Report errors in virNodeCountThreadSiblings

Use virFileReadAll which reports an error when the file is larger
than the specified maximum.

https://bugzilla.redhat.com/show_bug.cgi?id=1207849

src/nodeinfo.c

@@ -344,7 +344,6 @@ virNodeCountThreadSiblings(const char *dir, unsigned int cpu)
 {
     unsigned long ret = 0;
     char *path;
-    FILE *pathfp;
     char *str = NULL;
     size_t i;
 
@@ -352,26 +351,15 @@ virNodeCountThreadSiblings(const char *dir, unsigned int cpu)
                     dir, cpu) < 0)
         return 0;
 
-    pathfp = fopen(path, "r");
-    if (pathfp == NULL) {
+    if (!virFileExists(path)) {
         /* If file doesn't exist, then pretend our only
          * sibling is ourself */
-        if (errno == ENOENT) {
-            VIR_FREE(path);
-            return 1;
-        }
-        virReportSystemError(errno, _("cannot open %s"), path);
-        VIR_FREE(path);
-        return 0;
-    }
-
-    if (VIR_ALLOC_N(str, SYSFS_THREAD_SIBLINGS_LIST_LENGTH_MAX) < 0)
+        ret = 1;
         goto cleanup;
+    }
 
-    if (fgets(str, SYSFS_THREAD_SIBLINGS_LIST_LENGTH_MAX, pathfp) == NULL) {
-        virReportSystemError(errno, _("cannot read from %s"), path);
+    if (virFileReadAll(path, SYSFS_THREAD_SIBLINGS_LIST_LENGTH_MAX, &str) < 0)
         goto cleanup;
-    }
 
     i = 0;
     while (str[i] != '\0') {
@@ -386,9 +374,7 @@ virNodeCountThreadSiblings(const char *dir, unsigned int cpu)
 
  cleanup:
     VIR_FREE(str);
-    VIR_FORCE_FCLOSE(pathfp);
     VIR_FREE(path);
-
     return ret;
 }