fusefronted: move Create() and Open() to new file

And deduplicate the code a little.

3 files changed, 125 insertions, 118 deletions

diff --git a/internal/fusefrontend/file.go b/internal/fusefrontend/file.go
index 98e5802..33a3cbe 100644
--- a/internal/fusefrontend/file.go
+++ b/internal/fusefrontend/file.go
@@ -53,18 +53,31 @@ type File struct {
 	rootNode *RootNode
 }
 
-// NewFile returns a new go-fuse File instance.
-func NewFile(fd *os.File, rn *RootNode, st *syscall.Stat_t) *File {
+// NewFile returns a new go-fuse File instance based on an already-open file
+// descriptor. NewFile internally calls Fstat() on the fd. The resulting Stat_t
+// is returned because node.Create() needs it.
+//
+// `cName` is only used for error logging and may be left blank.
+func NewFile(fd int, cName string, rn *RootNode) (f *File, st *syscall.Stat_t, errno syscall.Errno) {
+	// Need device number and inode number for openfiletable locking
+	st = &syscall.Stat_t{}
+	if err := syscall.Fstat(fd, st); err != nil {
+		errno = fs.ToErrno(err)
+		return
+	}
 	qi := inomap.QInoFromStat(st)
 	e := openfiletable.Register(qi)
 
-	return &File{
-		fd:             fd,
+	osFile := os.NewFile(uintptr(fd), cName)
+
+	f = &File{
+		fd:             osFile,
 		contentEnc:     rn.contentEnc,
 		qIno:           qi,
 		fileTableEntry: e,
 		rootNode:       rn,
 	}
+	return f, st, 0
 }
 
 // intFd - return the backing file descriptor as an integer.
diff --git a/internal/fusefrontend/node.go b/internal/fusefrontend/node.go
index 2e5d370..5a7edc8 100644
--- a/internal/fusefrontend/node.go
+++ b/internal/fusefrontend/node.go
@@ -2,7 +2,6 @@ package fusefrontend
 
 import (
 	"context"
-	"os"
 	"syscall"
 
 	"golang.org/x/sys/unix"
@@ -78,69 +77,6 @@ func (n *Node) Getattr(ctx context.Context, f fs.FileHandle, out *fuse.AttrOut)
 	return 0
 }
 
-// Create - FUSE call. Creates a new file.
-//
-// Symlink-safe through the use of Openat().
-func (n *Node) Create(ctx context.Context, name string, flags uint32, mode uint32, out *fuse.EntryOut) (inode *fs.Inode, fh fs.FileHandle, fuseFlags uint32, errno syscall.Errno) {
-	dirfd, cName, errno := n.prepareAtSyscall(name)
-	if errno != 0 {
-		return
-	}
-	defer syscall.Close(dirfd)
-
-	var err error
-	fd := -1
-	// Make sure context is nil if we don't want to preserve the owner
-	rn := n.rootNode()
-	if !rn.args.PreserveOwner {
-		ctx = nil
-	}
-	newFlags := rn.mangleOpenFlags(flags)
-	// Handle long file name
-	ctx2 := toFuseCtx(ctx)
-	if !rn.args.PlaintextNames && nametransform.IsLongContent(cName) {
-		// Create ".name"
-		err = rn.nameTransform.WriteLongNameAt(dirfd, cName, name)
-		if err != nil {
-			return nil, nil, 0, fs.ToErrno(err)
-		}
-		// Create content
-		fd, err = syscallcompat.OpenatUser(dirfd, cName, newFlags|syscall.O_CREAT|syscall.O_EXCL, mode, ctx2)
-		if err != nil {
-			nametransform.DeleteLongNameAt(dirfd, cName)
-		}
-	} else {
-		// Create content, normal (short) file name
-		fd, err = syscallcompat.OpenatUser(dirfd, cName, newFlags|syscall.O_CREAT|syscall.O_EXCL, mode, ctx2)
-	}
-	if err != nil {
-		// xfstests generic/488 triggers this
-		if err == syscall.EMFILE {
-			var lim syscall.Rlimit
-			syscall.Getrlimit(syscall.RLIMIT_NOFILE, &lim)
-			tlog.Warn.Printf("Create %q: too many open files. Current \"ulimit -n\": %d", cName, lim.Cur)
-		}
-		return nil, nil, 0, fs.ToErrno(err)
-	}
-
-	// Get device number and inode number into `st`
-	var st syscall.Stat_t
-	err = syscall.Fstat(fd, &st)
-	if err != nil {
-		errno = fs.ToErrno(err)
-		return
-	}
-	// Save original stat values before newChild() translates the inode number.
-	// For an open fd, we assume the inode number cannot change behind our back,
-	// even in `-sharedstorage` mode.
-	origSt := st
-
-	ch := n.newChild(ctx, &st, out)
-
-	f := os.NewFile(uintptr(fd), cName)
-	return ch, NewFile(f, rn, &origSt), 0, 0
-}
-
 // Unlink - FUSE call. Delete a file.
 //
 // Symlink-safe through use of Unlinkat().
@@ -179,56 +115,6 @@ func (n *Node) Readlink(ctx context.Context) (out []byte, errno syscall.Errno) {
 	return n.readlink(dirfd, cName)
 }
 
-// Open - FUSE call. Open already-existing file.
-//
-// Symlink-safe through Openat().
-func (n *Node) Open(ctx context.Context, flags uint32) (fh fs.FileHandle, fuseFlags uint32, errno syscall.Errno) {
-	dirfd, cName, errno := n.prepareAtSyscall("")
-	if errno != 0 {
-		return
-	}
-	defer syscall.Close(dirfd)
-
-	rn := n.rootNode()
-	newFlags := rn.mangleOpenFlags(flags)
-	// Taking this lock makes sure we don't race openWriteOnlyFile()
-	rn.openWriteOnlyLock.RLock()
-	defer rn.openWriteOnlyLock.RUnlock()
-
-	if rn.args.KernelCache {
-		fuseFlags = fuse.FOPEN_KEEP_CACHE
-	}
-
-	// Open backing file
-	fd, err := syscallcompat.Openat(dirfd, cName, newFlags, 0)
-	// Handle a few specific errors
-	if err != nil {
-		if err == syscall.EMFILE {
-			var lim syscall.Rlimit
-			syscall.Getrlimit(syscall.RLIMIT_NOFILE, &lim)
-			tlog.Warn.Printf("Open %q: too many open files. Current \"ulimit -n\": %d", cName, lim.Cur)
-		}
-		if err == syscall.EACCES && (int(flags)&syscall.O_ACCMODE) == syscall.O_WRONLY {
-			fd, err = rn.openWriteOnlyFile(dirfd, cName, newFlags)
-		}
-	}
-	// Could not handle the error? Bail out
-	if err != nil {
-		errno = fs.ToErrno(err)
-		return
-	}
-
-	var st syscall.Stat_t
-	err = syscall.Fstat(fd, &st)
-	if err != nil {
-		errno = fs.ToErrno(err)
-		return
-	}
-	f := os.NewFile(uintptr(fd), cName)
-	fh = NewFile(f, rn, &st)
-	return
-}
-
 // Setattr - FUSE call. Called for chmod, truncate, utimens, ...
 func (n *Node) Setattr(ctx context.Context, f fs.FileHandle, in *fuse.SetAttrIn, out *fuse.AttrOut) (errno syscall.Errno) {
 	// Use the fd if the kernel gave us one
diff --git a/internal/fusefrontend/node_open_create.go b/internal/fusefrontend/node_open_create.go
new file mode 100644
index 0000000..8b31932
--- /dev/null
+++ b/internal/fusefrontend/node_open_create.go
@@ -0,0 +1,108 @@
+package fusefrontend
+
+import (
+	"context"
+	"syscall"
+
+	"github.com/hanwen/go-fuse/v2/fs"
+	"github.com/hanwen/go-fuse/v2/fuse"
+
+	"github.com/rfjakob/gocryptfs/internal/nametransform"
+	"github.com/rfjakob/gocryptfs/internal/syscallcompat"
+	"github.com/rfjakob/gocryptfs/internal/tlog"
+)
+
+// Open - FUSE call. Open already-existing file.
+//
+// Symlink-safe through Openat().
+func (n *Node) Open(ctx context.Context, flags uint32) (fh fs.FileHandle, fuseFlags uint32, errno syscall.Errno) {
+	dirfd, cName, errno := n.prepareAtSyscall("")
+	if errno != 0 {
+		return
+	}
+	defer syscall.Close(dirfd)
+
+	rn := n.rootNode()
+	newFlags := rn.mangleOpenFlags(flags)
+	// Taking this lock makes sure we don't race openWriteOnlyFile()
+	rn.openWriteOnlyLock.RLock()
+	defer rn.openWriteOnlyLock.RUnlock()
+
+	if rn.args.KernelCache {
+		fuseFlags = fuse.FOPEN_KEEP_CACHE
+	}
+
+	// Open backing file
+	fd, err := syscallcompat.Openat(dirfd, cName, newFlags, 0)
+	// Handle a few specific errors
+	if err != nil {
+		if err == syscall.EMFILE {
+			var lim syscall.Rlimit
+			syscall.Getrlimit(syscall.RLIMIT_NOFILE, &lim)
+			tlog.Warn.Printf("Open %q: too many open files. Current \"ulimit -n\": %d", cName, lim.Cur)
+		}
+		if err == syscall.EACCES && (int(flags)&syscall.O_ACCMODE) == syscall.O_WRONLY {
+			fd, err = rn.openWriteOnlyFile(dirfd, cName, newFlags)
+		}
+	}
+	// Could not handle the error? Bail out
+	if err != nil {
+		errno = fs.ToErrno(err)
+		return
+	}
+	fh, _, errno = NewFile(fd, cName, rn)
+	return fh, fuseFlags, errno
+}
+
+// Create - FUSE call. Creates a new file.
+//
+// Symlink-safe through the use of Openat().
+func (n *Node) Create(ctx context.Context, name string, flags uint32, mode uint32, out *fuse.EntryOut) (inode *fs.Inode, fh fs.FileHandle, fuseFlags uint32, errno syscall.Errno) {
+	dirfd, cName, errno := n.prepareAtSyscall(name)
+	if errno != 0 {
+		return
+	}
+	defer syscall.Close(dirfd)
+
+	var err error
+	fd := -1
+	// Make sure context is nil if we don't want to preserve the owner
+	rn := n.rootNode()
+	if !rn.args.PreserveOwner {
+		ctx = nil
+	}
+	newFlags := rn.mangleOpenFlags(flags)
+	// Handle long file name
+	ctx2 := toFuseCtx(ctx)
+	if !rn.args.PlaintextNames && nametransform.IsLongContent(cName) {
+		// Create ".name"
+		err = rn.nameTransform.WriteLongNameAt(dirfd, cName, name)
+		if err != nil {
+			return nil, nil, 0, fs.ToErrno(err)
+		}
+		// Create content
+		fd, err = syscallcompat.OpenatUser(dirfd, cName, newFlags|syscall.O_CREAT|syscall.O_EXCL, mode, ctx2)
+		if err != nil {
+			nametransform.DeleteLongNameAt(dirfd, cName)
+		}
+	} else {
+		// Create content, normal (short) file name
+		fd, err = syscallcompat.OpenatUser(dirfd, cName, newFlags|syscall.O_CREAT|syscall.O_EXCL, mode, ctx2)
+	}
+	if err != nil {
+		// xfstests generic/488 triggers this
+		if err == syscall.EMFILE {
+			var lim syscall.Rlimit
+			syscall.Getrlimit(syscall.RLIMIT_NOFILE, &lim)
+			tlog.Warn.Printf("Create %q: too many open files. Current \"ulimit -n\": %d", cName, lim.Cur)
+		}
+		return nil, nil, 0, fs.ToErrno(err)
+	}
+
+	fh, st, errno := NewFile(fd, cName, rn)
+	if errno != 0 {
+		return
+	}
+	inode = n.newChild(ctx, st, out)
+	return inode, fh, fuseFlags, errno
+}