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Re: [PATCH v9 04/26] win32: Simplify gmtime_r detection direct base on _


From: Yonggang Luo
Subject: Re: [PATCH v9 04/26] win32: Simplify gmtime_r detection direct base on _POSIX_THREAD_SAFE_FUNCTIONS.
Date: Tue, 15 Sep 2020 21:23:05 +0800



On Tue, Sep 15, 2020 at 9:00 PM Daniel P. Berrangé <berrange@redhat.com> wrote:
>
> On Tue, Sep 15, 2020 at 08:12:56PM +0800, Yonggang Luo wrote:
> > First, this reduce the size of configure, configure are tending to removal in future,
> > and this didn't introduce any new feature or remove any exist feature.
> > Second, the current localtime_r detection are conflict with ncursesw detection in
> > mingw, when ncursesw detected, it will provide the following compile flags
> > pkg-config --cflags ncursesw
> > -D_XOPEN_SOURCE=600 -D_POSIX_C_SOURCE=199506L -IC:/CI-Tools/msys64/mingw64/include/ncursesw
> > And the compile flag _POSIX_C_SOURCE will always cause _POSIX_THREAD_SAFE_FUNCTIONS to
> > be defined, in new version of mingw, that's will cause localtime_r to be defined.
> > But the configure script didn't provide _POSIX_C_SOURCE macro, and that's will result
> > localtime_r not detected because localtime_r are defined in forceinline manner.
>
> ncursesw is just one of the three curses impls we can select for
> building against, so it doesn't feel right to make an assumption
> that _POSIX_C_SOURCE is always defined.

That's what I am trying to do, not depends on if  _POSIX_C_SOURCE are defined.
After this patch, whenever   ncursesw or other  curses lib trying define or not define  _POSIX_C_SOURCE, the source will building properly
Because now, we don't make any assumption about  _POSIX_C_SOURCE, but before this patch,
The configure always assume msys2/mingw `not define _POSIX_C_SOURCE ` at all.
Now this restriction are removed, only depends on mingw related  _POSIX_THREAD_SAFE_FUNCTIONS
>
> >
> > And finally cause conflict between QEMU defined localtime_r
> > struct tm *localtime_r(const time_t *timep, struct tm *result);
> > with mingw defined localtime_r
> >
> > ```
> > #if defined(_POSIX_C_SOURCE) && !defined(_POSIX_THREAD_SAFE_FUNCTIONS)
> > #define _POSIX_THREAD_SAFE_FUNCTIONS 200112L
> > #endif
> >
> > #ifdef _POSIX_THREAD_SAFE_FUNCTIONS
> > __forceinline struct tm *__CRTDECL localtime_r(const time_t *_Time, struct tm *_Tm) {
> >   return localtime_s(_Tm, _Time) ? NULL : _Tm;
> > }
> > __forceinline struct tm *__CRTDECL gmtime_r(const time_t *_Time, struct tm *_Tm) {
> >   return gmtime_s(_Tm, _Time) ? NULL : _Tm;
> > }
> > __forceinline char *__CRTDECL ctime_r(const time_t *_Time, char *_Str) {
> >   return ctime_s(_Str, 0x7fffffff, _Time) ? NULL : _Str;
> > }
> > __forceinline char *__CRTDECL asctime_r(const struct tm *_Tm, char * _Str) {
> >   return asctime_s(_Str, 0x7fffffff, _Tm) ? NULL : _Str;
> > }
> > #endif
> > ```
> >
> > So I suggest remove this configure script, and restrict msys2/mingw version to easy to maintain.
> > And use _POSIX_THREAD_SAFE_FUNCTIONS to guard the localtime_r and counterpart functions
> >
> > Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
> > ---
> >  configure                 | 34 ----------------------------------
> >  include/sysemu/os-win32.h |  4 ++--
> >  util/oslib-win32.c        |  2 +-
> >  3 files changed, 3 insertions(+), 37 deletions(-)
> >
> > diff --git a/configure b/configure
> > index dc4b7a2e55..bac48b5b49 100755
> > --- a/configure
> > +++ b/configure
> > @@ -2496,37 +2496,6 @@ if test "$vhost_net" = ""; then
> >    test "$vhost_kernel" = "yes" && vhost_net=yes
> >  fi
> >
> > -##########################################
> > -# MinGW / Mingw-w64 localtime_r/gmtime_r check
> > -
> > -if test "$mingw32" = "yes"; then
> > -    # Some versions of MinGW / Mingw-w64 lack localtime_r
> > -    # and gmtime_r entirely.
> > -    #
> > -    # Some versions of Mingw-w64 define a macro for
> > -    # localtime_r/gmtime_r.
> > -    #
> > -    # Some versions of Mingw-w64 will define functions
> > -    # for localtime_r/gmtime_r, but only if you have
> > -    # _POSIX_THREAD_SAFE_FUNCTIONS defined. For fun
> > -    # though, unistd.h and pthread.h both define
> > -    # that for you.
> > -    #
> > -    # So this #undef localtime_r and #include <unistd.h>
> > -    # are not in fact redundant.
> > -cat > $TMPC << EOF
> > -#include <unistd.h>
> > -#include <time.h>
> > -#undef localtime_r
> > -int main(void) { localtime_r(NULL, NULL); return 0; }
> > -EOF
> > -    if compile_prog "" "" ; then
> > -        localtime_r="yes"
> > -    else
> > -        localtime_r="no"
> > -    fi
> > -fi
> > -
> >  ##########################################
> >  # pkg-config probe
> >
> > @@ -7088,9 +7057,6 @@ if [ "$bsd" = "yes" ] ; then
> >    echo "CONFIG_BSD=y" >> $config_host_mak
> >  fi
> >
> > -if test "$localtime_r" = "yes" ; then
> > -  echo "CONFIG_LOCALTIME_R=y" >> $config_host_mak
> > -fi
> >  if test "$qom_cast_debug" = "yes" ; then
> >    echo "CONFIG_QOM_CAST_DEBUG=y" >> $config_host_mak
> >  fi
> > diff --git a/include/sysemu/os-win32.h b/include/sysemu/os-win32.h
> > index d8978e28c0..3ac8a53bac 100644
> > --- a/include/sysemu/os-win32.h
> > +++ b/include/sysemu/os-win32.h
> > @@ -48,12 +48,12 @@
> >  #define siglongjmp(env, val) longjmp(env, val)
> >
> >  /* Missing POSIX functions. Don't use MinGW-w64 macros. */
> > -#ifndef CONFIG_LOCALTIME_R
> > +#ifndef _POSIX_THREAD_SAFE_FUNCTIONS
> >  #undef gmtime_r
> >  struct tm *gmtime_r(const time_t *timep, struct tm *result);
> >  #undef localtime_r
> >  struct tm *localtime_r(const time_t *timep, struct tm *result);
> > -#endif /* CONFIG_LOCALTIME_R */
> > +#endif
> >
> >  static inline void os_setup_signal_handling(void) {}
> >  static inline void os_daemonize(void) {}
> > diff --git a/util/oslib-win32.c b/util/oslib-win32.c
> > index c654dafd93..f2fa9a3549 100644
> > --- a/util/oslib-win32.c
> > +++ b/util/oslib-win32.c
> > @@ -106,7 +106,7 @@ void qemu_anon_ram_free(void *ptr, size_t size)
> >      }
> >  }
> >
> > -#ifndef CONFIG_LOCALTIME_R
> > +#ifndef _POSIX_THREAD_SAFE_FUNCTIONS
> >  /* FIXME: add proper locking */
> >  struct tm *gmtime_r(const time_t *timep, struct tm *result)
> >  {
> > --
> > 2.28.0.windows.1
> >
> >
>
> Regards,
> Daniel
> --
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>


--
         此致

罗勇刚
Yours
    sincerely,
Yonggang Luo

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