chrislu
3 years ago
2 changed files with 168 additions and 162 deletions
@ -0,0 +1,168 @@ |
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package mount |
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import ( |
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"github.com/hanwen/go-fuse/v2/fuse" |
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sys "golang.org/x/sys/unix" |
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"runtime" |
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"strings" |
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"syscall" |
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) |
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const ( |
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// https://man7.org/linux/man-pages/man7/xattr.7.html#:~:text=The%20VFS%20imposes%20limitations%20that,in%20listxattr(2)).
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MAX_XATTR_NAME_SIZE = 255 |
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MAX_XATTR_VALUE_SIZE = 65536 |
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XATTR_PREFIX = "xattr-" // same as filer
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) |
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// GetXAttr reads an extended attribute, and should return the
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// number of bytes. If the buffer is too small, return ERANGE,
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// with the required buffer size.
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func (wfs *WFS) GetXAttr(cancel <-chan struct{}, header *fuse.InHeader, attr string, dest []byte) (size uint32, code fuse.Status) { |
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//validate attr name
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if len(attr) > MAX_XATTR_NAME_SIZE { |
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if runtime.GOOS == "darwin" { |
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return 0, fuse.EPERM |
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} else { |
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return 0, fuse.ERANGE |
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} |
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} |
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if len(attr) == 0 { |
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return 0, fuse.EINVAL |
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} |
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_, entry, status := wfs.maybeReadEntry(header.NodeId) |
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if status != fuse.OK { |
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return 0, status |
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} |
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if entry == nil { |
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return 0, fuse.ENOENT |
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} |
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if entry.Extended == nil { |
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return 0, fuse.ENOATTR |
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} |
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data, found := entry.Extended[XATTR_PREFIX+attr] |
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if !found { |
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return 0, fuse.ENOATTR |
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} |
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if len(dest) < len(data) { |
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return uint32(len(data)), fuse.ERANGE |
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} |
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copy(dest, data) |
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return uint32(len(data)), fuse.OK |
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} |
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// SetXAttr writes an extended attribute.
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// https://man7.org/linux/man-pages/man2/setxattr.2.html
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// By default (i.e., flags is zero), the extended attribute will be
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// created if it does not exist, or the value will be replaced if
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// the attribute already exists. To modify these semantics, one of
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// the following values can be specified in flags:
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//
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// XATTR_CREATE
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// Perform a pure create, which fails if the named attribute
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// exists already.
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//
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// XATTR_REPLACE
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// Perform a pure replace operation, which fails if the named
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// attribute does not already exist.
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func (wfs *WFS) SetXAttr(cancel <-chan struct{}, input *fuse.SetXAttrIn, attr string, data []byte) fuse.Status { |
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//validate attr name
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if len(attr) > MAX_XATTR_NAME_SIZE { |
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if runtime.GOOS == "darwin" { |
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return fuse.EPERM |
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} else { |
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return fuse.ERANGE |
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} |
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} |
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if len(attr) == 0 { |
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return fuse.EINVAL |
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} |
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//validate attr value
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if len(data) > MAX_XATTR_VALUE_SIZE { |
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if runtime.GOOS == "darwin" { |
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return fuse.Status(syscall.E2BIG) |
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} else { |
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return fuse.ERANGE |
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} |
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} |
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path, entry, status := wfs.maybeReadEntry(input.NodeId) |
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if status != fuse.OK { |
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return status |
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} |
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if entry.Extended == nil { |
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entry.Extended = make(map[string][]byte) |
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} |
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oldData, _ := entry.Extended[XATTR_PREFIX+attr] |
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switch input.Flags { |
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case sys.XATTR_CREATE: |
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if len(oldData) > 0 { |
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break |
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} |
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fallthrough |
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case sys.XATTR_REPLACE: |
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fallthrough |
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default: |
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entry.Extended[XATTR_PREFIX+attr] = data |
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} |
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return wfs.saveEntry(path, entry) |
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} |
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// ListXAttr lists extended attributes as '\0' delimited byte
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// slice, and return the number of bytes. If the buffer is too
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// small, return ERANGE, with the required buffer size.
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func (wfs *WFS) ListXAttr(cancel <-chan struct{}, header *fuse.InHeader, dest []byte) (n uint32, code fuse.Status) { |
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_, entry, status := wfs.maybeReadEntry(header.NodeId) |
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if status != fuse.OK { |
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return 0, status |
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} |
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if entry == nil { |
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return 0, fuse.ENOENT |
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} |
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if entry.Extended == nil { |
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return 0, fuse.ENOATTR |
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} |
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var data []byte |
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for k := range entry.Extended { |
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if strings.HasPrefix(k, XATTR_PREFIX) { |
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data = append(data, k[len(XATTR_PREFIX):]...) |
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data = append(data, 0) |
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} |
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} |
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if len(dest) < len(data) { |
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return uint32(len(data)), fuse.ERANGE |
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} |
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copy(dest, data) |
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return uint32(len(data)), fuse.OK |
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} |
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// RemoveXAttr removes an extended attribute.
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func (wfs *WFS) RemoveXAttr(cancel <-chan struct{}, header *fuse.InHeader, attr string) fuse.Status { |
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if len(attr) == 0 { |
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return fuse.EINVAL |
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} |
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path, entry, status := wfs.maybeReadEntry(header.NodeId) |
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if status != fuse.OK { |
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return status |
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} |
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if entry.Extended == nil { |
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return fuse.ENOATTR |
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} |
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_, found := entry.Extended[XATTR_PREFIX+attr] |
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if !found { |
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return fuse.ENOATTR |
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} |
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delete(entry.Extended, XATTR_PREFIX+attr) |
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return wfs.saveEntry(path, entry) |
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} |
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