1 files changed, 72 insertions, 0 deletions
diff --git a/src/include/common/checksum_helper.h b/src/include/common/checksum_helper.h
new file mode 100644
index 0000000..cac7570
--- /dev/null
+++ b/src/include/common/checksum_helper.h
@@ -0,0 +1,72 @@
+/*-------------------------------------------------------------------------
+ *
+ * checksum_helper.h
+ *	  Compute a checksum of any of various types using common routines
+ *
+ * Portions Copyright (c) 2016-2021, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *		  src/include/common/checksum_helper.h
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef CHECKSUM_HELPER_H
+#define CHECKSUM_HELPER_H
+
+#include "common/cryptohash.h"
+#include "common/sha2.h"
+#include "port/pg_crc32c.h"
+
+/*
+ * Supported checksum types. It's not necessarily the case that code using
+ * these functions needs a cryptographically strong checksum; it may only
+ * need to detect accidental modification. That's why we include CRC-32C: it's
+ * much faster than any of the other algorithms. On the other hand, we omit
+ * MD5 here because any new that does need a cryptographically strong checksum
+ * should use something better.
+ */
+typedef enum pg_checksum_type
+{
+	CHECKSUM_TYPE_NONE,
+	CHECKSUM_TYPE_CRC32C,
+	CHECKSUM_TYPE_SHA224,
+	CHECKSUM_TYPE_SHA256,
+	CHECKSUM_TYPE_SHA384,
+	CHECKSUM_TYPE_SHA512
+} pg_checksum_type;
+
+/*
+ * This is just a union of all applicable context types.
+ */
+typedef union pg_checksum_raw_context
+{
+	pg_crc32c	c_crc32c;
+	pg_cryptohash_ctx *c_sha2;
+} pg_checksum_raw_context;
+
+/*
+ * This structure provides a convenient way to pass the checksum type and the
+ * checksum context around together.
+ */
+typedef struct pg_checksum_context
+{
+	pg_checksum_type type;
+	pg_checksum_raw_context raw_context;
+} pg_checksum_context;
+
+/*
+ * This is the longest possible output for any checksum algorithm supported
+ * by this file.
+ */
+#define PG_CHECKSUM_MAX_LENGTH		PG_SHA512_DIGEST_LENGTH
+
+extern bool pg_checksum_parse_type(char *name, pg_checksum_type *);
+extern char *pg_checksum_type_name(pg_checksum_type);
+
+extern int	pg_checksum_init(pg_checksum_context *, pg_checksum_type);
+extern int	pg_checksum_update(pg_checksum_context *, const uint8 *input,
+							   size_t len);
+extern int	pg_checksum_final(pg_checksum_context *, uint8 *output);
+
+#endif