Re: [PATCH] Fix string handling in virDomain{Get, Set}SchedulerParameters

["Richard W.M. Jones" <rjones@xxxxxxxxxx>]

Jim Meyering wrote:
> "Richard W.M. Jones" <rjones@xxxxxxxxxx> wrote:
> > This small patch fixes some bugs in the handling of the field string
> > in virDomainGetSchedulerParameters and makes a similar pre-emptive fix
> > to virDomainSetSchedulerParameters.
> >
> > Also, please don't use !strcmp(a,b), because it confuses me.  Better
> > is to write strcmp(a,b) == 0 to mean "strings match" and strcmp(a,b)
> > != 0 to mean "strings don't match".
>
> Hi Rich,
>
> I agree, but prefer to avoid direct use of strcmp altogether.
> I use this definition:
>
>   #define STREQ(a, b) (strcmp (a, b) == 0)
>
> Then all uses are either
>    STREQ(a, b) or
>  ! STREQ(a, b)

Let's try this updated patch.

Rich.

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Index: src/internal.h
===================================================================
RCS file: /data/cvs/libvirt/src/internal.h,v
retrieving revision 1.42
diff -u -p -r1.42 internal.h
--- src/internal.h	15 Jun 2007 08:18:55 -0000	1.42
+++ src/internal.h	22 Jun 2007 10:01:27 -0000
@@ -31,6 +31,10 @@ extern "C" {
 #include <ansidecl.h>
 #endif
 
+/* String equality tests, suggested by Jim Meyering. */
+#define STREQ(a,b) (strcmp((a),(b)) == 0)
+#define STRCASEEQ(a,b) (strcasecmp((a),(b)) == 0)
+
 /**
  * ATTRIBUTE_UNUSED:
  *
Index: src/xen_internal.c
===================================================================
RCS file: /data/cvs/libvirt/src/xen_internal.c,v
retrieving revision 1.79
diff -u -p -r1.79 xen_internal.c
--- src/xen_internal.c	6 Jun 2007 12:24:31 -0000	1.79
+++ src/xen_internal.c	22 Jun 2007 10:01:29 -0000
@@ -1071,8 +1071,6 @@ xenHypervisorGetSchedulerParameters(virD
 				 virSchedParameterPtr params, int *nparams)
 {
     xenUnifiedPrivatePtr priv;
-    char str_weight[] ="weight";
-    char str_cap[]    ="cap";
 
     if ((domain == NULL) || (domain->conn == NULL)) {
         virXenErrorFunc(VIR_ERR_INTERNAL_ERROR, __FUNCTION__,
@@ -1126,11 +1124,13 @@ xenHypervisorGetSchedulerParameters(virD
 		if (ret < 0)
 		    return(-1);
 
-		strncpy(params[0].field, str_weight, strlen(str_weight));
+		strncpy (params[0].field, "weight", VIR_DOMAIN_SCHED_FIELD_LENGTH);
+        params[0].field[VIR_DOMAIN_SCHED_FIELD_LENGTH-1] = '\0';
 		params[0].type = VIR_DOMAIN_SCHED_FIELD_UINT;
 		params[0].value.ui = op_dom.u.getschedinfo.u.credit.weight;
 
-		strncpy(params[1].field, str_cap, strlen(str_cap));
+		strncpy (params[1].field, "cap", VIR_DOMAIN_SCHED_FIELD_LENGTH);
+        params[1].field[VIR_DOMAIN_SCHED_FIELD_LENGTH-1] = '\0';
 		params[1].type = VIR_DOMAIN_SCHED_FIELD_UINT;
 		params[1].value.ui = op_dom.u.getschedinfo.u.credit.cap;
 
@@ -1161,8 +1161,6 @@ xenHypervisorSetSchedulerParameters(virD
 {
     int i;
     xenUnifiedPrivatePtr priv;
-    char str_weight[] ="weight";
-    char str_cap[]    ="cap";
 
     if ((domain == NULL) || (domain->conn == NULL)) {
         virXenErrorFunc (VIR_ERR_INTERNAL_ERROR, __FUNCTION__,
@@ -1227,11 +1225,11 @@ xenHypervisorSetSchedulerParameters(virD
             op_dom.u.getschedinfo.u.credit.cap    = (uint16_t)~0U;
 
             for (i = 0; i < nparams; i++) {
-                if (!strncmp(params[i].field,str_weight,strlen(str_weight)) &&
+                if (STREQ (params[i].field, "weight") &&
                     params[i].type == VIR_DOMAIN_SCHED_FIELD_UINT) {
                     op_dom.u.getschedinfo.u.credit.weight = params[i].value.ui;
 		    weight_set = 1;
-		} else if (!strncmp(params[i].field,str_cap,strlen(str_cap)) &&
+		} else if (STREQ (params[i].field, "cap") &&
                     params[i].type == VIR_DOMAIN_SCHED_FIELD_UINT) {
                     op_dom.u.getschedinfo.u.credit.cap = params[i].value.ui;
 		    cap_set = 1;

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