virsh: Allow extracting 'return' section of QMP command in 'qemu-monitor-command'

Simplify gathering the actual return value from a passed-through QMP
command when using 'qemu-monitor-command' by adding '--return-value'
switch which just extracts the 'return' section and alternatively
reports an error if the section is not present.

This simplifies gathering of some test data where the full reply would
need to be trimmed just for the actual return value.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

diff --git a/docs/manpages/virsh.rst b/docs/manpages/virsh.rst
index e10e5463a37579bad8ef6190a167e4df0e0e144c..dc404ddfe864892d6b779a6085c93fd16d03399b 100644 (file)
--- a/docs/manpages/virsh.rst
+++ b/docs/manpages/virsh.rst
@@ -7482,7 +7482,7 @@ qemu-monitor-command
 
 .. code-block::
 
-   qemu-monitor-command domain { [--hmp] | [--pretty] } command...
+   qemu-monitor-command domain { [--hmp] | [--pretty] [--return-value] } command...
 
 Send an arbitrary monitor command *command* to domain *domain* through the
 QEMU monitor.  The results of the command will be printed on stdout.
@@ -7495,6 +7495,9 @@ in QMP format to work properly.
 
 If *--pretty* is given the QMP reply is pretty-printed.
 
+If *--return-value* is given the 'return' key of the QMP response object is
+extracted rather than passing through the full reply from QEMU.
+
 If *--hmp* is passed, the command is considered to be a human monitor command
 and libvirt will automatically convert it into QMP and convert the result back.
 

diff --git a/tools/virsh-domain.c b/tools/virsh-domain.c
index 05a31f28cfa82de53f4e4e646a7ef800d59e4929..d184e25f42d51d2b0403e9a3a1fea11779750a50 100644 (file)
--- a/tools/virsh-domain.c
+++ b/tools/virsh-domain.c
@@ -9617,6 +9617,10 @@ static const vshCmdOptDef opts_qemu_monitor_command[] = {
      .type = VSH_OT_BOOL,
      .help = N_("pretty-print any qemu monitor protocol output")
     },
+    {.name = "return-value",
+     .type = VSH_OT_BOOL,
+     .help = N_("extract the value of the 'return' key from the returned string")
+    },
     {.name = "cmd",
      .type = VSH_OT_ARGV,
      .flags = VSH_OFLAG_REQ,
@@ -9631,11 +9635,17 @@ cmdQemuMonitorCommand(vshControl *ctl, const vshCmd *cmd)
     g_autoptr(virshDomain) dom = NULL;
     g_autofree char *monitor_cmd = NULL;
     g_autofree char *result = NULL;
+    g_autoptr(virJSONValue) resultjson = NULL;
     unsigned int flags = 0;
     const vshCmdOpt *opt = NULL;
     virBuffer buf = VIR_BUFFER_INITIALIZER;
+    bool pretty = vshCommandOptBool(cmd, "pretty");
+    bool returnval = vshCommandOptBool(cmd, "return-value");
+    virJSONValuePtr formatjson;
+    g_autofree char *jsonstr = NULL;
 
     VSH_EXCLUSIVE_OPTIONS("hmp", "pretty");
+    VSH_EXCLUSIVE_OPTIONS("hmp", "return-value");
 
     if (!(dom = virshCommandOptDomain(ctl, cmd, NULL)))
         return false;
@@ -9653,17 +9663,33 @@ cmdQemuMonitorCommand(vshControl *ctl, const vshCmd *cmd)
     if (virDomainQemuMonitorCommand(dom, monitor_cmd, &result, flags) < 0)
         return false;
 
-    if (vshCommandOptBool(cmd, "pretty")) {
-        char *tmp;
-        if ((tmp = virJSONStringReformat(result, true))) {
-            VIR_FREE(result);
-            result = tmp;
-            virTrimSpaces(result, NULL);
-        } else {
-            vshResetLibvirtError();
+    if (returnval || pretty) {
+        resultjson = virJSONValueFromString(result);
+
+        if (returnval && !resultjson) {
+            vshError(ctl, "failed to parse JSON returned by qemu");
+            return false;
         }
     }
-    vshPrint(ctl, "%s\n", result);
+
+    /* print raw non-prettified result */
+    if (!resultjson) {
+        vshPrint(ctl, "%s\n", result);
+        return true;
+    }
+
+    if (returnval) {
+        if (!(formatjson = virJSONValueObjectGet(resultjson, "return"))) {
+            vshError(ctl, "'return' member missing");
+            return false;
+        }
+    } else {
+        formatjson = resultjson;
+    }
+
+    jsonstr = virJSONValueToString(formatjson, pretty);
+    virTrimSpaces(jsonstr, NULL);
+    vshPrint(ctl, "%s", jsonstr);
     return true;
 }