682e642cfa
For Linux, everything effectively stays the same. For both path-based and fd-based Utimens() calls, we use unix.UtimesNanoAt(). To avoid introducing a separate syscall wrapper for futimens() (as done in go-fuse, for example), we instead use the /proc/self/fd - trick. On macOS, this changes quite a lot: * Path-based Utimens() calls were previously completely broken, since unix.UtimensNanoAt() ignores the passed file descriptor. Note that this cannot be fixed easily since there IS no appropriate syscall available on macOS prior to High Sierra (10.13). We emulate this case by using Fchdir() + setattrlist(). * Fd-based Utimens() calls were previously translated to f.GetAttr() (to fill any empty parameters) and syscall.Futimes(), which does not does support nanosecond precision. Both issues can be fixed by switching to fsetattrlist(). Fixes https://github.com/rfjakob/gocryptfs/issues/350
477 lines
15 KiB
Go
477 lines
15 KiB
Go
package fusefrontend
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// FUSE operations on file handles
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import (
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"bytes"
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"fmt"
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"io"
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"log"
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"os"
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"sync"
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"syscall"
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"time"
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"github.com/hanwen/go-fuse/fuse"
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"github.com/hanwen/go-fuse/fuse/nodefs"
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"github.com/rfjakob/gocryptfs/internal/contentenc"
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"github.com/rfjakob/gocryptfs/internal/openfiletable"
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"github.com/rfjakob/gocryptfs/internal/serialize_reads"
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"github.com/rfjakob/gocryptfs/internal/stupidgcm"
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"github.com/rfjakob/gocryptfs/internal/syscallcompat"
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"github.com/rfjakob/gocryptfs/internal/tlog"
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)
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var _ nodefs.File = &File{} // Verify that interface is implemented.
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// File - based on loopbackFile in go-fuse/fuse/nodefs/files.go
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type File struct {
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fd *os.File
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// Has Release() already been called on this file? This also means that the
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// wlock entry has been freed, so let's not crash trying to access it.
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// Due to concurrency, Release can overtake other operations. These will
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// return EBADF in that case.
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released bool
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// fdLock prevents the fd to be closed while we are in the middle of
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// an operation.
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// Every FUSE entrypoint should RLock(). The only user of Lock() is
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// Release(), which closes the fd and sets "released" to true.
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fdLock sync.RWMutex
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// Content encryption helper
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contentEnc *contentenc.ContentEnc
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// Device and inode number uniquely identify the backing file
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qIno openfiletable.QIno
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// Entry in the open file table
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fileTableEntry *openfiletable.Entry
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// Store where the last byte was written
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lastWrittenOffset int64
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// The opCount is used to judge whether "lastWrittenOffset" is still
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// guaranteed to be correct.
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lastOpCount uint64
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// Parent filesystem
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fs *FS
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// We embed a nodefs.NewDefaultFile() that returns ENOSYS for every operation we
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// have not implemented. This prevents build breakage when the go-fuse library
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// adds new methods to the nodefs.File interface.
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nodefs.File
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}
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// NewFile returns a new go-fuse File instance.
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func NewFile(fd *os.File, fs *FS) (*File, fuse.Status) {
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var st syscall.Stat_t
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err := syscall.Fstat(int(fd.Fd()), &st)
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if err != nil {
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tlog.Warn.Printf("NewFile: Fstat on fd %d failed: %v\n", fd.Fd(), err)
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return nil, fuse.ToStatus(err)
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}
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qi := openfiletable.QInoFromStat(&st)
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e := openfiletable.Register(qi)
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return &File{
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fd: fd,
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contentEnc: fs.contentEnc,
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qIno: qi,
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fileTableEntry: e,
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fs: fs,
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File: nodefs.NewDefaultFile(),
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}, fuse.OK
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}
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// intFd - return the backing file descriptor as an integer. Used for debug
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// messages.
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func (f *File) intFd() int {
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return int(f.fd.Fd())
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}
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// readFileID loads the file header from disk and extracts the file ID.
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// Returns io.EOF if the file is empty.
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func (f *File) readFileID() ([]byte, error) {
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// We read +1 byte to determine if the file has actual content
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// and not only the header. A header-only file will be considered empty.
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// This makes File ID poisoning more difficult.
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readLen := contentenc.HeaderLen + 1
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buf := make([]byte, readLen)
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n, err := f.fd.ReadAt(buf, 0)
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if err != nil {
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if err == io.EOF && n != 0 {
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tlog.Warn.Printf("readFileID %d: incomplete file, got %d instead of %d bytes",
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f.qIno.Ino, n, readLen)
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f.fs.reportMitigatedCorruption(fmt.Sprint(f.qIno.Ino))
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}
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return nil, err
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}
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buf = buf[:contentenc.HeaderLen]
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h, err := contentenc.ParseHeader(buf)
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if err != nil {
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return nil, err
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}
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return h.ID, nil
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}
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// createHeader creates a new random header and writes it to disk.
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// Returns the new file ID.
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// The caller must hold fileIDLock.Lock().
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func (f *File) createHeader() (fileID []byte, err error) {
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h := contentenc.RandomHeader()
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buf := h.Pack()
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// Prevent partially written (=corrupt) header by preallocating the space beforehand
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if !f.fs.args.NoPrealloc {
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err = syscallcompat.EnospcPrealloc(int(f.fd.Fd()), 0, contentenc.HeaderLen)
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if err != nil {
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if !syscallcompat.IsENOSPC(err) {
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tlog.Warn.Printf("ino%d: createHeader: prealloc failed: %s\n", f.qIno.Ino, err.Error())
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}
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return nil, err
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}
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}
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// Actually write header
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_, err = f.fd.WriteAt(buf, 0)
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if err != nil {
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return nil, err
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}
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return h.ID, err
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}
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// doRead - read "length" plaintext bytes from plaintext offset "off" and append
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// to "dst".
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// Arguments "length" and "off" do not have to be block-aligned.
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//
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// doRead reads the corresponding ciphertext blocks from disk, decrypts them and
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// returns the requested part of the plaintext.
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//
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// Called by Read() for normal reading,
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// by Write() and Truncate() via doWrite() for Read-Modify-Write.
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func (f *File) doRead(dst []byte, off uint64, length uint64) ([]byte, fuse.Status) {
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// Get the file ID, either from the open file table, or from disk.
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var fileID []byte
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f.fileTableEntry.IDLock.Lock()
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if f.fileTableEntry.ID != nil {
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// Use the cached value in the file table
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fileID = f.fileTableEntry.ID
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} else {
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// Not cached, we have to read it from disk.
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var err error
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fileID, err = f.readFileID()
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if err != nil {
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f.fileTableEntry.IDLock.Unlock()
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if err == io.EOF {
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// Empty file
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return nil, fuse.OK
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}
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tlog.Warn.Printf("doRead %d: corrupt header: %v", f.qIno.Ino, err)
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return nil, fuse.EIO
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}
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// Save into the file table
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f.fileTableEntry.ID = fileID
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}
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f.fileTableEntry.IDLock.Unlock()
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if fileID == nil {
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log.Panicf("fileID=%v", fileID)
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}
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// Read the backing ciphertext in one go
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blocks := f.contentEnc.ExplodePlainRange(off, length)
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alignedOffset, alignedLength := blocks[0].JointCiphertextRange(blocks)
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skip := blocks[0].Skip
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tlog.Debug.Printf("doRead: off=%d len=%d -> off=%d len=%d skip=%d\n",
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off, length, alignedOffset, alignedLength, skip)
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ciphertext := f.fs.contentEnc.CReqPool.Get()
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ciphertext = ciphertext[:int(alignedLength)]
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n, err := f.fd.ReadAt(ciphertext, int64(alignedOffset))
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if err != nil && err != io.EOF {
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tlog.Warn.Printf("read: ReadAt: %s", err.Error())
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return nil, fuse.ToStatus(err)
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}
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// The ReadAt came back empty. We can skip all the decryption and return early.
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if n == 0 {
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f.fs.contentEnc.CReqPool.Put(ciphertext)
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return dst, fuse.OK
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}
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// Truncate ciphertext buffer down to actually read bytes
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ciphertext = ciphertext[0:n]
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firstBlockNo := blocks[0].BlockNo
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tlog.Debug.Printf("ReadAt offset=%d bytes (%d blocks), want=%d, got=%d", alignedOffset, firstBlockNo, alignedLength, n)
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// Decrypt it
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plaintext, err := f.contentEnc.DecryptBlocks(ciphertext, firstBlockNo, fileID)
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f.fs.contentEnc.CReqPool.Put(ciphertext)
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if err != nil {
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if f.fs.args.ForceDecode && err == stupidgcm.ErrAuth {
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// We do not have the information which block was corrupt here anymore,
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// but DecryptBlocks() has already logged it anyway.
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tlog.Warn.Printf("doRead %d: off=%d len=%d: returning corrupt data due to forcedecode",
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f.qIno.Ino, off, length)
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} else {
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curruptBlockNo := firstBlockNo + f.contentEnc.PlainOffToBlockNo(uint64(len(plaintext)))
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tlog.Warn.Printf("doRead %d: corrupt block #%d: %v", f.qIno.Ino, curruptBlockNo, err)
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return nil, fuse.EIO
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}
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}
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// Crop down to the relevant part
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var out []byte
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lenHave := len(plaintext)
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lenWant := int(skip + length)
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if lenHave > lenWant {
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out = plaintext[skip:lenWant]
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} else if lenHave > int(skip) {
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out = plaintext[skip:lenHave]
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}
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// else: out stays empty, file was smaller than the requested offset
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out = append(dst, out...)
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f.fs.contentEnc.PReqPool.Put(plaintext)
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return out, fuse.OK
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}
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// Read - FUSE call
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func (f *File) Read(buf []byte, off int64) (resultData fuse.ReadResult, code fuse.Status) {
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if len(buf) > fuse.MAX_KERNEL_WRITE {
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// This would crash us due to our fixed-size buffer pool
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tlog.Warn.Printf("Read: rejecting oversized request with EMSGSIZE, len=%d", len(buf))
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return nil, fuse.Status(syscall.EMSGSIZE)
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}
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f.fdLock.RLock()
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defer f.fdLock.RUnlock()
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f.fileTableEntry.ContentLock.RLock()
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defer f.fileTableEntry.ContentLock.RUnlock()
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tlog.Debug.Printf("ino%d: FUSE Read: offset=%d length=%d", f.qIno.Ino, off, len(buf))
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if f.fs.args.SerializeReads {
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serialize_reads.Wait(off, len(buf))
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}
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out, status := f.doRead(buf[:0], uint64(off), uint64(len(buf)))
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if f.fs.args.SerializeReads {
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serialize_reads.Done()
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}
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if status != fuse.OK {
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return nil, status
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}
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tlog.Debug.Printf("ino%d: Read: status %v, returning %d bytes", f.qIno.Ino, status, len(out))
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return fuse.ReadResultData(out), status
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}
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// doWrite - encrypt "data" and write it to plaintext offset "off"
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//
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// Arguments do not have to be block-aligned, read-modify-write is
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// performed internally as necessary
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//
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// Called by Write() for normal writing,
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// and by Truncate() to rewrite the last file block.
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//
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// Empty writes do nothing and are allowed.
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func (f *File) doWrite(data []byte, off int64) (uint32, fuse.Status) {
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fileWasEmpty := false
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// Get the file ID, create a new one if it does not exist yet.
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var fileID []byte
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// The caller has exclusively locked ContentLock, which blocks all other
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// readers and writers. No need to take IDLock.
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if f.fileTableEntry.ID != nil {
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fileID = f.fileTableEntry.ID
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} else {
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// If the file ID is not cached, read it from disk
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var err error
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fileID, err = f.readFileID()
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// Write a new file header if the file is empty
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if err == io.EOF {
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fileID, err = f.createHeader()
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fileWasEmpty = true
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}
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if err != nil {
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return 0, fuse.ToStatus(err)
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}
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f.fileTableEntry.ID = fileID
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}
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// Handle payload data
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dataBuf := bytes.NewBuffer(data)
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blocks := f.contentEnc.ExplodePlainRange(uint64(off), uint64(len(data)))
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toEncrypt := make([][]byte, len(blocks))
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for i, b := range blocks {
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blockData := dataBuf.Next(int(b.Length))
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// Incomplete block -> Read-Modify-Write
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if b.IsPartial() {
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// Read
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oldData, status := f.doRead(nil, b.BlockPlainOff(), f.contentEnc.PlainBS())
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if status != fuse.OK {
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tlog.Warn.Printf("ino%d fh%d: RMW read failed: %s", f.qIno.Ino, f.intFd(), status.String())
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return 0, status
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}
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// Modify
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blockData = f.contentEnc.MergeBlocks(oldData, blockData, int(b.Skip))
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tlog.Debug.Printf("len(oldData)=%d len(blockData)=%d", len(oldData), len(blockData))
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}
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tlog.Debug.Printf("ino%d: Writing %d bytes to block #%d",
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f.qIno.Ino, len(blockData), b.BlockNo)
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// Write into the to-encrypt list
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toEncrypt[i] = blockData
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}
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// Encrypt all blocks
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ciphertext := f.contentEnc.EncryptBlocks(toEncrypt, blocks[0].BlockNo, f.fileTableEntry.ID)
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// Preallocate so we cannot run out of space in the middle of the write.
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// This prevents partially written (=corrupt) blocks.
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var err error
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cOff := int64(blocks[0].BlockCipherOff())
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if !f.fs.args.NoPrealloc {
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err = syscallcompat.EnospcPrealloc(int(f.fd.Fd()), cOff, int64(len(ciphertext)))
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if err != nil {
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if !syscallcompat.IsENOSPC(err) {
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tlog.Warn.Printf("ino%d fh%d: doWrite: prealloc failed: %v", f.qIno.Ino, f.intFd(), err)
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}
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if fileWasEmpty {
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// Kill the file header again
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f.fileTableEntry.ID = nil
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err2 := syscall.Ftruncate(int(f.fd.Fd()), 0)
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if err2 != nil {
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tlog.Warn.Printf("ino%d fh%d: doWrite: rollback failed: %v", f.qIno.Ino, f.intFd(), err2)
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}
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}
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return 0, fuse.ToStatus(err)
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}
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}
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// Write
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_, err = f.fd.WriteAt(ciphertext, cOff)
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// Return memory to CReqPool
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f.fs.contentEnc.CReqPool.Put(ciphertext)
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if err != nil {
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tlog.Warn.Printf("ino%d fh%d: doWrite: WriteAt off=%d len=%d failed: %v",
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f.qIno.Ino, f.intFd(), cOff, len(ciphertext), err)
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return 0, fuse.ToStatus(err)
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}
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return uint32(len(data)), fuse.OK
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}
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// isConsecutiveWrite returns true if the current write
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// directly (in time and space) follows the last write.
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// This is an optimisation for streaming writes on NFS where a
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// Stat() call is very expensive.
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// The caller must "wlock.lock(f.devIno.ino)" otherwise this check would be racy.
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func (f *File) isConsecutiveWrite(off int64) bool {
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opCount := openfiletable.WriteOpCount()
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return opCount == f.lastOpCount+1 && off == f.lastWrittenOffset+1
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}
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// Write - FUSE call
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//
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// If the write creates a hole, pads the file to the next block boundary.
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func (f *File) Write(data []byte, off int64) (uint32, fuse.Status) {
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if len(data) > fuse.MAX_KERNEL_WRITE {
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// This would crash us due to our fixed-size buffer pool
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tlog.Warn.Printf("Write: rejecting oversized request with EMSGSIZE, len=%d", len(data))
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return 0, fuse.Status(syscall.EMSGSIZE)
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}
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f.fdLock.RLock()
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defer f.fdLock.RUnlock()
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if f.released {
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// The file descriptor has been closed concurrently
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tlog.Warn.Printf("ino%d fh%d: Write on released file", f.qIno.Ino, f.intFd())
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return 0, fuse.EBADF
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}
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f.fileTableEntry.ContentLock.Lock()
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defer f.fileTableEntry.ContentLock.Unlock()
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tlog.Debug.Printf("ino%d: FUSE Write: offset=%d length=%d", f.qIno.Ino, off, len(data))
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// If the write creates a file hole, we have to zero-pad the last block.
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// But if the write directly follows an earlier write, it cannot create a
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// hole, and we can save one Stat() call.
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if !f.isConsecutiveWrite(off) {
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status := f.writePadHole(off)
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if !status.Ok() {
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return 0, status
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}
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}
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n, status := f.doWrite(data, off)
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if status.Ok() {
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f.lastOpCount = openfiletable.WriteOpCount()
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f.lastWrittenOffset = off + int64(len(data)) - 1
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}
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return n, status
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}
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// Release - FUSE call, close file
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func (f *File) Release() {
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f.fdLock.Lock()
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if f.released {
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log.Panicf("ino%d fh%d: double release", f.qIno.Ino, f.intFd())
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}
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f.fd.Close()
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f.released = true
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f.fdLock.Unlock()
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openfiletable.Unregister(f.qIno)
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}
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// Flush - FUSE call
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func (f *File) Flush() fuse.Status {
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f.fdLock.RLock()
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defer f.fdLock.RUnlock()
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// Since Flush() may be called for each dup'd fd, we don't
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// want to really close the file, we just want to flush. This
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// is achieved by closing a dup'd fd.
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newFd, err := syscall.Dup(int(f.fd.Fd()))
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if err != nil {
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return fuse.ToStatus(err)
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}
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err = syscall.Close(newFd)
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return fuse.ToStatus(err)
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}
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// Fsync FUSE call
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func (f *File) Fsync(flags int) (code fuse.Status) {
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f.fdLock.RLock()
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defer f.fdLock.RUnlock()
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return fuse.ToStatus(syscall.Fsync(int(f.fd.Fd())))
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}
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// Chmod FUSE call
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func (f *File) Chmod(mode uint32) fuse.Status {
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f.fdLock.RLock()
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defer f.fdLock.RUnlock()
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// os.File.Chmod goes through the "syscallMode" translation function that messes
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// up the suid and sgid bits. So use syscall.Fchmod directly.
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err := syscall.Fchmod(f.intFd(), mode)
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return fuse.ToStatus(err)
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}
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// Chown FUSE call
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func (f *File) Chown(uid uint32, gid uint32) fuse.Status {
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f.fdLock.RLock()
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defer f.fdLock.RUnlock()
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return fuse.ToStatus(f.fd.Chown(int(uid), int(gid)))
|
|
}
|
|
|
|
// GetAttr FUSE call (like stat)
|
|
func (f *File) GetAttr(a *fuse.Attr) fuse.Status {
|
|
f.fdLock.RLock()
|
|
defer f.fdLock.RUnlock()
|
|
|
|
tlog.Debug.Printf("file.GetAttr()")
|
|
st := syscall.Stat_t{}
|
|
err := syscall.Fstat(int(f.fd.Fd()), &st)
|
|
if err != nil {
|
|
return fuse.ToStatus(err)
|
|
}
|
|
a.FromStat(&st)
|
|
a.Size = f.contentEnc.CipherSizeToPlainSize(a.Size)
|
|
if f.fs.args.ForceOwner != nil {
|
|
a.Owner = *f.fs.args.ForceOwner
|
|
}
|
|
|
|
return fuse.OK
|
|
}
|
|
|
|
// Utimens FUSE call
|
|
func (f *File) Utimens(a *time.Time, m *time.Time) fuse.Status {
|
|
f.fdLock.RLock()
|
|
defer f.fdLock.RUnlock()
|
|
err := syscallcompat.FutimesNano(f.intFd(), a, m)
|
|
return fuse.ToStatus(err)
|
|
}
|