I wrote:
> Alexander Lakhin <exclusion@gmail.com> writes:
>> (Un)fortunately, tern (which is also a ppc animal) has produced the same
>> failure:
>> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=tern&dt=2024-11-16%2022%3A00%3A12
> Yeah, I saw that. Even more confused now about what it could be.
After testing on hornet's host, it seems that this is a pre-existing
issue that we didn't happen to hit before. Since the regex
'[^\d\D]' is unsatisfiable, it collapses to nothing (start state,
end state, and no arcs) in the first cleanup() call in optimize().
Then fixempties() counts the number of in-arcs and gets zero,
and then it does
arcarray = (struct arc **) MALLOC(totalinarcs * sizeof(struct arc *));
if (arcarray == NULL)
{
NERR(REG_ESPACE);
...
On a machine where malloc(0) returns NULL, this mistakenly
thinks that's an error.
I verified that
- if (arcarray == NULL)
+ if (arcarray == NULL && totalinarcs != 0)
makes the failure go away, but I wonder if any other places in
backend/regex/ are at the same hazard. Maybe the smartest fix
would be to put in a wrapper layer that does what pg_malloc
does:
/* Avoid unportable behavior of malloc(0) */
if (size == 0)
size = 1;
One other point is that this theory fails to explain why
hornet didn't fail in the v16 branch ... oh, wait:
v15 has
#define MALLOC(n) malloc(n)
where later branches have
#define MALLOC(n) palloc_extended((n), MCXT_ALLOC_NO_OOM)
So the right answer seems to be to figure out why we didn't
back-patch that change.
regards, tom lane
