[PATCH] Fix userspace compilation of ip_tables.h/ip6_tables.h in C++ mode

The implicit cast from void * is not allowed for C++ compilers, and the
arithmetic on void * generates warnings in C++ mode.

$ g++ -c t.cc
ip_tables.h:221:24: warning: pointer of type 'void *' used in arithmetic
ip_tables.h:221:24: error: invalid conversion from 'void*' to 'xt_entry_target*'

Signed-off-by: Jason Gunthorpe <redacted>
---
 include/linux/netfilter_ipv4/ip_tables.h  |    2 +-
 include/linux/netfilter_ipv6/ip6_tables.h |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/netfilter_ipv4/ip_tables.h b/include/linux/netfilter_ipv4/ip_tables.h
index db79231..050ad8a 100644
--- a/include/linux/netfilter_ipv4/ip_tables.h
+++ b/include/linux/netfilter_ipv4/ip_tables.h

@@ -226,7 +226,7 @@ struct ipt_get_entries {
 static __inline__ struct xt_entry_target *
 ipt_get_target(struct ipt_entry *e)
 {
-	return (void *)e + e->target_offset;
+	return (struct xt_entry_target *)((__u8 *)e + e->target_offset);
 }
 
 /*

diff --git a/include/linux/netfilter_ipv6/ip6_tables.h b/include/linux/netfilter_ipv6/ip6_tables.h
index 08c2cbb..3349bf1 100644
--- a/include/linux/netfilter_ipv6/ip6_tables.h
+++ b/include/linux/netfilter_ipv6/ip6_tables.h

@@ -263,7 +263,7 @@ struct ip6t_get_entries {
 static __inline__ struct xt_entry_target *
 ip6t_get_target(struct ip6t_entry *e)
 {
-	return (void *)e + e->target_offset;
+	return (struct xt_entry_target *)((__u8 *)e + e->target_offset);
 }
 
 /*

-- 
1.7.4.1

From: Jason Gunthorpe <redacted>
Date: Sun, 30 Sep 2012 17:17:37 -0600

The implicit cast from void * is not allowed for C++ compilers, and the
arithmetic on void * generates warnings in C++ mode.

$ g++ -c t.cc
ip_tables.h:221:24: warning: pointer of type 'void *' used in arithmetic
ip_tables.h:221:24: error: invalid conversion from 'void*' to 'xt_entry_target*'

Signed-off-by: Jason Gunthorpe <redacted>

Please post netfilter patches to netfilter-devel@vger.kernel.org

Thank you.