[Qemu-block] [RFC PATCH] block: Crude initial implementation of -blockdev

[Markus Armbruster]

The new command line option -blockdev works like QMP command
blockdev-add.  The option argument is JSON.  Example usage:

    -blockdev '{"node-name": "foo", "driver": "raw", "file": {"driver": "file", 
"filename": "foo.img"} }'

The JSON argument doesn't exactly blend into the existing option
syntax.  Alternative syntax is TBD.

Note that calling qmp_blockdev_add() (say via qmp_marshal_block_add())
right away would crash.  We need to stash the configuration for later
instead.  This is crudely done, and bypasses QemuOpts, even though
storing configuration is what QemuOpts is for.  Need to revamp option
infrastructure to support QAPI types like BlockdevOptions.

Signed-off-by: Markus Armbruster <address@hidden>
---
We need -blockdev to complete the blockdev-add job.  I'm working on it
for 2.9.  This patch is a quick hack to give people something to play
while I work on the real thing.

We need to agree on option argument syntax.  I'm going to post a
summary of our previous discussion.

 qemu-options.hx |  3 +++
 vl.c            | 41 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)

diff --git a/qemu-options.hx b/qemu-options.hx
index ad2f8fc..a66bd65 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -512,6 +512,9 @@ Use @var{file} as CD-ROM image (you cannot use 
@option{-hdc} and
 using @file{/dev/cdrom} as filename (@pxref{host_drives}).
 ETEXI
 
+DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev,
+    "-blockdev FIXME document\n", QEMU_OPTION_blockdev)
+
 DEF("drive", HAS_ARG, QEMU_OPTION_drive,
     "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n"
     "       [,cyls=c,heads=h,secs=s[,trans=t]][,snapshot=on|off]\n"
diff --git a/vl.c b/vl.c
index 0b72b12..51345c8 100644
--- a/vl.c
+++ b/vl.c
@@ -94,6 +94,9 @@ int main(int argc, char **argv)
 #include "migration/colo.h"
 #include "sysemu/kvm.h"
 #include "sysemu/hax.h"
+#include "qapi/qobject-input-visitor.h"
+#include "qapi/qobject-input-visitor.h"
+#include "qapi-visit.h"
 #include "qapi/qmp/qjson.h"
 #include "qemu/option.h"
 #include "qemu/config-file.h"
@@ -2965,6 +2968,12 @@ int main(int argc, char **argv, char **envp)
     Error *main_loop_err = NULL;
     Error *err = NULL;
     bool list_data_dirs = false;
+    typedef struct BlockdevOptions_queue {
+        BlockdevOptions *bdo;
+        Location loc;
+        QSIMPLEQ_ENTRY(BlockdevOptions_queue) entry;
+    } BlockdevOptions_queue;
+    QSIMPLEQ_HEAD(, BlockdevOptions_queue) bdo_queue = 
QSIMPLEQ_HEAD_INITIALIZER(bdo_queue);
 
     module_call_init(MODULE_INIT_TRACE);
 
@@ -3106,6 +3115,28 @@ int main(int argc, char **argv, char **envp)
                 drive_add(IF_DEFAULT, popt->index - QEMU_OPTION_hda, optarg,
                           HD_OPTS);
                 break;
+            case QEMU_OPTION_blockdev:
+                {
+                    QObject *args = qobject_from_json(optarg);
+                    Visitor *v;
+                    BlockdevOptions_queue *bdo;
+
+                    // TODO get error out of parser
+                    if (!args) {
+                        error_report("invalid JSON");
+                        exit(1);
+                    }
+
+                    bdo = g_new(BlockdevOptions_queue, 1);
+                    v = qobject_input_visitor_new(args, true);
+                    visit_type_BlockdevOptions(v, NULL, &bdo->bdo,
+                                               &error_fatal);
+                    visit_free(v);
+                    qobject_decref(args);
+                    loc_save(&bdo->loc);
+                    QSIMPLEQ_INSERT_TAIL(&bdo_queue, bdo, entry);
+                    break;
+                }
             case QEMU_OPTION_drive:
                 if (drive_def(optarg) == NULL) {
                     exit(1);
@@ -4418,6 +4449,16 @@ int main(int argc, char **argv, char **envp)
         qemu_opts_foreach(qemu_find_opts("drive"), drive_enable_snapshot,
                           NULL, NULL);
     }
+    while (!QSIMPLEQ_EMPTY(&bdo_queue)) {
+        BlockdevOptions_queue *bdo = QSIMPLEQ_FIRST(&bdo_queue);
+
+        QSIMPLEQ_REMOVE_HEAD(&bdo_queue, entry);
+        loc_push_restore(&bdo->loc);
+        qmp_blockdev_add(bdo->bdo, &error_fatal);
+        loc_pop(&bdo->loc);
+        qapi_free_BlockdevOptions(bdo->bdo);
+        g_free(bdo);
+    }
     if (qemu_opts_foreach(qemu_find_opts("drive"), drive_init_func,
                           &machine_class->block_default_type, NULL)) {
         exit(1);
-- 
2.7.4