[PATCH v2] migration: Silence compiler warning in global_state_store_running()

[Thomas Huth <thuth@redhat.com>]

GCC 9.3.0 on Ubuntu complains:

In file included from /usr/include/string.h:495,
                 from /home/travis/build/huth/qemu/include/qemu/osdep.h:87,
                 from ../migration/global_state.c:13:
In function ‘strncpy’,
    inlined from ‘global_state_store_running’ at ../migration/global_state.c:47:5:
/usr/include/x86_64-linux-gnu/bits/string_fortified.h:106:10: error:
 ‘__builtin_strncpy’ specified bound 100 equals destination size [-Werror=stringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

... but we apparently really want to do a strncpy here - the size is already
checked with the assert() statement right in front of it. To silence the
warning, simply replace it with our strpadcpy() function.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 v2: Use strpadcpy instead of QEMU_NONSTRING (and yes, this time it seems
     to really silence the compiler warning :-))

 migration/global_state.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/migration/global_state.c b/migration/global_state.c
index 25311479a4..a33947ca32 100644
--- a/migration/global_state.c
+++ b/migration/global_state.c
@@ -44,8 +44,8 @@ void global_state_store_running(void)
 {
     const char *state = RunState_str(RUN_STATE_RUNNING);
     assert(strlen(state) < sizeof(global_state.runstate));
-    strncpy((char *)global_state.runstate,
-           state, sizeof(global_state.runstate));
+    strpadcpy((char *)global_state.runstate, sizeof(global_state.runstate),
+              state, '\0');
 }
 
 bool global_state_received(void)
-- 
2.18.2