Some conditions in shm_toc_insert and shm_toc_allocate are bogus, like: if (toc_bytes + nbytes > total_bytes || toc_bytes + nbytes < toc_bytes)
Remove the condition `toc_bytes + nbytes < toc_bytes` and take a sizeof(shm_entry) into account in shm_toc_allocate though shm_toc_allocate does that too.
/* Check for memory exhaustion and overflow. */ - if (toc_bytes + nbytes > total_bytes || toc_bytes + nbytes < toc_bytes) + if (toc_bytes + sizeof(shm_toc_entry) + nbytes > total_bytes) { SpinLockRelease(&toc->toc_mutex);
shm_toc_freespace is introduced with shm_toc by original commit 6ddd5137b2, but is not used since then, so remove it.
