[Bug-gnulib] Patch proposal: 1-gary-safe-xfree.patch

[Gary V. Vaughan]

Flushing some changes I have in GNU m4 upstream :-)

Okay to commit?

This patch does change the semantics of XFREE slightly, but in a beneficial 
way.  Maybe XFREE should still be a macroised xfree for speed, and the XFREE 
implementation in this patch renamed to DELETE or something?  It is nice to 
have an xfree function to use for callbacks that autofree etc. when you still 
need the NULL safety.

Cheers,
        Gary.
--
  ())_.  Gary V. Vaughan    gary@(lilith.warpmail.net|gnu.org)
  ( '/   Research Scientist http://www.oranda.demon.co.uk       ,_())____
  / )=   GNU Hacker         http://www.gnu.org/software/libtool  \'      `&
`(_~)_   Tech' Author       http://sources.redhat.com/autobook   =`---d__/

Index: ChangeLog
from  Gary V. Vaughan  <address@hidden>

        * lib/xalloc.h (xfree): Make XFREE a function, without the
        disadvantage of multiple argument expansions.
        (XFREE): Use it to zero out freed variables.
        * lib/xmalloc.c (xfree): New function.

Index: lib/xalloc.h
===================================================================
RCS file: /cvsroot/gnulib/gnulib/lib/xalloc.h,v
retrieving revision 1.16
diff -u -p -u -r1.16 xalloc.h
--- lib/xalloc.h 22 Jul 2003 22:10:56 -0000 1.16
+++ lib/xalloc.h 10 Sep 2003 15:59:01 -0000
@@ -53,19 +53,21 @@ void *xcalloc (size_t n, size_t s);
 void *xrealloc (void *p, size_t n);
 char *xstrdup (const char *str);
 
+/* Only free P if it is non-NULL.  Unlike free(), this function
+   always returns NULL so that you can easily reset the address of any
+   variable whose memory you free:
+      foo = xfree (foo);
+   You can pass it to callbacks requiring free() if necessary:
+      lt_dlfree = (void (*)(void *)) xfree; */
+void *xfree (void *p);
+
 # define XMALLOC(Type, N_items) xmalloc (sizeof (Type) * (N_items))
 # define XCALLOC(Type, N_items) xcalloc (sizeof (Type), N_items)
 # define XREALLOC(Ptr, Type, N_items) xrealloc (Ptr, sizeof (Type) * (N_items))
+# define XFREE(Var)            ((Var) = xfree (Var))
 
 /* Declare and alloc memory for VAR of type TYPE. */
 # define NEW(Type, Var)  Type *(Var) = XMALLOC (Type, 1)
-
-/* Free VAR only if non NULL. */
-# define XFREE(Var)    \
-   do {                 \
-      if (Var)          \
-        free (Var);     \
-   } while (0)
 
 /* Return a pointer to a malloc'ed copy of the array SRC of NUM elements. */
 # define CCLONE(Src, Num) \
Index: lib/xmalloc.c
===================================================================
RCS file: /cvsroot/gnulib/gnulib/lib/xmalloc.c,v
retrieving revision 1.25
diff -u -p -u -r1.25 xmalloc.c
--- lib/xmalloc.c 22 Jul 2003 22:10:56 -0000 1.25
+++ lib/xmalloc.c 10 Sep 2003 15:59:01 -0000
@@ -110,3 +110,14 @@ xcalloc (size_t n, size_t s)
     xalloc_die ();
   return p;
 }
+
+/* Only free P if non-NULL.  */
+
+void *
+xfree (void *p)
+{
+  if (p)
+    free (p);
+  return 0;
+}
+