[libvirt PATCH v6 01/30] nodedev: capture and report stderror from mdevctl

[Jonathon Jongsma <jjongsma@xxxxxxxxxx>]

When an mdevctl command fails, there is not much information available
to the user about why it failed. This is partly because we were not
making use of the error message that mdevctl itself prints upon failure.

Signed-off-by: Jonathon Jongsma <jjongsma@xxxxxxxxxx>
---
 src/node_device/node_device_driver.c | 46 +++++++++++++++++-----------
 src/node_device/node_device_driver.h |  6 ++--
 tests/nodedevmdevctltest.c           |  6 ++--
 3 files changed, 36 insertions(+), 22 deletions(-)

diff --git a/src/node_device/node_device_driver.c b/src/node_device/node_device_driver.c
index 543e5bb90a..3851a3568f 100644
--- a/src/node_device/node_device_driver.c
+++ b/src/node_device/node_device_driver.c
@@ -700,7 +700,8 @@ nodeDeviceFindAddressByName(const char *name)
 
 virCommandPtr
 nodeDeviceGetMdevctlStartCommand(virNodeDeviceDefPtr def,
-                                 char **uuid_out)
+                                 char **uuid_out,
+                                 char **errmsg)
 {
     virCommandPtr cmd;
     g_autofree char *json = NULL;
@@ -725,15 +726,17 @@ nodeDeviceGetMdevctlStartCommand(virNodeDeviceDefPtr def,
 
     virCommandSetInputBuffer(cmd, json);
     virCommandSetOutputBuffer(cmd, uuid_out);
+    virCommandSetErrorBuffer(cmd, errmsg);
 
     return cmd;
 }
 
 static int
-virMdevctlStart(virNodeDeviceDefPtr def, char **uuid)
+virMdevctlStart(virNodeDeviceDefPtr def, char **uuid, char **errmsg)
 {
     int status;
-    g_autoptr(virCommand) cmd = nodeDeviceGetMdevctlStartCommand(def, uuid);
+    g_autoptr(virCommand) cmd = nodeDeviceGetMdevctlStartCommand(def, uuid,
+                                                                 errmsg);
     if (!cmd)
         return -1;
 
@@ -754,6 +757,7 @@ nodeDeviceCreateXMLMdev(virConnectPtr conn,
                         virNodeDeviceDefPtr def)
 {
     g_autofree char *uuid = NULL;
+    g_autofree char *errmsg = NULL;
 
     if (!def->parent) {
         virReportError(VIR_ERR_XML_ERROR, "%s",
@@ -761,9 +765,10 @@ nodeDeviceCreateXMLMdev(virConnectPtr conn,
         return NULL;
     }
 
-    if (virMdevctlStart(def, &uuid) < 0) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                       _("Unable to start mediated device"));
+    if (virMdevctlStart(def, &uuid, &errmsg) < 0) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("Unable to start mediated device '%s': %s"), def->name,
+                       errmsg && errmsg[0] ? errmsg : "Unknown Error");
         return NULL;
     }
 
@@ -828,23 +833,25 @@ nodeDeviceCreateXML(virConnectPtr conn,
 
 
 virCommandPtr
-nodeDeviceGetMdevctlStopCommand(const char *uuid)
-{
-    return virCommandNewArgList(MDEVCTL,
-                                "stop",
-                                "-u",
-                                uuid,
-                                NULL);
+nodeDeviceGetMdevctlStopCommand(const char *uuid, char **errmsg)
+{
+    virCommandPtr cmd = virCommandNewArgList(MDEVCTL,
+                                             "stop",
+                                             "-u",
+                                             uuid,
+                                             NULL);
+    virCommandSetErrorBuffer(cmd, errmsg);
+    return cmd;
 
 }
 
 static int
-virMdevctlStop(virNodeDeviceDefPtr def)
+virMdevctlStop(virNodeDeviceDefPtr def, char **errmsg)
 {
     int status;
     g_autoptr(virCommand) cmd = NULL;
 
-    cmd = nodeDeviceGetMdevctlStopCommand(def->caps->data.mdev.uuid);
+    cmd = nodeDeviceGetMdevctlStopCommand(def->caps->data.mdev.uuid, errmsg);
 
     if (virCommandRun(cmd, &status) < 0 || status != 0)
         return -1;
@@ -901,9 +908,12 @@ nodeDeviceDestroy(virNodeDevicePtr device)
 
         ret = 0;
     } else if (nodeDeviceHasCapability(def, VIR_NODE_DEV_CAP_MDEV)) {
-        if (virMdevctlStop(def) < 0) {
-            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                           _("Unable to stop mediated device"));
+        g_autofree char *errmsg = NULL;
+
+        if (virMdevctlStop(def, &errmsg) < 0) {
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                           _("Unable to destroy '%s': %s"), def->name,
+                           errmsg && errmsg[0] ? errmsg : "Unknown error");
             goto cleanup;
         }
         ret = 0;
diff --git a/src/node_device/node_device_driver.h b/src/node_device/node_device_driver.h
index 2113d2b0a5..4a40aa51f6 100644
--- a/src/node_device/node_device_driver.h
+++ b/src/node_device/node_device_driver.h
@@ -115,6 +115,8 @@ nodeConnectNodeDeviceEventDeregisterAny(virConnectPtr conn,
 
 virCommandPtr
 nodeDeviceGetMdevctlStartCommand(virNodeDeviceDefPtr def,
-                                 char **uuid_out);
+                                 char **uuid_out,
+                                 char **errmsg);
 virCommandPtr
-nodeDeviceGetMdevctlStopCommand(const char *uuid);
+nodeDeviceGetMdevctlStopCommand(const char *uuid,
+                                char **errmsg);
diff --git a/tests/nodedevmdevctltest.c b/tests/nodedevmdevctltest.c
index 1bad65549b..c12feaac55 100644
--- a/tests/nodedevmdevctltest.c
+++ b/tests/nodedevmdevctltest.c
@@ -58,6 +58,7 @@ testMdevctlStart(const char *virt_type,
     const char *actualCmdline = NULL;
     int ret = -1;
     g_autofree char *uuid = NULL;
+    g_autofree char *errmsg = NULL;
     g_autofree char *stdinbuf = NULL;
     g_autoptr(virCommand) cmd = NULL;
 
@@ -66,7 +67,7 @@ testMdevctlStart(const char *virt_type,
 
     /* this function will set a stdin buffer containing the json configuration
      * of the device. The json value is captured in the callback above */
-    cmd = nodeDeviceGetMdevctlStartCommand(def, &uuid);
+    cmd = nodeDeviceGetMdevctlStartCommand(def, &uuid, &errmsg);
 
     if (!cmd)
         goto cleanup;
@@ -117,11 +118,12 @@ testMdevctlStop(const void *data)
     const char *actualCmdline = NULL;
     int ret = -1;
     g_autoptr(virCommand) cmd = NULL;
+    g_autofree char *errmsg = NULL;
     g_autofree char *cmdlinefile =
         g_strdup_printf("%s/nodedevmdevctldata/mdevctl-stop.argv",
                         abs_srcdir);
 
-    cmd = nodeDeviceGetMdevctlStopCommand(uuid);
+    cmd = nodeDeviceGetMdevctlStopCommand(uuid, &errmsg);
 
     if (!cmd)
         goto cleanup;
-- 
2.26.3