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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 <dja@axtens.net> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This is GRUB 2, the second version of the GRand Unified Bootloader. GRUB 2 is rewritten from scratch to make GNU GRUB cleaner, safer, more robust, more powerful, and more portable. See the file NEWS for a description of recent changes to GRUB 2. See the file INSTALL for instructions on how to build and install the GRUB 2 data and program files. See the file MAINTAINERS for information about the GRUB maintainers, etc. If you found a security vulnerability in the GRUB please check the SECURITY file to get more information how to properly report this kind of bugs to the maintainers. Please visit the official web page of GRUB 2, for more information. The URL is <http://www.gnu.org/software/grub/grub.html>. More extensive documentation is available in the Info manual, accessible using 'info grub' after building and installing GRUB 2. There are a number of important user-visible differences from the first version of GRUB, now known as GRUB Legacy. For a summary, please see: info grub Introduction 'Changes from GRUB Legacy'