4922 all calloc() implementations should check for overflow

*** 22,49 ****
  /*
   * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  
- #pragma ident   "%Z%%M% %I%     %E% SMI"
- 
  #include <stdlib.h>
  #include <string.h>
  /*
   * calloc - allocate and clear memory block
   */
  
  void *
  calloc(size_t num, size_t size)
  {
          void *mp;
  
!         num *= size;
!         mp = malloc(num);
          if (mp == NULL)
                  return (NULL);
!         (void) memset(mp, 0, num);
          return (mp);
  }
  
  /*ARGSUSED*/
  void
--- 22,61 ----
  /*
   * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  
  #include <stdlib.h>
  #include <string.h>
+ #include <errno.h>
+ 
  /*
   * calloc - allocate and clear memory block
   */
  
  void *
  calloc(size_t num, size_t size)
  {
          void *mp;
+         size_t total;
+ 
+         if (num == 0 || size == 0) {
+                 total = 0;
+         } else {
+                 total = num * size;
+ 
+                 /* check for overflow */
+                 if ((total / num) != size) {
+                         errno = ENOMEM;
+                         return (NULL);
+                 }
+         }
  
!         mp = malloc(total);
          if (mp == NULL)
                  return (NULL);
!         (void) memset(mp, 0, total);
          return (mp);
  }
  
  /*ARGSUSED*/
  void