Revert refactoring of hex code to src/common/

This is a combined revert of the following commits:
- c3826f8, a refactoring piece that moved the hex decoding code to
src/common/.  This code was cleaned up by aef8948, as it originally
included no overflow checks in the same way as the base64 routines in
src/common/ used by SCRAM, making it unsafe for its purpose.
- aef8948, a more advanced refactoring of the hex encoding/decoding code
to src/common/ that added sanity checks on the result buffer for hex
decoding and encoding.  As reported by Hans Buschmann, those overflow
checks are expensive, and it is possible to see a performance drop in
the decoding/encoding of bytea or LOs the longer they are.  Simple SQLs
working on large bytea values show a clear difference in perf profile.
- ccf4e27, a cleanup made possible by aef8948.

The reverts of all those commits bring back the performance of hex
decoding and encoding back to what it was in ~13.  Fow now and
post-beta3, this is the simplest option.

Reported-by: Hans Buschmann
Discussion: https://postgr.es/m/1629039545467.80333@nidsa.net
Backpatch-through: 14

2 files changed, 4 insertions, 25 deletions

diff --git a/src/include/common/hex.h b/src/include/common/hex.h
deleted file mode 100644
index 150771a14d7..00000000000
--- a/src/include/common/hex.h
+++ /dev/null
@@ -1,25 +0,0 @@
-/*------------------------------------------------------------------------
- *
- *	hex.h
- *	  Encoding and decoding routines for hex strings.
- *
- *	Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
- *	Portions Copyright (c) 1994, Regents of the University of California
- *
- * IDENTIFICATION
- *		  src/include/common/hex.h
- *
- *------------------------------------------------------------------------
- */
-
-#ifndef COMMON_HEX_H
-#define COMMON_HEX_H
-
-extern uint64 pg_hex_decode(const char *src, size_t srclen,
-							char *dst, size_t dstlen);
-extern uint64 pg_hex_encode(const char *src, size_t srclen,
-							char *dst, size_t dstlen);
-extern uint64 pg_hex_enc_len(size_t srclen);
-extern uint64 pg_hex_dec_len(size_t srclen);
-
-#endif							/* COMMON_HEX_H */
diff --git a/src/include/common/sha2.h b/src/include/common/sha2.h
index dfeee6bceba..f4bae35af10 100644
--- a/src/include/common/sha2.h
+++ b/src/include/common/sha2.h
@@ -18,11 +18,15 @@
 /*** SHA224/256/384/512 Various Length Definitions ***********************/
 #define PG_SHA224_BLOCK_LENGTH			64
 #define PG_SHA224_DIGEST_LENGTH			28
+#define PG_SHA224_DIGEST_STRING_LENGTH	(PG_SHA224_DIGEST_LENGTH * 2 + 1)
 #define PG_SHA256_BLOCK_LENGTH			64
 #define PG_SHA256_DIGEST_LENGTH			32
+#define PG_SHA256_DIGEST_STRING_LENGTH	(PG_SHA256_DIGEST_LENGTH * 2 + 1)
 #define PG_SHA384_BLOCK_LENGTH			128
 #define PG_SHA384_DIGEST_LENGTH			48
+#define PG_SHA384_DIGEST_STRING_LENGTH	(PG_SHA384_DIGEST_LENGTH * 2 + 1)
 #define PG_SHA512_BLOCK_LENGTH			128
 #define PG_SHA512_DIGEST_LENGTH			64
+#define PG_SHA512_DIGEST_STRING_LENGTH	(PG_SHA512_DIGEST_LENGTH * 2 + 1)
 
 #endif							/* _PG_SHA2_H_ */