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package mount
import ( "github.com/hanwen/go-fuse/v2/fuse" sys "golang.org/x/sys/unix" "runtime" "strings" "syscall" )
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
)
// 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) {
if wfs.option.DisableXAttr { return 0, fuse.Status(syscall.ENOTSUP) }
//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 {
if wfs.option.DisableXAttr { return fuse.Status(syscall.ENOTSUP) }
if wfs.IsOverQuota { return fuse.Status(syscall.ENOSPC) }
//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, fh, entry, status := wfs.maybeReadEntry(input.NodeId) if status != fuse.OK { return status } if entry == nil { return fuse.ENOENT } if fh != nil { //fh.entryLock.Lock()
//defer fh.entryLock.Unlock()
}
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) {
if wfs.option.DisableXAttr { return 0, fuse.Status(syscall.ENOTSUP) }
_, _, 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.OK }
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 {
if wfs.option.DisableXAttr { return fuse.Status(syscall.ENOTSUP) }
if len(attr) == 0 { return fuse.EINVAL } path, fh, entry, status := wfs.maybeReadEntry(header.NodeId) if status != fuse.OK { return status } if entry == nil { return fuse.OK } if fh != nil { //fh.entryLock.Lock()
//defer fh.entryLock.Unlock()
}
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) }
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