From ef2407fd0ae0ccc31cd894f0e2f84e0a871547a4 Mon Sep 17 00:00:00 2001
From: "Joe Richey joerichey@google.com" <joerichey@google.com>
Date: Wed, 4 Oct 2017 18:35:48 -0700
Subject: ext4: Initial work for fscrypt-ext4

---
 .gitignore           |  2 +-
 ext4/ext4.go         | 37 +++++++++++++++++++++++++++++++++++++
 ext4/feature_flag.go | 36 ++++++++++++++++++++++++++++++++++++
 3 files changed, 74 insertions(+), 1 deletion(-)
 create mode 100644 ext4/ext4.go
 create mode 100644 ext4/feature_flag.go

diff --git a/.gitignore b/.gitignore
index 345dfa1..c308c32 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,5 @@
 fscrypt
-fscrypt.*
+fscrypt-ext4
 fscrypt_image
 pam_fscrypt.so
 .vscode
diff --git a/ext4/ext4.go b/ext4/ext4.go
new file mode 100644
index 0000000..cbe87da
--- /dev/null
+++ b/ext4/ext4.go
@@ -0,0 +1,37 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+)
+
+func printUsage(w io.Writer, name string) {
+	fmt.Fprintf(w, "Usage: %s [enable|disable] <device> [--force]\n\n", name)
+	fmt.Fprintln(w, "Enable or disable encryption on an ext4 filesystem.")
+	fmt.Fprintln(w, "  <device> - Path to the filesystem device")
+	fmt.Fprintln(w, "  --force  - Automatically proceed with the operation")
+}
+
+func main() {
+	if len(os.Args) != 3 {
+		printUsage(os.Stderr, os.Args[0])
+		os.Exit(1)
+	}
+	switch os.Args[1] {
+	case "enable":
+		fmt.Println("Enabling encryption!!")
+	case "disable":
+		fmt.Println("Disabling encryption!!")
+	default:
+		fmt.Fprintf(os.Stderr, "%s: invalid command %q\n", os.Args[0], os.Args[1])
+		printUsage(os.Stderr, os.Args[0])
+		os.Exit(1)
+	}
+
+	if isExt4EncryptionEnabled(os.Args[2]) {
+		fmt.Printf("%q has encryption\n", os.Args[2])
+	} else {
+		fmt.Printf("%q doesn't have encryption\n", os.Args[2])
+	}
+}
diff --git a/ext4/feature_flag.go b/ext4/feature_flag.go
new file mode 100644
index 0000000..4c64e0a
--- /dev/null
+++ b/ext4/feature_flag.go
@@ -0,0 +1,36 @@
+package main
+
+/*
+#cgo LDFLAGS: -lext2fs
+#include <ext2fs/ext2_fs.h>
+#include <ext2fs/ext2fs.h>
+
+#include <stdlib.h>
+*/
+import "C"
+import (
+	"fmt"
+	"unsafe"
+)
+
+// isExt4EncryptionEnabled returns true if the provided ext4 filesystem (as a
+// path to a device or mountpoint) has the encrypt feature flag enabled.
+func isExt4EncryptionEnabled(path string) bool {
+	cPath := C.CString(path)
+	defer C.free(unsafe.Pointer(cPath))
+
+	var fs C.ext2_filsys
+	ret := C.ext2fs_open(cPath, 0, 0, 0, C.unix_io_manager, &fs)
+	if ret != 0 {
+		panic(fmt.Errorf("Got error code %v when opening %s", ret, path))
+	}
+
+	hasEncryption := C.ext2fs_has_feature_encrypt(fs.super)
+	return hasEncryption != 0
+}
+
+// enableExt4Encryption enables encryption on the filesystem at the specified
+// path.
+
+// disableExt4Encryption disables encryption on the filesystem at the specified
+// path. Note that this operation is not supported and can cause data loss.
-- 
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