From 18b3bdb1584fd8e3dde89a95c0dfff910dd95ae1 Mon Sep 17 00:00:00 2001
From: Jakob Unterwurzacher
Date: Sat, 1 Aug 2020 20:48:32 +0200
Subject: v2api/reverse: start fusefrontend_reverse v2 API implementation

---
 internal/fusefrontend_reverse/excluder.go  | 61 ++++++++++++++++++++++++++++++
 internal/fusefrontend_reverse/node.go      | 11 ++++++
 internal/fusefrontend_reverse/root_node.go | 39 +++++++++++++++++++
 3 files changed, 111 insertions(+)
 create mode 100644 internal/fusefrontend_reverse/excluder.go
 create mode 100644 internal/fusefrontend_reverse/node.go
 create mode 100644 internal/fusefrontend_reverse/root_node.go

diff --git a/internal/fusefrontend_reverse/excluder.go b/internal/fusefrontend_reverse/excluder.go
new file mode 100644
index 0000000..337c3d2
--- /dev/null
+++ b/internal/fusefrontend_reverse/excluder.go
@@ -0,0 +1,61 @@
+package fusefrontend_reverse
+
+import (
+	"io/ioutil"
+	"os"
+	"strings"
+
+	"github.com/rfjakob/gocryptfs/internal/exitcodes"
+	"github.com/rfjakob/gocryptfs/internal/fusefrontend"
+	"github.com/rfjakob/gocryptfs/internal/tlog"
+
+	"github.com/sabhiram/go-gitignore"
+)
+
+// 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
+	}
+	return nil
+}
+
+// getExclusionPatters prepares a list of patterns to be excluded.
+// Patterns passed in the -exclude command line option are prefixed
+// with a leading '/' to preserve backwards compatibility (before
+// wildcard matching was implemented, exclusions always were matched
+// against the full path).
+func getExclusionPatterns(args fusefrontend.Args) []string {
+	patterns := make([]string, len(args.Exclude)+len(args.ExcludeWildcard))
+	// add -exclude
+	for i, p := range args.Exclude {
+		patterns[i] = "/" + p
+	}
+	// add -exclude-wildcard
+	copy(patterns[len(args.Exclude):], args.ExcludeWildcard)
+	// add -exclude-from
+	for _, file := range args.ExcludeFrom {
+		lines, err := getLines(file)
+		if err != nil {
+			tlog.Fatal.Printf("Error reading exclusion patterns: %q", err)
+			os.Exit(exitcodes.ExcludeError)
+		}
+		patterns = append(patterns, lines...)
+	}
+	return patterns
+}
+
+// getLines reads a file and splits it into lines
+func getLines(file string) ([]string, error) {
+	buffer, err := ioutil.ReadFile(file)
+	if err != nil {
+		return nil, err
+	}
+	return strings.Split(string(buffer), "\n"), nil
+}
diff --git a/internal/fusefrontend_reverse/node.go b/internal/fusefrontend_reverse/node.go
new file mode 100644
index 0000000..6a1294a
--- /dev/null
+++ b/internal/fusefrontend_reverse/node.go
@@ -0,0 +1,11 @@
+package fusefrontend_reverse
+
+import (
+	"github.com/hanwen/go-fuse/v2/fs"
+)
+
+// Node is a file or directory in the filesystem tree
+// in a `gocryptfs -reverse` mount.
+type Node struct {
+	fs.Inode
+}
diff --git a/internal/fusefrontend_reverse/root_node.go b/internal/fusefrontend_reverse/root_node.go
new file mode 100644
index 0000000..726380f
--- /dev/null
+++ b/internal/fusefrontend_reverse/root_node.go
@@ -0,0 +1,39 @@
+package fusefrontend_reverse
+
+import (
+	"github.com/rfjakob/gocryptfs/internal/contentenc"
+	"github.com/rfjakob/gocryptfs/internal/fusefrontend"
+	"github.com/rfjakob/gocryptfs/internal/inomap"
+	"github.com/rfjakob/gocryptfs/internal/nametransform"
+
+	"github.com/sabhiram/go-gitignore"
+)
+
+// RootNode is the root directory in a `gocryptfs -reverse` mount
+type RootNode struct {
+	Node
+	// Stores configuration arguments
+	args fusefrontend.Args
+	// Filename encryption helper
+	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
+	// inoMap translates inode numbers from different devices to unique inode
+	// numbers.
+	inoMap *inomap.InoMap
+}
+
+// NewRootNode returns an encrypted FUSE overlay filesystem.
+// In this case (reverse mode) the backing directory is plain-text and
+// ReverseFS provides an encrypted view.
+func NewRootNode(args fusefrontend.Args, c *contentenc.ContentEnc, n nametransform.NameTransformer) *RootNode {
+	return &RootNode{
+		args:          args,
+		nameTransform: n,
+		contentEnc:    c,
+		inoMap:        inomap.New(),
+		excluder:      prepareExcluder(args),
+	}
+}
-- 
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