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-rw-r--r--internal/fusefrontend_reverse_v1api/virtualfile.go110
1 files changed, 110 insertions, 0 deletions
diff --git a/internal/fusefrontend_reverse_v1api/virtualfile.go b/internal/fusefrontend_reverse_v1api/virtualfile.go
new file mode 100644
index 0000000..f258e7f
--- /dev/null
+++ b/internal/fusefrontend_reverse_v1api/virtualfile.go
@@ -0,0 +1,110 @@
+package fusefrontend_reverse
+
+import (
+ "log"
+ "path/filepath"
+ "syscall"
+
+ "golang.org/x/sys/unix"
+
+ "github.com/hanwen/go-fuse/v2/fuse"
+ "github.com/hanwen/go-fuse/v2/fuse/nodefs"
+
+ "github.com/rfjakob/gocryptfs/internal/inomap"
+ "github.com/rfjakob/gocryptfs/internal/nametransform"
+ "github.com/rfjakob/gocryptfs/internal/pathiv"
+ "github.com/rfjakob/gocryptfs/internal/syscallcompat"
+ "github.com/rfjakob/gocryptfs/internal/tlog"
+)
+
+const (
+ // virtualFileMode is the mode to use for virtual files (gocryptfs.diriv and
+ // *.name). They are always readable, as stated in func Access
+ virtualFileMode = syscall.S_IFREG | 0444
+ // We use inomap's `Tag` feature to generate unique inode numbers for
+ // virtual files. These are the tags we use.
+ inoTagDirIV = 1
+ inoTagNameFile = 2
+)
+
+func (rfs *ReverseFS) newDirIVFile(cRelPath string) (nodefs.File, fuse.Status) {
+ cDir := nametransform.Dir(cRelPath)
+ dir, err := rfs.decryptPath(cDir)
+ if err != nil {
+ return nil, fuse.ToStatus(err)
+ }
+ iv := pathiv.Derive(cDir, pathiv.PurposeDirIV)
+ return rfs.newVirtualFile(iv, rfs.args.Cipherdir, dir, inoTagDirIV)
+}
+
+type virtualFile struct {
+ // Embed nodefs.defaultFile for a ENOSYS implementation of all methods
+ nodefs.File
+ // pointer to parent filesystem
+ rfs *ReverseFS
+ // file content
+ content []byte
+ // backing directory
+ cipherdir string
+ // path to a parent file (relative to cipherdir)
+ parentFile string
+ // inomap `Tag`.
+ // Depending on the file type, either `inoTagDirIV` or `inoTagNameFile`.
+ inoTag uint8
+}
+
+// newVirtualFile creates a new in-memory file that does not have a representation
+// on disk. "content" is the file content. Timestamps and file owner are copied
+// from "parentFile" (plaintext path relative to "cipherdir").
+// For a "gocryptfs.diriv" file, you would use the parent directory as
+// "parentFile".
+func (rfs *ReverseFS) newVirtualFile(content []byte, cipherdir string, parentFile string, inoTag uint8) (nodefs.File, fuse.Status) {
+ if inoTag == 0 {
+ log.Panicf("BUG: inoTag for virtual file is zero - this will cause ino collisions!")
+ }
+ return &virtualFile{
+ File: nodefs.NewDefaultFile(),
+ rfs: rfs,
+ content: content,
+ cipherdir: cipherdir,
+ parentFile: parentFile,
+ inoTag: inoTag,
+ }, fuse.OK
+}
+
+// Read - FUSE call
+func (f *virtualFile) Read(buf []byte, off int64) (resultData fuse.ReadResult, status fuse.Status) {
+ if off >= int64(len(f.content)) {
+ return nil, fuse.OK
+ }
+ end := int(off) + len(buf)
+ if end > len(f.content) {
+ end = len(f.content)
+ }
+ return fuse.ReadResultData(f.content[off:end]), fuse.OK
+}
+
+// GetAttr - FUSE call
+func (f *virtualFile) GetAttr(a *fuse.Attr) fuse.Status {
+ dir := filepath.Dir(f.parentFile)
+ dirfd, err := syscallcompat.OpenDirNofollow(f.cipherdir, dir)
+ if err != nil {
+ return fuse.ToStatus(err)
+ }
+ defer syscall.Close(dirfd)
+ name := filepath.Base(f.parentFile)
+ var st2 unix.Stat_t
+ err = syscallcompat.Fstatat(dirfd, name, &st2, unix.AT_SYMLINK_NOFOLLOW)
+ if err != nil {
+ tlog.Debug.Printf("GetAttr: Fstatat %q: %v\n", f.parentFile, err)
+ return fuse.ToStatus(err)
+ }
+ st := syscallcompat.Unix2syscall(st2)
+ q := inomap.NewQIno(uint64(st.Dev), f.inoTag, uint64(st.Ino))
+ st.Ino = f.rfs.inoMap.Translate(q)
+ st.Size = int64(len(f.content))
+ st.Mode = virtualFileMode
+ st.Nlink = 1
+ a.FromStat(&st)
+ return fuse.OK
+}