UDFs

Hi.

Trying to implement some simple digest routines via UDFs and for whatever
reason I get: ERROR: invalid memory alloc request size 4294967293 on
PG_RETURN_TEXT_P(); any ideas what the issue is exactly?

The code is verified as working when pulled out of a UDF and put into a
normal C program. Thanks.

dp_blag=# CREATE OR REPLACE FUNCTION sha512(text) RETURNS text AS
'dp_sha512.so','dp_sha512' LANGUAGE C STRICT;
CREATE FUNCTION
dp_blag=# SELECT sha512('jf');
ERROR: invalid memory alloc request size 4294967293

PG_FUNCTION_INFO_V1(dp_sha512);

Datum
dp_sha512(PG_FUNCTION_ARGS)
{
text * hash;
text * plain;
int32 hlen;

plain = (text *)PG_GETARG_TEXT_P(0);

if (NULL == plain) {
ereport(ERROR,
(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
errmsg("invalid argument to function"))
);
PG_RETURN_NULL();
}

hlen = SHA512_DIGEST_LENGTH;

hash = (text *)palloc(hlen+1);

if (NULL == hash) {
ereport(ERROR,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg("palloc() failed"))
);
PG_RETURN_NULL();
}

memset(VARDATA(hash), 0, hlen);
SHA512(VARDATA(plain), hlen, VARDATA(hash));
PG_RETURN_TEXT_P(hash);
}