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-rw-r--r--frontend/fe_file.go144
1 files changed, 144 insertions, 0 deletions
diff --git a/frontend/fe_file.go b/frontend/fe_file.go
new file mode 100644
index 0000000..4bd623f
--- /dev/null
+++ b/frontend/fe_file.go
@@ -0,0 +1,144 @@
+package frontend
+
+// frontend sits between FUSE and ClueFS
+// and uses cryptfs for all crypto operations
+//
+// cryptfs
+// ^
+// |
+// v
+// FUSE <-> frontend <-> ClueFS
+//
+// This file handles files access
+
+import (
+ "fmt"
+ "github.com/rfjakob/gocryptfs/cryptfs"
+ "github.com/rfjakob/cluefs/lib/cluefs"
+
+ "bazil.org/fuse"
+ fusefs "bazil.org/fuse/fs"
+ "golang.org/x/net/context"
+)
+
+func fixFlags(flags fuse.OpenFlags) (fuse.OpenFlags, bool) {
+ fmt.Printf("fixFlags: Before: %s\n", flags.String())
+ var writeOnly bool
+ // We always need read access to do read-modify-write cycles
+ if flags & fuse.OpenWriteOnly > 0 {
+ flags = flags &^ fuse.OpenWriteOnly
+ flags = flags | fuse.OpenReadWrite
+ writeOnly = true
+ }
+ // We also cannot open the file in append mode, we need to seek back for RMW
+ flags = flags &^ fuse.OpenAppend
+ fmt.Printf("fixFlags: After: %s\n", flags.String())
+ return flags, writeOnly
+}
+
+func max(x int, y int) int {
+ if x > y {
+ return x
+ }
+ return y
+}
+
+type File struct {
+ *cluefs.File
+ crfs *cryptfs.CryptFS
+ // Remember if the file is supposed to be write-only
+ writeOnly bool
+}
+
+func (f *File) Open(ctx context.Context, req *fuse.OpenRequest, resp *fuse.OpenResponse) (fusefs.Handle, error) {
+ fmt.Printf("File.Open\n")
+
+ req.Flags, f.writeOnly = fixFlags(req.Flags)
+
+ h, err := f.File.Open(ctx, req, resp)
+ if err != nil {
+ return nil, err
+ }
+ clueFile := h.(*cluefs.File)
+ return &File {
+ File: clueFile,
+ crfs: f.crfs,
+ }, nil
+}
+
+func (f *File) Read(ctx context.Context, req *fuse.ReadRequest, resp *fuse.ReadResponse) error {
+ iblocks := f.crfs.SplitRange(uint64(req.Offset), uint64(req.Size))
+ for _, ib := range iblocks {
+ var partReq fuse.ReadRequest
+ var partResp fuse.ReadResponse
+ o, l := ib.CiphertextRange()
+ partReq.Offset = int64(o)
+ partReq.Size = int(l)
+ partResp.Data = make([]byte, int(l))
+ err := f.File.Read(ctx, &partReq, &partResp)
+ if err != nil {
+ return err
+ }
+ plaintext, err := f.crfs.DecryptBlock(partResp.Data)
+ if err != nil {
+ fmt.Printf("Read: Error reading block %d: %s\n", ib.BlockNo, err.Error())
+ return err
+ }
+ plaintext = ib.CropBlock(plaintext)
+ resp.Data = append(resp.Data, plaintext...)
+ }
+ return nil
+}
+
+func (f *File) Write(ctx context.Context, req *fuse.WriteRequest, resp *fuse.WriteResponse) error {
+ fmt.Printf("File.Write\n")
+ resp.Size = 0
+ iblocks := f.crfs.SplitRange(uint64(req.Offset), uint64(len(req.Data)))
+ var blockData []byte
+ for _, ib := range iblocks {
+ if ib.IsPartial() {
+ // RMW
+ blockData = make([]byte, f.crfs.PlainBS())
+ var readReq fuse.ReadRequest
+ var readResp fuse.ReadResponse
+ o, l := ib.PlaintextRange()
+ readReq.Offset = int64(o)
+ readReq.Size = int(l)
+ err := f.Read(ctx, &readReq, &readResp)
+ if err != nil {
+ return err
+ }
+ copy(blockData, readResp.Data)
+ copy(blockData[ib.Offset:ib.Offset+ib.Length], req.Data)
+ blockLen := max(len(readResp.Data), int(ib.Offset+ib.Length))
+ blockData = blockData[0:blockLen]
+ } else {
+ blockData = req.Data[0:f.crfs.PlainBS()]
+ }
+ ciphertext := f.crfs.EncryptBlock(blockData)
+ var partReq fuse.WriteRequest
+ var partResp fuse.WriteResponse
+ o, _ := ib.CiphertextRange()
+ partReq.Data = ciphertext
+ partReq.Offset = int64(o)
+ err := f.File.Write(ctx, &partReq, &partResp)
+ if err != nil {
+ fmt.Printf("Write failure: %s\n", err.Error())
+ return err
+ }
+ // Remove written data from the front of the request
+ req.Data = req.Data[len(blockData):len(req.Data)]
+ resp.Size += len(blockData)
+ }
+ return nil
+}
+
+func (f *File) Attr(ctx context.Context, attr *fuse.Attr) error {
+ fmt.Printf("Attr\n")
+ err := f.File.Node.Attr(ctx, attr)
+ if err != nil {
+ return err
+ }
+ attr.Size = f.crfs.PlainSize(attr.Size)
+ return nil
+}