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[libvirt] [PATCH] qemu: Add shortcut for HMP pass through



Currently users who want to use virDomainQemuMonitorCommand() API or
it's virsh equivalent has to use the same protocol as libvirt uses for
communication to qemu. Since the protocol is QMP with current qemu and
HMP much more usable for humans, one ends up typing something like the
following:

    virsh qemu-monitor-command DOM \
'{"execute":"human-monitor-command","arguments":{"command-line":"info kvm"}}'

which is not a very convenient way of debugging qemu.

This patch introduces --hmp option to qemu-monitor-command, which says
that the provided command is in HMP. If libvirt uses QMP to talk with
qemu, the command will automatically be converted into QMP. So the
example above is simplified to just

    virsh qemu-monitor-command --hmp DOM "info kvm"

Also the result is converted from

    {"return":"kvm support: enabled\r\n"}

to just plain HMP:

    kvm support: enabled

If libvirt talks to qemu in HMP, --hmp flag is obviously a noop.
---
 include/libvirt/libvirt-qemu.h |    5 +++++
 src/internal.h                 |    1 +
 src/qemu/qemu_driver.c         |    7 +++++--
 src/qemu/qemu_monitor.c        |    9 ++++++---
 src/qemu/qemu_monitor.h        |    5 ++++-
 src/qemu/qemu_monitor_json.c   |   27 ++++++++++++++++++++++++---
 src/qemu/qemu_monitor_json.h   |    3 ++-
 tools/virsh.c                  |    7 ++++++-
 8 files changed, 53 insertions(+), 11 deletions(-)

diff --git a/include/libvirt/libvirt-qemu.h b/include/libvirt/libvirt-qemu.h
index 9c191c7..9257c2f 100644
--- a/include/libvirt/libvirt-qemu.h
+++ b/include/libvirt/libvirt-qemu.h
@@ -20,6 +20,11 @@
 extern "C" {
 # endif
 
+enum {
+    VIR_DOMAIN_QEMU_MONITOR_COMMAND_DEFAULT = 0,
+    VIR_DOMAIN_QEMU_MONITOR_COMMAND_HMP     = (1 << 0), /* cmd is in HMP */
+} virDomainQemuMonitorCommandFlags;
+
 int virDomainQemuMonitorCommand(virDomainPtr domain, const char *cmd,
                                 char **result, unsigned int flags);
 
diff --git a/src/internal.h b/src/internal.h
index 038b862..dc1d9cb 100644
--- a/src/internal.h
+++ b/src/internal.h
@@ -38,6 +38,7 @@
 # define N_(str) str
 
 # include "libvirt/libvirt.h"
+# include "libvirt/libvirt-qemu.h"
 # include "libvirt/virterror.h"
 
 # include "libvirt_internal.h"
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 23e0db0..bb50264 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -10226,8 +10226,9 @@ static int qemuDomainMonitorCommand(virDomainPtr domain, const char *cmd,
     virDomainObjPtr vm = NULL;
     int ret = -1;
     qemuDomainObjPrivatePtr priv;
+    bool hmp;
 
-    virCheckFlags(0, -1);
+    virCheckFlags(VIR_DOMAIN_QEMU_MONITOR_COMMAND_HMP, -1);
 
     qemuDriverLock(driver);
     vm = virDomainFindByUUID(&driver->domains, domain->uuid);
@@ -10253,10 +10254,12 @@ static int qemuDomainMonitorCommand(virDomainPtr domain, const char *cmd,
         priv->monitor_warned = 1;
     }
 
+    hmp = !!(flags & VIR_DOMAIN_QEMU_MONITOR_COMMAND_HMP);
+
     if (qemuDomainObjBeginJobWithDriver(driver, vm) < 0)
         goto cleanup;
     qemuDomainObjEnterMonitorWithDriver(driver, vm);
-    ret = qemuMonitorArbitraryCommand(priv->mon, cmd, result);
+    ret = qemuMonitorArbitraryCommand(priv->mon, cmd, result, hmp);
     qemuDomainObjExitMonitorWithDriver(driver, vm);
     if (qemuDomainObjEndJob(vm) == 0) {
         vm = NULL;
diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
index 0c14277..fdb6b79 100644
--- a/src/qemu/qemu_monitor.c
+++ b/src/qemu/qemu_monitor.c
@@ -2007,14 +2007,17 @@ int qemuMonitorDeleteSnapshot(qemuMonitorPtr mon, const char *name)
     return ret;
 }
 
-int qemuMonitorArbitraryCommand(qemuMonitorPtr mon, const char *cmd, char **reply)
+int qemuMonitorArbitraryCommand(qemuMonitorPtr mon,
+                                const char *cmd,
+                                char **reply,
+                                bool hmp)
 {
     int ret;
 
-    DEBUG("mon=%p, cmd=%s, reply=%p", mon, cmd, reply);
+    DEBUG("mon=%p, cmd=%s, reply=%p, hmp=%d", mon, cmd, reply, hmp);
 
     if (mon->json)
-        ret = qemuMonitorJSONArbitraryCommand(mon, cmd, reply);
+        ret = qemuMonitorJSONArbitraryCommand(mon, cmd, reply, hmp);
     else
         ret = qemuMonitorTextArbitraryCommand(mon, cmd, reply);
     return ret;
diff --git a/src/qemu/qemu_monitor.h b/src/qemu/qemu_monitor.h
index 92c550b..0ea1330 100644
--- a/src/qemu/qemu_monitor.h
+++ b/src/qemu/qemu_monitor.h
@@ -397,7 +397,10 @@ int qemuMonitorCreateSnapshot(qemuMonitorPtr mon, const char *name);
 int qemuMonitorLoadSnapshot(qemuMonitorPtr mon, const char *name);
 int qemuMonitorDeleteSnapshot(qemuMonitorPtr mon, const char *name);
 
-int qemuMonitorArbitraryCommand(qemuMonitorPtr mon, const char *cmd, char **reply);
+int qemuMonitorArbitraryCommand(qemuMonitorPtr mon,
+                                const char *cmd,
+                                char **reply,
+                                bool hmp);
 
 /**
  * When running two dd process and using <> redirection, we need a
diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
index ca06e7e..9ac12f8 100644
--- a/src/qemu/qemu_monitor_json.c
+++ b/src/qemu/qemu_monitor_json.c
@@ -2457,20 +2457,41 @@ int qemuMonitorJSONDeleteSnapshot(qemuMonitorPtr mon, const char *name)
 
 int qemuMonitorJSONArbitraryCommand(qemuMonitorPtr mon,
                                     const char *cmd_str,
-                                    char **reply_str)
+                                    char **reply_str,
+                                    bool hmp)
 {
     virJSONValuePtr cmd = NULL;
     virJSONValuePtr reply = NULL;
     int ret = -1;
 
-    cmd = virJSONValueFromString(cmd_str);
+    if (!hmp) {
+        cmd = virJSONValueFromString(cmd_str);
+    } else {
+        cmd = qemuMonitorJSONMakeCommand("human-monitor-command",
+                                         "s:command-line", cmd_str,
+                                         NULL);
+    }
+
     if (!cmd)
         return -1;
 
     if (qemuMonitorJSONCommand(mon, cmd, &reply) < 0)
         goto cleanup;
 
-    *reply_str = virJSONValueToString(reply);
+    if (!hmp) {
+        *reply_str = virJSONValueToString(reply);
+    } else if (qemuMonitorJSONCheckError(cmd, reply)) {
+        goto cleanup;
+    } else {
+        const char *data;
+        if (!(data = virJSONValueObjectGetString(reply, "return"))) {
+            qemuReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                            _("human monitor command was missing return data"));
+            goto cleanup;
+        }
+        *reply_str = strdup(data);
+    }
+
     if (!(*reply_str))
         goto cleanup;
 
diff --git a/src/qemu/qemu_monitor_json.h b/src/qemu/qemu_monitor_json.h
index 4c47f10..4ae472a 100644
--- a/src/qemu/qemu_monitor_json.h
+++ b/src/qemu/qemu_monitor_json.h
@@ -209,6 +209,7 @@ int qemuMonitorJSONDeleteSnapshot(qemuMonitorPtr mon, const char *name);
 
 int qemuMonitorJSONArbitraryCommand(qemuMonitorPtr mon,
                                     const char *cmd_str,
-                                    char **reply_str);
+                                    char **reply_str,
+                                    bool hmp);
 
 #endif /* QEMU_MONITOR_JSON_H */
diff --git a/tools/virsh.c b/tools/virsh.c
index 4533d38..59d3de5 100644
--- a/tools/virsh.c
+++ b/tools/virsh.c
@@ -9932,6 +9932,7 @@ static const vshCmdInfo info_qemu_monitor_command[] = {
 static const vshCmdOptDef opts_qemu_monitor_command[] = {
     {"domain", VSH_OT_DATA, VSH_OFLAG_REQ, N_("domain name, id or uuid")},
     {"cmd", VSH_OT_DATA, VSH_OFLAG_REQ, N_("command")},
+    {"hmp", VSH_OT_BOOL, 0, N_("command is in human monitor protocol")},
     {NULL, 0, 0, NULL}
 };
 
@@ -9942,6 +9943,7 @@ cmdQemuMonitorCommand(vshControl *ctl, const vshCmd *cmd)
     int ret = FALSE;
     char *monitor_cmd;
     char *result = NULL;
+    unsigned int flags = 0;
 
     if (!vshConnectionUsability(ctl, ctl->conn))
         goto cleanup;
@@ -9956,7 +9958,10 @@ cmdQemuMonitorCommand(vshControl *ctl, const vshCmd *cmd)
         goto cleanup;
     }
 
-    if (virDomainQemuMonitorCommand(dom, monitor_cmd, &result, 0) < 0)
+    if (vshCommandOptBool(cmd, "hmp"))
+        flags |= VIR_DOMAIN_QEMU_MONITOR_COMMAND_HMP;
+
+    if (virDomainQemuMonitorCommand(dom, monitor_cmd, &result, flags) < 0)
         goto cleanup;
 
     printf("%s\n", result);
-- 
1.7.4


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