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Ensure pg_dump_sort.c sorts null vs non-null namespace consistently.

Tue, 7 Aug 2018 17:13:42 +0000 (13:13 -0400)

The original coding here (which is, I believe, my fault) supposed that
it didn't need to concern itself with the possibility that one object
of a given type-priority has a namespace while another doesn't. But
that's not reliably true anymore, if it ever was; and if it does happen
then it's possible that DOTypeNameCompare returns self-inconsistent
comparison results. That leads to unspecified behavior in qsort()
and a resultant weird output order from pg_dump.

This should end up being only a cosmetic problem, because any ordering
constraints that actually matter should be enforced by the later
dependency-based sort. Still, it's a bug, so back-patch.

Report and fix by Jacob Champion, though I editorialized on his
patch to the extent of making NULL sort after non-NULL, for consistency
with our usual sorting definitions.

Discussion: https://postgr.es/m/CABAq_6Hw+V-Kj7PNfD5tgOaWT_-qaYkc+SRmJkPLeUjYXLdxwQ@mail.gmail.com

src/bin/pg_dump/pg_dump_sort.c patch | blob | blame | history

diff --git a/src/bin/pg_dump/pg_dump_sort.c b/src/bin/pg_dump/pg_dump_sort.c

index d2b0949d6b3eb2083b018eef75b38565c8788ec9..6227a8fd26843452f36c62733bbf6026b95581d3 100644 (file)

--- a/src/bin/pg_dump/pg_dump_sort.c

+++ b/src/bin/pg_dump/pg_dump_sort.c

@@ -223,7 +223,7 @@ DOTypeNameCompare(const void *p1, const void *p2)

DumpableObject *obj2 = *(DumpableObject *const *) p2;

int cmpval;

- /* Sort by type */

+ /* Sort by type's priority */

cmpval = dbObjectTypePriority[obj1->objType] -

dbObjectTypePriority[obj2->objType];

@@ -231,17 +231,24 @@ DOTypeNameCompare(const void *p1, const void *p2)

return cmpval;

- * Sort by namespace. Note that all objects of the same type should

- * either have or not have a namespace link, so we needn't be fancy about

- * cases where one link is null and the other not.

+ * Sort by namespace. Typically, all objects of the same priority would

+ * either have or not have a namespace link, but there are exceptions.

+ * Sort NULL namespace after non-NULL in such cases.

- if (obj1->namespace && obj2->namespace)

+ if (obj1->namespace)

{

- cmpval = strcmp(obj1->namespace->dobj.name,

- obj2->namespace->dobj.name);

- if (cmpval != 0)

- return cmpval;

+ if (obj2->namespace)

+ {

+ cmpval = strcmp(obj1->namespace->dobj.name,

+ obj2->namespace->dobj.name);

+ if (cmpval != 0)

+ return cmpval;

+ }

+ else

+ return -1;

}

+ else if (obj2->namespace)

+ return 1;

/* Sort by name */

cmpval = strcmp(obj1->name, obj2->name);

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