[Spice-devel] [PATCH spice-server] Make reds_stat utility work with both 32 and 64 bit architectures.

[Pavel Grunt]

On Wed, 2016-10-26 at 16:06 +0100, Frediano Ziglio wrote:
> 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 at redhat.com>
Acked-by: Pavel Grunt <pgrunt at redhat.com>
> ---
>  tools/reds_stat.c | 20 +++++++++++++++++---
>  1 file changed, 17 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/reds_stat.c b/tools/reds_stat.c
> index 3e966d4..69260bf 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");
> -- 
> 2.7.4
> 
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