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authorJakob Unterwurzacher2020-08-09 22:11:46 +0200
committerJakob Unterwurzacher2020-08-09 22:11:46 +0200
commit6d4f1a6888cafd218cb97bd11de6a7553d9bc8f1 (patch)
tree7b48b6e97c4c73a4e0e9dce3456768526c46da65 /internal/fusefrontend_reverse/virtualnode.go
parent527609266386890fe1657c225c643ca448bcd71d (diff)
v2api/reverse: implement Read
Diffstat (limited to 'internal/fusefrontend_reverse/virtualnode.go')
-rw-r--r--internal/fusefrontend_reverse/virtualnode.go117
1 files changed, 117 insertions, 0 deletions
diff --git a/internal/fusefrontend_reverse/virtualnode.go b/internal/fusefrontend_reverse/virtualnode.go
new file mode 100644
index 0000000..2ee9548
--- /dev/null
+++ b/internal/fusefrontend_reverse/virtualnode.go
@@ -0,0 +1,117 @@
+package fusefrontend_reverse
+
+import (
+ "context"
+ "log"
+ "syscall"
+
+ "github.com/hanwen/go-fuse/v2/fs"
+ "github.com/hanwen/go-fuse/v2/fuse"
+
+ "github.com/rfjakob/gocryptfs/internal/configfile"
+ "github.com/rfjakob/gocryptfs/internal/inomap"
+ "github.com/rfjakob/gocryptfs/internal/nametransform"
+)
+
+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
+)
+
+type fileType int
+
+// Values returned by lookupFileType
+const (
+ // A real file/directory/symlink in the backing plaintext directory
+ typeReal fileType = iota
+ // A DirIV (gocryptfs.diriv) file
+ typeDiriv
+ // A gocryptfs.longname.*.name file for a file with a long name
+ typeName
+ // The config file gocryptfs.conf
+ typeConfig
+)
+
+// lookupFileType returns the type of child file name
+// (one of the fileType constants above). Called from Lookup().
+func (n *Node) lookupFileType(cName string) fileType {
+ rn := n.rootNode()
+ // In -plaintextname mode, neither diriv nor longname files exist.
+ if !rn.args.PlaintextNames {
+ // Is it a gocryptfs.diriv file?
+ if cName == nametransform.DirIVFilename {
+ return typeDiriv
+ }
+ // Is it a gocryptfs.longname.*.name file?
+ if t := nametransform.NameType(cName); t == nametransform.LongNameFilename {
+ return typeName
+ }
+ }
+ // gocryptfs.conf in the root directory. This is passed through to
+ // .gocryptfs.reverse.conf in the backing plaintext directory.
+ if n.isRoot() && !rn.args.ConfigCustom && cName == configfile.ConfDefaultName {
+ return typeConfig
+ }
+ return typeReal
+}
+
+// VirtualMemNode is an in-memory node that does not have a representation
+// on disk.
+type VirtualMemNode struct {
+ fs.Inode
+
+ // file content
+ content []byte
+ // attributes for Getattr()
+ attr fuse.Attr
+}
+
+// newVirtualMemNode 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" (file descriptor).
+// For a "gocryptfs.diriv" file, you would use the parent directory as
+// "parentFile".
+func (n *Node) newVirtualMemNode(content []byte, parentStat *syscall.Stat_t, inoTag uint8) (vf *VirtualMemNode, errno syscall.Errno) {
+ if inoTag == 0 {
+ log.Panicf("BUG: inoTag for virtual file is zero - this will cause ino collisions!")
+ }
+
+ // Adjust inode number and size
+ rn := n.rootNode()
+ st := parentStat
+ q := inomap.NewQIno(uint64(st.Dev), inoTag, uint64(st.Ino))
+ st.Ino = rn.inoMap.Translate(q)
+ st.Size = int64(len(content))
+ st.Mode = virtualFileMode
+ st.Nlink = 1
+ var a fuse.Attr
+ a.FromStat(st)
+
+ vf = &VirtualMemNode{content: content, attr: a}
+ return
+}
+
+// Open - FUSE call
+func (f *VirtualMemNode) Open(ctx context.Context, flags uint32) (fh fs.FileHandle, fuseFlags uint32, errno syscall.Errno) {
+ return nil, fuse.FOPEN_KEEP_CACHE, 0
+}
+
+// GetAttr - FUSE call
+func (f *VirtualMemNode) Getattr(ctx context.Context, fh fs.FileHandle, out *fuse.AttrOut) syscall.Errno {
+ out.Attr = f.attr
+ return 0
+}
+
+// Read - FUSE call
+func (f *VirtualMemNode) Read(ctx context.Context, fh fs.FileHandle, dest []byte, off int64) (fuse.ReadResult, syscall.Errno) {
+ end := int(off) + len(dest)
+ if end > len(f.content) {
+ end = len(f.content)
+ }
+ return fuse.ReadResultData(f.content[off:end]), 0
+}