Handle the case of io.EOF when reading the second meta page

Signed-off-by: Benjamin Wang <wachao@vmware.com>

db.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"hash/fnv"
+	"io"
 	"os"
 	"runtime"
 	"sort"
@@ -377,7 +378,8 @@ func (db *DB) getPageSizeFromSecondMeta() (int, bool, error) {
 		if pos >= fileSize-1024 {
 			break
 		}
-		if bw, err := db.file.ReadAt(buf[:], pos); err == nil && bw == len(buf) {
+		bw, err := db.file.ReadAt(buf[:], pos)
+		if (err == nil && bw == len(buf)) || (err == io.EOF && int64(bw) == (fileSize-pos)) {
 			metaCanRead = true
 			if m := db.pageInBuffer(buf[:], 0).meta(); m.validate() == nil {
 				return int(m.pageSize), metaCanRead, nil

db_test.go

@@ -233,10 +233,9 @@ func TestOpen_ReadPageSize_FromMeta1_OS(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	// Reopen data file.
 	// Reopen data file.
 	db = btesting.MustOpenDBWithOption(t, path, nil)
-	require.Equalf(t, os.Getpagesize(), db.Info().PageSize, "The page size is expected to be %d, but actually is %d", os.Getpagesize(), db.Info().PageSize)
+	require.Equalf(t, os.Getpagesize(), db.Info().PageSize, "check page size failed")
 }
 
 // Ensure that it can read the page size from the second meta page if the first one is invalid.
@@ -257,17 +256,18 @@ func TestOpen_ReadPageSize_FromMeta1_Given(t *testing.T) {
 		require.NoError(t, err)
 
 		// Rewrite meta pages.
+		if i%3 == 0 {
+			t.Logf("#%d: Intentionally corrupt the first meta page for pageSize %d", i, givenPageSize)
 			meta0 := (*meta)(unsafe.Pointer(&buf[pageHeaderSize]))
 			meta0.pgid++
 			err = os.WriteFile(path, buf, 0666)
 			require.NoError(t, err)
+		}
 
 		// Reopen data file.
 		db = btesting.MustOpenDBWithOption(t, path, nil)
-		require.Equalf(t, givenPageSize, db.Info().PageSize, "The page size is expected to be %d, but actually is %d", givenPageSize, db.Info().PageSize)
-		// The db.DB is set to nil in MustClose(), so the testing Cleanup
-		// will do nothing when executing PostTestCleanup().
-		db.PostTestCleanup()
+		require.Equalf(t, givenPageSize, db.Info().PageSize, "check page size failed")
+		db.MustClose()
 	}
 }