contenthash: include basename in content checksum for wildcards

While we generally ignore the basename in this layer, for wildcards
there in no other place to add the basename to the checksum as they
can not be resolved earlier. Before the basename that was in the
checksum was the wildcard itself, so if the wildcard remained same,
content remained same but the file where wildcard pointed to was
renamed, the cache was not invalidated.

Unfortunately, this change breaks cache for all copy commands that
use a wildcard.

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

cache/contenthash/checksum.go

@@ -406,17 +406,19 @@ func (cc *cacheContext) ChecksumWildcard(ctx context.Context, mountable cache.Mo
 		return digest.FromBytes([]byte{}), nil
 	}
 
-	if len(wildcards) > 1 {
-		digester := digest.Canonical.Digester()
-		for i, w := range wildcards {
-			if i != 0 {
-				digester.Hash().Write([]byte{0})
-			}
-			digester.Hash().Write([]byte(w.Record.Digest))
-		}
-		return digester.Digest(), nil
+	if len(wildcards) == 1 && path.Base(p) == path.Base(wildcards[0].Path) {
+		return wildcards[0].Record.Digest, nil
 	}
-	return wildcards[0].Record.Digest, nil
+
+	digester := digest.Canonical.Digester()
+	for i, w := range wildcards {
+		if i != 0 {
+			digester.Hash().Write([]byte{0})
+		}
+		digester.Hash().Write([]byte(path.Base(w.Path)))
+		digester.Hash().Write([]byte(w.Record.Digest))
+	}
+	return digester.Digest(), nil
 }
 
 func (cc *cacheContext) Checksum(ctx context.Context, mountable cache.Mountable, p string, followLinks bool, s session.Group) (digest.Digest, error) {

cache/contenthash/checksum_test.go

@@ -179,9 +179,9 @@ func TestChecksumWildcard(t *testing.T) {
 
 	dgst, err := cc.ChecksumWildcard(context.TODO(), ref, "f*o", false, nil)
 	require.NoError(t, err)
-	require.Equal(t, dgstFileData0, dgst)
+	require.Equal(t, digest.FromBytes(append([]byte("foo"), []byte(dgstFileData0)...)), dgst)
 
-	expFoos := digest.Digest("sha256:c9f914ad7ad8fe6092ce67484b43ca39c2087aabf9e4a1b223249b0f8b09b9f2")
+	expFoos := digest.Digest("sha256:7f51c821895cfc116d3f64231dfb438e87a237ecbbe027cd96b7ee5e763cc569")
 
 	dgst, err = cc.ChecksumWildcard(context.TODO(), ref, "f*", false, nil)
 	require.NoError(t, err)
@@ -189,15 +189,17 @@ func TestChecksumWildcard(t *testing.T) {
 
 	dgst, err = cc.ChecksumWildcard(context.TODO(), ref, "x/d?", false, nil)
 	require.NoError(t, err)
-	require.Equal(t, dgstDirD0, dgst)
+	require.Equal(t, digest.FromBytes(append([]byte("d0"), []byte(dgstDirD0)...)), dgst)
 
 	dgst, err = cc.ChecksumWildcard(context.TODO(), ref, "x/d?/def", true, nil)
 	require.NoError(t, err)
 	require.Equal(t, dgstFileData0, dgst)
 
+	expFoos2 := digest.Digest("sha256:8afc09c7018d65d5eb318a9ef55cb704dec1f06d288181d913fc27a571aa042d")
+
 	dgst, err = cc.ChecksumWildcard(context.TODO(), ref, "y*", true, nil)
 	require.NoError(t, err)
-	require.Equal(t, expFoos, dgst)
+	require.Equal(t, expFoos2, dgst)
 
 	err = ref.Release(context.TODO())
 	require.NoError(t, err)

frontend/dockerfile/dockerfile_test.go

@@ -109,6 +109,7 @@ var allTests = []integration.Test{
 	testDefaultShellAndPath,
 	testDockerfileLowercase,
 	testExportCacheLoop,
+	testWildcardRenameCache,
 }
 
 var fileOpTests = []integration.Test{
@@ -3832,6 +3833,52 @@ LABEL foo=bar
 	require.Equal(t, "baz", v)
 }
 
+// #2008
+func testWildcardRenameCache(t *testing.T, sb integration.Sandbox) {
+	skipDockerd(t, sb)
+	f := getFrontend(t, sb)
+
+	dockerfile := []byte(`
+FROM alpine
+COPY file* /files/
+RUN ls /files/file1
+`)
+	dir, err := tmpdir(
+		fstest.CreateFile("Dockerfile", dockerfile, 0600),
+		fstest.CreateFile("file1", []byte("foo"), 0600),
+	)
+	require.NoError(t, err)
+	defer os.RemoveAll(dir)
+
+	c, err := client.New(context.TODO(), sb.Address())
+	require.NoError(t, err)
+	defer c.Close()
+
+	destDir, err := ioutil.TempDir("", "buildkit")
+	require.NoError(t, err)
+	defer os.RemoveAll(destDir)
+
+	_, err = f.Solve(context.TODO(), c, client.SolveOpt{
+		LocalDirs: map[string]string{
+			builder.DefaultLocalNameDockerfile: dir,
+			builder.DefaultLocalNameContext:    dir,
+		},
+	}, nil)
+	require.NoError(t, err)
+
+	err = os.Rename(filepath.Join(dir, "file1"), filepath.Join(dir, "file2"))
+	require.NoError(t, err)
+
+	// cache should be invalidated and build should fail
+	_, err = f.Solve(context.TODO(), c, client.SolveOpt{
+		LocalDirs: map[string]string{
+			builder.DefaultLocalNameDockerfile: dir,
+			builder.DefaultLocalNameContext:    dir,
+		},
+	}, nil)
+	require.Error(t, err)
+}
+
 func testOnBuildCleared(t *testing.T, sb integration.Sandbox) {
 	f := getFrontend(t, sb)