[Swan-dev] strip_prefix + enum_show + bitnamesof

[Andrew Cagney]

I was trying to log the contents of an lset_t, but couldn't seem to
find the right method.  For instance, given the enum:

enum ikev2_trans_type_esn {
        IKEv2_ESN_DISABLED = 0,
        IKEv2_ESN_ENABLED = 1,
};

then I can display a truncated value vis:

   strip_prefix("ESN_", enum_enum_show(ikev2_trans_type_esn_names,
IKEv2_ESN_DISABLED))
   -> "DISABLED"

for lset_t, I'd like something similar:

  lset_t s = LELEM(IKEv2_ESN_DISABLED) + LELEM(IKEv2_ESN_ENABLED);
  bitenumsof(ikev2_trans_type_esn_names, s)
  -> DISABLED+ENABLED

trying to do it with the existing code is, er, annoying:

- the array ikev2_trans_type_esn_name containing the values I need is
out-of-reach - static
- the names have ESN_ hard-wired, and enum_names doesn't know this -
have to keep repeating the magic prefix

and while I'm at it:

- oh for "struct lswlog" so I could just accumulate my message in a
buffer and then send it out (to log or debug or ...)

Andrew