fs: a much more complete directory hierarchy and everything mostly working in read-only mode.

nostrfs/asyncfile.go

@@ -0,0 +1,56 @@
+package nostrfs
+
+import (
+	"context"
+	"sync/atomic"
+	"syscall"
+
+	"github.com/hanwen/go-fuse/v2/fs"
+	"github.com/hanwen/go-fuse/v2/fuse"
+	"github.com/nbd-wtf/go-nostr"
+)
+
+type AsyncFile struct {
+	fs.Inode
+	ctx     context.Context
+	fetched atomic.Bool
+	data    []byte
+	ts      nostr.Timestamp
+	load    func() ([]byte, nostr.Timestamp)
+}
+
+var (
+	_ = (fs.NodeOpener)((*AsyncFile)(nil))
+	_ = (fs.NodeGetattrer)((*AsyncFile)(nil))
+)
+
+func (af *AsyncFile) Getattr(ctx context.Context, f fs.FileHandle, out *fuse.AttrOut) syscall.Errno {
+	if af.fetched.CompareAndSwap(false, true) {
+		af.data, af.ts = af.load()
+	}
+
+	out.Size = uint64(len(af.data))
+	out.Mtime = uint64(af.ts)
+	return fs.OK
+}
+
+func (af *AsyncFile) Open(ctx context.Context, flags uint32) (fs.FileHandle, uint32, syscall.Errno) {
+	if af.fetched.CompareAndSwap(false, true) {
+		af.data, af.ts = af.load()
+	}
+
+	return nil, fuse.FOPEN_KEEP_CACHE, 0
+}
+
+func (af *AsyncFile) Read(
+	ctx context.Context,
+	f fs.FileHandle,
+	dest []byte,
+	off int64,
+) (fuse.ReadResult, syscall.Errno) {
+	end := int(off) + len(dest)
+	if end > len(af.data) {
+		end = len(af.data)
+	}
+	return fuse.ReadResultData(af.data[off:end]), 0
+}