flinfo NULL in DirectFunctionCall callee?
Hello,
I'm writing a multirange_cmp function which calls range_cmp to compare
individual elements. It looks like this:
cmp = DatumGetInt32(DirectFunctionCall2(
range_cmp,
RangeTypePGetDatum(r1),
RangeTypePGetDatum(r2)));
But I get a segfault when range_cmp tries to reach its
fcinfo->flinfo->fn_extra, because it has a NULL flinfo, as you can see
from these debugging messages:
NOTICE: multirange_cmp fcinfo = 0x7f875a0a66c0
NOTICE: multirange_cmp flinfo = 0x7f875a0a6690
NOTICE: multirange_cmp fn_extra = 0x7f875a099450
NOTICE: range_cmp fcinfo = 0x7ffee5ff9820
NOTICE: range_cmp flinfo = 0x0
Is it expected for flinfo to be null when using DirectFunctionCall*?
Is there something else I should use instead? It looks like
FunctionCall2 would let me pass my own flinfo, but I'm not sure how to
set that up first.
Thanks!
Paul
Paul A Jungwirth <pj@illuminatedcomputing.com> writes:
Is it expected for flinfo to be null when using DirectFunctionCall*?
Yes, per the comment on those functions:
* These are for invocation of a specifically named function with a
* directly-computed parameter list. Note that neither arguments nor result
* are allowed to be NULL. Also, the function cannot be one that needs to
* look at FmgrInfo, since there won't be any.
Is there something else I should use instead? It looks like
FunctionCall2 would let me pass my own flinfo, but I'm not sure how to
set that up first.
Use fmgr_info() or a sibling to fill in the FmgrInfo.
regards, tom lane
On Mon, Aug 26, 2019 at 8:12 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
Paul A Jungwirth <pj@illuminatedcomputing.com> writes:
Is it expected for flinfo to be null when using DirectFunctionCall*?
Yes, per the comment on those functions:
* These are for invocation of a specifically named function with a
* directly-computed parameter list. Note that neither arguments nor result
* are allowed to be NULL. Also, the function cannot be one that needs to
* look at FmgrInfo, since there won't be any.
Thanks Tom! Alas I saw that same comment in fmgr.h but it was missing
the last sentence. Would you like a patch updating it there? Is that
the kind of thing you make CF entries for? (And sorry this is veering
into pgsql-hackers territory....)
Use fmgr_info() or a sibling to fill in the FmgrInfo.
Thanks for this too! I wound up just adding a range_cmp_internal to
avoid the whole issue, which is a pattern already used by a bunch of
the other range_* functions.
Yours,
Paul
Paul A Jungwirth <pj@illuminatedcomputing.com> writes:
On Mon, Aug 26, 2019 at 8:12 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
Yes, per the comment on those functions:
* These are for invocation of a specifically named function with a
* directly-computed parameter list. Note that neither arguments nor result
* are allowed to be NULL. Also, the function cannot be one that needs to
* look at FmgrInfo, since there won't be any.
Thanks Tom! Alas I saw that same comment in fmgr.h but it was missing
the last sentence.
Oh, hm, that's not very nice. Fixed.
Would you like a patch updating it there? Is that
the kind of thing you make CF entries for?
Not really worth the overhead, for something as simple as this.
regards, tom lane