[Qemu-trivial] [PATCH trivial v2] vl: avoid closing stdout with 'writeconfig'

[Chen Gang <gang.chen.5i5j@gmail.com>]

'writeconfig' supports output to stdout (with '-'); when that happens,
we must not close stdout, or further command line options that also use
stdout will be impacted. (Although 'writeconfig' was copied from
'readconfig', the latter does not have the problem because it does not
support reading from '-')

Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
---
 vl.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/vl.c b/vl.c
index 9975e5a..215467f 100644
--- a/vl.c
+++ b/vl.c
@@ -3855,7 +3855,9 @@ int main(int argc, char **argv, char **envp)
                         }
                     }
                     qemu_config_write(fp);
-                    fclose(fp);
+                    if (fp != stdout) {
+                        fclose(fp);
+                    }
                     break;
                 }
             case QEMU_OPTION_qtest:
-- 
1.7.11.7