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authorJakob Unterwurzacher2016-08-30 00:23:55 +0200
committerJakob Unterwurzacher2016-09-25 16:43:17 +0200
commit777eb8e62f19895e9b2d3d8364a6ae1c40ff3ebc (patch)
tree4aab732aa3f78c667a36c4fa198f10df7e447ae8 /internal/fusefrontend_reverse/rfile.go
parent5931eea3877ae34cdb18ac36e5cf5fba3f74b82b (diff)
reverse: rename types to reverseXYZ
...to prevent confusion with the forward variants. FS -> reverseFS file -> reverseFile Also add an incomplete read implementation.
Diffstat (limited to 'internal/fusefrontend_reverse/rfile.go')
-rw-r--r--internal/fusefrontend_reverse/rfile.go64
1 files changed, 58 insertions, 6 deletions
diff --git a/internal/fusefrontend_reverse/rfile.go b/internal/fusefrontend_reverse/rfile.go
index 746a0d6..15f2764 100644
--- a/internal/fusefrontend_reverse/rfile.go
+++ b/internal/fusefrontend_reverse/rfile.go
@@ -1,27 +1,79 @@
package fusefrontend_reverse
import (
+ "fmt"
+ "io"
"os"
"github.com/hanwen/go-fuse/fuse"
"github.com/hanwen/go-fuse/fuse/nodefs"
"github.com/rfjakob/gocryptfs/internal/contentenc"
+ "github.com/rfjakob/gocryptfs/internal/tlog"
)
-type file struct {
+var zeroFileId []byte
+
+func init() {
+ zeroFileId = make([]byte, 16)
+}
+
+type reverseFile struct {
+ // Embed nodefs.defaultFile for a ENOSYS implementation of all methods
+ nodefs.File
+ // Backing FD
fd *os.File
// Content encryption helper
contentEnc *contentenc.ContentEnc
-
- // nodefs.defaultFile returns ENOSYS for all operations
- nodefs.File
}
func NewFile(fd *os.File, contentEnc *contentenc.ContentEnc) (nodefs.File, fuse.Status) {
- return &file{
+ return &reverseFile{
+ File: nodefs.NewDefaultFile(),
fd: fd,
contentEnc: contentEnc,
- File: nodefs.NewDefaultFile(),
}, fuse.OK
}
+
+// GetAttr - FUSE call
+func (rf *reverseFile) GetAttr(*fuse.Attr) fuse.Status {
+ fmt.Printf("reverseFile.GetAttr fd=%d\n", rf.fd.Fd())
+ return fuse.ENOSYS
+}
+
+// Read - FUSE call
+func (rf *reverseFile) Read(buf []byte, off int64) (resultData fuse.ReadResult, status fuse.Status) {
+ // TODO prefix file header
+
+ length := uint64(len(buf))
+ blocks := rf.contentEnc.ExplodeCipherRange(uint64(off), length)
+
+ // Read the backing plaintext in one go
+ alignedOffset, alignedLength := contentenc.JointPlaintextRange(blocks)
+ tlog.Warn.Printf("alignedOffset=%d, alignedLength=%d\n", alignedOffset, alignedLength)
+ plaintext := make([]byte, int(alignedLength))
+ n, err := rf.fd.ReadAt(plaintext, int64(alignedOffset))
+ if err != nil && err != io.EOF {
+ tlog.Warn.Printf("reverseFile.Read: ReadAt: %s", err.Error())
+ return nil, fuse.ToStatus(err)
+ }
+ // Truncate buffer down to actually read bytes
+ plaintext = plaintext[0:n]
+
+ // Encrypt blocks
+ ciphertext := rf.contentEnc.EncryptBlocks(plaintext, blocks[0].BlockNo, zeroFileId)
+
+ // Crop down to the relevant part
+ var out []byte
+ lenHave := len(ciphertext)
+ skip := blocks[0].Skip
+ endWant := int(skip + length)
+ if lenHave > endWant {
+ out = plaintext[skip:endWant]
+ } else if lenHave > int(skip) {
+ out = plaintext[skip:lenHave]
+ }
+ // else: out stays empty, file was smaller than the requested offset
+
+ return fuse.ReadResultData(out), fuse.OK
+}