From a4c9223b9da14add2cb9522fb5c75fc252243d4a Mon Sep 17 00:00:00 2001
From: chrislu <chris.lu@gmail.com>
Date: Sun, 13 Feb 2022 00:58:46 -0800
Subject: [PATCH] support xattr

---
 weed/mount/weedfs_attr.go | 155 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 151 insertions(+), 4 deletions(-)

diff --git a/weed/mount/weedfs_attr.go b/weed/mount/weedfs_attr.go
index 09acd303b..71aaa8c44 100644
--- a/weed/mount/weedfs_attr.go
+++ b/weed/mount/weedfs_attr.go
@@ -4,11 +4,21 @@ import (
 	"github.com/chrislusf/seaweedfs/weed/filer"
 	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
 	"github.com/hanwen/go-fuse/v2/fuse"
+	sys "golang.org/x/sys/unix"
 	"os"
+	"runtime"
+	"strings"
 	"syscall"
 	"time"
 )
 
+const (
+	// https://man7.org/linux/man-pages/man7/xattr.7.html#:~:text=The%20VFS%20imposes%20limitations%20that,in%20listxattr(2)).
+	MAX_XATTR_NAME_SIZE  = 255
+	MAX_XATTR_VALUE_SIZE = 65536
+	XATTR_PREFIX         = "xattr-" // same as filer
+)
+
 func (wfs *WFS) GetAttr(cancel <-chan struct{}, input *fuse.GetAttrIn, out *fuse.AttrOut) (code fuse.Status) {
 	if input.NodeId == 1 {
 		wfs.setRootAttr(out)
@@ -57,20 +67,157 @@ func (wfs *WFS) SetAttr(cancel <-chan struct{}, input *fuse.SetAttrIn, out *fuse
 	return wfs.saveEntry(path, entry)
 
 }
+
+// GetXAttr reads an extended attribute, and should return the
+// number of bytes. If the buffer is too small, return ERANGE,
+// with the required buffer size.
 func (wfs *WFS) GetXAttr(cancel <-chan struct{}, header *fuse.InHeader, attr string, dest []byte) (size uint32, code fuse.Status) {
-	return 0, fuse.ENOSYS
+
+	//validate attr name
+	if len(attr) > MAX_XATTR_NAME_SIZE {
+		if runtime.GOOS == "darwin" {
+			return 0, fuse.EPERM
+		} else {
+			return 0, fuse.ERANGE
+		}
+	}
+	if len(attr) == 0 {
+		return 0, fuse.EINVAL
+	}
+
+	_, entry, status := wfs.maybeReadEntry(header.NodeId)
+	if status != fuse.OK {
+		return 0, status
+	}
+	if entry == nil {
+		return 0, fuse.ENOENT
+	}
+	if entry.Extended == nil {
+		return 0, fuse.ENOATTR
+	}
+	data, found := entry.Extended[XATTR_PREFIX+attr]
+	if !found {
+		return 0, fuse.ENOATTR
+	}
+	if len(dest) < len(data) {
+		return uint32(len(data)), fuse.ERANGE
+	}
+	copy(dest, data)
+
+	return uint32(len(data)), fuse.OK
 }
 
+// SetXAttr writes an extended attribute.
+// https://man7.org/linux/man-pages/man2/setxattr.2.html
+//        By default (i.e., flags is zero), the extended attribute will be
+//       created if it does not exist, or the value will be replaced if
+//       the attribute already exists.  To modify these semantics, one of
+//       the following values can be specified in flags:
+//
+//       XATTR_CREATE
+//              Perform a pure create, which fails if the named attribute
+//              exists already.
+//
+//       XATTR_REPLACE
+//              Perform a pure replace operation, which fails if the named
+//              attribute does not already exist.
 func (wfs *WFS) SetXAttr(cancel <-chan struct{}, input *fuse.SetXAttrIn, attr string, data []byte) fuse.Status {
-	return fuse.ENOSYS
+	//validate attr name
+	if len(attr) > MAX_XATTR_NAME_SIZE {
+		if runtime.GOOS == "darwin" {
+			return fuse.EPERM
+		} else {
+			return fuse.ERANGE
+		}
+	}
+	if len(attr) == 0 {
+		return fuse.EINVAL
+	}
+	//validate attr value
+	if len(data) > MAX_XATTR_VALUE_SIZE {
+		if runtime.GOOS == "darwin" {
+			return fuse.Status(syscall.E2BIG)
+		} else {
+			return fuse.ERANGE
+		}
+	}
+
+	path, entry, status := wfs.maybeReadEntry(input.NodeId)
+	if status != fuse.OK {
+		return status
+	}
+	if entry.Extended == nil {
+		entry.Extended = make(map[string][]byte)
+	}
+	oldData, _ := entry.Extended[XATTR_PREFIX+attr]
+	switch input.Flags {
+	case sys.XATTR_CREATE:
+		if len(oldData) > 0 {
+			break
+		}
+		fallthrough
+	case sys.XATTR_REPLACE:
+		fallthrough
+	default:
+		entry.Extended[XATTR_PREFIX+attr] = data
+	}
+
+	return wfs.saveEntry(path, entry)
+
 }
 
+// ListXAttr lists extended attributes as '\0' delimited byte
+// slice, and return the number of bytes. If the buffer is too
+// small, return ERANGE, with the required buffer size.
 func (wfs *WFS) ListXAttr(cancel <-chan struct{}, header *fuse.InHeader, dest []byte) (n uint32, code fuse.Status) {
-	return 0, fuse.ENOSYS
+	_, entry, status := wfs.maybeReadEntry(header.NodeId)
+	if status != fuse.OK {
+		return 0, status
+	}
+	if entry == nil {
+		return 0, fuse.ENOENT
+	}
+	if entry.Extended == nil {
+		return 0, fuse.ENOATTR
+	}
+
+	var data []byte
+	for k := range entry.Extended {
+		if strings.HasPrefix(k, XATTR_PREFIX) {
+			data = append(data, k[len(XATTR_PREFIX):]...)
+			data = append(data, 0)
+		}
+	}
+	if len(dest) < len(data) {
+		return uint32(len(data)), fuse.ERANGE
+	}
+
+	copy(dest, data)
+
+	return uint32(len(data)), fuse.OK
 }
 
+// RemoveXAttr removes an extended attribute.
 func (wfs *WFS) RemoveXAttr(cancel <-chan struct{}, header *fuse.InHeader, attr string) fuse.Status {
-	return fuse.ENOSYS
+	if len(attr) == 0 {
+		return fuse.EINVAL
+	}
+	path, entry, status := wfs.maybeReadEntry(header.NodeId)
+	if status != fuse.OK {
+		return status
+	}
+	if entry.Extended == nil {
+		return fuse.ENOATTR
+	}
+	_, found := entry.Extended[XATTR_PREFIX+attr]
+
+	if !found {
+		return fuse.ENOATTR
+	}
+
+	delete(entry.Extended, XATTR_PREFIX+attr)
+
+	return wfs.saveEntry(path, entry)
 }
 
 func (wfs *WFS) setRootAttr(out *fuse.AttrOut) {