[Qemu-devel] [PATCH v2] qemu-config: Accept empty option values

[Eduardo Habkost <ehabkost@redhat.com>]

Currently it is impossible to set an option in a config file to an empty
string, because the parser matches only lines containing non-empty
strings between double-quotes.

As sscanf() "[" conversion specifier only matches non-empty strings, add
a special case for empty strings.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
Changes v1 -> v2:
* Move value[0]='\0' assignment outside if condition. Nobody seemed
  to like the comma operator usage in v1 (including myself), and then I
  noticed that it was also making checkpatch.pl sad.
---
 util/qemu-config.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/util/qemu-config.c b/util/qemu-config.c
index 2d32ce7..a393a3d 100644
--- a/util/qemu-config.c
+++ b/util/qemu-config.c
@@ -413,7 +413,9 @@ int qemu_config_parse(FILE *fp, QemuOptsList **lists, const char *fname)
             opts = qemu_opts_create(list, NULL, 0, &error_abort);
             continue;
         }
-        if (sscanf(line, " %63s = \"%1023[^\"]\"", arg, value) == 2) {
+        value[0] = '\0';
+        if (sscanf(line, " %63s = \"%1023[^\"]\"", arg, value) == 2 ||
+            sscanf(line, " %63s = \"\"", arg) == 1) {
             /* arg = value */
             if (opts == NULL) {
                 error_report("no group defined");
-- 
2.1.0