sync code with last improvements from OpenBSD

proto/xorgproto/include/X11/Xalloca.h

@@ -0,0 +1,121 @@
+/*
+
+Copyright 1995, 1998  The Open Group
+
+Permission to use, copy, modify, distribute, and sell this software and its
+documentation for any purpose is hereby granted without fee, provided that
+the above copyright notice appear in all copies and that both that
+copyright notice and this permission notice appear in supporting
+documentation.
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR
+OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
+
+Except as contained in this notice, the name of The Open Group shall
+not be used in advertising or otherwise to promote the sale, use or
+other dealings in this Software without prior written authorization
+from The Open Group.
+
+*/
+/*
+ * The purpose of this header is to define the macros ALLOCATE_LOCAL and
+ * DEALLOCATE_LOCAL appropriately for the platform being compiled on.
+ * These macros are used to make fast, function-local memory allocations.
+ * Their characteristics are as follows:
+ *
+ * void *ALLOCATE_LOCAL(size_t size)
+ *    Returns a pointer to size bytes of memory, or NULL if the allocation
+ *    failed.  The memory must be freed with DEALLOCATE_LOCAL before the
+ *    function that made the allocation returns.  You should not ask for
+ *    large blocks of memory with this function, since on many platforms
+ *    the memory comes from the stack, which may have limited size.
+ *
+ * void DEALLOCATE_LOCAL(void *)
+ *    Frees the memory allocated by ALLOCATE_LOCAL.  Omission of this
+ *    step may be harmless on some platforms, but will result in
+ *    memory leaks or worse on others.
+ *
+ * Before including this file, you should define two macros,
+ * ALLOCATE_LOCAL_FALLBACK and DEALLOCATE_LOCAL_FALLBACK, that have the
+ * same characteristics as ALLOCATE_LOCAL and DEALLOCATE_LOCAL.  The
+ * header uses the fallbacks if it doesn't know a "better" way to define
+ * ALLOCATE_LOCAL and DEALLOCATE_LOCAL.  Typical usage would be:
+ *
+ *    #define ALLOCATE_LOCAL_FALLBACK(_size) malloc(_size)
+ *    #define DEALLOCATE_LOCAL_FALLBACK(_ptr) free(_ptr)
+ *    #include "Xalloca.h"
+ */
+
+#ifndef XALLOCA_H
+#define XALLOCA_H 1
+
+#ifndef INCLUDE_ALLOCA_H
+/* Need to add more here to match Imake *.cf's */
+# if defined(HAVE_ALLOCA_H) || defined(__SUNPRO_C) || defined(__SUNPRO_CC)
+#  define INCLUDE_ALLOCA_H
+# endif
+#endif
+
+#ifdef INCLUDE_ALLOCA_H
+#  include <alloca.h>
+#endif
+
+#ifndef NO_ALLOCA
+/*
+ * os-dependent definition of local allocation and deallocation
+ * If you want something other than (DE)ALLOCATE_LOCAL_FALLBACK
+ * for ALLOCATE/DEALLOCATE_LOCAL then you add that in here.
+ */
+
+
+#  ifdef __GNUC__
+#    ifndef alloca
+#      define alloca __builtin_alloca
+#    endif /* !alloca */
+#    define ALLOCATE_LOCAL(size) alloca((size_t)(size))
+#  else /* ! __GNUC__ */
+
+/*
+ * warning: old mips alloca (pre 2.10) is unusable, new one is built in
+ * Test is easy, the new one is named __builtin_alloca and comes
+ * from alloca.h which #defines alloca.
+ */
+#      if defined(__sun) || defined(alloca)
+/*
+ * Some System V boxes extract alloca.o from /lib/libPW.a; if you
+ * decide that you don't want to use alloca, you might want to fix it here.
+ */
+/* alloca might be a macro taking one arg (hi, Sun!), so give it one. */
+#        if !defined(__cplusplus)
+#          define __Xnullarg		/* as nothing */
+           extern void *alloca(__Xnullarg);
+#        endif
+#        define ALLOCATE_LOCAL(size) alloca((size_t)(size))
+#      endif /* who does alloca */
+#  endif /* __GNUC__ */
+
+#endif /* NO_ALLOCA */
+
+#if !defined(ALLOCATE_LOCAL)
+#  if defined(ALLOCATE_LOCAL_FALLBACK) && defined(DEALLOCATE_LOCAL_FALLBACK)
+#    define ALLOCATE_LOCAL(_size)  ALLOCATE_LOCAL_FALLBACK(_size)
+#    define DEALLOCATE_LOCAL(_ptr) DEALLOCATE_LOCAL_FALLBACK(_ptr)
+#  else /* no fallbacks supplied; error */
+#    define ALLOCATE_LOCAL(_size)  ALLOCATE_LOCAL_FALLBACK undefined!
+#    define DEALLOCATE_LOCAL(_ptr) DEALLOCATE_LOCAL_FALLBACK undefined!
+#  endif /* defined(ALLOCATE_LOCAL_FALLBACK && DEALLOCATE_LOCAL_FALLBACK) */
+#else
+#  if !defined(DEALLOCATE_LOCAL)
+#    define DEALLOCATE_LOCAL(_ptr) do {} while(0)
+#  endif
+#endif /* defined(ALLOCATE_LOCAL) */
+
+#endif /* XALLOCA_H */