From: Herton Ronaldo Krzesinski <herton@mandriva.com.br>
To: linux-wireless@vger.kernel.org
Subject: Build problem when using linux/wireless.h header
Date: Mon, 18 Feb 2008 14:49:01 -0300
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Message-Id: <200802181449.03719.herton@mandriva.com.br> (sfid-20080218_174919_220100_D5CA8064)
Sender: linux-wireless-owner@vger.kernel.org

An error when building airpwn (airpwn.sf.net) was reported to me:

In file included from airpwn.c:36:
/usr/include/linux/wireless.h:886: error: 'IFNAMSIZ' undeclared here (not in a 
function)
airpwn.c: In function 'process_ip_packet':
airpwn.c:482: warning: ignoring return value of 'write', declared with 
attribute warn_unused_result
airpwn.c:483: warning: ignoring return value of 'write', declared with 
attribute warn_unused_result
airpwn.c:484: warning: ignoring return value of 'write', declared with 
attribute warn_unused_result
make[1]: *** [airpwn.o] Error 1

This is on a system with sanitized kernel headers installed. airpwn uses 
<linux/wireless.h>. The problem here is that wireless.h have:

#ifdef __KERNEL__
#include <linux/types.h>                /* for "caddr_t" et al          */
#include <linux/socket.h>               /* for "struct sockaddr" et al  */
#include <linux/if.h>                   /* for IFNAMSIZ and co... */
#endif  /* __KERNEL__ */

This when exported to user space is removed, but they are needed later on, 
otherwise you get build problems when using this header. One can say that the 
program including wireless.h should include manually the required headers, 
but doesn't seem very nice. Also wireless-tools include a copy of wireless.h, 
seems an unecessary duplication. So what about doing this:

- Don't export wireless.h from kernel to user space, since wireless-tools 
already provide it.
- Patch wireless-tools to include missing headers like this patch:

diff -p -up wireless_tools.29/wireless.21.h.orig wireless_tools.29/wireless.21.h
--- wireless_tools.29/wireless.21.h.orig	2008-02-18 13:19:47.000000000 -0300
+++ wireless_tools.29/wireless.21.h	2008-02-18 13:20:44.000000000 -0300
@@ -76,6 +76,10 @@
 #include <linux/types.h>		/* for "caddr_t" et al		*/
 #include <linux/socket.h>		/* for "struct sockaddr" et al	*/
 #include <linux/if.h>			/* for IFNAMSIZ and co... */
+#else
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <net/if.h>
 #endif	/* __KERNEL__ */
 
 /***************************** VERSION *****************************/
diff -p -up wireless_tools.29/wireless.22.h.orig wireless_tools.29/wireless.22.h
--- wireless_tools.29/wireless.22.h.orig	2008-02-18 13:19:53.000000000 -0300
+++ wireless_tools.29/wireless.22.h	2008-02-18 13:21:00.000000000 -0300
@@ -76,6 +76,10 @@
 #include <linux/types.h>		/* for "caddr_t" et al		*/
 #include <linux/socket.h>		/* for "struct sockaddr" et al	*/
 #include <linux/if.h>			/* for IFNAMSIZ and co... */
+#else
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <net/if.h>
 #endif	/* __KERNEL__ */
 
 /***************************** VERSION *****************************/

--
[]'s
Herton