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-rw-r--r--src/backend/utils/adt/varbit.c165
-rw-r--r--src/include/utils/varbit.h5
-rw-r--r--src/test/regress/expected/bit.out66
-rw-r--r--src/test/regress/sql/bit.sql7
4 files changed, 154 insertions, 89 deletions
diff --git a/src/backend/utils/adt/varbit.c b/src/backend/utils/adt/varbit.c
index d969a5b9c23..c36d8ded40a 100644
--- a/src/backend/utils/adt/varbit.c
+++ b/src/backend/utils/adt/varbit.c
@@ -3,6 +3,21 @@
* varbit.c
* Functions for the SQL datatypes BIT() and BIT VARYING().
*
+ * The data structure contains the following elements:
+ * header -- length of the whole data structure (incl header)
+ * in bytes (as with all varying length datatypes)
+ * data section -- private data section for the bits data structures
+ * bitlength -- length of the bit string in bits
+ * bitdata -- bit string, most significant byte first
+ *
+ * The length of the bitdata vector should always be exactly as many
+ * bytes as are needed for the given bitlength. If the bitlength is
+ * not a multiple of 8, the extra low-order padding bits of the last
+ * byte must be zeroes.
+ *
+ * attypmod is defined as the length of the bit string in bits, or for
+ * varying bits the maximum length.
+ *
* Code originally contributed by Adriaan Joubert.
*
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
@@ -27,6 +42,40 @@
#define HEXDIG(z) ((z)<10 ? ((z)+'0') : ((z)-10+'A'))
+/* Mask off any bits that should be zero in the last byte of a bitstring */
+#define VARBIT_PAD(vb) \
+ do { \
+ int32 pad_ = VARBITPAD(vb); \
+ Assert(pad_ >= 0 && pad_ < BITS_PER_BYTE); \
+ if (pad_ > 0) \
+ *(VARBITS(vb) + VARBITBYTES(vb) - 1) &= BITMASK << pad_; \
+ } while (0)
+
+/*
+ * Many functions work byte-by-byte, so they have a pointer handy to the
+ * last-plus-one byte, which saves a cycle or two.
+ */
+#define VARBIT_PAD_LAST(vb, ptr) \
+ do { \
+ int32 pad_ = VARBITPAD(vb); \
+ Assert(pad_ >= 0 && pad_ < BITS_PER_BYTE); \
+ if (pad_ > 0) \
+ *((ptr) - 1) &= BITMASK << pad_; \
+ } while (0)
+
+/* Assert proper padding of a bitstring */
+#ifdef USE_ASSERT_CHECKING
+#define VARBIT_CORRECTLY_PADDED(vb) \
+ do { \
+ int32 pad_ = VARBITPAD(vb); \
+ Assert(pad_ >= 0 && pad_ < BITS_PER_BYTE); \
+ Assert(pad_ == 0 || \
+ (*(VARBITS(vb) + VARBITBYTES(vb) - 1) & ~(BITMASK << pad_)) == 0); \
+ } while (0)
+#else
+#define VARBIT_CORRECTLY_PADDED(vb) ((void) 0)
+#endif
+
static VarBit *bit_catenate(VarBit *arg1, VarBit *arg2);
static VarBit *bitsubstring(VarBit *arg, int32 s, int32 l,
bool length_not_specified);
@@ -87,24 +136,6 @@ anybit_typmodout(int32 typmod)
}
-/*----------
- * attypmod -- contains the length of the bit string in bits, or for
- * varying bits the maximum length.
- *
- * The data structure contains the following elements:
- * header -- length of the whole data structure (incl header)
- * in bytes. (as with all varying length datatypes)
- * data section -- private data section for the bits data structures
- * bitlength -- length of the bit string in bits
- * bitdata -- bit string, most significant byte first
- *
- * The length of the bitdata vector should always be exactly as many
- * bytes as are needed for the given bitlength. If the bitlength is
- * not a multiple of 8, the extra low-order padding bits of the last
- * byte must be zeroes.
- *----------
- */
-
/*
* bit_in -
* converts a char string to the internal representation of a bitstring.
@@ -264,6 +295,9 @@ bit_out(PG_FUNCTION_ARGS)
len,
bitlen;
+ /* Assertion to help catch any bit functions that don't pad correctly */
+ VARBIT_CORRECTLY_PADDED(s);
+
bitlen = VARBITLEN(s);
len = (bitlen + 3) / 4;
result = (char *) palloc(len + 2);
@@ -304,8 +338,6 @@ bit_recv(PG_FUNCTION_ARGS)
VarBit *result;
int len,
bitlen;
- int ipad;
- bits8 mask;
bitlen = pq_getmsgint(buf, sizeof(int32));
if (bitlen < 0 || bitlen > VARBITMAXLEN)
@@ -330,13 +362,8 @@ bit_recv(PG_FUNCTION_ARGS)
pq_copymsgbytes(buf, (char *) VARBITS(result), VARBITBYTES(result));
- /* Make sure last byte is zero-padded if needed */
- ipad = VARBITPAD(result);
- if (ipad > 0)
- {
- mask = BITMASK << ipad;
- *(VARBITS(result) + VARBITBYTES(result) - 1) &= mask;
- }
+ /* Make sure last byte is correctly zero-padded */
+ VARBIT_PAD(result);
PG_RETURN_VARBIT_P(result);
}
@@ -367,8 +394,6 @@ bit(PG_FUNCTION_ARGS)
bool isExplicit = PG_GETARG_BOOL(2);
VarBit *result;
int rlen;
- int ipad;
- bits8 mask;
/* No work if typmod is invalid or supplied data matches it already */
if (len <= 0 || len > VARBITMAXLEN || len == VARBITLEN(arg))
@@ -394,12 +419,7 @@ bit(PG_FUNCTION_ARGS)
* if source data was shorter than target length (we assume the last byte
* of the source data was itself correctly zero-padded).
*/
- ipad = VARBITPAD(result);
- if (ipad > 0)
- {
- mask = BITMASK << ipad;
- *(VARBITS(result) + VARBITBYTES(result) - 1) &= mask;
- }
+ VARBIT_PAD(result);
PG_RETURN_VARBIT_P(result);
}
@@ -574,6 +594,9 @@ varbit_out(PG_FUNCTION_ARGS)
k,
len;
+ /* Assertion to help catch any bit functions that don't pad correctly */
+ VARBIT_CORRECTLY_PADDED(s);
+
len = VARBITLEN(s);
result = (char *) palloc(len + 1);
sp = VARBITS(s);
@@ -620,8 +643,6 @@ varbit_recv(PG_FUNCTION_ARGS)
VarBit *result;
int len,
bitlen;
- int ipad;
- bits8 mask;
bitlen = pq_getmsgint(buf, sizeof(int32));
if (bitlen < 0 || bitlen > VARBITMAXLEN)
@@ -646,13 +667,8 @@ varbit_recv(PG_FUNCTION_ARGS)
pq_copymsgbytes(buf, (char *) VARBITS(result), VARBITBYTES(result));
- /* Make sure last byte is zero-padded if needed */
- ipad = VARBITPAD(result);
- if (ipad > 0)
- {
- mask = BITMASK << ipad;
- *(VARBITS(result) + VARBITBYTES(result) - 1) &= mask;
- }
+ /* Make sure last byte is correctly zero-padded */
+ VARBIT_PAD(result);
PG_RETURN_VARBIT_P(result);
}
@@ -729,8 +745,6 @@ varbit(PG_FUNCTION_ARGS)
bool isExplicit = PG_GETARG_BOOL(2);
VarBit *result;
int rlen;
- int ipad;
- bits8 mask;
/* No work if typmod is invalid or supplied data matches it already */
if (len <= 0 || len >= VARBITLEN(arg))
@@ -749,13 +763,8 @@ varbit(PG_FUNCTION_ARGS)
memcpy(VARBITS(result), VARBITS(arg), VARBITBYTES(result));
- /* Make sure last byte is zero-padded if needed */
- ipad = VARBITPAD(result);
- if (ipad > 0)
- {
- mask = BITMASK << ipad;
- *(VARBITS(result) + VARBITBYTES(result) - 1) &= mask;
- }
+ /* Make sure last byte is correctly zero-padded */
+ VARBIT_PAD(result);
PG_RETURN_VARBIT_P(result);
}
@@ -1013,6 +1022,8 @@ bit_catenate(VarBit *arg1, VarBit *arg2)
}
}
+ /* The pad bits should be already zero at this point */
+
return result;
}
@@ -1046,14 +1057,12 @@ bitsubstring(VarBit *arg, int32 s, int32 l, bool length_not_specified)
int bitlen,
rbitlen,
len,
- ipad = 0,
ishift,
i;
int e,
s1,
e1;
- bits8 mask,
- *r,
+ bits8 *r,
*ps;
bitlen = VARBITLEN(arg);
@@ -1118,13 +1127,9 @@ bitsubstring(VarBit *arg, int32 s, int32 l, bool length_not_specified)
r++;
}
}
- /* Do we need to pad at the end? */
- ipad = VARBITPAD(result);
- if (ipad > 0)
- {
- mask = BITMASK << ipad;
- *(VARBITS(result) + len - 1) &= mask;
- }
+
+ /* Make sure last byte is correctly zero-padded */
+ VARBIT_PAD(result);
}
return result;
@@ -1246,7 +1251,7 @@ bit_and(PG_FUNCTION_ARGS)
for (i = 0; i < VARBITBYTES(arg1); i++)
*r++ = *p1++ & *p2++;
- /* Padding is not needed as & of 0 pad is 0 */
+ /* Padding is not needed as & of 0 pads is 0 */
PG_RETURN_VARBIT_P(result);
}
@@ -1268,7 +1273,6 @@ bit_or(PG_FUNCTION_ARGS)
bits8 *p1,
*p2,
*r;
- bits8 mask;
bitlen1 = VARBITLEN(arg1);
bitlen2 = VARBITLEN(arg2);
@@ -1287,13 +1291,7 @@ bit_or(PG_FUNCTION_ARGS)
for (i = 0; i < VARBITBYTES(arg1); i++)
*r++ = *p1++ | *p2++;
- /* Pad the result */
- mask = BITMASK << VARBITPAD(result);
- if (mask)
- {
- r--;
- *r &= mask;
- }
+ /* Padding is not needed as | of 0 pads is 0 */
PG_RETURN_VARBIT_P(result);
}
@@ -1315,7 +1313,6 @@ bitxor(PG_FUNCTION_ARGS)
bits8 *p1,
*p2,
*r;
- bits8 mask;
bitlen1 = VARBITLEN(arg1);
bitlen2 = VARBITLEN(arg2);
@@ -1335,13 +1332,7 @@ bitxor(PG_FUNCTION_ARGS)
for (i = 0; i < VARBITBYTES(arg1); i++)
*r++ = *p1++ ^ *p2++;
- /* Pad the result */
- mask = BITMASK << VARBITPAD(result);
- if (mask)
- {
- r--;
- *r &= mask;
- }
+ /* Padding is not needed as ^ of 0 pads is 0 */
PG_RETURN_VARBIT_P(result);
}
@@ -1357,7 +1348,6 @@ bitnot(PG_FUNCTION_ARGS)
VarBit *result;
bits8 *p,
*r;
- bits8 mask;
result = (VarBit *) palloc(VARSIZE(arg));
SET_VARSIZE(result, VARSIZE(arg));
@@ -1368,13 +1358,8 @@ bitnot(PG_FUNCTION_ARGS)
for (; p < VARBITEND(arg); p++)
*r++ = ~*p;
- /* Pad the result */
- mask = BITMASK << VARBITPAD(result);
- if (mask)
- {
- r--;
- *r &= mask;
- }
+ /* Must zero-pad the result, because extra bits are surely 1's here */
+ VARBIT_PAD_LAST(result, r);
PG_RETURN_VARBIT_P(result);
}
@@ -1441,6 +1426,8 @@ bitshiftleft(PG_FUNCTION_ARGS)
*r = 0;
}
+ /* The pad bits should be already zero at this point */
+
PG_RETURN_VARBIT_P(result);
}
@@ -1507,6 +1494,8 @@ bitshiftright(PG_FUNCTION_ARGS)
if ((++r) < VARBITEND(result))
*r = (*p << (BITS_PER_BYTE - ishift)) & BITMASK;
}
+ /* We may have shifted 1's into the pad bits, so fix that */
+ VARBIT_PAD_LAST(result, r);
}
PG_RETURN_VARBIT_P(result);
diff --git a/src/include/utils/varbit.h b/src/include/utils/varbit.h
index 641731c4177..e947de55be4 100644
--- a/src/include/utils/varbit.h
+++ b/src/include/utils/varbit.h
@@ -21,6 +21,11 @@
/*
* Modeled on struct varlena from postgres.h, but data type is bits8.
+ *
+ * Caution: if bit_len is not a multiple of BITS_PER_BYTE, the low-order
+ * bits of the last byte of bit_dat[] are unused and MUST be zeroes.
+ * (This allows bit_cmp() to not bother masking the last byte.)
+ * Also, there should not be any excess bytes counted in the header length.
*/
typedef struct
{
diff --git a/src/test/regress/expected/bit.out b/src/test/regress/expected/bit.out
index ef8aaea3eff..255b39b07e2 100644
--- a/src/test/regress/expected/bit.out
+++ b/src/test/regress/expected/bit.out
@@ -477,6 +477,50 @@ SELECT POSITION(B'1101' IN b),
0 | 0 | 0000000000000001
(16 rows)
+SELECT b, b >> 1 AS bsr, b << 1 AS bsl
+ FROM BIT_SHIFT_TABLE ;
+ b | bsr | bsl
+------------------+------------------+------------------
+ 1101100000000000 | 0110110000000000 | 1011000000000000
+ 0110110000000000 | 0011011000000000 | 1101100000000000
+ 0011011000000000 | 0001101100000000 | 0110110000000000
+ 0001101100000000 | 0000110110000000 | 0011011000000000
+ 0000110110000000 | 0000011011000000 | 0001101100000000
+ 0000011011000000 | 0000001101100000 | 0000110110000000
+ 0000001101100000 | 0000000110110000 | 0000011011000000
+ 0000000110110000 | 0000000011011000 | 0000001101100000
+ 0000000011011000 | 0000000001101100 | 0000000110110000
+ 0000000001101100 | 0000000000110110 | 0000000011011000
+ 0000000000110110 | 0000000000011011 | 0000000001101100
+ 0000000000011011 | 0000000000001101 | 0000000000110110
+ 0000000000001101 | 0000000000000110 | 0000000000011010
+ 0000000000000110 | 0000000000000011 | 0000000000001100
+ 0000000000000011 | 0000000000000001 | 0000000000000110
+ 0000000000000001 | 0000000000000000 | 0000000000000010
+(16 rows)
+
+SELECT b::bit(15), b::bit(15) >> 1 AS bsr, b::bit(15) << 1 AS bsl
+ FROM BIT_SHIFT_TABLE ;
+ b | bsr | bsl
+-----------------+-----------------+-----------------
+ 110110000000000 | 011011000000000 | 101100000000000
+ 011011000000000 | 001101100000000 | 110110000000000
+ 001101100000000 | 000110110000000 | 011011000000000
+ 000110110000000 | 000011011000000 | 001101100000000
+ 000011011000000 | 000001101100000 | 000110110000000
+ 000001101100000 | 000000110110000 | 000011011000000
+ 000000110110000 | 000000011011000 | 000001101100000
+ 000000011011000 | 000000001101100 | 000000110110000
+ 000000001101100 | 000000000110110 | 000000011011000
+ 000000000110110 | 000000000011011 | 000000001101100
+ 000000000011011 | 000000000001101 | 000000000110110
+ 000000000001101 | 000000000000110 | 000000000011010
+ 000000000000110 | 000000000000011 | 000000000001100
+ 000000000000011 | 000000000000001 | 000000000000110
+ 000000000000001 | 000000000000000 | 000000000000010
+ 000000000000000 | 000000000000000 | 000000000000000
+(16 rows)
+
CREATE TABLE VARBIT_SHIFT_TABLE(v BIT VARYING(20));
INSERT INTO VARBIT_SHIFT_TABLE VALUES (B'11011');
INSERT INTO VARBIT_SHIFT_TABLE SELECT CAST(v || B'0' AS BIT VARYING(6)) >>1 FROM VARBIT_SHIFT_TABLE;
@@ -507,6 +551,28 @@ SELECT POSITION(B'1101' IN v),
16 | 16 | 00000000000000011011
(16 rows)
+SELECT v, v >> 1 AS vsr, v << 1 AS vsl
+ FROM VARBIT_SHIFT_TABLE ;
+ v | vsr | vsl
+----------------------+----------------------+----------------------
+ 11011 | 01101 | 10110
+ 011011 | 001101 | 110110
+ 0011011 | 0001101 | 0110110
+ 00011011 | 00001101 | 00110110
+ 000011011 | 000001101 | 000110110
+ 0000011011 | 0000001101 | 0000110110
+ 00000011011 | 00000001101 | 00000110110
+ 000000011011 | 000000001101 | 000000110110
+ 0000000011011 | 0000000001101 | 0000000110110
+ 00000000011011 | 00000000001101 | 00000000110110
+ 000000000011011 | 000000000001101 | 000000000110110
+ 0000000000011011 | 0000000000001101 | 0000000000110110
+ 00000000000011011 | 00000000000001101 | 00000000000110110
+ 000000000000011011 | 000000000000001101 | 000000000000110110
+ 0000000000000011011 | 0000000000000001101 | 0000000000000110110
+ 00000000000000011011 | 00000000000000001101 | 00000000000000110110
+(16 rows)
+
DROP TABLE BIT_SHIFT_TABLE;
DROP TABLE VARBIT_SHIFT_TABLE;
-- Get/Set bit
diff --git a/src/test/regress/sql/bit.sql b/src/test/regress/sql/bit.sql
index a73da8cb8f6..f47b8699207 100644
--- a/src/test/regress/sql/bit.sql
+++ b/src/test/regress/sql/bit.sql
@@ -168,6 +168,10 @@ SELECT POSITION(B'1101' IN b),
POSITION(B'11011' IN b),
b
FROM BIT_SHIFT_TABLE ;
+SELECT b, b >> 1 AS bsr, b << 1 AS bsl
+ FROM BIT_SHIFT_TABLE ;
+SELECT b::bit(15), b::bit(15) >> 1 AS bsr, b::bit(15) << 1 AS bsl
+ FROM BIT_SHIFT_TABLE ;
CREATE TABLE VARBIT_SHIFT_TABLE(v BIT VARYING(20));
@@ -180,7 +184,8 @@ SELECT POSITION(B'1101' IN v),
POSITION(B'11011' IN v),
v
FROM VARBIT_SHIFT_TABLE ;
-
+SELECT v, v >> 1 AS vsr, v << 1 AS vsl
+ FROM VARBIT_SHIFT_TABLE ;
DROP TABLE BIT_SHIFT_TABLE;
DROP TABLE VARBIT_SHIFT_TABLE;
generated by cgit v1.2.3 (git 2.25.1) at 2025-06-02 19:30:35 +0000