[libvirt] [PATCH] qemu: Report error if qemu monitor command not found for BlockJob

[Adam Litke]

From: Osier Yang <jyang at redhat.com>

* src/qemu/qemu_monitor_json.c: Handle error "CommandNotFound" and
report the error.

* src/qemu/qemu_monitor_text.c: If a sub info command is not found,
it prints the output of "help info", for other commands,
"unknown command" is printed.

Without this patch, libvirt always report:

An error occurred, but the cause is unknown

This patch was adapted from a patch by Osier Yang <jyang at redhat.com> to break
out detection of unrecognized text monitor commands into a separate function.

Signed-off-by: Adam Litke <agl at us.ibm.com>
---
 src/qemu/qemu_monitor_json.c |   34 ++++++++++++++++++-----------
 src/qemu/qemu_monitor_text.c |   47 +++++++++++++++++++++++++++++++++---------
 2 files changed, 58 insertions(+), 23 deletions(-)

diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
index 7adfb26..715b26e 100644
--- a/src/qemu/qemu_monitor_json.c
+++ b/src/qemu/qemu_monitor_json.c
@@ -2909,20 +2909,25 @@ int qemuMonitorJSONBlockJob(qemuMonitorPtr mon,
     int ret = -1;
     virJSONValuePtr cmd = NULL;
     virJSONValuePtr reply = NULL;
-
-    if (mode == BLOCK_JOB_ABORT)
-        cmd = qemuMonitorJSONMakeCommand("block_job_cancel",
-                                         "s:device", device, NULL);
-    else if (mode == BLOCK_JOB_INFO)
-        cmd = qemuMonitorJSONMakeCommand("query-block-jobs", NULL);
-    else if (mode == BLOCK_JOB_SPEED)
-        cmd = qemuMonitorJSONMakeCommand("block_job_set_speed",
-                                         "s:device", device,
-                                         "U:value", bandwidth * 1024ULL * 1024ULL,
+    const char *cmd_name = NULL;
+
+    if (mode == BLOCK_JOB_ABORT) {
+        cmd_name = "block_job_cancel";
+        cmd = qemuMonitorJSONMakeCommand(cmd_name, "s:device", device, NULL);
+    } else if (mode == BLOCK_JOB_INFO) {
+        cmd_name = "query-block-jobs";
+        cmd = qemuMonitorJSONMakeCommand(cmd_name, NULL);
+    } else if (mode == BLOCK_JOB_SPEED) {
+        cmd_name = "block_job_set_speed";
+        cmd = qemuMonitorJSONMakeCommand(cmd_name, "s:device",
+                                         device, "U:value",
+                                         bandwidth * 1024ULL * 1024ULL,
                                          NULL);
-    else if (mode == BLOCK_JOB_PULL)
-        cmd = qemuMonitorJSONMakeCommand("block_stream",
-                                         "s:device", device, NULL);
+    } else if (mode == BLOCK_JOB_PULL) {
+        cmd_name = "block_stream";
+        cmd = qemuMonitorJSONMakeCommand(cmd_name, "s:device",
+                                         device, NULL);
+    }
 
     if (!cmd)
         return -1;
@@ -2939,6 +2944,9 @@ int qemuMonitorJSONBlockJob(qemuMonitorPtr mon,
         else if (qemuMonitorJSONHasError(reply, "NotSupported"))
             qemuReportError(VIR_ERR_OPERATION_INVALID,
                 _("Operation is not supported for device: %s"), device);
+        else if (qemuMonitorJSONHasError(reply, "CommandNotFound"))
+            qemuReportError(VIR_ERR_OPERATION_INVALID,
+                _("Command '%s' is not found"), cmd_name);
         else
             qemuReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                 _("Unexpected error"));
diff --git a/src/qemu/qemu_monitor_text.c b/src/qemu/qemu_monitor_text.c
index 52d924a..9119f06 100644
--- a/src/qemu/qemu_monitor_text.c
+++ b/src/qemu/qemu_monitor_text.c
@@ -271,6 +271,20 @@ qemuMonitorTextCommandWithFd(qemuMonitorPtr mon,
                                              scm_fd, reply);
 }
 
+/* Check monitor output for evidence that the command was not recognized.
+ * For 'info' commands, qemu returns help text.  For other commands, qemu
+ * returns 'unknown command:'.
+ */
+static int
+qemuMonitorTextCommandNotFound(const char *reply)
+{
+    if (strstr(reply, "unknown command:"))
+        return 1;
+    if (strstr(reply, "info version"))
+        return 1;
+    return 0;
+}
+
 
 static int
 qemuMonitorSendDiskPassphrase(qemuMonitorPtr mon,
@@ -3031,18 +3045,24 @@ int qemuMonitorTextBlockJob(qemuMonitorPtr mon,
     char *cmd = NULL;
     char *reply = NULL;
     int ret;
-
-    if (mode == BLOCK_JOB_ABORT)
-        ret = virAsprintf(&cmd, "block_job_cancel %s", device);
-    else if (mode == BLOCK_JOB_INFO)
-        ret = virAsprintf(&cmd, "info block-jobs");
-    else if (mode == BLOCK_JOB_SPEED)
-        ret = virAsprintf(&cmd, "block_job_set_speed %s %llu", device,
+    const char *cmd_name = NULL;
+
+    if (mode == BLOCK_JOB_ABORT) {
+        cmd_name = "block_job_cancel";
+        ret = virAsprintf(&cmd, "%s %s", cmd_name, device);
+    } else if (mode == BLOCK_JOB_INFO) {
+        cmd_name = "info block-jobs";
+        ret = virAsprintf(&cmd, "%s", cmd_name);
+    } else if (mode == BLOCK_JOB_SPEED) {
+        cmd_name = "block_job_set_speed";
+        ret = virAsprintf(&cmd, "%s %s %llu", cmd_name, device,
                           bandwidth * 1024ULL * 1024ULL);
-    else if (mode == BLOCK_JOB_PULL)
-        ret = virAsprintf(&cmd, "block_stream %s", device);
-    else
+    } else if (mode == BLOCK_JOB_PULL) {
+        cmd_name = "block_stream";
+        ret = virAsprintf(&cmd, "%s %s", cmd_name, device);
+    } else {
         return -1;
+    }
 
     if (ret < 0) {
         virReportOOMError();
@@ -3056,6 +3076,13 @@ int qemuMonitorTextBlockJob(qemuMonitorPtr mon,
         goto cleanup;
     }
 
+    if (qemuMonitorTextCommandNotFound(reply)) {
+        qemuReportError(VIR_ERR_OPERATION_INVALID,
+                        _("Command '%s' is not found"), cmd_name);
+        ret = -1;
+        goto cleanup;
+    }
+
     ret = qemuMonitorTextParseBlockJob(reply, device, info);
 
 cleanup:
-- 
1.7.3