truncate: Fix bug that caused xfstests generic/030 to fail

The bug was caused by using cipherOff where plainOff should
have been used.
Renamed the symbols for less confusion.

2 files changed, 11 insertions, 10 deletions

diff --git a/main_test.go b/main_test.go
index de433c7..16b9619 100644
--- a/main_test.go
+++ b/main_test.go
@@ -127,22 +127,22 @@ func TestTruncate(t *testing.T) {
 	// Grow to two blocks
 	file.Truncate(7000)
 	if md5fn(fn) != "95d4ec7038e3e4fdbd5f15c34c3f0b34" {
-		t.Fail()
+		t.Errorf("Fail 7000")
 	}
 	// Shrink - needs RMW
 	file.Truncate(6999)
 	if md5fn(fn) != "35fd15873ec6c35380064a41b9b9683b" {
-		t.Fail()
+		t.Errorf("Fail 6999")
 	}
 	// Shrink to one partial block
 	file.Truncate(465)
 	if md5fn(fn) != "a1534d6e98a6b21386456a8f66c55260" {
-		t.Fail()
+		t.Errorf("Fail 465")
 	}
 	// Grow to exactly one block
 	file.Truncate(4096)
 	if md5fn(fn) != "620f0b67a91f7f74151bc5be745b7110" {
-		t.Fail()
+		t.Errorf("Fail 4096")
 	}
 }
 
diff --git a/pathfs_frontend/file.go b/pathfs_frontend/file.go
index b328b61..697d58d 100644
--- a/pathfs_frontend/file.go
+++ b/pathfs_frontend/file.go
@@ -270,29 +270,30 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
 			}
 		}
 		return fuse.OK
-		// File shrinks
 	} else {
+		// File shrinks
 		blockNo := f.cfs.BlockNoPlainOff(newSize)
-		lastBlockOff := blockNo * f.cfs.CipherBS()
-		lastBlockLen := newSize - blockNo * f.cfs.PlainBS()
+		cipherOff := blockNo * f.cfs.CipherBS()
+		plainOff := blockNo * f.cfs.PlainBS()
+		lastBlockLen := newSize - plainOff
 		var data []byte
 		if lastBlockLen > 0 {
 			var status fuse.Status
-			data, status = f.doRead(lastBlockOff, lastBlockLen)
+			data, status = f.doRead(plainOff, lastBlockLen)
 			if status != fuse.OK {
 				cryptfs.Warn.Printf("shrink doRead returned error: %v", err)
 				return status
 			}
 		}
 		f.lock.Lock()
-		err = syscall.Ftruncate(int(f.fd.Fd()), int64(lastBlockOff))
+		err = syscall.Ftruncate(int(f.fd.Fd()), int64(cipherOff))
 		f.lock.Unlock()
 		if err != nil {
 			cryptfs.Warn.Printf("shrink Ftruncate returned error: %v", err)
 			return fuse.ToStatus(err)
 		}
 		if lastBlockLen > 0 {
-			_, status := f.doWrite(data, int64(lastBlockOff))
+			_, status := f.doWrite(data, int64(plainOff))
 			return status
 		}
 		return fuse.OK