[libvirt] [RFC] virfile: fix cast-align error

[Bjoern Walk]

Marc Hartmayer <mhartmay at linux.ibm.com> [2018-10-08, 08:41PM +0200]:
> Use the correct type in order to fix the following error on s390x:
> 
> In function 'virFileIsSharedFSType':
> ../../src/util/virfile.c:3578:38: error: cast increases required alignment of target type [-Werror=cast-align]
>          virFileIsSharedFixFUSE(path, (long *) &sb.f_type);
> 
> Signed-off-by: Marc Hartmayer <mhartmay at linux.ibm.com>
> ---
>  src/util/virfile.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/src/util/virfile.c b/src/util/virfile.c
> index 2a7e87102a25..832d832696d5 100644
> --- a/src/util/virfile.c
> +++ b/src/util/virfile.c
> @@ -3466,7 +3466,7 @@ int virFilePrintf(FILE *fp, const char *msg, ...)
>  
>  static int
>  virFileIsSharedFixFUSE(const char *path,
> -                       long *f_type)
> +                       unsigned int *f_type)
>  {
>      char *dirpath = NULL;
>      const char **mounts = NULL;
> @@ -3575,7 +3575,7 @@ virFileIsSharedFSType(const char *path,
>  
>      if (sb.f_type == FUSE_SUPER_MAGIC) {
>          VIR_DEBUG("Found FUSE mount for path=%s. Trying to fix it", path);
> -        virFileIsSharedFixFUSE(path, (long *) &sb.f_type);
> +        virFileIsSharedFixFUSE(path, &sb.f_type);
>      }

Using an unsigned int is fine as per statfs(2):

    NOTES
       The __fsword_t type used for various fields in the statfs structure defini‐
       tion is a glibc internal type, not intended for public  use.   This  leaves
       the programmer in a bit of a conundrum when trying to copy or compare these
       fields to local variables in a program.  Using unsigned int for such  vari‐
       ables suffices on most systems.

I would prefer an explicit cast though.

>  
>      VIR_DEBUG("Check if path %s with FS magic %lld is shared",
>                path, (long long int)sb.f_type);

Should we also fix this cast?

Reviewed-by: Bjoern Walk <bwalk at linux.ibm.com>

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