Re: [PATCH v2] libselinux: use designated initializers for label initfuncs

On Wed, Jul 15, 2026 at 9:05 AM Stephen Smalley
<[email protected]> wrote:
>
> On Tue, Jul 14, 2026 at 7:25 PM Thiébaud Weksteen <[email protected]> wrote:
> >
> > Previously, the initfuncs array relied on implicit positional ordering
> > to match backend context constants (e.g., SELABEL_CTX_FILE). If constants
> > were reordered or added, array indexing could become misaligned.
> >
> > Use C99 designated initializers in initfuncs to explicitly bind each
> > initialization function to its corresponding context constant.
> >
> > Additionally, define _SELABEL_CTX_NUM in include/selinux/label.h
> > to count total backends, and add a compile-time static_assert ensuring
> > initfuncs stays in sync with _SELABEL_CTX_NUM.
> >
> > Signed-off-by: Thiébaud Weksteen <[email protected]>
>
> Acked-by: Stephen Smalley <[email protected]>
>

Merged.
Thanks,
Jim

>
> > ---
> > v2: Rebase on selinux/main and format
> >
> >  libselinux/include/selinux/label.h |  5 +++++
> >  libselinux/src/label.c             | 18 ++++++++++++------
> >  2 files changed, 17 insertions(+), 6 deletions(-)
> >
> > diff --git a/libselinux/include/selinux/label.h b/libselinux/include/selinux/label.h
> > index 748b0db0..bde2501f 100644
> > --- a/libselinux/include/selinux/label.h
> > +++ b/libselinux/include/selinux/label.h
> > @@ -37,6 +37,11 @@ struct selabel_handle;
> >  #define SELABEL_CTX_ANDROID_PROP 4
> >  /* Android service contexts */
> >  #define SELABEL_CTX_ANDROID_SERVICE 5
> > +/*
> > + * Total number of context backends. When adding a new backend,
> > + * please increase this value.
> > + */
> > +#define _SELABEL_CTX_NUM 6
> >
> >  /*
> >   * Available options
> > diff --git a/libselinux/src/label.c b/libselinux/src/label.c
> > index 1ccd1abe..991b9769 100644
> > --- a/libselinux/src/label.c
> > +++ b/libselinux/src/label.c
> > @@ -4,6 +4,7 @@
> >   * Author : Eamon Walsh <[email protected]>
> >   */
> >
> > +#include <assert.h>
> >  #include <sys/types.h>
> >  #include <ctype.h>
> >  #include <errno.h>
> > @@ -45,14 +46,19 @@ typedef int (*selabel_initfunc)(struct selabel_handle *rec,
> >                                 const struct selinux_opt *opts, unsigned nopts);
> >
> >  static const selabel_initfunc initfuncs[] = {
> > -       &selabel_file_init,
> > -       CONFIG_MEDIA_BACKEND(selabel_media_init),
> > -       CONFIG_X_BACKEND(selabel_x_init),
> > -       CONFIG_DB_BACKEND(selabel_db_init),
> > -       CONFIG_ANDROID_BACKEND(selabel_property_init),
> > -       CONFIG_ANDROID_BACKEND(selabel_service_init),
> > +       [SELABEL_CTX_FILE] = &selabel_file_init,
> > +       [SELABEL_CTX_MEDIA] = CONFIG_MEDIA_BACKEND(selabel_media_init),
> > +       [SELABEL_CTX_X] = CONFIG_X_BACKEND(selabel_x_init),
> > +       [SELABEL_CTX_DB] = CONFIG_DB_BACKEND(selabel_db_init),
> > +       [SELABEL_CTX_ANDROID_PROP] =
> > +               CONFIG_ANDROID_BACKEND(selabel_property_init),
> > +       [SELABEL_CTX_ANDROID_SERVICE] =
> > +               CONFIG_ANDROID_BACKEND(selabel_service_init),
> >  };
> >
> > +static_assert(ARRAY_SIZE(initfuncs) == _SELABEL_CTX_NUM,
> > +             "initfuncs array size does not match _SELABEL_CTX_NUM");
> > +
> >  static inline struct selabel_digest *
> >  selabel_is_digest_set(const struct selinux_opt *opts, unsigned n)
> >  {
> > --
> > 2.55.0.229.g6434b31f56-goog
> >