The shuffle descriptors need to be unused for input *and* output

The memory used to hold shuffle descriptors must be unused during the
entire execution of the shuffle sequence, and therefore needs to be
free at input *and* output time.

Once we have picked a region for the shuffle descriptors, we can free
this working copy and start over with a clean memory map, the only
thing we do there is mark as reserved the memory used by the
descriptors.

diff --git a/com32/lib/syslinux/shuffle.c b/com32/lib/syslinux/shuffle.c
index 708382c..cb2751a 100644 (file)
--- a/com32/lib/syslinux/shuffle.c
+++ b/com32/lib/syslinux/shuffle.c
@@ -89,17 +89,28 @@ int syslinux_prepare_shuffle(struct syslinux_movelist *fraglist,
       nzero++;
   }
 
+  /* Find the larges contiguous region unused by input *and* output;
+     this is where we put the move descriptor list */
+
   rxmap = syslinux_dup_memmap(memmap);
+  if (!rxmap)
+    goto bail;
   for (mp = fraglist; mp; mp = mp->next) {
-    if (syslinux_add_memmap(&rxmap, mp->src, mp->len, SMT_ALLOC))
+    if (syslinux_add_memmap(&rxmap, mp->src, mp->len, SMT_ALLOC) ||
+       syslinux_add_memmap(&rxmap, mp->dst, mp->len, SMT_ALLOC))
       goto bail;
   }
-    
   if (syslinux_memmap_largest(rxmap, SMT_FREE, &desczone, &descfree))
     goto bail;
 
+  syslinux_free_memmap(rxmap);
+
   dprintf("desczone = 0x%08x, descfree = 0x%08x\n", desczone, descfree);
 
+  rxmap = syslinux_dup_memmap(memmap);
+  if (!rxmap)
+    goto bail;
+
   desc_blocks = (nzero+DESC_BLOCK_SIZE)/(DESC_BLOCK_SIZE-1);
   for (;;) {
     addr_t descmem = desc_blocks*
@@ -108,8 +119,9 @@ int syslinux_prepare_shuffle(struct syslinux_movelist *fraglist,
     if (descfree < descmem)
       goto bail;               /* No memory block large enough */
 
+    /* Mark memory used by shuffle descriptors as reserved */
     descaddr = desczone + descfree - descmem;
-    if (syslinux_add_memmap(&rxmap, descaddr, descmem, SMT_ALLOC))
+    if (syslinux_add_memmap(&rxmap, descaddr, descmem, SMT_RESERVED))
       goto bail;
 
 #if DEBUG
@@ -118,7 +130,7 @@ int syslinux_prepare_shuffle(struct syslinux_movelist *fraglist,
 
     if (syslinux_compute_movelist(&moves, fraglist, rxmap))
       goto bail;
-    
+
     nmoves = 0;
     for (mp = moves; mp; mp = mp->next)
       nmoves++;
@@ -182,7 +194,7 @@ int syslinux_prepare_shuffle(struct syslinux_movelist *fraglist,
        dp++; np++;
        nb = 0;
       }
-      
+
       dp->dst = ml->start;
       dp->src = (addr_t)-1;    /* bzero region */
       dp->len = ml->next->start - ml->start;