+void *mh_xrealloc(void *ptr, size_t size);
+
+/* Call calloc(3), exiting on NULL return. */
+void *mh_xcalloc(size_t nelem, size_t elsize);
+
+/* Duplicate a NUL-terminated string, exit on failure. */
+char *mh_xstrdup(const char *src);
+
+/* Call free(3), if ptr isn't NULL. */
+void mh_xfree(void *ptr);
+
+/* Set p to point to newly allocated, uninitialised, memory. */
+#define NEW(p) ((p) = mh_xmalloc(sizeof *(p)))
+
+/* Set p to point to newly allocated, zeroed, memory. */
+#define NEW0(p) ((p) = mh_xcalloc(1, sizeof *(p)))