On 2024-01-25 Th 14:31, Tom Lane wrote:
Andrew Dunstan <and...@dunslane.net> writes:
Thanks, I have pushed this.
The buildfarm is pretty widely unhappy, mostly failing on
select jsonb_path_query('1.23', '$.string()');
On a guess, I tried running that under valgrind, and behold it said
==00:00:00:05.637 435530== Conditional jump or move depends on uninitialised
value(s)
==00:00:00:05.637 435530== at 0x8FD131: executeItemOptUnwrapTarget
(jsonpath_exec.c:1547)
==00:00:00:05.637 435530== by 0x8FED03: executeItem (jsonpath_exec.c:626)
==00:00:00:05.637 435530== by 0x8FED03: executeNextItem
(jsonpath_exec.c:1604)
==00:00:00:05.637 435530== by 0x8FCA58: executeItemOptUnwrapTarget
(jsonpath_exec.c:956)
==00:00:00:05.637 435530== by 0x8FFDE4: executeItem (jsonpath_exec.c:626)
==00:00:00:05.637 435530== by 0x8FFDE4: executeJsonPath.constprop.30
(jsonpath_exec.c:612)
==00:00:00:05.637 435530== by 0x8FFF8C: jsonb_path_query_internal
(jsonpath_exec.c:438)
It's fairly obviously right about that:
JsonbValue jbv;
...
jb = &jbv;
Assert(tmp != NULL); /* We must have set tmp above */
jb->val.string.val = (jb->type == jbvString) ? tmp :
pstrdup(tmp);
^^^^^^^^^^^^^^^^^^^^^
Presumably, this is a mistaken attempt to test the type
of the thing previously pointed to by "jb".
On the whole, what I'd be inclined to do here is get rid
of this test altogether and demand that every path through
the preceding "switch" deliver a value that doesn't need
pstrdup(). The only path that doesn't do that already is
case jbvBool:
tmp = (jb->val.boolean) ? "true" : "false";
break;
and TBH I'm not sure that we really need a pstrdup there
either. The constants are immutable enough. Is something
likely to try to pfree the pointer later? I tried
@@ -1544,7 +1544,7 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt,
JsonPathItem *jsp,
jb = &jbv;
Assert(tmp != NULL); /* We must have set tmp above */
- jb->val.string.val = (jb->type == jbvString) ? tmp :
pstrdup(tmp);
+ jb->val.string.val = tmp;
jb->val.string.len = strlen(jb->val.string.val);
jb->type = jbvString;
and that quieted valgrind for this particular query and still
passes regression.
Your fix looks sane. I also don't see why we need the pstrdup.
(The reported crashes seem to be happening later during a
recursive invocation, seemingly because JsonbType(jb) is
returning garbage. So there may be another bug after this one.)
I don't think so. AIUI The first call deals with the '$' and the second
one deals with the '.string()', which is why we see the error on the
second call.
cheers
andrew
--
Andrew Dunstan
EDB: https://www.enterprisedb.com
