[Olsr-dev] [PATCH v1 1/2] android: fix type punning warnings on IN6_IS_ADDR_V4MAPPED

[Hans-Christoph Steiner]

On 10/22/2012 04:59 AM, Ferry Huberts wrote:
> 
> 
> On 19-10-12 18:12, Hans-Christoph Steiner wrote:
>>
>> Android is not GNU and its not UNIX, so including a header from GNU seems like
>> a bad idea.  Android does not use GNU libc nor does it use BSD libc.  It uses
>> bionic libc.  Yes, Android uses the Linux kernel, but these headers are not
>> from the Linux kernel, they are related to libc.
>>
>> I think we'll have to do something ugly anyhow, unfortunately.  Maybe for
>> android, the v6 part of p->prefix.v6 will need to be defined the same way that
>> its done in the Android in6.h header and wrapped in a #ifdef __ANDROID__ #else
>>
> 
> I see no problem in doing it this way.
> However, if you want it different, then can you please show us that change/patch?
> 
> We're almost at the point of zero warnings after we fix this one, so why stop
> now?


Because preventing bugs is far more important than compiler warnings.
Compiler warnings are a useful tool, but never a goal.  Using the wrong
headers is a recipe for disaster, especially when the whole problem you are
trying to solve comes from differences in GNU libc and Android's bionic libc.

.hc


> 
> 
>> .hc
>>
>> On 10/19/2012 12:05 PM, Ferry Huberts wrote:
>>> From: Ferry Huberts <(spam-protected)>
>>>
>>> Signed-off-by: Ferry Huberts <(spam-protected)>
>>> ---
>>>   android/linux/olsr_netinet_in.h | 52
>>> +++++++++++++++++++++++++++++++++++++++++
>>>   src/ipcalc.h                    |  4 ++++
>>>   2 files changed, 56 insertions(+)
>>>   create mode 100644 android/linux/olsr_netinet_in.h
>>>
>>> diff --git a/android/linux/olsr_netinet_in.h b/android/linux/olsr_netinet_in.h
>>> new file mode 100644
>>> index 0000000..7500c80
>>> --- /dev/null
>>> +++ b/android/linux/olsr_netinet_in.h
>>> @@ -0,0 +1,52 @@
>>> +/* Copyright (C) 1991-2001, 2003, 2004, 2006, 2007, 2008, 2011
>>> +   Free Software Foundation, Inc.
>>> +   This file is part of the GNU C Library.
>>> +
>>> +   The GNU C Library is free software; you can redistribute it and/or
>>> +   modify it under the terms of the GNU Lesser General Public
>>> +   License as published by the Free Software Foundation; either
>>> +   version 2.1 of the License, or (at your option) any later version.
>>> +
>>> +   The GNU C Library is distributed in the hope that it will be useful,
>>> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
>>> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>>> +   Lesser General Public License for more details.
>>> +
>>> +   You should have received a copy of the GNU Lesser General Public
>>> +   License along with the GNU C Library; if not, write to the Free
>>> +   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
>>> +   02111-1307 USA.
>>> +
>>> +
>>> +   This is a stripped copy of netinet/in.h that includes only the
>>> +   IN6_IS_ADDR_V4MAPPED define. It is used to fix warnings on the
>>> +   Android build.
>>> +*/
>>> +
>>> +#ifndef    _OLSR_NETINET_IN_H
>>> +#define    _OLSR_NETINET_IN_H    1
>>> +
>>> +#ifdef IN6_IS_ADDR_V4MAPPED
>>> +  #undef IN6_IS_ADDR_V4MAPPED
>>> +#endif
>>> +
>>> +
>>> +#ifdef __GNUC__
>>> +
>>> +# define IN6_IS_ADDR_V4MAPPED(a) \
>>> +  (__extension__                                  \
>>> +   ({ __const struct in6_addr *__a = (__const struct in6_addr *)
>>> (a);          \
>>> +      __a->s6_addr32[0] == 0                              \
>>> +      && __a->s6_addr32[1] == 0                              \
>>> +      && __a->s6_addr32[2] == htonl (0xffff); }))
>>> +
>>> +#else
>>> +
>>> +# define IN6_IS_ADDR_V4MAPPED(a) \
>>> +    ((((__const uint32_t *) (a))[0] == 0)                      \
>>> +     && (((__const uint32_t *) (a))[1] == 0)                  \
>>> +     && (((__const uint32_t *) (a))[2] == htonl (0xffff)))
>>> +
>>> +#endif
>>> +
>>> +#endif    /* _OLSR_NETINET_IN_H */
>>> diff --git a/src/ipcalc.h b/src/ipcalc.h
>>> index 30b8068..4dde3f4 100644
>>> --- a/src/ipcalc.h
>>> +++ b/src/ipcalc.h
>>> @@ -49,6 +49,10 @@
>>>   #include <arpa/inet.h>
>>>   #include <netinet/in.h>
>>>
>>> +#ifdef __ANDROID__
>>> +  #include <linux/olsr_netinet_in.h>
>>> +#endif
>>> +
>>>   extern const struct olsr_ip_prefix ipv4_internet_route;
>>>   extern const struct olsr_ip_prefix ipv6_mappedv4_route;
>>>   extern const struct olsr_ip_prefix ipv6_internet_route;
>>>
>