af5441dcd9
This fixes a build problem on 32-bit hosts: internal/fusefrontend/file.go:400: cannot use a.Unix() (type int64) as type int32 in assignment internal/fusefrontend/file.go:406: cannot use m.Unix() (type int64) as type int32 in assignment It also enables full nanosecond timestamps for dates after 1970.
427 lines
11 KiB
Go
427 lines
11 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/syscallcompat"
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"github.com/rfjakob/gocryptfs/internal/tlog"
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)
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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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// Was the file opened O_WRONLY?
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writeOnly bool
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// Content encryption helper
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contentEnc *contentenc.ContentEnc
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// Inode number
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ino uint64
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// File header
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header *contentenc.FileHeader
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}
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func NewFile(fd *os.File, writeOnly bool, contentEnc *contentenc.ContentEnc) (nodefs.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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wlock.register(st.Ino)
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return &file{
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fd: fd,
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writeOnly: writeOnly,
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contentEnc: contentEnc,
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ino: st.Ino,
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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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func (f *file) InnerFile() nodefs.File {
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return nil
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}
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func (f *file) SetInode(n *nodefs.Inode) {
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}
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// readHeader - load the file header from disk
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//
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// Returns io.EOF if the file is empty
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func (f *file) readHeader() error {
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buf := make([]byte, contentenc.HEADER_LEN)
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_, err := f.fd.ReadAt(buf, 0)
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if err != nil {
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return err
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}
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h, err := contentenc.ParseHeader(buf)
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if err != nil {
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return err
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}
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f.header = h
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return nil
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}
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// createHeader - create a new random header and write it to disk
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func (f *file) createHeader() 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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err := syscallcompat.EnospcPrealloc(int(f.fd.Fd()), 0, contentenc.HEADER_LEN)
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if err != nil {
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tlog.Warn.Printf("ino%d: createHeader: prealloc failed: %s\n", f.ino, err.Error())
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return err
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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 err
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}
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f.header = h
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return nil
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}
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func (f *file) String() string {
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return fmt.Sprintf("cryptFile(%s)", f.fd.Name())
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}
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// doRead - returns "length" plaintext bytes from plaintext offset "off".
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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() for Read-Modify-Write
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func (f *file) doRead(off uint64, length uint64) ([]byte, fuse.Status) {
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// Read file header
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if f.header == nil {
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err := f.readHeader()
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if err == io.EOF {
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return nil, fuse.OK
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}
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if err != nil {
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return nil, fuse.ToStatus(err)
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}
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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("JointCiphertextRange(%d, %d) -> %d, %d, %d", off, length, alignedOffset, alignedLength, skip)
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ciphertext := make([]byte, 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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// 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, f.header.Id)
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if err != nil {
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curruptBlockNo := firstBlockNo + f.contentEnc.PlainOffToBlockNo(uint64(len(plaintext)))
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cipherOff := f.contentEnc.BlockNoToCipherOff(curruptBlockNo)
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plainOff := f.contentEnc.BlockNoToPlainOff(curruptBlockNo)
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tlog.Warn.Printf("ino%d: doRead: corrupt block #%d (plainOff=%d, cipherOff=%d)",
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f.ino, curruptBlockNo, plainOff, cipherOff)
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return nil, fuse.EIO
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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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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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f.fdLock.RLock()
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defer f.fdLock.RUnlock()
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tlog.Debug.Printf("ino%d: FUSE Read: offset=%d length=%d", f.ino, len(buf), off)
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if f.writeOnly {
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tlog.Warn.Printf("ino%d: Tried to read from write-only file", f.ino)
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return nil, fuse.EBADF
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}
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out, status := f.doRead(uint64(off), uint64(len(buf)))
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if status == fuse.EIO {
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tlog.Warn.Printf("ino%d: Read failed with EIO, offset=%d, length=%d", f.ino, len(buf), off)
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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.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 neccessary
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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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// Read header from disk, create a new one if the file is empty
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if f.header == nil {
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err := f.readHeader()
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if err == io.EOF {
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err = f.createHeader()
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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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}
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var written uint32
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status := fuse.OK
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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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for _, 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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o := b.BlockPlainOff()
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var oldData []byte
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oldData, status = f.doRead(o, 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.ino, f.intFd(), status.String())
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return written, 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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// Encrypt
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blockOffset := b.BlockCipherOff()
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blockData = f.contentEnc.EncryptBlock(blockData, b.BlockNo, f.header.Id)
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tlog.Debug.Printf("ino%d: Writing %d bytes to block #%d",
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f.ino, uint64(len(blockData))-f.contentEnc.BlockOverhead(), b.BlockNo)
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// Prevent partially written (=corrupt) blocks by preallocating the space beforehand
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err := syscallcompat.EnospcPrealloc(int(f.fd.Fd()), int64(blockOffset), int64(len(blockData)))
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if err != nil {
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tlog.Warn.Printf("ino%d fh%d: doWrite: prealloc failed: %s", f.ino, f.intFd(), err.Error())
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status = fuse.ToStatus(err)
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break
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}
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// Write
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_, err = f.fd.WriteAt(blockData, int64(blockOffset))
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if err != nil {
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tlog.Warn.Printf("doWrite: Write failed: %s", err.Error())
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status = fuse.ToStatus(err)
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break
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}
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written += uint32(b.Length)
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}
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return written, status
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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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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, which also means
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// the wlock has been freed. Exit here so we don't crash trying to access
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// it.
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tlog.Warn.Printf("ino%d fh%d: Write on released file", f.ino, f.intFd())
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return 0, fuse.EBADF
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}
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wlock.lock(f.ino)
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defer wlock.unlock(f.ino)
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tlog.Debug.Printf("ino%d: FUSE Write: offset=%d length=%d", f.ino, off, len(data))
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fi, err := f.fd.Stat()
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if err != nil {
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tlog.Warn.Printf("Write: Fstat failed: %v", err)
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return 0, fuse.ToStatus(err)
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}
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plainSize := f.contentEnc.CipherSizeToPlainSize(uint64(fi.Size()))
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if f.createsHole(plainSize, off) {
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status := f.zeroPad(plainSize)
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if status != fuse.OK {
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tlog.Warn.Printf("zeroPad returned error %v", status)
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return 0, status
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}
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}
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return f.doWrite(data, off)
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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.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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wlock.unregister(f.ino)
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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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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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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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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)))
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}
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func (f *file) GetAttr(a *fuse.Attr) fuse.Status {
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f.fdLock.RLock()
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defer f.fdLock.RUnlock()
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tlog.Debug.Printf("file.GetAttr()")
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st := syscall.Stat_t{}
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err := syscall.Fstat(int(f.fd.Fd()), &st)
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if err != nil {
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return fuse.ToStatus(err)
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}
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a.FromStat(&st)
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a.Size = f.contentEnc.CipherSizeToPlainSize(a.Size)
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return fuse.OK
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}
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const _UTIME_OMIT = ((1 << 30) - 2)
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// utimeToTimespec converts a "time.Time" pointer as passed to Utimens to a
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// Timespec that can be passed to the utimensat syscall.
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func utimeToTimespec(t *time.Time) (ts syscall.Timespec) {
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if t == nil {
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ts.Nsec = _UTIME_OMIT
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} else {
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ts = syscall.NsecToTimespec(t.UnixNano())
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// For dates before 1970, NsecToTimespec incorrectly returns negative
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// nanoseconds. Ticket: https://github.com/golang/go/issues/12777
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if ts.Nsec < 0 {
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ts.Nsec = 0
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}
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}
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return ts
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}
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func (f *file) Utimens(a *time.Time, m *time.Time) fuse.Status {
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f.fdLock.RLock()
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defer f.fdLock.RUnlock()
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ts := make([]syscall.Timespec, 2)
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ts[0] = utimeToTimespec(a)
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ts[1] = utimeToTimespec(m)
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fn := fmt.Sprintf("/proc/self/fd/%d", f.fd.Fd())
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err := syscall.UtimesNano(fn, ts)
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if err != nil {
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tlog.Debug.Printf("UtimesNano on %q failed: %v", fn, err)
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}
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if err == syscall.ENOENT {
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// If /proc/self/fd/X did not exist, the actual error is that the file
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// descriptor was invalid.
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return fuse.EBADF
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}
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return fuse.ToStatus(err)
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}
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