qtest: Don't segfault with invalid -qtest option

This prints an error message, instead of core dump, when "-qtest"
option value is invalid, e.g.:

    $ ./x86_64-softmmu/qemu-system-x86_64 -qtest unknown
        qemu-system-x86_64: Failed to initialize device for qtest:
        "unknown"

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>

1 files changed, 7 insertions, 1 deletions

diff --git a/qtest.c b/qtest.c
index a738afc724..ae941d6551 100644
--- a/qtest.c
+++ b/qtest.c
@@ -507,12 +507,18 @@ int qtest_init_accel(void)
     return 0;
 }
 
-void qtest_init(const char *qtest_chrdev, const char *qtest_log)
+void qtest_init(const char *qtest_chrdev, const char *qtest_log, Error **errp)
 {
     CharDriverState *chr;
 
     chr = qemu_chr_new("qtest", qtest_chrdev, NULL);
 
+    if (chr == NULL) {
+        error_setg(errp, "Failed to initialize device for qtest: \"%s\"",
+                   qtest_chrdev);
+        return;
+    }
+
     qemu_chr_add_handlers(chr, qtest_can_read, qtest_read, qtest_event, chr);
     qemu_chr_fe_set_echo(chr, true);