add directory gnu

gnu/glibc/glibc-1.03/malloc/TODO

@@ -0,0 +1,20 @@
+0.  Access data structures with accessor macros, then turn the heapinfo
+into several arrays for faster access on machines with addressing modes.
+Also, this eventually raises the possibility of maintaining multiple
+heaps.
+1.  Possible heuristic to catch multiple frees.  Introduce an extra word
+of heapinfo that says whether the remaining info is for something
+busy or something free.  Then we can catch attempts to free already-free
+large blocks, as well as things not belonging to malloc at all.  In the
+case of a fragment, we can check if the fragment looks like it *already*
+belongs to the fragment list, by comparing it with the "first" fragment
+of the block, or checking its "prev" pointer to see if it points into
+the block.  Then if it looks like it might we can exhaustively search
+the block's free list to see if the fragment is there or not.  Extending
+the heapinfo structure would have the benefit of making it a power of
+two and thus making array indexing faster, perhaps.  Suitably adapted,
+this heuristic could also catch invalid pointers passed to realloc.
+
+All of these additional features require the inclusion of <malloc.h>.
+3.  indirect reference allocator: ialloc(), ifree(), irealloc().
+4.  garbage collecting allocator: galloc(), garbage(), gfree(), grealloc().