dir",
		"ADD lib2/sub/foo file data0",
		"ADD link1 symlink /lib",
		"ADD link2 symlink /lib/",
		"ADD link3 symlink /lib/.",
		"ADD link4 symlink /lib/../lib",
		"ADD link5 symlink ../lib",
	}
	ref := createRef(t, cm, ch)

	dgst, err := Checksum(context.TODO(), ref, "link1/sub/foo", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	dgst, err = Checksum(context.TODO(), ref, "link2/sub/foo", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	dgst, err = Checksum(context.TODO(), ref, "link3/sub/foo", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	dgst, err = Checksum(context.TODO(), ref, "link4/sub/foo", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	dgst, err = Checksum(context.TODO(), ref, "link5/sub/foo", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	dgst, err = Checksum(context.TODO(), ref, "link1/sub/link/sub/foo", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	err = ref.Release(context.TODO())
	require.NoError(t, err)
}

func TestSymlinkInPathHandleChange(t *testing.T) {
	t.Parallel()
	tmpdir, err := ioutil.TempDir("", "buildkit-state")
	require.NoError(t, err)
	defer os.RemoveAll(tmpdir)

	snapshotter, err := native.NewSnapshotter(filepath.Join(tmpdir, "snapshots"))
	require.NoError(t, err)
	cm, _ := setupCacheManager(t, tmpdir, "native", snapshotter)
	defer cm.Close()

	ch := []string{
		"ADD d1 dir",
		"ADD d1/sub dir",
		"ADD d1/sub/foo file data0",
		"ADD d1/sub/bar symlink /link",
		"ADD d1/sub/baz symlink ../../../link",
		"ADD d1/sub/bay symlink ../../../../link/.", // weird link
		"ADD d1/def symlink sub",
		"ADD sub dir",
		"ADD sub/d0 dir",
		"ADD sub/d0/abc file data0",
		"ADD sub/d0/def symlink abc",
		"ADD sub/d0/ghi symlink nosuchfile",
		"ADD link symlink sub/d0",
	}

	ref := createRef(t, cm, nil)

	cc, err := newCacheContext(ref.Metadata(), nil)
	require.NoError(t, err)

	err = emit(cc.HandleChange, changeStream(ch))
	require.NoError(t, err)

	dgst, err := cc.Checksum(context.TODO(), ref, "d1/def/foo", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	dgst, err = cc.Checksum(context.TODO(), ref, "d1/def/bar/abc", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	dgstFileData0, err := cc.Checksum(context.TODO(), ref, "sub/d0", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgstDirD0)

	dgstFileData0, err = cc.Checksum(context.TODO(), ref, "d1/def/baz", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgstDirD0)

	dgstFileData0, err = cc.Checksum(context.TODO(), ref, "d1/def/bay", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgstDirD0)

	dgstFileData0, err = cc.Checksum(context.TODO(), ref, "link", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgstDirD0)

	err = ref.Release(context.TODO())
	require.NoError(t, err)
}

func TestPersistence(t *testing.T) {
	t.Parallel()
	tmpdir, err := ioutil.TempDir("", "buildkit-state")
	require.NoError(t, err)
	defer os.RemoveAll(tmpdir)

	snapshotter, err := native.NewSnapshotter(filepath.Join(tmpdir, "snapshots"))
	require.NoError(t, err)
	cm, closeBolt := setupCacheManager(t, tmpdir, "native", snapshotter)
	defer cm.Close()

	ch := []string{
		"ADD foo file data0",
		"ADD bar file data1",
		"ADD d0 dir",
		"ADD d0/abc file data0",
		"ADD d0/def symlink abc",
		"ADD d0/ghi symlink nosuchfile",
	}

	ref := createRef(t, cm, ch)
	id := ref.ID()

	dgst, err := Checksum(context.TODO(), ref, "foo", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	err = ref.Release(context.TODO())
	require.NoError(t, err)

	ref, err = cm.Get(context.TODO(), id)
	require.NoError(t, err)

	dgst, err = Checksum(context.TODO(), ref, "foo", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)

	err = ref.Release(context.TODO())
	require.NoError(t, err)

	time.Sleep(100 * time.Millisecond) // saving happens on the background

	// we can't close snapshotter and open it twice (especially, its internal bbolt store)
	cm.Close()
	closeBolt()
	getDefaultManager().lru.Purge()
	cm, closeBolt = setupCacheManager(t, tmpdir, "native", snapshotter)
	defer closeBolt()
	defer cm.Close()

	ref, err = cm.Get(context.TODO(), id)
	require.NoError(t, err)

	dgst, err = Checksum(context.TODO(), ref, "foo", true)
	require.NoError(t, err)
	require.Equal(t, dgstFileData0, dgst)
}

func createRef(t *testing.T, cm cache.Manager, files []string) cache.ImmutableRef {
	if runtime.GOOS == "windows" && len(files) > 0 {
		// lm.Mount() will fail
		t.Skip("Depends on unimplemented containerd bind-mount support on Windows")
	}

	mref, err := cm.New(context.TODO(), nil, cache.CachePolicyRetain)
	require.NoError(t, err)

	mounts, err := mref.Mount(context.TODO(), false)
	require.NoError(t, err)

	lm := snapshot.LocalMounter(mounts)

	mp, err := lm.Mount()
	require.NoError(t, err)

	err = writeChanges(mp, changeStream(files))
	lm.Unmount()
	require.NoError(t, err)

	ref, err := mref.Commit(context.TODO())
	require.NoError(t, err)

	return ref
}

func setupCacheManager(t *testing.T, tmpdir string, snapshotterName string, snapshotter snapshots.Snapshotter) (cache.Manager, func()) {
	md, err := metadata.NewStore(filepath.Join(tmpdir, "metadata.db"))
	require.NoError(t, err)

	store, err := local.NewStore(tmpdir)
	require.NoError(t, err)

	db, err := bolt.Open(filepath.Join(tmpdir, "containerdmeta.db"), 0644, nil)
	require.NoError(t, err)

	mdb := ctdmetadata.NewDB(db, store, map[string]snapshots.Snapshotter{
		snapshotterName: snapshotter,
	})

	cm, err := cache.NewManager(cache.ManagerOpt{
		Snapshotter:    snapshot.FromContainerdSnapshotter(snapshotterName, containerdsnapshot.NSSnapshotter("buildkit", mdb.Snapshotter(snapshotterName)), nil),
		MetadataStore:  md,
		LeaseManager:   leaseutil.WithNamespace(ctdmetadata.NewLeaseManager(mdb), "buildkit"),
		ContentStore:   mdb.ContentStore(),
		GarbageCollect: mdb.GarbageCollect,
	})
	require.NoError(t, err)

	return cm, func() {
		db.Close()
	}
}

type badMountable struct{}

func (bm *badMountable) Mount(ctx context.Context, readonly bool) (snapshot.Mountable, error) {
	return nil, errors.New("tried to mount bad mountable")
}

// newBadMountable returns a cache.Mountable that will fail to mount, for use in APIs
// that require a Mountable, but which should never actually try to access the filesystem.
func newBadMountable() cache.Mountable {
	return &badMountable{}
}

// these test helpers are from tonistiigi/fsutil

type change struct {
	kind fsutil.ChangeKind
	path string
	fi   os.FileInfo
	data string
}

func changeStream(dt []string) (changes []*change) {
	for _, s := range dt {
		changes = append(changes, parseChange(s))
	}
	return
}

func parseChange(str string) *change {
	f := strings.Fields(str)
	errStr := fmt.Sprintf("invalid change %q", str)
	if len(f) < 3 {
		panic(errStr)
	}
	c := &change{}
	switch f[0] {
	case "ADD":
		c.kind = fsutil.ChangeKindAdd
	case "CHG":
		c.kind = fsutil.ChangeKindModify
	case "DEL":
		c.kind = fsutil.ChangeKindDelete
	default:
		panic(errStr)
	}
	c.path = f[1]
	st := &fstypes.Stat{}
	switch f[2] {
	case "file":
		if len(f) > 3 {
			if f[3][0] == '>' {
				st.Linkname = f[3][1:]
			} else {
				c.data = f[3]
				st.Size_ = int64(len(f[3]))
			}
		}
		st.Mode |= 0644
	case "dir":
		st.Mode |= uint32(os.ModeDir)
		st.Mode |= 0755
	case "symlink":
		if len(f) < 4 {
			panic(errStr)
		}
		st.Mode |= uint32(os.ModeSymlink)
		st.Linkname = f[3]
		st.Mode |= 0777
	}

	c.fi = &fsutil.StatInfo{Stat: st}
	return c
}

func emit(fn fsutil.HandleChangeFn, inp []*change) error {
	for _, c := range inp {
		stat, ok := c.fi.Sys().(*fstypes.Stat)
		if !ok {
			return errors.Errorf("invalid non-stat change %s", c.fi.Name())
		}
		fi := c.fi
		if c.kind != fsutil.ChangeKindDelete {
			h, err := NewFromStat(stat)
			if err != nil {
				return err
			}
			if _, err := io.Copy(h, strings.NewReader(c.data)); err != nil {
				return err
			}
			fi = &withHash{FileInfo: c.fi, digest: digest.NewDigest(digest.SHA256, h)}
		}
		if err := fn(c.kind, c.path, fi, nil); err != nil {
			return err
		}
	}
	return nil
}

type withHash struct {
	digest digest.Digest
	os.FileInfo
}

func (wh *withHash) Digest() digest.Digest {
	return wh.digest
}

func writeChanges(root string, inp []*change) error {
	for _, c := range inp {
		if c.kind == fsutil.ChangeKindAdd {
			p := filepath.Join(root, c.path)
			stat, ok := c.fi.Sys().(*fstypes.Stat)
			if !ok {
				return errors.Errorf("invalid non-stat change %s", p)
			}
			if c.fi.IsDir() {
				// The snapshot root ('/') is always created with 0755.
				// We use the same permission mode here.
				if err := os.Mkdir(p, 0755); err != nil {
					return errors.WithStack(err)
				}
			} else if c.fi.Mode()&os.ModeSymlink != 0 {
				if err := os.Symlink(stat.Linkname, p); err != nil {
					return errors.WithStack(err)
				}
			} else if len(stat.Linkname) > 0 {
				link := filepath.Join(root, stat.Linkname)
				if !filepath.IsAbs(link) {
					link = filepath.Join(filepath.Dir(p), stat.Linkname)
				}
				if err := os.Link(link, p); err != nil {
					return errors.WithStack(err)
				}
			} else {
				f, err := os.Create(p)
				if err != nil {
					return errors.WithStack(err)
				}
				if len(c.data) > 0 {
					if _, err := f.Write([]byte(c.data)); err != nil {
						return errors.WithStack(err)
					}
				}
				f.Close()
			}
		}
	}
	return nil
}