qemu-io: add support for --object command line arg

Allow creation of user creatable object types with qemu-io
via a new --object command line arg. This will be used to supply
passwords and/or encryption keys to the various block driver
backends via the recently added 'secret' object type.

 # printf letmein > mypasswd.txt
 # qemu-io --object secret,id=sec0,file=mypasswd.txt \
      ...other args...

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

qemu-io.c

@@ -18,6 +18,7 @@
 #include "qemu/config-file.h"
 #include "qemu/readline.h"
 #include "qapi/qmp/qstring.h"
+#include "qom/object_interfaces.h"
 #include "sysemu/block-backend.h"
 #include "block/block_int.h"
 #include "trace/control.h"
@@ -200,6 +201,8 @@ static void usage(const char *name)
 "Usage: %s [-h] [-V] [-rsnm] [-f FMT] [-c STRING] ... [file]\n"
 "QEMU Disk exerciser\n"
 "\n"
+"  --object OBJECTDEF   define an object such as 'secret' for\n"
+"                       passwords and/or encryption keys\n"
 "  -c, --cmd STRING     execute command with its arguments\n"
 "                       from the given string\n"
 "  -f, --format FMT     specifies the block driver to use\n"
@@ -361,6 +364,20 @@ static void reenable_tty_echo(void)
     qemu_set_tty_echo(STDIN_FILENO, true);
 }
 
+enum {
+    OPTION_OBJECT = 256,
+};
+
+static QemuOptsList qemu_object_opts = {
+    .name = "object",
+    .implied_opt_name = "qom-type",
+    .head = QTAILQ_HEAD_INITIALIZER(qemu_object_opts.head),
+    .desc = {
+        { }
+    },
+};
+
+
 int main(int argc, char **argv)
 {
     int readonly = 0;
@@ -379,6 +396,7 @@ int main(int argc, char **argv)
         { "discard", 1, NULL, 'd' },
         { "cache", 1, NULL, 't' },
         { "trace", 1, NULL, 'T' },
+        { "object", 1, NULL, OPTION_OBJECT },
         { NULL, 0, NULL, 0 }
     };
     int c;
@@ -395,6 +413,7 @@ int main(int argc, char **argv)
     qemu_init_exec_dir(argv[0]);
 
     module_call_init(MODULE_INIT_QOM);
+    qemu_add_opts(&qemu_object_opts);
     bdrv_init();
 
     while ((c = getopt_long(argc, argv, sopt, lopt, &opt_index)) != -1) {
@@ -446,6 +465,14 @@ int main(int argc, char **argv)
         case 'h':
             usage(progname);
             exit(0);
+        case OPTION_OBJECT: {
+            QemuOpts *qopts = NULL;
+            qopts = qemu_opts_parse_noisily(&qemu_object_opts,
+                                            optarg, true);
+            if (!qopts) {
+                exit(1);
+            }
+        }   break;
         default:
             usage(progname);
             exit(1);
@@ -462,6 +489,13 @@ int main(int argc, char **argv)
         exit(1);
     }
 
+    if (qemu_opts_foreach(&qemu_object_opts,
+                          user_creatable_add_opts_foreach,
+                          NULL, &local_error)) {
+        error_report_err(local_error);
+        exit(1);
+    }
+
     /* initialize commands */
     qemuio_add_command(&quit_cmd);
     qemuio_add_command(&open_cmd);