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Fix integer-to-bit-string conversions to handle the first fractional byte

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correctly when the output bit width is wider than the given integer by
something other than a multiple of 8 bits.

This has been wrong since I first wrote that code for 8.0 :-(.  Kudos to
Roman Kononov for being the first to notice, though I didn't use his
patch.  Per bug #5237.
This commit is contained in:
Tom Lane 2009-12-12 19:24:35 +00:00
parent 02490d4692
commit a4e035b2f1
1 changed files with 13 additions and 3 deletions
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16
src/backend/utils/adt/varbit.c
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@ -9,7 +9,7 @@
* Portions Copyright (c) 1994, Regents of the University of California * Portions Copyright (c) 1994, Regents of the University of California
* *
* IDENTIFICATION * IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/varbit.c,v 1.58 2009/01/01 17:23:50 momjian Exp $ * $PostgreSQL: pgsql/src/backend/utils/adt/varbit.c,v 1.59 2009/12/12 19:24:35 tgl Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -1346,7 +1346,12 @@ bitfromint4(PG_FUNCTION_ARGS)
/* store first fractional byte */ /* store first fractional byte */
if (destbitsleft > srcbitsleft) if (destbitsleft > srcbitsleft)
{ {
*r++ = (bits8) ((a >> (srcbitsleft - 8)) & BITMASK); int val = (int) (a >> (destbitsleft - 8));
/* Force sign-fill in case the compiler implements >> as zero-fill */
if (a < 0)
val |= (-1) << (srcbitsleft + 8 - destbitsleft);
*r++ = (bits8) (val & BITMASK);
destbitsleft -= 8; destbitsleft -= 8;
} }
/* Now srcbitsleft and destbitsleft are the same, need not track both */ /* Now srcbitsleft and destbitsleft are the same, need not track both */
@ -1425,7 +1430,12 @@ bitfromint8(PG_FUNCTION_ARGS)
/* store first fractional byte */ /* store first fractional byte */
if (destbitsleft > srcbitsleft) if (destbitsleft > srcbitsleft)
{ {
*r++ = (bits8) ((a >> (srcbitsleft - 8)) & BITMASK); int val = (int) (a >> (destbitsleft - 8));
/* Force sign-fill in case the compiler implements >> as zero-fill */
if (a < 0)
val |= (-1) << (srcbitsleft + 8 - destbitsleft);
*r++ = (bits8) (val & BITMASK);
destbitsleft -= 8; destbitsleft -= 8;
} }
/* Now srcbitsleft and destbitsleft are the same, need not track both */ /* Now srcbitsleft and destbitsleft are the same, need not track both */