Path: utzoo!censor!geac!jtsv16!uunet!husc6!bloom-beacon!earth.cray.COM!jlf
From: jlf@earth.cray.COM (John Freeman)
Newsgroups: comp.windows.x
Subject: Re: XtAppCreateShell. What am I doing wrong?
Message-ID: <8906051426.AA08822@thelake.cray.com>
Date: 5 Jun 89 14:26:17 GMT
Organization: The Internet
Lines: 50

> I notice that Xlib has code surrounded by #ifdefs on the preprocessor
> variable "MALLOC_0_RETURNS_NULL".  Very nice for SVIDish systems.  I
> also noticed (via the aforementioned error message) that the toolkit
> was not quite so, 
> 
> I have no idea whether this could be the problem the original poster
> was facing, but if so...just go into Xt/Alloc.c and make sure all the
> allocation routines check for requests for 0 bytes, and pass on to
> the libc equivalents requests for 1 (or more) bytes instead.

The port of the toolkit by Cray Research does exactly what you
suggest in Xt/Alloc.c.  Here are the diffs:

-------------------------------------------------------------------------------
diff -c ~/X11R3/lib/Xt/Alloc.c .
*** /usr/earth3/jlf/X11R3/lib/Xt/Alloc.c        Tue Sep  6 15:26:46 1988
--- ./Alloc.c   Mon Dec 19 17:37:54 1988
***************
*** 41,46 ****
--- 41,47 ----
      unsigned size;
  {
      char *ptr;
+     if (size == 0) size = 1;
      if ((ptr = malloc(size)) == NULL)
          XtErrorMsg("allocError","malloc","XtToolkitError",
                   "Cannot perform malloc", (String *)NULL, (Cardinal *)NULL);
***************
*** 51,56 ****
--- 52,58 ----
      char     *ptr;
      unsigned size;
  {
+    if (size == 0) size = 1;
     if (ptr == NULL) return(XtMalloc(size));
     else if ((ptr = realloc(ptr, size)) == NULL)
              XtErrorMsg("allocError","realloc","XtToolkitError",
***************
*** 62,67 ****
--- 64,73 ----
      unsigned num, size;
  {
      char *ptr;
+     if ((size == 0) || (num == 0)) {
+       size = 1;
+       num = 1;
+     }
      if ((ptr = calloc(num, size)) == NULL)
           XtErrorMsg("allocError","calloc","XtToolkitError",
                  "Cannot perform calloc", (String *)NULL, (Cardinal *)NULL);