Re: [Qemu-devel] [PATCH] configure: Define NCURSES_WIDECHAR if we're using curses

[Kamil Rytarowski <n54@gmx.com>]

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On 02.06.2017 23:58, Laszlo Ersek wrote:
> On 06/02/17 16:35, Peter Maydell wrote:
>> We want the wide character functions from the ncurses header.
>> Unfortunately it doesn't provide them by default, but only
>> if either:
>>  * NCURSES_WIDECHAR is defined (for ncurses 20111030 and up)
>>  * _XOPEN_SOURCE/_XOPEN_SOURCE_EXTENDED are suitably defined
>>
>> So far we have been implicitly relying on the latter, because
>> for GNU libc when we define _GNU_SOURCE this causes libc
>> to define the _XOPEN_SOURCE macros for us. Unfortunately
>> this doesn't work on all libcs, because some (like OSX and
>> musl libc) do not define _XOPEN_SOURCE when _GNU_SOURCE
>> is defined.
>>
>> We can't fix this by defining _XOPEN_SOURCE ourselves, because
>> that also means "and don't provide any functions that aren't in
>> that standard", and not all libcs provide any way to override
>> that to also get the non-standard functions. In particular
>> FreeBSD has no such mechanism, and OSX's _DARWIN_C_SOURCE
>> doesn't reenable everything (for instance getpagesize()
>> is still not prototyped if _DARWIN_C_SOURCE and _XOPEN_SOURCE
>> are both defined).
>>
>> So we have to define NCURSES_WIDECHAR. (This will only work
>> if your ncurses is at least 20111030, as older versions
>> don't honour this macro.)
>>
>> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
>> ---
>> Testing from the people with musl libc and OSX-with-ncurses
>> appreciated, as I don't have any systems which have the bug
>> which this patch is attempting to fix...
>>
>>  configure | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/configure b/configure
>> index 0586ec9..6aca5d1 100755
>> --- a/configure
>> +++ b/configure
>> @@ -3053,6 +3053,8 @@ int main(void) {
>>  EOF
>>    IFS=:
>>    for curses_inc in $curses_inc_list; do
>> +    # Make sure we get the wide character prototypes
>> +    curses_inc="-DNCURSES_WIDECHAR $curses_inc"
>>      IFS=:
>>      for curses_lib in $curses_lib_list; do
>>        unset IFS
>>
> 
> Given that we're already consciously using non-portable functions, this
> solution looks the least messy to me.
> 

These functions are enough portable to work on NetBSD curses(3).

pkgsrc had an equivalent patch to define NCURSES_WIDECHAR=1 to fix build
on Darwin.

> Acked-by: Laszlo Ersek <lersek@redhat.com>
> 
> Thanks
> Laszlo
> 



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