From ac687d53593d8215b881db92fe2d1bbbd2d2d774 Mon Sep 17 00:00:00 2001
From: Jakob Unterwurzacher <jakobunt@gmail.com>
Date: Wed, 9 Sep 2020 11:17:19 +0200
Subject: [PATCH] v2api: add Darwin xattr support

---
 internal/fusefrontend/node.go              |   8 +-
 internal/fusefrontend/node_xattr_darwin.go | 106 +++++++++++++++++++++
 2 files changed, 110 insertions(+), 4 deletions(-)

diff --git a/internal/fusefrontend/node.go b/internal/fusefrontend/node.go
index 00d06f5..bc4eb3b 100644
--- a/internal/fusefrontend/node.go
+++ b/internal/fusefrontend/node.go
@@ -480,7 +480,7 @@ func (n *Node) Rename(ctx context.Context, name string, newParent fs.InodeEmbedd
 	// Easy case.
 	rn := n.rootNode()
 	if rn.args.PlaintextNames {
-		return fs.ToErrno(unix.Renameat2(dirfd, cName, dirfd2, cName2, uint(flags)))
+		return fs.ToErrno(syscallcompat.Renameat2(dirfd, cName, dirfd2, cName2, uint(flags)))
 	}
 	// Long destination file name: create .name file
 	nameFileAlreadyThere := false
@@ -498,8 +498,8 @@ func (n *Node) Rename(ctx context.Context, name string, newParent fs.InodeEmbedd
 	}
 	// Actual rename
 	tlog.Debug.Printf("Renameat %d/%s -> %d/%s\n", dirfd, cName, dirfd2, cName2)
-	err = unix.Renameat2(dirfd, cName, dirfd2, cName2, uint(flags))
-	if (flags&unix.RENAME_NOREPLACE == 0) && (err == syscall.ENOTEMPTY || err == syscall.EEXIST) {
+	err = syscallcompat.Renameat2(dirfd, cName, dirfd2, cName2, uint(flags))
+	if (flags&syscallcompat.RENAME_NOREPLACE == 0) && (err == syscall.ENOTEMPTY || err == syscall.EEXIST) {
 		// If an empty directory is overwritten we will always get an error as
 		// the "empty" directory will still contain gocryptfs.diriv.
 		// Interestingly, ext4 returns ENOTEMPTY while xfs returns EEXIST.
@@ -507,7 +507,7 @@ func (n *Node) Rename(ctx context.Context, name string, newParent fs.InodeEmbedd
 		// again.
 		tlog.Debug.Printf("Rename: Handling ENOTEMPTY")
 		if n2.Rmdir(ctx, newName) == 0 {
-			err = unix.Renameat2(dirfd, cName, dirfd2, cName2, uint(flags))
+			err = syscallcompat.Renameat2(dirfd, cName, dirfd2, cName2, uint(flags))
 		}
 	}
 	if err != nil {
diff --git a/internal/fusefrontend/node_xattr_darwin.go b/internal/fusefrontend/node_xattr_darwin.go
index e69de29..82c0dff 100644
--- a/internal/fusefrontend/node_xattr_darwin.go
+++ b/internal/fusefrontend/node_xattr_darwin.go
@@ -0,0 +1,106 @@
+package fusefrontend
+
+import (
+	"syscall"
+
+	"golang.org/x/sys/unix"
+
+	"github.com/hanwen/go-fuse/v2/fs"
+
+	"github.com/rfjakob/gocryptfs/internal/syscallcompat"
+)
+
+// On Darwin we have to unset XATTR_NOSECURITY 0x0008
+func filterXattrSetFlags(flags int) int {
+	// See https://opensource.apple.com/source/xnu/xnu-1504.15.3/bsd/sys/xattr.h.auto.html
+	const XATTR_NOSECURITY = 0x0008
+
+	return flags &^ XATTR_NOSECURITY
+}
+
+func (n *Node) getXAttr(cAttr string) (out []byte, errno syscall.Errno) {
+	dirfd, cName, errno := n.prepareAtSyscall("")
+	if errno != 0 {
+		return
+	}
+	defer syscall.Close(dirfd)
+
+	// O_NONBLOCK to not block on FIFOs.
+	fd, err := syscallcompat.Openat(dirfd, cName, syscall.O_RDONLY|syscall.O_NONBLOCK, 0)
+	if err != nil {
+		return nil, fs.ToErrno(err)
+	}
+	defer syscall.Close(fd)
+
+	cData, err := syscallcompat.Fgetxattr(fd, cAttr)
+	if err != nil {
+		return nil, fs.ToErrno(err)
+	}
+
+	return cData, 0
+}
+
+func (n *Node) setXAttr(cAttr string, cData []byte, flags uint32) (errno syscall.Errno) {
+	dirfd, cName, errno := n.prepareAtSyscall("")
+	if errno != 0 {
+		return
+	}
+	defer syscall.Close(dirfd)
+
+	// O_NONBLOCK to not block on FIFOs.
+	fd, err := syscallcompat.Openat(dirfd, cName, syscall.O_WRONLY|syscall.O_NONBLOCK, 0)
+	// Directories cannot be opened read-write. Retry.
+	if err == syscall.EISDIR {
+		fd, err = syscallcompat.Openat(dirfd, cName, syscall.O_RDONLY|syscall.O_DIRECTORY|syscall.O_NONBLOCK, 0)
+	}
+	if err != nil {
+		fs.ToErrno(err)
+	}
+	defer syscall.Close(fd)
+
+	err = unix.Fsetxattr(fd, cAttr, cData, int(flags))
+	return fs.ToErrno(err)
+}
+
+func (n *Node) removeXAttr(cAttr string) (errno syscall.Errno) {
+	dirfd, cName, errno := n.prepareAtSyscall("")
+	if errno != 0 {
+		return
+	}
+	defer syscall.Close(dirfd)
+
+	// O_NONBLOCK to not block on FIFOs.
+	fd, err := syscallcompat.Openat(dirfd, cName, syscall.O_WRONLY|syscall.O_NONBLOCK, 0)
+	// Directories cannot be opened read-write. Retry.
+	if err == syscall.EISDIR {
+		fd, err = syscallcompat.Openat(dirfd, cName, syscall.O_RDONLY|syscall.O_DIRECTORY|syscall.O_NONBLOCK, 0)
+	}
+	if err != nil {
+		return fs.ToErrno(err)
+	}
+	defer syscall.Close(fd)
+
+	err = unix.Fremovexattr(fd, cAttr)
+	return fs.ToErrno(err)
+}
+
+func (n *Node) listXAttr() (out []string, errno syscall.Errno) {
+	dirfd, cName, errno := n.prepareAtSyscall("")
+	if errno != 0 {
+		return
+	}
+	defer syscall.Close(dirfd)
+
+	// O_NONBLOCK to not block on FIFOs.
+	fd, err := syscallcompat.Openat(dirfd, cName, syscall.O_RDONLY|syscall.O_NONBLOCK, 0)
+	if err != nil {
+		return nil, fs.ToErrno(err)
+	}
+	defer syscall.Close(fd)
+
+	cNames, err := syscallcompat.Flistxattr(fd)
+	if err != nil {
+		return nil, fs.ToErrno(err)
+	}
+	return cNames, 0
+}