[PATCH] virtiofsd: use g_date_time_get_microsecond to get subsecond

[Yusuke Okada <yokada.996@gmail.com>]

From: Yusuke Okada <okada.yusuke@jp.fujitsu.com>

The "%f" specifier in g_date_time_format() is only available in glib
2.65.2 or later. If combined with older glib, the function returns null
and the timestamp displayed as "(null)".

For backward compatibility, g_date_time_get_microsecond should be used
to retrieve subsecond.

In this patch the g_date_time_format() leaves subsecond field as "%06d"
and let next snprintf to format with g_date_time_get_microsecond.

Signed-off-by: Yusuke Okada <okada.yusuke@jp.fujitsu.com>
---
 tools/virtiofsd/passthrough_ll.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index 371a7bead6..20f0f41f99 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -4185,6 +4185,7 @@ static void setup_nofile_rlimit(unsigned long rlimit_nofile)
 static void log_func(enum fuse_log_level level, const char *fmt, va_list ap)
 {
     g_autofree char *localfmt = NULL;
+    char buf[64];
 
     if (current_log_level < level) {
         return;
@@ -4197,9 +4198,11 @@ static void log_func(enum fuse_log_level level, const char *fmt, va_list ap)
                                        fmt);
         } else {
             g_autoptr(GDateTime) now = g_date_time_new_now_utc();
-            g_autofree char *nowstr = g_date_time_format(now, "%Y-%m-%d %H:%M:%S.%f%z");
+            g_autofree char *nowstr = g_date_time_format(now,
+                                       "%Y-%m-%d %H:%M:%S.%%06d%z");
+            snprintf(buf, 64, nowstr, g_date_time_get_microsecond(now));
             localfmt = g_strdup_printf("[%s] [ID: %08ld] %s",
-                                       nowstr, syscall(__NR_gettid), fmt);
+                                       buf, syscall(__NR_gettid), fmt);
         }
         fmt = localfmt;
     }
-- 
2.31.1