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diff --git a/storage/innobase/buf/buf0checksum.cc b/storage/innobase/buf/buf0checksum.cc
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+++ b/storage/innobase/buf/buf0checksum.cc
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+/*****************************************************************************
+
+Copyright (c) 1995, 2016, Oracle and/or its affiliates. All Rights Reserved.
+Copyright (c) 2017, 2019, MariaDB Corporation.
+
+This program is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation; version 2 of the License.
+
+This program is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA
+
+*****************************************************************************/
+
+/**************************************************//**
+@file buf/buf0checksum.cc
+Buffer pool checksum functions, also linked from /extra/innochecksum.cc
+
+Created Aug 11, 2011 Vasil Dimov
+*******************************************************/
+
+#include "buf0checksum.h"
+#include "fil0fil.h"
+#include "ut0crc32.h"
+#include "ut0rnd.h"
+
+#ifndef UNIV_INNOCHECKSUM
+#include "srv0srv.h"
+#endif /* !UNIV_INNOCHECKSUM */
+
+/** the value of innodb_checksum_algorithm */
+ulong	srv_checksum_algorithm;
+
+/** Calculate the CRC32 checksum of a page. The value is stored to the page
+when it is written to a file and also checked for a match when reading from
+the file. Note that we must be careful to calculate the same value on all
+architectures.
+@param[in]	page			buffer page (srv_page_size bytes)
+@return	CRC-32C */
+uint32_t buf_calc_page_crc32(const byte* page)
+{
+	/* Note: innodb_checksum_algorithm=crc32 could and should have
+	included the entire page in the checksum, and CRC-32 values
+	should be combined with the CRC-32 function, not with
+	exclusive OR. We stick to the current algorithm in order to
+	remain compatible with old data files. */
+	return ut_crc32(page + FIL_PAGE_OFFSET,
+			FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION
+			- FIL_PAGE_OFFSET)
+		^ ut_crc32(page + FIL_PAGE_DATA,
+			   srv_page_size
+			   - (FIL_PAGE_DATA + FIL_PAGE_END_LSN_OLD_CHKSUM));
+}
+
+/** Calculate a 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.
+@param[in]	page	file page (srv_page_size bytes)
+@return checksum */
+uint32_t
+buf_calc_page_new_checksum(const byte* page)
+{
+	ulint checksum;
+
+	/* Since the field FIL_PAGE_FILE_FLUSH_LSN, and in versions <= 4.1.x
+	FIL_PAGE_ARCH_LOG_NO_OR_SPACE_ID, are written outside the buffer pool
+	to the first pages of data files, we have to skip them in the page
+	checksum calculation.
+	We must also skip the field FIL_PAGE_SPACE_OR_CHKSUM where the
+	checksum is stored, and also the last 8 bytes of page because
+	there we store the old formula checksum. */
+
+	checksum = ut_fold_binary(page + FIL_PAGE_OFFSET,
+				  FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION
+				  - FIL_PAGE_OFFSET)
+		+ ut_fold_binary(page + FIL_PAGE_DATA,
+				 srv_page_size - FIL_PAGE_DATA
+				 - FIL_PAGE_END_LSN_OLD_CHKSUM);
+	return(static_cast<uint32_t>(checksum));
+}
+
+/** In MySQL before 4.0.14 or 4.1.1 there was an InnoDB bug that
+the checksum only looked at the first few bytes of the page.
+This calculates that old checksum.
+NOTE: we must first store the new formula checksum to
+FIL_PAGE_SPACE_OR_CHKSUM before calculating and storing this old checksum
+because this takes that field as an input!
+@param[in]	page	file page (srv_page_size bytes)
+@return checksum */
+uint32_t
+buf_calc_page_old_checksum(const byte* page)
+{
+	return(static_cast<uint32_t>
+	       (ut_fold_binary(page, FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION)));
+}
+
+/** Return a printable string describing the checksum algorithm.
+@param[in]	algo	algorithm
+@return algorithm name */
+const char*
+buf_checksum_algorithm_name(srv_checksum_algorithm_t algo)
+{
+	switch (algo) {
+	case SRV_CHECKSUM_ALGORITHM_CRC32:
+		return("crc32");
+	case SRV_CHECKSUM_ALGORITHM_STRICT_CRC32:
+		return("strict_crc32");
+	case SRV_CHECKSUM_ALGORITHM_INNODB:
+		return("innodb");
+	case SRV_CHECKSUM_ALGORITHM_STRICT_INNODB:
+		return("strict_innodb");
+	case SRV_CHECKSUM_ALGORITHM_NONE:
+		return("none");
+	case SRV_CHECKSUM_ALGORITHM_STRICT_NONE:
+		return("strict_none");
+	case SRV_CHECKSUM_ALGORITHM_FULL_CRC32:
+		return("full_crc32");
+	case SRV_CHECKSUM_ALGORITHM_STRICT_FULL_CRC32:
+		return("strict_full_crc32");
+	}
+
+	ut_error;
+	return(NULL);
+}