82 lines
1.9 KiB
Go
82 lines
1.9 KiB
Go
package fusefrontend_reverse
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import (
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"bytes"
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"context"
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"os"
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"syscall"
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"github.com/hanwen/go-fuse/v2/fs"
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"github.com/hanwen/go-fuse/v2/fuse"
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"github.com/rfjakob/gocryptfs/v2/internal/contentenc"
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)
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type File struct {
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// Backing FD
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fd *os.File
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// File header (contains the IV)
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header contentenc.FileHeader
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// IV for block 0
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block0IV []byte
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// Content encryption helper
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contentEnc *contentenc.ContentEnc
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}
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// Read - FUSE call
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func (f *File) Read(ctx context.Context, buf []byte, ioff int64) (resultData fuse.ReadResult, errno syscall.Errno) {
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length := uint64(len(buf))
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off := uint64(ioff)
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out := bytes.NewBuffer(buf[:0])
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var header []byte
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// Synthesize file header
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if off < contentenc.HeaderLen {
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header = f.header.Pack()
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// Truncate to requested part
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end := int(off) + len(buf)
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if end > len(header) {
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end = len(header)
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}
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header = header[off:end]
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// Write into output buffer and adjust offsets
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out.Write(header)
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hLen := uint64(len(header))
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off += hLen
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length -= hLen
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}
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// Read actual file data
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if length > 0 {
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fileData, err := f.readBackingFile(off, length)
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if err != nil {
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return nil, fs.ToErrno(err)
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}
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if len(fileData) == 0 {
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// If we could not read any actual data, we also don't want to
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// return the file header. An empty file stays empty in encrypted
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// form.
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return nil, 0
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}
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out.Write(fileData)
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}
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return fuse.ReadResultData(out.Bytes()), 0
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}
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// Release - FUSE call, close file
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func (f *File) Release(context.Context) syscall.Errno {
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return fs.ToErrno(f.fd.Close())
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}
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// Lseek - FUSE call.
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func (f *File) Lseek(ctx context.Context, off uint64, whence uint32) (uint64, syscall.Errno) {
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plainOff := f.contentEnc.CipherSizeToPlainSize(off)
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newPlainOff, err := syscall.Seek(int(f.fd.Fd()), int64(plainOff), int(whence))
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if err != nil {
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return 0, fs.ToErrno(err)
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}
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newOff := f.contentEnc.PlainSizeToCipherSize(uint64(newPlainOff))
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return newOff, 0
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}
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