On 05/27/2014 10:05 PM, Jim Fehlig wrote:
> The attached patch is an attempt to fix recent build failures I've
> noticed with libselinux 2.3
>
> CC securityselinuxhelper.lo
> securityselinuxhelper.c:159:5: error: conflicting types for 'setcon_raw'
> int setcon_raw(security_context_t context)
> ^
> Noticing that security_context_t changed to 'const char *', my first
> thought was to use AC_CHECK_TYPE to check for security_conext_t, but
> alas the typedef remains in 2.3 with the comment "No longer used; here
> for compatibility with legacy callers".
>
> I then pursued the approach in this patch of defining a config var based
> on 'pkg-config --modversion', which works in a test script, but not in
> the context of the LIBVIRT_CHECK_SELINUX macro. Probably due to some
> missed quoting, but I'm reaching the m4 knowledge barrier. Before
> attempting to bypass that, I'd like to see what others think of this
> approach. Is there a simpler solution?
So the difference is deciding whether the const is present? It should be
possible to write an AC_COMPILE_IF test that passes or fails based on
whether you have a compatible redeclaration of the function.
>
> if test "$with_selinux" = "yes"; then
> + AC_MSG_CHECKING([SELinux version])
> + ver=$(pkg-config --modversion libselinux)
> + major_ver=`echo $ver | awk -F. '{print $1}'`
> + minor_ver=`echo $ver | awk -F. '{print $2}'`
> + SELINUX_VER=`expr $major_ver + $minor_ver`
> + AC_MSG_RESULT([$SELINUX_VER])
> + if test $SELINUX_VER -ge 2003; then
> + AC_DEFINE_UNQUOTED([SELINUX_CTX_CHAR_PTR], 1,
> + [SELinux uses char * for security context])
> + fi
Eww. Version-check tests are inherently fragile; we want to do a
feature check (does a const char * compile) not a version check. I'll
take some time tomorrow to propose an alternative. My idea is to define
a new macro VIR_SELINUX_CTX_CONST to either '' or 'const' depending on
which version builds, without messing around with fragile version checks.
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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