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// Copyright 2016 the Go-FUSE Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package fuse
// all of the code for DirEntryList.
import (
"fmt"
"unsafe"
)
var eightPadding [8]byte
const direntSize = int(unsafe.Sizeof(_Dirent{}))
// DirEntry is a type for PathFileSystem and NodeFileSystem to return
// directory contents in.
type DirEntry struct {
// Mode is the file's mode. Only the high bits (eg. S_IFDIR)
// are considered.
Mode uint32
// Name is the basename of the file in the directory.
Name string
// Ino is the inode number.
Ino uint64
}
func (d DirEntry) String() string {
return fmt.Sprintf("%o: %q ino=%d", d.Mode, d.Name, d.Ino)
}
// DirEntryList holds the return value for READDIR and READDIRPLUS
// opcodes.
type DirEntryList struct {
buf []byte
// capacity of the underlying buffer
size int
// offset is the requested location in the directory. go-fuse
// currently counts in number of directory entries, but this is an
// implementation detail and may change in the future.
// If `offset` and `fs.fileEntry.dirOffset` disagree, then a
// directory seek has taken place.
offset uint64
// pointer to the last serialized _Dirent. Used by FixMode().
lastDirent *_Dirent
}
// NewDirEntryList creates a DirEntryList with the given data buffer
// and offset.
func NewDirEntryList(data []byte, off uint64) *DirEntryList {
return &DirEntryList{
buf: data[:0],
size: len(data),
offset: off,
}
}
// AddDirEntry tries to add an entry, and reports whether it
// succeeded.
func (l *DirEntryList) AddDirEntry(e DirEntry) bool {
return l.Add(0, e.Name, e.Ino, e.Mode)
}
// Add adds a direntry to the DirEntryList, returning whether it
// succeeded.
func (l *DirEntryList) Add(prefix int, name string, inode uint64, mode uint32) bool {
if inode == 0 {
inode = FUSE_UNKNOWN_INO
}
padding := (8 - len(name)&7) & 7
delta := padding + direntSize + len(name) + prefix
oldLen := len(l.buf)
newLen := delta + oldLen
if newLen > l.size {
return false
}
l.buf = l.buf[:newLen]
oldLen += prefix
dirent := (*_Dirent)(unsafe.Pointer(&l.buf[oldLen]))
dirent.Off = l.offset + 1
dirent.Ino = inode
dirent.NameLen = uint32(len(name))
dirent.Typ = modeToType(mode)
oldLen += direntSize
copy(l.buf[oldLen:], name)
oldLen += len(name)
if padding > 0 {
copy(l.buf[oldLen:], eightPadding[:padding])
}
l.offset = dirent.Off
return true
}
// AddDirLookupEntry is used for ReadDirPlus. If reserves and zeroizes space
// for an EntryOut struct and serializes a DirEntry.
// On success, it returns pointers to both structs.
// If not enough space was left, it returns two nil pointers.
//
// The resulting READDIRPLUS output buffer looks like this in memory:
// 1) EntryOut{}
// 2) _Dirent{}
// 3) Name (null-terminated)
// 4) Padding to align to 8 bytes
// [repeat]
func (l *DirEntryList) AddDirLookupEntry(e DirEntry) *EntryOut {
const entryOutSize = int(unsafe.Sizeof(EntryOut{}))
oldLen := len(l.buf)
ok := l.Add(entryOutSize, e.Name, e.Ino, e.Mode)
if !ok {
return nil
}
l.lastDirent = (*_Dirent)(unsafe.Pointer(&l.buf[oldLen+entryOutSize]))
entryOut := (*EntryOut)(unsafe.Pointer(&l.buf[oldLen]))
*entryOut = EntryOut{} // zeroize
return entryOut
}
// modeToType converts a file *mode* (as used in syscall.Stat_t.Mode)
// to a file *type* (as used in _Dirent.Typ).
// Equivalent to IFTODT() in libc (see man 5 dirent).
func modeToType(mode uint32) uint32 {
return (mode & 0170000) >> 12
}
// FixMode overrides the file mode of the last direntry that was added. This can
// be needed when a directory changes while READDIRPLUS is running.
// Only the file type bits of mode are considered, the rest is masked out.
func (l *DirEntryList) FixMode(mode uint32) {
l.lastDirent.Typ = modeToType(mode)
}
func (l *DirEntryList) bytes() []byte {
return l.buf
}
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