xap_helper: use _OPENBSD_SOURCE on NetBSD for reallocarray

NetBSD prefers reallocarr(3) for predictable zero-sized
allocation behavior; but no other OS seems to have reallocarr(3).
reallocarray(3) appears in by OpenBSD, FreeBSD, glibc, and musl,
so continue to go with that.

diff --git a/lib/PublicInbox/xap_helper.h b/lib/PublicInbox/xap_helper.h
index 3f45e1c7054235d3893d6cb2265e5cfb79ae71c4..add2fe8ca7d586316052a1ce0d9cf2d936d42d94 100644 (file)
--- a/lib/PublicInbox/xap_helper.h
+++ b/lib/PublicInbox/xap_helper.h
@@ -14,6 +14,9 @@
 #ifndef _ALL_SOURCE
 #      define _ALL_SOURCE
 #endif
+#if defined(__NetBSD__) && !defined(_OPENBSD_SOURCE) // for reallocarray(3)
+#      define _OPENBSD_SOURCE
+#endif
 #include <sys/file.h>
 #include <sys/mman.h>
 #include <sys/resource.h>