On Thu, Feb 20, 2025 at 6:16 PM William Roberts
<bill.c.roberts@xxxxxxxxx> wrote:
>
> On Thu, Feb 20, 2025 at 3:13 PM Rahul Sandhu <nvraxn@xxxxxxxxx> wrote:
> >
> > Passing a const char *path to basename(3) is a glibc specific
> > extension.
> >
> > Signed-off-by: Rahul Sandhu <nvraxn@xxxxxxxxx>
> > ---
> > libsemanage/src/conf-parse.y | 3 +++
> > libsemanage/src/direct_api.c | 3 +++
> > 2 files changed, 6 insertions(+)
> >
> > diff --git a/libsemanage/src/conf-parse.y b/libsemanage/src/conf-parse.y
> > index 6cb8a598..97cc5438 100644
> > --- a/libsemanage/src/conf-parse.y
> > +++ b/libsemanage/src/conf-parse.y
> > @@ -50,6 +50,9 @@ static external_prog_t *new_external;
> > static int parse_errors;
> >
> > #define PASSIGN(p1,p2) { free(p1); p1 = p2; }
> > +#if !defined(__GLIBC__)
> > +#define basename(src) (strrchr(src, '/') ? strrchr(src, '/') + 1 : src)
> > +#endif
> >
> > %}
> >
> > diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
> > index 99cba7f7..4459a7d7 100644
> > --- a/libsemanage/src/direct_api.c
> > +++ b/libsemanage/src/direct_api.c
> > @@ -63,6 +63,9 @@
> > #define PIPE_READ 0
> > #define PIPE_WRITE 1
> > #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
> > +#if !defined(__GLIBC__)
> > +#define basename(src) (strrchr(src, '/') ? strrchr(src, '/') + 1 : src)
> > +#endif
> >
> > static void semanage_direct_destroy(semanage_handle_t * sh);
> > static int semanage_direct_disconnect(semanage_handle_t * sh);
> > --
> > 2.48.1
> >
>
> What system are you on where you run libsemange without glibc, just curious?
>
> I am not opposed to adding an implementation for basename where the
> input can be read only for non-glibc, but this patch doesn't work:
> Per the man page, https://man7.org/linux/man-pages/man3/basename.3.html,
> basename("/") should return "/", this one return "\0"
> basename("/usr/"); should return "usr", this returns "\0".
>
> There are two ways you could approach this:
> 1. If you wanted to do an implementation, I would add it to
> utilities.c/h and call it something other than basename so we don't
> get any odd issues with it choosing the one from the headers over the
> macro. Perhaps libsemange_basename(). On glibc systems this would just
> call basename directly and on non-glibc systems do the implementation
> with your own logic.
> 2. Just copy the path into a modifiable buffer on non-glibc systems
>
> I would do both approaches. Create a utility routine that calls
> basename for glibc and for non-glibc just copies it to a modifiable
> buffer and then calls basename over rolling our own and the bugs
> associated with it, also add a unit test for this. This would keep the
> logic in one place and be dirt simple.
>
Looking even more closely it's only the conf-parse.y usage where
selinux_policy_root() returns a const char *,
the usage in direct_api.c path is a char *, so we only need one spot
changed and that can just be a simple
copy to an intermediate buffer or am I missing something else here
you're pointing out?
> Bill
