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postgresql/src/backend/utils/adt/encode.c

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/*-------------------------------------------------------------------------
*
* encode.c
* Various data encoding/decoding things.
*
* Copyright (c) 2001-2023, PostgreSQL Global Development Group
*
*
* IDENTIFICATION
* src/backend/utils/adt/encode.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <ctype.h>
#include "mb/pg_wchar.h"
#include "utils/builtins.h"
#include "utils/memutils.h"
#include "varatt.h"
/*
* Encoding conversion API.
* encode_len() and decode_len() compute the amount of space needed, while
* encode() and decode() perform the actual conversions. It is okay for
* the _len functions to return an overestimate, but not an underestimate.
* (Having said that, large overestimates could cause unnecessary errors,
* so it's better to get it right.) The conversion routines write to the
* buffer at *res and return the true length of their output.
*/
struct pg_encoding
{
uint64 (*encode_len) (const char *data, size_t dlen);
uint64 (*decode_len) (const char *data, size_t dlen);
uint64 (*encode) (const char *data, size_t dlen, char *res);
uint64 (*decode) (const char *data, size_t dlen, char *res);
};
static const struct pg_encoding *pg_find_encoding(const char *name);
/*
* SQL functions.
*/
Datum
binary_encode(PG_FUNCTION_ARGS)
{
bytea *data = PG_GETARG_BYTEA_PP(0);
Datum name = PG_GETARG_DATUM(1);
text *result;
char *namebuf;
char *dataptr;
size_t datalen;
uint64 resultlen;
uint64 res;
const struct pg_encoding *enc;
namebuf = TextDatumGetCString(name);
enc = pg_find_encoding(namebuf);
if (enc == NULL)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("unrecognized encoding: \"%s\"", namebuf)));
dataptr = VARDATA_ANY(data);
datalen = VARSIZE_ANY_EXHDR(data);
resultlen = enc->encode_len(dataptr, datalen);
/*
* resultlen possibly overflows uint32, therefore on 32-bit machines it's
* unsafe to rely on palloc's internal check.
*/
if (resultlen > MaxAllocSize - VARHDRSZ)
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("result of encoding conversion is too large")));
result = palloc(VARHDRSZ + resultlen);
res = enc->encode(dataptr, datalen, VARDATA(result));
/* Make this FATAL 'cause we've trodden on memory ... */
if (res > resultlen)
elog(FATAL, "overflow - encode estimate too small");
SET_VARSIZE(result, VARHDRSZ + res);
PG_RETURN_TEXT_P(result);
}
Datum
binary_decode(PG_FUNCTION_ARGS)
{
text *data = PG_GETARG_TEXT_PP(0);
Datum name = PG_GETARG_DATUM(1);
bytea *result;
char *namebuf;
char *dataptr;
size_t datalen;
uint64 resultlen;
uint64 res;
const struct pg_encoding *enc;
namebuf = TextDatumGetCString(name);
enc = pg_find_encoding(namebuf);
if (enc == NULL)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("unrecognized encoding: \"%s\"", namebuf)));
dataptr = VARDATA_ANY(data);
datalen = VARSIZE_ANY_EXHDR(data);
resultlen = enc->decode_len(dataptr, datalen);
/*
* resultlen possibly overflows uint32, therefore on 32-bit machines it's
* unsafe to rely on palloc's internal check.
*/
if (resultlen > MaxAllocSize - VARHDRSZ)
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("result of decoding conversion is too large")));
result = palloc(VARHDRSZ + resultlen);
res = enc->decode(dataptr, datalen, VARDATA(result));
/* Make this FATAL 'cause we've trodden on memory ... */
if (res > resultlen)
elog(FATAL, "overflow - decode estimate too small");
SET_VARSIZE(result, VARHDRSZ + res);
PG_RETURN_BYTEA_P(result);
}
/*
* HEX
*/
static const char hextbl[] = "0123456789abcdef";
static const int8 hexlookup[128] = {
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1,
-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
};
uint64
hex_encode(const char *src, size_t len, char *dst)
{
const char *end = src + len;
while (src < end)
{
*dst++ = hextbl[(*src >> 4) & 0xF];
*dst++ = hextbl[*src & 0xF];
src++;
}
return (uint64) len * 2;
}
static inline bool
get_hex(const char *cp, char *out)
{
unsigned char c = (unsigned char) *cp;
int res = -1;
if (c < 127)
res = hexlookup[c];
*out = (char) res;
return (res >= 0);
}
uint64
hex_decode(const char *src, size_t len, char *dst)
{
return hex_decode_safe(src, len, dst, NULL);
}
uint64
hex_decode_safe(const char *src, size_t len, char *dst, Node *escontext)
{
const char *s,
*srcend;
char v1,
v2,
*p;
srcend = src + len;
s = src;
p = dst;
while (s < srcend)
{
if (*s == ' ' || *s == '\n' || *s == '\t' || *s == '\r')
{
s++;
continue;
}
if (!get_hex(s, &v1))
ereturn(escontext, 0,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("invalid hexadecimal digit: \"%.*s\"",
pg_mblen(s), s)));
s++;
if (s >= srcend)
ereturn(escontext, 0,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("invalid hexadecimal data: odd number of digits")));
if (!get_hex(s, &v2))
ereturn(escontext, 0,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("invalid hexadecimal digit: \"%.*s\"",
pg_mblen(s), s)));
s++;
*p++ = (v1 << 4) | v2;
}
return p - dst;
}
static uint64
hex_enc_len(const char *src, size_t srclen)
{
return (uint64) srclen << 1;
}
static uint64
hex_dec_len(const char *src, size_t srclen)
{
return (uint64) srclen >> 1;
}
/*
* BASE64
*/
static const char _base64[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
static const int8 b64lookup[128] = {
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,
};
static uint64
pg_base64_encode(const char *src, size_t len, char *dst)
{
char *p,
*lend = dst + 76;
const char *s,
*end = src + len;
int pos = 2;
uint32 buf = 0;
s = src;
p = dst;
while (s < end)
{
buf |= (unsigned char) *s << (pos << 3);
pos--;
s++;
/* write it out */
if (pos < 0)
{
*p++ = _base64[(buf >> 18) & 0x3f];
*p++ = _base64[(buf >> 12) & 0x3f];
*p++ = _base64[(buf >> 6) & 0x3f];
*p++ = _base64[buf & 0x3f];
pos = 2;
buf = 0;
}
if (p >= lend)
{
*p++ = '\n';
lend = p + 76;
}
}
if (pos != 2)
{
*p++ = _base64[(buf >> 18) & 0x3f];
*p++ = _base64[(buf >> 12) & 0x3f];
*p++ = (pos == 0) ? _base64[(buf >> 6) & 0x3f] : '=';
*p++ = '=';
}
return p - dst;
}
static uint64
pg_base64_decode(const char *src, size_t len, char *dst)
{
const char *srcend = src + len,
*s = src;
char *p = dst;
char c;
int b = 0;
uint32 buf = 0;
int pos = 0,
end = 0;
while (s < srcend)
{
c = *s++;
if (c == ' ' || c == '\t' || c == '\n' || c == '\r')
continue;
if (c == '=')
{
/* end sequence */
if (!end)
{
if (pos == 2)
end = 1;
else if (pos == 3)
end = 2;
else
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("unexpected \"=\" while decoding base64 sequence")));
}
b = 0;
}
else
{
b = -1;
if (c > 0 && c < 127)
b = b64lookup[(unsigned char) c];
if (b < 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("invalid symbol \"%.*s\" found while decoding base64 sequence",
pg_mblen(s - 1), s - 1)));
}
/* add it to buffer */
buf = (buf << 6) + b;
pos++;
if (pos == 4)
{
*p++ = (buf >> 16) & 255;
if (end == 0 || end > 1)
*p++ = (buf >> 8) & 255;
if (end == 0 || end > 2)
*p++ = buf & 255;
buf = 0;
pos = 0;
}
}
if (pos != 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("invalid base64 end sequence"),
errhint("Input data is missing padding, is truncated, or is otherwise corrupted.")));
return p - dst;
}
static uint64
pg_base64_enc_len(const char *src, size_t srclen)
{
/* 3 bytes will be converted to 4, linefeed after 76 chars */
return ((uint64) srclen + 2) * 4 / 3 + (uint64) srclen / (76 * 3 / 4);
}
static uint64
pg_base64_dec_len(const char *src, size_t srclen)
{
return ((uint64) srclen * 3) >> 2;
}
/*
* Escape
* Minimally escape bytea to text.
* De-escape text to bytea.
*
* We must escape zero bytes and high-bit-set bytes to avoid generating
* text that might be invalid in the current encoding, or that might
* change to something else if passed through an encoding conversion
* (leading to failing to de-escape to the original bytea value).
* Also of course backslash itself has to be escaped.
*
* De-escaping processes \\ and any \### octal
*/
#define VAL(CH) ((CH) - '0')
#define DIG(VAL) ((VAL) + '0')
static uint64
esc_encode(const char *src, size_t srclen, char *dst)
{
const char *end = src + srclen;
char *rp = dst;
uint64 len = 0;
while (src < end)
{
unsigned char c = (unsigned char) *src;
if (c == '\0' || IS_HIGHBIT_SET(c))
{
rp[0] = '\\';
rp[1] = DIG(c >> 6);
rp[2] = DIG((c >> 3) & 7);
rp[3] = DIG(c & 7);
rp += 4;
len += 4;
}
else if (c == '\\')
{
rp[0] = '\\';
rp[1] = '\\';
rp += 2;
len += 2;
}
else
{
*rp++ = c;
len++;
}
src++;
}
return len;
}
static uint64
esc_decode(const char *src, size_t srclen, char *dst)
{
const char *end = src + srclen;
char *rp = dst;
uint64 len = 0;
while (src < end)
{
if (src[0] != '\\')
*rp++ = *src++;
else if (src + 3 < end &&
(src[1] >= '0' && src[1] <= '3') &&
(src[2] >= '0' && src[2] <= '7') &&
(src[3] >= '0' && src[3] <= '7'))
{
int val;
val = VAL(src[1]);
val <<= 3;
val += VAL(src[2]);
val <<= 3;
*rp++ = val + VAL(src[3]);
src += 4;
}
else if (src + 1 < end &&
(src[1] == '\\'))
{
*rp++ = '\\';
src += 2;
}
else
{
/*
* One backslash, not followed by ### valid octal. Should never
* get here, since esc_dec_len does same check.
*/
ereport(ERROR,
(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
errmsg("invalid input syntax for type %s", "bytea")));
}
len++;
}
return len;
}
static uint64
esc_enc_len(const char *src, size_t srclen)
{
const char *end = src + srclen;
uint64 len = 0;
while (src < end)
{
if (*src == '\0' || IS_HIGHBIT_SET(*src))
len += 4;
else if (*src == '\\')
len += 2;
else
len++;
src++;
}
return len;
}
static uint64
esc_dec_len(const char *src, size_t srclen)
{
const char *end = src + srclen;
uint64 len = 0;
while (src < end)
{
if (src[0] != '\\')
src++;
else if (src + 3 < end &&
(src[1] >= '0' && src[1] <= '3') &&
(src[2] >= '0' && src[2] <= '7') &&
(src[3] >= '0' && src[3] <= '7'))
{
/*
* backslash + valid octal
*/
src += 4;
}
else if (src + 1 < end &&
(src[1] == '\\'))
{
/*
* two backslashes = backslash
*/
src += 2;
}
else
{
/*
* one backslash, not followed by ### valid octal
*/
ereport(ERROR,
(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
errmsg("invalid input syntax for type %s", "bytea")));
}
len++;
}
return len;
}
/*
* Common
*/
static const struct
{
const char *name;
struct pg_encoding enc;
} enclist[] =
{
{
"hex",
{
hex_enc_len, hex_dec_len, hex_encode, hex_decode
}
},
{
"base64",
{
pg_base64_enc_len, pg_base64_dec_len, pg_base64_encode, pg_base64_decode
}
},
{
"escape",
{
esc_enc_len, esc_dec_len, esc_encode, esc_decode
}
},
{
NULL,
{
NULL, NULL, NULL, NULL
}
}
};
static const struct pg_encoding *
pg_find_encoding(const char *name)
{
int i;
for (i = 0; enclist[i].name; i++)
if (pg_strcasecmp(enclist[i].name, name) == 0)
return &enclist[i].enc;
return NULL;
}
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