Make reds_stat utility work with both 32 and 64 bit architectures.

Due to alignment problems the structure of statistics file is
different between 32 and 64 bit. This as on 32 bit uint64_t is
aligned to 4 bytes instead of 8 so sizeof(SpiceStat) can be either
20 (32 bit) or 24 (64 bit).
This cause reds_stat utility to be bit dependent.
Detect the correct SpiceStat size and use that information.

Signed-off-by: Frediano Ziglio <fziglio@redhat.com>
Acked-by: Pavel Grunt <pgrunt@redhat.com>

1 files changed, 17 insertions, 3 deletions

diff --git a/tools/reds_stat.c b/tools/reds_stat.c
index 3e966d48..69260bf8 100644
--- a/tools/reds_stat.c
+++ b/tools/reds_stat.c
@@ -25,18 +25,22 @@
 #include <string.h>
 #include <unistd.h>
 #include <inttypes.h>
+#include <sys/stat.h>
 #include <spice/stats.h>
+#include <common/verify.h>
 
 #define TAB_LEN 4
 #define VALUE_TABS 7
 #define INVALID_STAT_REF (~(uint32_t)0)
 
-static SpiceStat *reds_stat = (SpiceStat *)MAP_FAILED;
+verify(sizeof(SpiceStat) == 20 || sizeof(SpiceStat) == 24);
+
+static SpiceStatNode *reds_nodes = NULL;
 static uint64_t *values = NULL;
 
 static void print_stat_tree(int32_t node_index, int depth)
 {
-    SpiceStatNode *node = &reds_stat->nodes[node_index];
+    SpiceStatNode *node = &reds_nodes[node_index];
 
     if ((node->flags & SPICE_STAT_NODE_MASK_SHOW) == SPICE_STAT_NODE_MASK_SHOW) {
         printf("%*s%s", depth * TAB_LEN, "", node->name);
@@ -66,6 +70,9 @@ int main(int argc, char **argv)
     int shm_name_len;
     int ret = -1;
     int fd;
+    struct stat st;
+    unsigned header_size = sizeof(SpiceStat);
+    SpiceStat *reds_stat = (SpiceStat *)MAP_FAILED;
 
     if (argc != 2 || !(kvm_pid = atoi(argv[1]))) {
         printf("usage: reds_stat [qemu_pid] (e.g. `pgrep qemu`)\n");
@@ -84,6 +91,12 @@ int main(int argc, char **argv)
     }
     shm_size = sizeof(SpiceStat);
     reds_stat = (SpiceStat *)mmap(NULL, shm_size, PROT_READ, MAP_SHARED, fd, 0);
+    if (fstat(fd, &st) == 0) {
+        unsigned size = st.st_size % sizeof(SpiceStatNode);
+        if (size == 20 || size == 24) {
+            header_size = size;
+        }
+    }
     if (reds_stat == (SpiceStat *)MAP_FAILED) {
         perror("mmap");
         goto error;
@@ -104,12 +117,13 @@ int main(int argc, char **argv)
         if (num_of_nodes != reds_stat->num_of_nodes) {
             num_of_nodes = reds_stat->num_of_nodes;
             shm_old_size = shm_size;
-            shm_size = sizeof(SpiceStat) + num_of_nodes * sizeof(SpiceStatNode);
+            shm_size = header_size + num_of_nodes * sizeof(SpiceStatNode);
             reds_stat = mremap(reds_stat, shm_old_size, shm_size, MREMAP_MAYMOVE);
             if (reds_stat == (SpiceStat *)MAP_FAILED) {
                 perror("mremap");
                 goto error;
             }
+            reds_nodes = (SpiceStatNode *)((char *) reds_stat + header_size);
             values = (uint64_t *)realloc(values, num_of_nodes * sizeof(uint64_t));
             if (values == NULL) {
                 perror("realloc");