iproute2: clearer error messages for fifo and tbf qdiscs

Clearer error messages for fifo and tbf qdiscs:
- Say who is complaining
- Don't just say a parameter is bad, show the offending parameter
- Be clearer about duplicate parameters vs illegal pairs of parameters
- Try to give multiple error messages rather than let the user discover the errors one by one
- When there are parameter aliases, try to use the variant that was used, or at least mention them all

Note that in the old version an empty parameter list to tbf would just cause an explain() message
without a specific error message. By simply removing the relevant error check, the code now
handles this error more gracefully by printing an error message for all mandatory parameters.
It still prints the explain() message.

Signed-off-by: Kees van Reeuwijk <reeuwijk@few.vu.nl>
2 files changed