7329: Fix infinite loop in Compare when reading an empty file (whether

or not the buf we're comparing is also empty).

diff --git a/services/keepstore/volume_unix.go b/services/keepstore/volume_unix.go
index bc6a6e08ce175b2eab67b3beeefbb7636bcb8a14..6c0f5c4e978d995b5c9308f52d5d2414045d64fc 100644 (file)
--- a/services/keepstore/volume_unix.go
+++ b/services/keepstore/volume_unix.go
@@ -122,6 +122,13 @@ func (v *UnixVolume) Compare(loc string, expect []byte) error {
        bufLen := 1 << 20
        if int64(bufLen) > stat.Size() {
                bufLen = int(stat.Size())
+               if bufLen < 1 {
+                       // len(buf)==0 would prevent us from handling
+                       // empty files the same way as non-empty
+                       // files, because reading 0 bytes at a time
+                       // never reaches EOF.
+                       bufLen = 1
+               }
        }
        cmp := expect
        buf := make([]byte, bufLen)
@@ -143,11 +150,6 @@ func (v *UnixVolume) Compare(loc string, expect []byte) error {
                                return nil
                        } else if err != nil {
                                return err
-                       } else if len(expect) == 0 && n == 0 && bytes.Compare(buf, expect) == 0 {
-                               // When reading an empty block, EOF is not returned. Probably a Go issue.
-                               // This is resulting in an infinite loop resulting in #7329
-                               // Handle empty block scenario explicitly until the EOF issue is resolved.
-                               return nil
                        }
                }
        })