net/if.h check fails on some darwin versions

[jmroot]

The autoconf manual mentions a portability issue with checking for net/if.h: https://www.gnu.org/software/autoconf/manual/autoconf-2.69/html_node/Header-Portability.html

Specifically, sys/socket.h must be included first. On some darwin versions, AC_INCLUDES_DEFAULT happens to take care of this, but on other versions, net/if.h is not found currently, leading to build failure.

This seems to fix the problem, using the recommended check from the autoconf manual:

--- configure.ac.orig	2020-10-08 17:24:21.000000000 +1100
+++ configure.ac	2020-10-15 05:10:19.000000000 +1100
@@ -399,7 +399,21 @@
 PKG_PROG_PKG_CONFIG
 
 # Checks for header files.
-AC_CHECK_HEADERS([stdarg.h stdbool.h netinet/in.h netinet/tcp.h sys/param.h sys/select.h sys/socket.h sys/un.h sys/uio.h sys/resource.h arpa/inet.h syslog.h netdb.h sys/wait.h pwd.h glob.h grp.h login_cap.h winsock2.h ws2tcpip.h endian.h sys/endian.h libkern/OSByteOrder.h sys/ipc.h sys/shm.h ifaddrs.h net/if.h],,, [AC_INCLUDES_DEFAULT])
+AC_CHECK_HEADERS([stdarg.h stdbool.h netinet/in.h netinet/tcp.h sys/param.h sys/select.h sys/socket.h sys/un.h sys/uio.h sys/resource.h arpa/inet.h syslog.h netdb.h sys/wait.h pwd.h glob.h grp.h login_cap.h winsock2.h ws2tcpip.h endian.h sys/endian.h libkern/OSByteOrder.h sys/ipc.h sys/shm.h ifaddrs.h],,, [AC_INCLUDES_DEFAULT])
+AC_CHECK_HEADERS([net/if.h], [], [],
+          [#include <stdio.h>
+          #ifdef STDC_HEADERS
+          # include <stdlib.h>
+          # include <stddef.h>
+          #else
+          # ifdef HAVE_STDLIB_H
+          #  include <stdlib.h>
+          # endif
+          #endif
+          #ifdef HAVE_SYS_SOCKET_H
+          # include <sys/socket.h>
+          #endif
+          ])
 
 # Check for Apple header. This uncovers TARGET_OS_IPHONE, TARGET_OS_TV or TARGET_OS_WATCH
 AC_CHECK_HEADERS([TargetConditionals.h])

[gthess]

Thanks!