[v2] virfile: fix cast-align error

[libvirt] [RFC v2] virfile: fix cast-align error

Posted by Marc Hartmayer 7 years, 2 months ago

On s390x the struct member f_type of statsfs is hard coded to
'unsigned int'. So let's try to determine the type by means of the GNU
extension typeof.

This fixes the following error:
../../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@linux.ibm.com>
---
 src/util/virfile.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/util/virfile.c b/src/util/virfile.c
index 2a7e87102a25..6cde4ab6c23b 100644
--- a/src/util/virfile.c
+++ b/src/util/virfile.c
@@ -3464,9 +3464,15 @@ int virFilePrintf(FILE *fp, const char *msg, ...)
 
 # define PROC_MOUNTS "/proc/mounts"
 
+# ifdef __GNUC__
+typedef typeof(((struct statfs*)0)->f_type) f_type_type;
+# else
+typedef long f_type_type;
+# endif
+
 static int
 virFileIsSharedFixFUSE(const char *path,
-                       long *f_type)
+                       f_type_type *f_type)
 {
     char *dirpath = NULL;
     const char **mounts = NULL;
@@ -3575,7 +3581,7 @@ 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);
     }
 
     VIR_DEBUG("Check if path %s with FS magic %lld is shared",
-- 
2.17.0

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Re: [libvirt] [RFC v2] virfile: fix cast-align error

Posted by Daniel P. Berrangé 7 years, 2 months ago

On Tue, Oct 09, 2018 at 05:55:29PM +0200, Marc Hartmayer wrote:
> On s390x the struct member f_type of statsfs is hard coded to
> 'unsigned int'. So let's try to determine the type by means of the GNU
> extension typeof.
> 
> This fixes the following error:
> ../../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@linux.ibm.com>
> ---
>  src/util/virfile.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/src/util/virfile.c b/src/util/virfile.c
> index 2a7e87102a25..6cde4ab6c23b 100644
> --- a/src/util/virfile.c
> +++ b/src/util/virfile.c
> @@ -3464,9 +3464,15 @@ int virFilePrintf(FILE *fp, const char *msg, ...)
>  
>  # define PROC_MOUNTS "/proc/mounts"
>  
> +# ifdef __GNUC__
> +typedef typeof(((struct statfs*)0)->f_type) f_type_type;
> +# else
> +typedef long f_type_type;
> +# endif

These games are rather overkill IMHO.

> +
>  static int
>  virFileIsSharedFixFUSE(const char *path,
> -                       long *f_type)
> +                       f_type_type *f_type)

Make this  'long long'

>  {
>      char *dirpath = NULL;
>      const char **mounts = NULL;
> @@ -3575,7 +3581,7 @@ virFileIsSharedFSType(const char *path,

Add a local variable

   long long f_type;

and then after the stat() call

   f_type = sb.f_type;

and change everything that follows to use the local variable

>      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);
>      }
>  
>      VIR_DEBUG("Check if path %s with FS magic %lld is shared",

This also removes the need to cast to long long in this VIR_DEBUG
call


Regards,
Daniel
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