Add const qualifiers to bufpage.h

This makes use of the new PageData type.

PageGetSpecialPointer() had to be turned back into a macro, because it
is used in a way that sometimes it takes const and returns const and
sometimes takes non-const and returns non-const.

Discussion: https://www.postgresql.org/message-id/flat/692ee0da-49da-4d32-8dca-da224cc2800e@eisentraut.org

1 files changed, 16 insertions, 16 deletions

diff --git a/src/backend/storage/page/bufpage.c b/src/backend/storage/page/bufpage.c
index 30d059c88b5..a931cdba151 100644
--- a/src/backend/storage/page/bufpage.c
+++ b/src/backend/storage/page/bufpage.c
@@ -85,9 +85,9 @@ PageInit(Page page, Size pageSize, Size specialSize)
  * to pgstat.
  */
 bool
-PageIsVerifiedExtended(Page page, BlockNumber blkno, int flags)
+PageIsVerifiedExtended(const PageData *page, BlockNumber blkno, int flags)
 {
-	PageHeader	p = (PageHeader) page;
+	const PageHeaderData *p = (const PageHeaderData *) page;
 	size_t	   *pagebytes;
 	bool		checksum_failure = false;
 	bool		header_sane = false;
@@ -351,7 +351,7 @@ PageAddItemExtended(Page page,
  *		The returned page is not initialized at all; caller must do that.
  */
 Page
-PageGetTempPage(Page page)
+PageGetTempPage(const PageData *page)
 {
 	Size		pageSize;
 	Page		temp;
@@ -368,7 +368,7 @@ PageGetTempPage(Page page)
  *		The page is initialized by copying the contents of the given page.
  */
 Page
-PageGetTempPageCopy(Page page)
+PageGetTempPageCopy(const PageData *page)
 {
 	Size		pageSize;
 	Page		temp;
@@ -388,7 +388,7 @@ PageGetTempPageCopy(Page page)
  *		given page, and the special space is copied from the given page.
  */
 Page
-PageGetTempPageCopySpecial(Page page)
+PageGetTempPageCopySpecial(const PageData *page)
 {
 	Size		pageSize;
 	Page		temp;
@@ -893,16 +893,16 @@ PageTruncateLinePointerArray(Page page)
  * PageGetHeapFreeSpace on heap pages.
  */
 Size
-PageGetFreeSpace(Page page)
+PageGetFreeSpace(const PageData *page)
 {
+	const PageHeaderData *phdr = (const PageHeaderData *) page;
 	int			space;
 
 	/*
 	 * Use signed arithmetic here so that we behave sensibly if pd_lower >
 	 * pd_upper.
 	 */
-	space = (int) ((PageHeader) page)->pd_upper -
-		(int) ((PageHeader) page)->pd_lower;
+	space = (int) phdr->pd_upper - (int) phdr->pd_lower;
 
 	if (space < (int) sizeof(ItemIdData))
 		return 0;
@@ -920,16 +920,16 @@ PageGetFreeSpace(Page page)
  * PageGetHeapFreeSpace on heap pages.
  */
 Size
-PageGetFreeSpaceForMultipleTuples(Page page, int ntups)
+PageGetFreeSpaceForMultipleTuples(const PageData *page, int ntups)
 {
+	const PageHeaderData *phdr = (const PageHeaderData *) page;
 	int			space;
 
 	/*
 	 * Use signed arithmetic here so that we behave sensibly if pd_lower >
 	 * pd_upper.
 	 */
-	space = (int) ((PageHeader) page)->pd_upper -
-		(int) ((PageHeader) page)->pd_lower;
+	space = (int) phdr->pd_upper - (int) phdr->pd_lower;
 
 	if (space < (int) (ntups * sizeof(ItemIdData)))
 		return 0;
@@ -944,16 +944,16 @@ PageGetFreeSpaceForMultipleTuples(Page page, int ntups)
  *		without any consideration for adding/removing line pointers.
  */
 Size
-PageGetExactFreeSpace(Page page)
+PageGetExactFreeSpace(const PageData *page)
 {
+	const PageHeaderData *phdr = (const PageHeaderData *) page;
 	int			space;
 
 	/*
 	 * Use signed arithmetic here so that we behave sensibly if pd_lower >
 	 * pd_upper.
 	 */
-	space = (int) ((PageHeader) page)->pd_upper -
-		(int) ((PageHeader) page)->pd_lower;
+	space = (int) phdr->pd_upper - (int) phdr->pd_lower;
 
 	if (space < 0)
 		return 0;
@@ -977,7 +977,7 @@ PageGetExactFreeSpace(Page page)
  * on the number of line pointers, we make this extra check.)
  */
 Size
-PageGetHeapFreeSpace(Page page)
+PageGetHeapFreeSpace(const PageData *page)
 {
 	Size		space;
 
@@ -1001,7 +1001,7 @@ PageGetHeapFreeSpace(Page page)
 				 */
 				for (offnum = FirstOffsetNumber; offnum <= nline; offnum = OffsetNumberNext(offnum))
 				{
-					ItemId		lp = PageGetItemId(page, offnum);
+					ItemId		lp = PageGetItemId(unconstify(PageData *, page), offnum);
 
 					if (!ItemIdIsUsed(lp))
 						break;