From a9d2e5dd17fc9b3b7a8db302fdc94712b1f39d82 Mon Sep 17 00:00:00 2001
From: unknown <heikki@donna.mysql.fi>
Date: Tue, 1 May 2001 20:57:49 +0300
Subject: log0recv.c	Add checksum to written pages to check that they are
 also read in unchanged buf0buf.h	Add checksum to written pages to check
 that they are also read in unchanged buf0flu.c	Add checksum to written pages
 to check that they are also read in unchanged buf0buf.c	Add checksum
 to written pages to check that they are also read in unchanged

innobase/buf/buf0buf.c:
  Add checksum to written pages to check that they are also read in unchanged
innobase/buf/buf0flu.c:
  Add checksum to written pages to check that they are also read in unchanged
innobase/include/buf0buf.h:
  Add checksum to written pages to check that they are also read in unchanged
innobase/log/log0recv.c:
  Add checksum to written pages to check that they are also read in unchanged
---
 innobase/buf/buf0buf.c | 56 +++++++++++++++++++++++++++++++++++++++++---------
 innobase/buf/buf0flu.c |  6 ++++++
 2 files changed, 52 insertions(+), 10 deletions(-)

(limited to 'innobase/buf')

diff --git a/innobase/buf/buf0buf.c b/innobase/buf/buf0buf.c
index 34fbc5b9f98..0046a3761a6 100644
--- a/innobase/buf/buf0buf.c
+++ b/innobase/buf/buf0buf.c
@@ -204,7 +204,28 @@ ulint		buf_dbg_counter	= 0; /* This is used to insert validation
 ibool		buf_debug_prints = FALSE; /* If this is set TRUE,
 					the program prints info whenever
 					read-ahead or flush occurs */
-					
+
+/************************************************************************
+Calculates a page checksum which is stored to the page when it is written
+to a file. Note that we must be careful to calculate the same value
+on 32-bit and 64-bit architectures. */
+
+ulint
+buf_calc_page_checksum(
+/*===================*/
+		       /* out: checksum */
+	byte*    page) /* in: buffer page */
+{
+  ulint checksum;
+
+  checksum = ut_fold_binary(page, FIL_PAGE_FILE_FLUSH_LSN);
+  + ut_fold_binary(page + FIL_PAGE_DATA, UNIV_PAGE_SIZE - FIL_PAGE_DATA
+		   - FIL_PAGE_END_LSN);
+  checksum = checksum & 0xFFFFFFFF;
+
+  return(checksum);
+}
+
 /************************************************************************
 Initializes a buffer control block when the buf_pool is created. */
 static
@@ -1171,12 +1192,36 @@ buf_page_io_complete(
 	dulint		id;
 	dict_index_t*	index;
 	ulint		io_type;
+	ulint           checksum;
 
 	ut_ad(block);
 
 	io_type = block->io_fix;
 
 	if (io_type == BUF_IO_READ) {
+		checksum = buf_calc_page_checksum(block->frame);
+
+		/* From version 3.23.38 up we store the page checksum
+		   to the 4 upper bytes of the page end lsn field */
+
+		if ((mach_read_from_4(block->frame + FIL_PAGE_LSN + 4)
+		    != mach_read_from_4(block->frame + UNIV_PAGE_SIZE
+					- FIL_PAGE_END_LSN + 4))
+		    || (checksum != mach_read_from_4(block->frame
+                                        + UNIV_PAGE_SIZE
+					- FIL_PAGE_END_LSN)
+			&& mach_read_from_4(block->frame + FIL_PAGE_LSN)
+			    != mach_read_from_4(block->frame
+                                        + UNIV_PAGE_SIZE
+						- FIL_PAGE_END_LSN))) {
+		  fprintf(stderr,
+			  "InnoDB: Database page corruption or a failed\n"
+			  "InnoDB: file read of page %lu.\n", block->offset);
+		  fprintf(stderr,
+			  "InnoDB: You may have to recover from a backup.\n");
+		  exit(1);
+		}
+
 		if (recv_recovery_is_on()) {
 			recv_recover_page(TRUE, block->frame, block->space,
 								block->offset);
@@ -1208,17 +1253,8 @@ buf_page_io_complete(
 		ut_ad(buf_pool->n_pend_reads > 0);
 		buf_pool->n_pend_reads--;
 		buf_pool->n_pages_read++;
-/*		
-		if (0 != ut_dulint_cmp(
-				mach_read_from_8(block->frame + FIL_PAGE_LSN),
-				mach_read_from_8(block->frame + UNIV_PAGE_SIZE
-						- FIL_PAGE_END_LSN))) {
 
-			printf("DB error: file page corrupted!\n");
 
-			ut_error;
-		}
-*/
 		rw_lock_x_unlock_gen(&(block->lock), BUF_IO_READ);
 		rw_lock_x_unlock_gen(&(block->read_lock), BUF_IO_READ);
 
diff --git a/innobase/buf/buf0flu.c b/innobase/buf/buf0flu.c
index 443256cca34..90bdde1ebc6 100644
--- a/innobase/buf/buf0flu.c
+++ b/innobase/buf/buf0flu.c
@@ -222,6 +222,12 @@ buf_flush_write_block_low(
 	mach_write_to_8(block->frame + UNIV_PAGE_SIZE - FIL_PAGE_END_LSN,
 						block->newest_modification);
 
+	/* We overwrite the first 4 bytes of the end lsn field to store
+	a page checksum */
+
+	mach_write_to_4(block->frame + UNIV_PAGE_SIZE - FIL_PAGE_END_LSN,
+			buf_calc_page_checksum(block->frame));
+
 	fil_io(OS_FILE_WRITE | OS_AIO_SIMULATED_WAKE_LATER,
 		FALSE, block->space, block->offset, 0, UNIV_PAGE_SIZE,
 		 			(void*)block->frame, (void*)block);
-- 
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