[libvirt] [PATCH] Add error handling to optional arguments in cmdCPUStats

[John Ferlan]

https://bugzilla.redhat.com/show_bug.cgi?id=907732

Also added informational message when count value is larger than number
of CPUs present.  Original code commit '31047e2b' quietly changes it and
continues on.

Prior to this patch, no errors were seen for following sequences

virsh cpu-stats guest xyz
virsh cpu-stats guest --start xyz
virsh cpu-stats guest --count xyz
virsh cpu-stats guest --count 99999999999

With this patch, the following errors are displayed

error: Invalid value for start CPU
error: Invalid value for start CPU
error: Invalid value for number of CPUs to show
error: Invalid value for number of CPUs to show

Passing a value such as 9 to count will display the following:

Only 4 CPUs available to show
CPU0:
        cpu_time            19.860859202 seconds
        vcpu_time           17.551435620 seconds
...
---
 tools/virsh-domain.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/tools/virsh-domain.c b/tools/virsh-domain.c
index c088468..3dbfa53 100644
--- a/tools/virsh-domain.c
+++ b/tools/virsh-domain.c
@@ -6111,7 +6111,7 @@ static const vshCmdInfo info_cpu_stats[] = {
     {.name = "desc",
      .data = N_("Display per-CPU and total statistics about the domain's CPUs")
     },
-    {.name = NULL},
+    {.name = NULL}
 };
 
 static const vshCmdOptDef opts_cpu_stats[] = {
@@ -6132,7 +6132,7 @@ static const vshCmdOptDef opts_cpu_stats[] = {
      .type = VSH_OT_INT,
      .help = N_("Number of shown CPUs at most")
     },
-    {.name = NULL},
+    {.name = NULL}
 };
 
 static bool
@@ -6149,9 +6149,18 @@ cmdCPUStats(vshControl *ctl, const vshCmd *cmd)
         return false;
 
     show_total = vshCommandOptBool(cmd, "total");
-    if (vshCommandOptInt(cmd, "start", &cpu) > 0)
+    if (vshCommandOptInt(cmd, "start", &cpu) < 0) {
+        vshError(ctl, "%s", _("Invalid value for start CPU"));
+        goto cleanup;
+    }
+    if (cpu >= 0)
         show_per_cpu = true;
-    if (vshCommandOptInt(cmd, "count", &show_count) > 0)
+
+    if (vshCommandOptInt(cmd, "count", &show_count) < 0) {
+        vshError(ctl, "%s", _("Invalid value for number of CPUs to show"));
+        goto cleanup;
+    }
+    if (show_count >= 0)
         show_per_cpu = true;
 
     /* default show per_cpu and total */
@@ -6170,8 +6179,10 @@ cmdCPUStats(vshControl *ctl, const vshCmd *cmd)
     /* get number of cpus on the node */
     if ((max_id = virDomainGetCPUStats(dom, NULL, 0, 0, 0, flags)) < 0)
         goto failed_stats;
-    if (show_count < 0 || show_count > max_id)
+    if (show_count < 0 || show_count > max_id) {
+        vshPrint(ctl, _("Only %d CPUs available to show\n"), max_id);
         show_count = max_id;
+    }
 
     /* get percpu information */
     if ((nparams = virDomainGetCPUStats(dom, NULL, 0, 0, 1, flags)) < 0)
-- 
1.8.1.4