[PATCH v4 2/6] util: refactor qemu_open_old to split off variadic args handling

["Daniel P. Berrangé" <berrange@redhat.com>]

This simple refactoring prepares for future patches. The variadic args
handling is split from the main bulk of the open logic. The duplicated
calls to open() are removed in favour of updating the "flags" variable
to have O_CLOEXEC.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 util/osdep.c | 40 +++++++++++++++++++++++++++-------------
 1 file changed, 27 insertions(+), 13 deletions(-)

diff --git a/util/osdep.c b/util/osdep.c
index 9df1b6adec..9ff92551e7 100644
--- a/util/osdep.c
+++ b/util/osdep.c
@@ -22,6 +22,7 @@
  * THE SOFTWARE.
  */
 #include "qemu/osdep.h"
+#include "qapi/error.h"
 
 /* Needed early for CONFIG_BSD etc. */
 
@@ -282,10 +283,10 @@ int qemu_lock_fd_test(int fd, int64_t start, int64_t len, bool exclusive)
 /*
  * Opens a file with FD_CLOEXEC set
  */
-int qemu_open_old(const char *name, int flags, ...)
+static int
+qemu_open_internal(const char *name, int flags, mode_t mode)
 {
     int ret;
-    int mode = 0;
 
 #ifndef _WIN32
     const char *fdset_id_str;
@@ -323,22 +324,35 @@ int qemu_open_old(const char *name, int flags, ...)
     }
 #endif
 
-    if (flags & O_CREAT) {
-        va_list ap;
-
-        va_start(ap, flags);
-        mode = va_arg(ap, int);
-        va_end(ap);
-    }
-
 #ifdef O_CLOEXEC
-    ret = open(name, flags | O_CLOEXEC, mode);
-#else
+    flags |= O_CLOEXEC;
+#endif /* O_CLOEXEC */
+
     ret = open(name, flags, mode);
+
+#ifndef O_CLOEXEC
     if (ret >= 0) {
         qemu_set_cloexec(ret);
     }
-#endif
+#endif /* ! O_CLOEXEC */
+
+    return ret;
+}
+
+
+int qemu_open_old(const char *name, int flags, ...)
+{
+    va_list ap;
+    mode_t mode = 0;
+    int ret;
+
+    va_start(ap, flags);
+    if (flags & O_CREAT) {
+        mode = va_arg(ap, int);
+    }
+    va_end(ap);
+
+    ret = qemu_open_internal(name, flags, mode);
 
 #ifdef O_DIRECT
     if (ret == -1 && errno == EINVAL && (flags & O_DIRECT)) {
-- 
2.26.2