On Thu, Nov 25, 2021 at 02:22:46AM +1100, Daniel Axtens wrote: > When iterating through the singly linked list of free blocks, > grub_real_malloc uses p and q for the current and previous blocks > respectively. This isn't super clear, so swap to using prev and cur. > > This makes another quirk more obvious. The comment at the top of > grub_real_malloc might lead you to believe that the function will > allocate from *first if there is space in that block. > > It actually doesn't do that, and it can't do that with the current > data structures. If we used up all of *first, we would need to change > the ->next of the previous block to point to *first->next, but we > can't do that because it's a singly linked list and we don't have > access to *first's previous block. > > What grub_real_malloc actually does is set *first to the initial > previous block, and *first->next is the block we try to allocate > from. That allows us to keep all the data structures consistent. > > Document that. > > Signed-off-by: Daniel Axtens <d...@axtens.net>
Reviewed-by: Daniel Kiper <daniel.ki...@oracle.com> Daniel _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
