[PATCH 2/2] hmp: Add 'openfd' command

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Wire up the hmp 'openfd' to open a file and add it to the monitor's
fd stash.
Example usage:

(qemu) openfd mig "my.mig"
(qemu) migrate -d "fd:mig"

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 hmp-commands.hx        | 16 +++++++++++++++-
 include/monitor/hmp.h  |  1 +
 monitor/hmp-cmds.c     | 10 ++++++++++
 tests/qtest/test-hmp.c |  2 ++
 4 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/hmp-commands.hx b/hmp-commands.hx
index 28256209b5..c10d5b3668 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1606,7 +1606,7 @@ ERST
         .name       = "closefd",
         .args_type  = "fdname:s",
         .params     = "closefd name",
-        .help       = "close a file descriptor previously passed via SCM rights",
+        .help       = "close a named file descriptor",
         .cmd        = hmp_closefd,
     },
 
@@ -1617,6 +1617,20 @@ SRST
   used by another monitor command.
 ERST
 
+    {
+        .name       = "openfd",
+        .args_type  = "fdname:s,filename:s",
+        .params     = "openfd name filename",
+        .help       = "open the named file (read write) and assign it a name",
+        .cmd        = hmp_openfd,
+    },
+
+SRST
+``openfd`` *fdname* *filename*
+  Open the named file and store it using the name *fdname* for later use by
+  other monitor comands.
+ERST
+
     {
         .name       = "block_passwd",
         .args_type  = "device:B,password:s",
diff --git a/include/monitor/hmp.h b/include/monitor/hmp.h
index c986cfd28b..7beaf3eab7 100644
--- a/include/monitor/hmp.h
+++ b/include/monitor/hmp.h
@@ -83,6 +83,7 @@ void hmp_netdev_add(Monitor *mon, const QDict *qdict);
 void hmp_netdev_del(Monitor *mon, const QDict *qdict);
 void hmp_getfd(Monitor *mon, const QDict *qdict);
 void hmp_closefd(Monitor *mon, const QDict *qdict);
+void hmp_openfd(Monitor *mon, const QDict *qdict);
 void hmp_sendkey(Monitor *mon, const QDict *qdict);
 void hmp_screendump(Monitor *mon, const QDict *qdict);
 void hmp_chardev_add(Monitor *mon, const QDict *qdict);
diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
index 9c61e769ca..62a3a8a514 100644
--- a/monitor/hmp-cmds.c
+++ b/monitor/hmp-cmds.c
@@ -1659,6 +1659,16 @@ void hmp_closefd(Monitor *mon, const QDict *qdict)
     hmp_handle_error(mon, err);
 }
 
+void hmp_openfd(Monitor *mon, const QDict *qdict)
+{
+    const char *fdname = qdict_get_str(qdict, "fdname");
+    const char *filename = qdict_get_str(qdict, "filename");
+    Error *err = NULL;
+
+    qmp_openfd(fdname, filename, &err);
+    hmp_handle_error(mon, err);
+}
+
 void hmp_sendkey(Monitor *mon, const QDict *qdict)
 {
     const char *keys = qdict_get_str(qdict, "keys");
diff --git a/tests/qtest/test-hmp.c b/tests/qtest/test-hmp.c
index b8b1271b9e..66a4f34348 100644
--- a/tests/qtest/test-hmp.c
+++ b/tests/qtest/test-hmp.c
@@ -57,6 +57,8 @@ static const char *hmp_cmds[] = {
     "o /w 0 0x1234",
     "object_add memory-backend-ram,id=mem1,size=256M",
     "object_del mem1",
+    "openfd null \"/dev/null\"",
+    "closefd null", /* purposely after openfd */
     "pmemsave 0 4096 \"/dev/null\"",
     "p $pc + 8",
     "qom-list /",
-- 
2.26.2