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Make bit/varbit substring() treat any negative length as meaning "all the rest

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of the string".  The previous coding treated only -1 that way, and would
produce an invalid result value for other negative values.

We ought to fix it so that 2-parameter bit substring() is a different C
function and the 3-parameter form throws error for negative length, but
that takes a pg_proc change which is impractical in the back branches;
and in any case somebody might be relying on -1 working this way.
So just do this as a back-patchable fix.
This commit is contained in:
Tom Lane 2010-01-07 19:53:32 +00:00
parent c79a6b110c
commit ae76ee9af9
1 changed files with 17 additions and 7 deletions
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24
src/backend/utils/adt/varbit.c
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@ -9,7 +9,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/varbit.c,v 1.47.2.2 2009/12/12 19:25:04 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/varbit.c,v 1.47.2.3 2010/01/07 19:53:32 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -864,13 +864,23 @@ bitsubstr(PG_FUNCTION_ARGS)
*ps;
bitlen = VARBITLEN(arg);
/* If we do not have an upper bound, set bitlen */
if (l == -1)
l = bitlen;
e = s + l;
s1 = Max(s, 1);
e1 = Min(e, bitlen + 1);
if (s1 > bitlen || e1 < 1)
/* If we do not have an upper bound, use end of string */
if (l < 0)
{
e1 = bitlen + 1;
}
else
{
e = s + l;
/* guard against overflow, even though we don't allow L<0 here */
if (e < s)
ereport(ERROR,
(errcode(ERRCODE_SUBSTRING_ERROR),
errmsg("negative substring length not allowed")));
e1 = Min(e, bitlen + 1);
}
if (s1 > bitlen || e1 <= s1)
{
/* Need to return a zero-length bitstring */
len = VARBITTOTALLEN(0);