Limit to_tsvector_byid's initial array allocation to something sane.

The initial estimate of the number of distinct ParsedWords is just
that: an estimate.  Don't let it exceed what palloc is willing to
allocate.  If in fact we need more entries, we'll eventually fail
trying to enlarge the array.  But if we don't, this allows success on
inputs that currently draw "invalid memory alloc request size".

Per bug #18080 from Uwe Binder.  Back-patch to all supported branches.

Discussion: https://postgr.es/m/18080-d5c5e58fef8c99b7@postgresql.org

diff --git a/src/backend/tsearch/to_tsany.c b/src/backend/tsearch/to_tsany.c
index e7cd6264db27533fef506100443ea9ad7252230c..31a2e38260a83b05450cc3f7bd11ca87ee43d7fe 100644 (file)
--- a/src/backend/tsearch/to_tsany.c
+++ b/src/backend/tsearch/to_tsany.c
@@ -242,6 +242,8 @@ to_tsvector_byid(PG_FUNCTION_ARGS)
                                                 * number */
    if (prs.lenwords < 2)
        prs.lenwords = 2;
+   else if (prs.lenwords > MaxAllocSize / sizeof(ParsedWord))
+       prs.lenwords = MaxAllocSize / sizeof(ParsedWord);
    prs.curwords = 0;
    prs.pos = 0;
    prs.words = (ParsedWord *) palloc(sizeof(ParsedWord) * prs.lenwords);