[Patch] cygheap.cc: Allow _crealloc to shrink memory-block.

[Bas van Gompel]

Hi,

Following (trivial IMO) patch, allows memory blocks on the cygheap to
be shrunk.

There are some issues with this:
- The code is slightly slower.
- This change is in a block of code marked ``copyright D. J. Delorie''.
- I'm not sure _crealloc is ever called with a smaller size. (If it
  isn't, this patch is useless.)

(I did test this, and it WJFFM.)


ChangeLog-entry:

20040-10-13  Bas van Gompel  <[EMAIL PROTECTED]>

        * cygheap.cc (_crealloc): Allow memory-block to shrink.


--- src/winsup/cygwin/cygheap.cc        2 Jun 2004 21:20:53 -0000       1.103
+++ src/winsup/cygwin/cygheap.cc        12 Oct 2004 02:43:30 -0000
@@ -324,16 +324,22 @@ _cfree (void *ptr)
 static void *__stdcall
 _crealloc (void *ptr, unsigned size)
 {
+  unsigned sz;
   void *newptr;
   if (ptr == NULL)
     newptr = _cmalloc (size);
   else
     {
       unsigned oldsize = 1 << to_cmalloc (ptr)->b;
-      if (size <= oldsize)
+
+     /* Calculate size as a power of two. */
+      for (sz = 8; sz && sz < size; sz <<= 1)
+       continue;
+
+      if (sz == oldsize)
        return ptr;
       newptr = _cmalloc (size);
-      memcpy (newptr, ptr, oldsize);
+      memcpy (newptr, ptr, min(sz, oldsize));
       _cfree (ptr);
     }
   return newptr;


Buzz.
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