[xml] Return value of xmlCharEncodingInputFunc

[Ralf Junker <ralfjunker gmx de>]

Hi,

I am in doubt about the -1 return value of these function prototypes:

  * xmlCharEncodingInputFunc
  * xmlCharEncodingOutputFunc

The documentation says that -1 means "lack of space". However, in various implementations of these function 
prototype I see this:

  if ((out == NULL) || (outlen == NULL) || (inlen == NULL)) return(-1);

So I wonder if the -1 result value means

  1. lack of space in the output buffer
  2. illegal arguments passed

The difference is that with 1 I would need to provide more output, but with 2. I would issue a parameter 
error.

Does anyone which one of the two (or yet another) is the corret understanding of -1?

Many thanks,

Ralf