[PATCH 3/4] qemu-io-cmds: avoid gcc 10 warning

[Christian Borntraeger]

With gcc 10 on Fedora32 I do get:

Compiling C object libblock.fa.p/qemu-io-cmds.c.o
In file included from /usr/include/stdio.h:867,
                 from /home/cborntra/REPOS/qemu/include/qemu/osdep.h:85,
                 from ../qemu-io-cmds.c:11:
In function ‘printf’,
    inlined from ‘help_oneline’ at ../qemu-io-cmds.c:2389:9,
    inlined from ‘help_all’ at ../qemu-io-cmds.c:2414:9,
    inlined from ‘help_f’ at ../qemu-io-cmds.c:2424:9:
/usr/include/bits/stdio2.h:107:10: error: ‘%s’ directive argument is null 
[-Werror=format-overflow=]
  107 |   return __printf_chk (__USE_FORTIFY_LEVEL - 1, __fmt, __va_arg_pack 
());
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

Let us check for null.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 qemu-io-cmds.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
index baeae86d8c85..c2080aa398a9 100644
--- a/qemu-io-cmds.c
+++ b/qemu-io-cmds.c
@@ -2386,7 +2386,9 @@ static void help_oneline(const char *cmd, const cmdinfo_t 
*ct)
     if (cmd) {
         printf("%s ", cmd);
     } else {
-        printf("%s ", ct->name);
+        if (ct->name) {
+            printf("%s ", ct->name);
+        }
         if (ct->altname) {
             printf("(or %s) ", ct->altname);
         }
-- 
2.26.2