* gmalloc.c: Fix bug that causes malloc & free to

fail on systems where pointers have the high bit set (0x800efcf0
for example).  The problem is that the difference between two
pointers is a signed integer, so the computation

	(char *) 0x800efcf0 - (char *) 0

yields a negative value.  The sign of the result of the modulus
operator is machine dependent for negative operands, thus it is
possible for it to end up negative.  From Fred Fish.

diff --git a/gdb/gmalloc.c b/gdb/gmalloc.c
index d533eaa49602d27a58f8c3de00dc8f8a01c2afde..cfd657959702a72f6170bc4016070cda04882588 100755 (executable)
--- a/gdb/gmalloc.c
+++ b/gdb/gmalloc.c
@@ -559,7 +559,7 @@ DEFUN(__free, (ptr), PTR ptr)
          prev = (struct list *) ptr;
          _heapinfo[block].busy.info.frag.nfree = 1;
          _heapinfo[block].busy.info.frag.first = (unsigned int)
-           (((char *) ptr - (char *) NULL) % BLOCKSIZE >> type);
+           (((unsigned int)((char *) ptr - (char *) NULL)) % BLOCKSIZE >> type);
          prev->next = _fraghead[type].next;
          prev->prev = &_fraghead[type];
          prev->prev->next = prev;
@@ -656,7 +656,7 @@ DEFUN(align, (size), size_t size)
   unsigned int adj;
 
   result = (*__morecore)(size);
-  adj = (unsigned int) ((char *) result - (char *) NULL) % BLOCKSIZE;
+  adj = (unsigned int) ((unsigned int)((char *) result - (char *) NULL)) % BLOCKSIZE;
   if (adj != 0)
     {
       adj = BLOCKSIZE - adj;
@@ -770,7 +770,7 @@ DEFUN(malloc, (size), size_t size)
          block = BLOCK(result);
          if (--_heapinfo[block].busy.info.frag.nfree != 0)
            _heapinfo[block].busy.info.frag.first = (unsigned int)
-             (((char *) next->next - (char *) NULL) % BLOCKSIZE) >> log;
+             (((unsigned int)((char *) next->next - (char *) NULL)) % BLOCKSIZE) >> log;
 
          /* Update the statistics.  */
          ++_chunks_used;
@@ -1145,7 +1145,7 @@ DEFUN(valloc, (size), size_t size)
   result = malloc(size + pagesize);
   if (result == NULL)
     return NULL;
-  adj = (unsigned int) ((char *) result - (char *) NULL) % pagesize;
+  adj = (unsigned int) ((unsigned int)((char *) result - (char *) NULL)) % pagesize;
   if (adj != 0)
     result = (char *) result + pagesize - adj;
   return result;