.

wcfs/wcfs.go

@@ -483,6 +483,7 @@ import (
 	"fmt"
 	"io"
 	stdlog "log"
+	"math"
 	"os"
 	"runtime"
 	"sort"
@@ -505,6 +506,7 @@ import (
 	"lab.nexedi.com/kirr/neo/go/zodb/btree"
 	_ "lab.nexedi.com/kirr/neo/go/zodb/wks"
 
+	"github.com/johncgriffin/overflow"
 	"github.com/hanwen/go-fuse/fuse"
 	"github.com/hanwen/go-fuse/fuse/nodefs"
 	"github.com/pkg/errors"
@@ -1155,7 +1157,10 @@ func (f *BigFile) Read(_ nodefs.File, dest []byte, off int64, fctx *fuse.Context
 	defer f.head.zheadMu.RUnlock()
 
 	// cap read request to file size
-	end := off + int64(len(dest))		// XXX overflow?
+	end, ok := overflow.Add64(off, int64(len(dest)))
+	if !ok {
+		end = math.MaxInt64 // cap read request till max possible file size
+	}
 	if end > f.size {
 		end = f.size
 	}