Fix various instances of undefined behavior
Mostly this involves checking for NULL pointer before doing operations
that add a non-zero offset.
The exception is an overflow warning in heap_fetch_toast_slice(). This
was caused by unneeded parentheses forcing an expression to be
evaluated to a negative integer, which then got cast to size_t.
Per clang 21 undefined behavior sanitizer.
Backpatch to all supported versions.
Co-authored-by: Alexander Lakhin <exclusion@gmail.com>
Reported-by: Alexander Lakhin <exclusion@gmail.com>
Discussion: https://postgr.es/m/777bd201-6e3a-4da0-a922-4ea9de46a3ee@gmail.com
Backpatch-through: 14
Branch
------
REL_14_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/fc56793c9ae5b88f5c14daadf927c6d495cca39e
Modified Files
--------------
contrib/pg_trgm/trgm_gist.c | 5 ++++-
src/backend/access/heap/heaptoast.c | 2 +-
src/backend/utils/adt/multirangetypes.c | 5 +++--
src/backend/utils/sort/sharedtuplestore.c | 3 ++-
4 files changed, 10 insertions(+), 5 deletions(-)
