[libvirt] [PATCH v2] build: fix build with libselinux 2.3

[Eric Blake]

On 05/28/2014 06:44 AM, Cédric Bosdonnat wrote:
> Several function signatures changed in libselinux 2.3, now taking
> a 'const char *' instead of 'security_context_t'.  The latter is
> defined in selinux/selinux.h as
> 
>   typedef char *security_context_t;
> ---
>  m4/virt-selinux.m4            | 18 ++++++++++++++++++
>  tests/securityselinuxhelper.c | 16 ++++++++++++++++
>  2 files changed, 34 insertions(+)
> 
> diff --git a/m4/virt-selinux.m4 b/m4/virt-selinux.m4
> index 003c2a8..c299793 100644
> --- a/m4/virt-selinux.m4
> +++ b/m4/virt-selinux.m4
> @@ -28,6 +28,24 @@ AC_DEFUN([LIBVIRT_CHECK_SELINUX],[
>      [with_selinux_mount=check])
>  
>    if test "$with_selinux" = "yes"; then
> +  AC_CACHE_CHECK([for selinux setcon parameter type], [gt_cv_setcon_param],
> +    [AC_COMPILE_IFELSE(
> +      [AC_LANG_PROGRAM(
> +         [[
> +#include <selinux/selinux.h>
> +
> +int setcon(const security_context_t context) {

So this tests if we are compatible with the old signature...

> +    return 0;
> +}
> +         ]],
> +         [[]])],
> +         [gt_cv_setcon_param='security_context'],

...if so, we set the param to one value,...

Typo - there is no 'security_context'.

> +         [gt_cv_setcon_param='const char*'])])

...if not, we assume const char* works instead.  I wonder if it ias
better to check for the new signature, and if it fails assume the old;
but unless a third signature ever appears in the future, it probably
doesn't matter.

> +    if test "$gt_cv_setcon_param" = 'const char*'; then
> +       AC_DEFINE_UNQUOTED([SELINUX_CTX_CHAR_PTR], 1,
> +                          [SELinux uses char * for security context])

I'll still like to try and do a slicker macro that is either '' or
'const', because then...

> +    fi
> +
>      AC_MSG_CHECKING([SELinux mount point])
>      if test "$with_selinux_mount" = "check" || test -z "$with_selinux_mount"; then
>        if test -d /sys/fs/selinux ; then
> diff --git a/tests/securityselinuxhelper.c b/tests/securityselinuxhelper.c
> index dbc4c29..af4fae4 100644
> --- a/tests/securityselinuxhelper.c
> +++ b/tests/securityselinuxhelper.c
> @@ -156,7 +156,11 @@ int getpidcon(pid_t pid, security_context_t *context)
>      return getpidcon_raw(pid, context);
>  }
>  
> +#ifdef SELINUX_CTX_CHAR_PTR
> +int setcon_raw(const char *context)
> +#else
>  int setcon_raw(security_context_t context)
> +#endif

...here you would just need:

int setcon_raw(POSSIBLY_CONST char *context)

instead of #ifdefs.


-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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