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| author | David Rowley <drowley@postgresql.org> | 2023-04-21 10:02:25 +1200 |
|---|---|---|
| committer | David Rowley <drowley@postgresql.org> | 2023-04-21 10:02:25 +1200 |
| commit | 63a03aea6bc89060010255e8e61c83f95e1daec8 (patch) | |
| tree | a28e3634155ca56856f2fdf7284cf11351415633 /src | |
| parent | 94d73f9abdf13e6dd93d96d0e4b197479c8756de (diff) | |
| download | postgresql-63a03aea6bc89060010255e8e61c83f95e1daec8.tar.gz postgresql-63a03aea6bc89060010255e8e61c83f95e1daec8.zip | |
Fix list_copy_head() with empty Lists
list_copy_head() given an empty List would crash from trying to
dereference the List to obtain its length. Since NIL is how we represent
an empty List, we should just be returning another empty List in this
case.
list_copy_head() is new to v16, so let's fix it now before too many people
start coding around the buggy NIL behavior.
Reported-by: Miroslav Bendik
Discussion: https://postgr.es/m/CAPoEpV02WhawuWnmnKet6BqU63bEu7oec0pJc=nKMtPsHMzTXQ@mail.gmail.com
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/nodes/list.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/src/backend/nodes/list.c b/src/backend/nodes/list.c index 75aa5baa807..90f93e893cf 100644 --- a/src/backend/nodes/list.c +++ b/src/backend/nodes/list.c @@ -1553,11 +1553,11 @@ list_copy_head(const List *oldlist, int len) { List *newlist; - len = Min(oldlist->length, len); - - if (len <= 0) + if (oldlist == NIL || len <= 0) return NIL; + len = Min(oldlist->length, len); + newlist = new_list(oldlist->type, len); memcpy(newlist->elements, oldlist->elements, len * sizeof(ListCell)); |