diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/include/storage/bufpage.h | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/src/include/storage/bufpage.h b/src/include/storage/bufpage.h index 5dbabb31684..5f8012e0ed6 100644 --- a/src/include/storage/bufpage.h +++ b/src/include/storage/bufpage.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/storage/bufpage.h,v 1.57 2003/12/11 21:21:55 tgl Exp $ + * $PostgreSQL: pgsql/src/include/storage/bufpage.h,v 1.58 2004/06/05 17:42:46 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -283,13 +283,14 @@ typedef PageHeaderData *PageHeader; * Since offset numbers are 1-based, this is also the number * of items on the page. * - * NOTE: to ensure sane behavior if the page is not initialized - * (pd_lower == 0), cast the unsigned values to int before dividing. - * That way we get -1 or so, not a huge positive number... + * NOTE: if the page is not initialized (pd_lower == 0), we must + * return zero to ensure sane behavior. Accept double evaluation + * of the argument so that we can ensure this. */ #define PageGetMaxOffsetNumber(page) \ - (((int) (((PageHeader) (page))->pd_lower - SizeOfPageHeaderData)) \ - / ((int) sizeof(ItemIdData))) + (((PageHeader) (page))->pd_lower <= SizeOfPageHeaderData ? 0 : \ + ((((PageHeader) (page))->pd_lower - SizeOfPageHeaderData) \ + / sizeof(ItemIdData))) #define PageGetLSN(page) \ (((PageHeader) (page))->pd_lsn) |