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Re: [Qemu-devel] [PATCH v2 REPOST] oslib-win32: only provide localtime_r


From: Denis V. Lunev
Subject: Re: [Qemu-devel] [PATCH v2 REPOST] oslib-win32: only provide localtime_r/gmtime_r if missing
Date: Tue, 22 Sep 2015 17:36:21 +0300
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0

On 09/22/2015 05:13 PM, Daniel P. Berrange wrote:
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
which QEMU takes care to disable. Latest versions of Mingw64
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 <address@hidden>
---
  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
+
+if test "$mingw32" = "yes"; then
+    # Some versions of Mingw32/64 lack localtime_r
+    # and gmtime_r entirely
+    #
+    # Some versions of Mingw64 define a macro for
+    # localtime_r/gmtime_r/etc
+    #
+    # 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
+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 */
+#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)
  {
Reviewed-by: Denis V. Lunev <address@hidden>



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