From 15b0b4a5fd268b421ddc347e4417b2538a540922 Mon Sep 17 00:00:00 2001
From: Jakob Unterwurzacher
Date: Sat, 15 Aug 2020 16:08:16 +0200
Subject: v2api/reverse: start wiring up -exclude functionality

Exclude in readdir is missing.
---
 internal/fusefrontend_reverse/excluder.go      | 20 ++++---
 internal/fusefrontend_reverse/excluder_test.go | 83 ++++++++++++++++++++++++++
 internal/fusefrontend_reverse/mocks_test.go    | 32 ++++++++++
 internal/fusefrontend_reverse/root_node.go     | 10 +++-
 internal/fusefrontend_reverse/rpath.go         |  4 ++
 5 files changed, 139 insertions(+), 10 deletions(-)
 create mode 100644 internal/fusefrontend_reverse/excluder_test.go
 create mode 100644 internal/fusefrontend_reverse/mocks_test.go

diff --git a/internal/fusefrontend_reverse/excluder.go b/internal/fusefrontend_reverse/excluder.go
index 337c3d2..b6cb961 100644
--- a/internal/fusefrontend_reverse/excluder.go
+++ b/internal/fusefrontend_reverse/excluder.go
@@ -15,15 +15,19 @@ import (
 // prepareExcluder creates an object to check if paths are excluded
 // based on the patterns specified in the command line.
 func prepareExcluder(args fusefrontend.Args) *ignore.GitIgnore {
-	if len(args.Exclude) > 0 || len(args.ExcludeWildcard) > 0 || len(args.ExcludeFrom) > 0 {
-		excluder, err := ignore.CompileIgnoreLines(getExclusionPatterns(args)...)
-		if err != nil {
-			tlog.Fatal.Printf("Error compiling exclusion rules: %q", err)
-			os.Exit(exitcodes.ExcludeError)
-		}
-		return excluder
+	if len(args.Exclude) == 0 && len(args.ExcludeWildcard) == 0 && len(args.ExcludeFrom) == 0 {
+		return nil
+	}
+	patterns := getExclusionPatterns(args)
+	if len(patterns) == 0 {
+		panic(patterns)
+	}
+	excluder, err := ignore.CompileIgnoreLines(patterns...)
+	if err != nil {
+		tlog.Fatal.Printf("Error compiling exclusion rules: %v", err)
+		os.Exit(exitcodes.ExcludeError)
 	}
-	return nil
+	return excluder
 }
 
 // getExclusionPatters prepares a list of patterns to be excluded.
diff --git a/internal/fusefrontend_reverse/excluder_test.go b/internal/fusefrontend_reverse/excluder_test.go
new file mode 100644
index 0000000..47b430a
--- /dev/null
+++ b/internal/fusefrontend_reverse/excluder_test.go
@@ -0,0 +1,83 @@
+package fusefrontend_reverse
+
+import (
+	"io/ioutil"
+	"os"
+	"reflect"
+	"testing"
+
+	"github.com/rfjakob/gocryptfs/internal/fusefrontend"
+)
+
+func TestShouldNoCreateExcluderIfNoPattersWereSpecified(t *testing.T) {
+	var args fusefrontend.Args
+	excluder := prepareExcluder(args)
+	if excluder != nil {
+		t.Error("Should not have created excluder")
+	}
+}
+
+func TestShouldPrefixExcludeValuesWithSlash(t *testing.T) {
+	var args fusefrontend.Args
+	args.Exclude = []string{"file1", "dir1/file2.txt"}
+	args.ExcludeWildcard = []string{"*~", "build/*.o"}
+
+	expected := []string{"/file1", "/dir1/file2.txt", "*~", "build/*.o"}
+
+	patterns := getExclusionPatterns(args)
+	if !reflect.DeepEqual(patterns, expected) {
+		t.Errorf("expected %q, got %q", expected, patterns)
+	}
+}
+
+func TestShouldReadExcludePatternsFromFiles(t *testing.T) {
+	tmpfile1, err := ioutil.TempFile("", "excludetest")
+	if err != nil {
+		t.Fatal(err)
+	}
+	exclude1 := tmpfile1.Name()
+	defer os.Remove(exclude1)
+	defer tmpfile1.Close()
+
+	tmpfile2, err := ioutil.TempFile("", "excludetest")
+	if err != nil {
+		t.Fatal(err)
+	}
+	exclude2 := tmpfile2.Name()
+	defer os.Remove(exclude2)
+	defer tmpfile2.Close()
+
+	tmpfile1.WriteString("file1.1\n")
+	tmpfile1.WriteString("file1.2\n")
+	tmpfile2.WriteString("file2.1\n")
+	tmpfile2.WriteString("file2.2\n")
+
+	var args fusefrontend.Args
+	args.ExcludeWildcard = []string{"cmdline1"}
+	args.ExcludeFrom = []string{exclude1, exclude2}
+
+	// An empty string is returned for the last empty line
+	// It's ignored when the patterns are actually compiled
+	expected := []string{"cmdline1", "file1.1", "file1.2", "", "file2.1", "file2.2", ""}
+
+	patterns := getExclusionPatterns(args)
+	if !reflect.DeepEqual(patterns, expected) {
+		t.Errorf("expected %q, got %q", expected, patterns)
+	}
+}
+
+func TestShouldReturnFalseIfThereAreNoExclusions(t *testing.T) {
+	var rfs RootNode
+	if rfs.isExcludedPlain("any/path") {
+		t.Error("Should not exclude any path if no exclusions were specified")
+	}
+}
+
+func TestShouldCallIgnoreParserToCheckExclusion(t *testing.T) {
+	rfs, ignorerMock := createRFSWithMocks()
+
+	rfs.isExcludedPlain("some/path")
+	if ignorerMock.calledWith != "some/path" {
+		t.Error("Failed to call IgnoreParser")
+	}
+}
diff --git a/internal/fusefrontend_reverse/mocks_test.go b/internal/fusefrontend_reverse/mocks_test.go
new file mode 100644
index 0000000..2d14c1d
--- /dev/null
+++ b/internal/fusefrontend_reverse/mocks_test.go
@@ -0,0 +1,32 @@
+package fusefrontend_reverse
+
+import (
+	"github.com/rfjakob/gocryptfs/internal/nametransform"
+)
+
+type IgnoreParserMock struct {
+	toExclude  string
+	calledWith string
+}
+
+func (parser *IgnoreParserMock) MatchesPath(f string) bool {
+	parser.calledWith = f
+	return f == parser.toExclude
+}
+
+type NameTransformMock struct {
+	nametransform.NameTransform
+}
+
+func (n *NameTransformMock) DecryptName(cipherName string, iv []byte) (string, error) {
+	return "mockdecrypt_" + cipherName, nil
+}
+
+func createRFSWithMocks() (*RootNode, *IgnoreParserMock) {
+	ignorerMock := &IgnoreParserMock{}
+	nameTransformMock := &NameTransformMock{}
+	var rfs RootNode
+	rfs.excluder = ignorerMock
+	rfs.nameTransform = nameTransformMock
+	return &rfs, ignorerMock
+}
diff --git a/internal/fusefrontend_reverse/root_node.go b/internal/fusefrontend_reverse/root_node.go
index 4297ecf..4346306 100644
--- a/internal/fusefrontend_reverse/root_node.go
+++ b/internal/fusefrontend_reverse/root_node.go
@@ -27,8 +27,8 @@ type RootNode struct {
 	nameTransform nametransform.NameTransformer
 	// Content encryption helper
 	contentEnc *contentenc.ContentEnc
-	// Tests whether a path is excluded (hiden) from the user. Used by -exclude.
-	excluder ignore.IgnoreParser
+	// Tests whether a path is excluded (hidden) from the user. Used by -exclude.
+	excluder *ignore.GitIgnore
 	// inoMap translates inode numbers from different devices to unique inode
 	// numbers.
 	inoMap *inomap.InoMap
@@ -78,3 +78,9 @@ func (rn *RootNode) findLongnameParent(fd int, diriv []byte, longname string) (p
 	}
 	return
 }
+
+// isExcludedPlain finds out if the plaintext path "pPath" is
+// excluded (used when -exclude is passed by the user).
+func (rn *RootNode) isExcludedPlain(pPath string) bool {
+	return rn.excluder != nil && rn.excluder.MatchesPath(pPath)
+}
diff --git a/internal/fusefrontend_reverse/rpath.go b/internal/fusefrontend_reverse/rpath.go
index 2ac65be..1e44638 100644
--- a/internal/fusefrontend_reverse/rpath.go
+++ b/internal/fusefrontend_reverse/rpath.go
@@ -109,6 +109,10 @@ func (rn *RootNode) openBackingDir(cPath string) (dirfd int, pName string, err e
 	if err != nil {
 		return
 	}
+	if rn.isExcludedPlain(pRelPath) {
+		err = syscall.EPERM
+		return
+	}
 	// Open directory, safe against symlink races
 	pDir := filepath.Dir(pRelPath)
 	dirfd, err = syscallcompat.OpenDirNofollow(rn.args.Cipherdir, pDir)
-- 
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