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Commit23a4157

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Adjust DatumGetBool macro so that it isn't fooled by garbage in the Datum
to the left of the actual bool value. While in most cases there won't beany, our support for old-style user-defined functions violates the C specto the extent of calling functions that might return char or short througha function pointer declared to return "char *", which we then coerce toDatum. It is not surprising that the result might contain garbagehigh-order bits ... what is surprising is that we didn't see such caseslong ago. Per report from Magnus.
1 parent547b6e5 commit23a4157

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‎src/include/postgres.h

Lines changed: 11 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@
1010
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
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* Portions Copyright (c) 1995, Regents of the University of California
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*
13-
* $PostgreSQL: pgsql/src/include/postgres.h,v 1.77 2007/02/27 23:48:09 tgl Exp $
13+
* $PostgreSQL: pgsql/src/include/postgres.h,v 1.78 2007/03/23 20:24:41 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
@@ -125,13 +125,18 @@ typedef struct varattrib
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*
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*sizeof(short) == 2
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*
128-
*If your machine meets these requirements, Datums should also be checked
129-
*to see if the positioning is correct.
128+
* When a type narrower than Datum is stored in a Datum, we place it in the
129+
* low-order bits and are careful that the DatumGetXXX macro for it discards
130+
* the unused high-order bits (as opposed to, say, assuming they are zero).
131+
* This is needed to support old-style user-defined functions, since depending
132+
* on architecture and compiler, the return value of a function returning char
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* or short may contain garbage when called as if it returned Datum.
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*/
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typedefunsigned longDatum;/* XXX sizeof(long) >= sizeof(void *) */
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#defineSIZEOF_DATUM SIZEOF_UNSIGNED_LONG
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typedefDatum*DatumPtr;
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#defineGET_1_BYTE(datum)(((Datum) (datum)) & 0x000000ff)
@@ -145,10 +150,11 @@ typedef Datum *DatumPtr;
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* DatumGetBool
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*Returns boolean value of a datum.
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*
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* Note: any nonzero value will be considered TRUE.
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* Note: any nonzero value will be considered TRUE, but we ignore bits to
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* the left of the width of bool, per comment above.
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*/
150156

151-
#defineDatumGetBool(X) ((bool) (((Datum) (X)) != 0))
157+
#defineDatumGetBool(X) ((bool) (((bool) (X)) != 0))
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/*
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* BoolGetDatum

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