Re: [Qemu-devel] [PATCH v2 REPOST] oslib-win32: only provide localtime_r/gmtime_r if missing

[Stefan Weil <sw@weilnetz.de>]

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Hi,

I suggest cleaning some comments, mostly using the "official"
spellings for MinGW and Mingw-w64.

Am 22.09.2015 um 16:13 schrieb Daniel P. Berrange:
> The oslib-win32 file currently provides a localtime_r and
> gmtime_r replacement unconditionally. Some versions of
> Mingw64 would provide crude macros for localtime_r/gmtime_r

MinGW / Mingw-w64

> which QEMU takes care to disable. Latest versions of Mingw64

Mingw-w64

> now provide actual functions for localtime_r/gmtime_r, but
> with a twist that you have to include unistd.h or pthread.h
> before including time.h.  By luck some files in QEMU have
> such an include order, resulting in compile errors:
> 
>   CC    util/osdep.o
> In file included from include/qemu-common.h:48:0,
>                  from util/osdep.c:48:
> include/sysemu/os-win32.h:77:12: error: redundant redeclaration of 'gmtime_r' [-Werror=redundant-decls]
>  struct tm *gmtime_r(const time_t *timep, struct tm *result);
>             ^
> In file included from include/qemu-common.h:35:0,
>                  from util/osdep.c:48:
> /usr/i686-w64-mingw32/sys-root/mingw/include/time.h:272:107: note: previous definition of 'gmtime_r' was here
> In file included from include/qemu-common.h:48:0,
>                  from util/osdep.c:48:
> include/sysemu/os-win32.h:79:12: error: redundant redeclaration of 'localtime_r' [-Werror=redundant-decls]
>  struct tm *localtime_r(const time_t *timep, struct tm *result);
>             ^
> In file included from include/qemu-common.h:35:0,
>                  from util/osdep.c:48:
> /usr/i686-w64-mingw32/sys-root/mingw/include/time.h:269:107: note: previous definition of 'localtime_r' was here
> 
> This change adds a configure test to see if localtime_r
> exits, and only enables the QEMU impl if missing. We also
> re-arrange qemu-common.h try attempt to guarantee that all
> source files get unistd.h before time.h and thus see the
> localtime_r/gmtime_r defs.
> 
> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
> ---
>  configure                 | 34 ++++++++++++++++++++++++++++++++++
>  include/qemu/osdep.h      |  4 +++-
>  include/sysemu/os-win32.h |  2 ++
>  util/oslib-win32.c        |  2 ++
>  4 files changed, 41 insertions(+), 1 deletion(-)
> 
> diff --git a/configure b/configure
> index 52f5b79..4654be8 100755
> --- a/configure
> +++ b/configure
> @@ -1737,6 +1737,37 @@ else
>  fi
>  
>  ##########################################
> +# Mingw64 localtime_r/gmtime_r check

MinGW / Mingw-w64

> +
> +if test "$mingw32" = "yes"; then
> +    # Some versions of Mingw32/64 lack localtime_r

MinGW / Mingw-w64

> +    # and gmtime_r entirely

Missing .

> +    #
> +    # Some versions of Mingw64 define a macro for

Mingw-w64

> +    # localtime_r/gmtime_r/etc

Why etc? Missing .

> +    #
> +    # Some versions of Ming64 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

Missing .

> +cat > $TMPC << EOF
> +#include <unistd.h>
> +#include <time.h>
> +#undef localtime_r
> +int main(void) { localtime_r(NULL, NULL); return 0; }
> +EOF
> +    if compile_prog "" "" ; then
> +        localtime_r="yes"
> +    else
> +        localtime_r="no"
> +    fi
> +fi
> +
> +##########################################
>  # pkg-config probe
>  
>  if ! has "$pkg_config_exe"; then
> @@ -5050,6 +5081,9 @@ fi
>  if test "$zero_malloc" = "yes" ; then
>    echo "CONFIG_ZERO_MALLOC=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/qemu/osdep.h b/include/qemu/osdep.h
> index ab3c876..e490028 100644
> --- a/include/qemu/osdep.h
> +++ b/include/qemu/osdep.h
> @@ -38,10 +38,12 @@
>  #include <strings.h>
>  #include <inttypes.h>
>  #include <limits.h>
> +/* Put unistd.h before time.h as that triggers localtime_r/gmtime_r
> + * function availability on recentish Mingw64 platforms */

Mingw-w64. I'm not sure how long this hack will work.
A future patch could add -DPOSIX_C_SOURCE to the compiler options
if configure has set $localtime_r.

> +#include <unistd.h>
>  #include <time.h>
>  #include <ctype.h>
>  #include <errno.h>
> -#include <unistd.h>
>  #include <fcntl.h>
>  #include <sys/stat.h>
>  #include <sys/time.h>
> diff --git a/include/sysemu/os-win32.h b/include/sysemu/os-win32.h
> index 706d85a..13dcef6 100644
> --- a/include/sysemu/os-win32.h
> +++ b/include/sysemu/os-win32.h
> @@ -73,10 +73,12 @@
>  #define siglongjmp(env, val) longjmp(env, val)
>  
>  /* Missing POSIX functions. Don't use MinGW-w64 macros. */
> +#ifndef CONFIG_LOCALTIME_R
>  #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 */
>  
>  
>  static inline void os_setup_signal_handling(void) {}
> diff --git a/util/oslib-win32.c b/util/oslib-win32.c
> index 730a670..08f5a9c 100644
> --- a/util/oslib-win32.c
> +++ b/util/oslib-win32.c
> @@ -95,6 +95,7 @@ void qemu_anon_ram_free(void *ptr, size_t size)
>      }
>  }
>  
> +#ifndef CONFIG_LOCALTIME_R
>  /* FIXME: add proper locking */
>  struct tm *gmtime_r(const time_t *timep, struct tm *result)
>  {
> @@ -118,6 +119,7 @@ struct tm *localtime_r(const time_t *timep, struct tm *result)
>      }
>      return p;
>  }
> +#endif /* CONFIG_LOCALTIME_R */
>  
>  void qemu_set_block(int fd)
>  {
> 

Otherwise this patch looks good.

If you agree, I'd clean the comments before I add
the patch to my patch queue for Windows
(git://qemu.weilnetz.de/qemu.git wxx).

Regards
Stefan



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