nodeinfo: Increase the num of CPU thread siblings to a larger value

Current libvirt can only handle up to 1023 bytes when it
reads Linux sysfs topology/thread_siblings. This isn't enough for
Linux distributions that support a large value. This patch fixes
the problem by using VIR_ALLOC()/VIR_FREE(), instead of using a
fixed-size (1024) local char array. In the meanwhile
SYSFS_THREAD_SIBLINGS_LIST_LENGTH_MAX is increased to 8192 which
should be large enough for a foreseeable future.
Signed-off-by: NWei Huang <wei@redhat.com>

src/nodeinfo.c

@@ -287,7 +287,7 @@ freebsdNodeGetMemoryStats(virNodeMemoryStatsPtr params,
 # define PROCSTAT_PATH "/proc/stat"
 # define MEMINFO_PATH "/proc/meminfo"
 # define SYSFS_MEMORY_SHARED_PATH "/sys/kernel/mm/ksm"
-# define SYSFS_THREAD_SIBLINGS_LIST_LENGTH_MAX 1024
+# define SYSFS_THREAD_SIBLINGS_LIST_LENGTH_MAX 8192
 
 # define LINUX_NB_CPU_STATS 4
 # define LINUX_NB_MEMORY_STATS_ALL 4
@@ -345,7 +345,7 @@ virNodeCountThreadSiblings(const char *dir, unsigned int cpu)
     unsigned long ret = 0;
     char *path;
     FILE *pathfp;
-    char str[1024];
+    char *str = NULL;
     size_t i;
 
     if (virAsprintf(&path, "%s/cpu%u/topology/thread_siblings",
@@ -365,7 +365,10 @@ virNodeCountThreadSiblings(const char *dir, unsigned int cpu)
         return 0;
     }
 
-    if (fgets(str, sizeof(str), pathfp) == NULL) {
+    if (VIR_ALLOC_N(str, SYSFS_THREAD_SIBLINGS_LIST_LENGTH_MAX) < 0)
+        goto cleanup;
+
+    if (fgets(str, SYSFS_THREAD_SIBLINGS_LIST_LENGTH_MAX, pathfp) == NULL) {
         virReportSystemError(errno, _("cannot read from %s"), path);
         goto cleanup;
     }
@@ -382,6 +385,7 @@ virNodeCountThreadSiblings(const char *dir, unsigned int cpu)
     }
 
  cleanup:
+    VIR_FREE(str);
     VIR_FORCE_FCLOSE(pathfp);
     VIR_FREE(path);