w32: Disable buffering for log file

W32 does not support line buffering, but it supports unbuffered output.

Unbuffered output is better for writing to qemu.log than fully buffered
output because it also shows the latest log messages when an application
crash occurs.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/exec.c b/exec.c
index 6b92198e62..d8b2180170 100644
--- a/exec.c
+++ b/exec.c
@@ -1603,8 +1603,10 @@ void cpu_set_log(int log_flags)
             static char logfile_buf[4096];
             setvbuf(logfile, logfile_buf, _IOLBF, sizeof(logfile_buf));
         }
-#elif !defined(_WIN32)
-        /* Win32 doesn't support line-buffering and requires size >= 2 */
+#elif defined(_WIN32)
+        /* Win32 doesn't support line-buffering, so use unbuffered output. */
+        setvbuf(logfile, NULL, _IONBF, 0);
+#else
         setvbuf(logfile, NULL, _IOLBF, 0);
 #endif
         log_append = 1;