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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 byaef8948, 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 byaef8948. 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
This commit is contained in:
Michael Paquier
@@ -58,7 +58,6 @@ OBJS_COMMON = \
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file_perm.o \
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file_utils.o \
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hashfn.o \
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hex.o \
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ip.o \
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jsonapi.o \
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keywords.o \
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192
src/common/hex.c
192
src/common/hex.c
@@ -1,192 +0,0 @@
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/*-------------------------------------------------------------------------
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*
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* hex.c
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* Encoding and decoding routines for hex.
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*
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* Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* src/common/hex.c
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef FRONTEND
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#include "postgres.h"
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#else
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#include "postgres_fe.h"
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#endif
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#include "common/hex.h"
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#ifdef FRONTEND
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#include "common/logging.h"
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#endif
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#include "mb/pg_wchar.h"
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static const int8 hexlookup[128] = {
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1,
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-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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};
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static const char hextbl[] = "0123456789abcdef";
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static inline char
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get_hex(const char *cp)
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{
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unsigned char c = (unsigned char) *cp;
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int res = -1;
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if (c < 127)
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res = hexlookup[c];
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if (res < 0)
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{
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#ifdef FRONTEND
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pg_log_fatal("invalid hexadecimal digit");
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exit(EXIT_FAILURE);
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#else
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("invalid hexadecimal digit: \"%.*s\"",
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pg_mblen(cp), cp)));
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#endif
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}
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return (char) res;
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}
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/*
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* pg_hex_encode
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*
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* Encode into hex the given string. Returns the length of the encoded
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* string.
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*/
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uint64
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pg_hex_encode(const char *src, size_t srclen, char *dst, size_t dstlen)
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{
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const char *end = src + srclen;
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char *p;
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p = dst;
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while (src < end)
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{
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/*
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* Leave if there is an overflow in the area allocated for the encoded
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* string.
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*/
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if ((p - dst + 2) > dstlen)
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{
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#ifdef FRONTEND
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pg_log_fatal("overflow of destination buffer in hex encoding");
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exit(EXIT_FAILURE);
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#else
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elog(ERROR, "overflow of destination buffer in hex encoding");
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#endif
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}
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*p++ = hextbl[(*src >> 4) & 0xF];
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*p++ = hextbl[*src & 0xF];
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src++;
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}
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Assert((p - dst) <= dstlen);
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return p - dst;
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}
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/*
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* pg_hex_decode
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*
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* Decode the given hex string. Returns the length of the decoded string.
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*/
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uint64
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pg_hex_decode(const char *src, size_t srclen, char *dst, size_t dstlen)
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{
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const char *s,
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*srcend;
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char v1,
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v2,
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*p;
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srcend = src + srclen;
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s = src;
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p = dst;
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while (s < srcend)
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{
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if (*s == ' ' || *s == '\n' || *s == '\t' || *s == '\r')
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{
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s++;
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continue;
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}
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v1 = get_hex(s) << 4;
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s++;
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if (s >= srcend)
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{
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#ifdef FRONTEND
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pg_log_fatal("invalid hexadecimal data: odd number of digits");
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exit(EXIT_FAILURE);
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#else
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("invalid hexadecimal data: odd number of digits")));
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#endif
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}
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v2 = get_hex(s);
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s++;
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/* overflow check */
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if ((p - dst + 1) > dstlen)
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{
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#ifdef FRONTEND
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pg_log_fatal("overflow of destination buffer in hex decoding");
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exit(EXIT_FAILURE);
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#else
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elog(ERROR, "overflow of destination buffer in hex decoding");
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#endif
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}
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*p++ = v1 | v2;
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}
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Assert((p - dst) <= dstlen);
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return p - dst;
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}
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/*
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* pg_hex_enc_len
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*
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* Returns to caller the length of the string if it were encoded with
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* hex based on the length provided by caller. This is useful to estimate
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* how large a buffer allocation needs to be done before doing the actual
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* encoding.
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*/
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uint64
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pg_hex_enc_len(size_t srclen)
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{
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return (uint64) srclen << 1;
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}
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/*
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* pg_hex_dec_len
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*
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* Returns to caller the length of the string if it were to be decoded
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* with hex, based on the length given by caller. This is useful to
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* estimate how large a buffer allocation needs to be done before doing
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* the actual decoding.
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*/
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uint64
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pg_hex_dec_len(size_t srclen)
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{
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return (uint64) srclen >> 1;
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}
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