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-rw-r--r--lib/xalloc.h20
1 files changed, 19 insertions, 1 deletions
diff --git a/lib/xalloc.h b/lib/xalloc.h
index f80977e30..b743d6843 100644
--- a/lib/xalloc.h
+++ b/lib/xalloc.h
@@ -1,7 +1,7 @@
/* xalloc.h -- malloc with out-of-memory checking
Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
- 1999, 2000, 2003, 2004 Free Software Foundation, Inc.
+ 1999, 2000, 2003, 2004, 2005 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@@ -56,6 +56,24 @@ void *x2nrealloc (void *p, size_t *pn, size_t s);
void *xmemdup (void const *p, size_t s);
char *xstrdup (char const *str);
+/* Verify a requirement at compile-time (unlike assert, which is runtime). */
+# undef VERIFY_EXPR
+# define VERIFY_EXPR(assertion) \
+ (void)((struct {char a[(assertion) ? 1 : -1]; } *) 0)
+
+/* This is simply a shorthand for the common case in which
+ the third argument to x2nrealloc would be `sizeof (*P)'.
+ Ensure that sizeof (*P) is *not* 1. In that case, it'd be
+ better to use X2REALLOC, although not strictly necessary. */
+# define X2NREALLOC(P, PN) (VERIFY_EXPR (sizeof(*P) != 1), \
+ x2nrealloc (P, PN, sizeof (*P)))
+
+/* Using x2realloc (when appropriate) usually makes your code more
+ readable than using x2nrealloc, but it also makes it so your
+ code will malfunction if sizeof (*P) ever becomes 2 or greater.
+ So use this macro instead of using x2realloc directly. */
+# define X2REALLOC(P, PN) (VERIFY_EXPR (sizeof(*P) == 1), x2realloc (P, PN))
+
/* Return 1 if an array of N objects, each of size S, cannot exist due
to size arithmetic overflow. S must be positive and N must be
nonnegative. This is a macro, not an inline function, so that it