[PATCH v2] Check and report for incomplete 'global' option format

[Rohit Kumar <rohit.kumar3@nutanix.com>]

Qemu might crash when provided incomplete '-global' option.
For example:
        qemu-system-x86_64 -global driver=isa-fdc
        qemu-system-x86_64: ../../devel/qemu/qapi/string-input-visitor.c:394:
        string_input_visitor_new: Assertion `str' failed.
        Aborted (core dumped)

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/604
Signed-off-by: Rohit Kumar <rohit.kumar3@nutanix.com>
---
 diff to v1:
  - Removed '\n' from error log message.

 softmmu/qdev-monitor.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/softmmu/qdev-monitor.c b/softmmu/qdev-monitor.c
index 01f3834db5..51b33caeca 100644
--- a/softmmu/qdev-monitor.c
+++ b/softmmu/qdev-monitor.c
@@ -1020,6 +1020,7 @@ int qemu_global_option(const char *str)
     char driver[64], property[64];
     QemuOpts *opts;
     int rc, offset;
+    Error *err = NULL;
 
     rc = sscanf(str, "%63[^.=].%63[^=]%n", driver, property, &offset);
     if (rc == 2 && str[offset] == '=') {
@@ -1031,7 +1032,12 @@ int qemu_global_option(const char *str)
     }
 
     opts = qemu_opts_parse_noisily(&qemu_global_opts, str, false);
-    if (!opts) {
+    if (!opts || !qemu_opt_get(opts, "driver") || !qemu_opt_get(opts,"property") ||
+    !qemu_opt_get(opts, "value")) {
+        error_setg(&err, "Invalid 'global' option format! "
+        "Use -global <driver>.<property>=<value> or "
+        "-global driver=driver,property=property,value=value");
+        error_report_err(err);
         return -1;
     }
 
-- 
2.25.1