[Web-SIG] Prototype of wsgi.input.readline().

[Chris McDonough]

Graham Dumpleton wrote:
> As I think we all know, no one implements readline() for wsgi.input as
> defined in the WSGI specification. The reason for this is that stuff
> like cgi.FieldStorage would refuse to work and would just generate an
> exception. This is because cgi.FieldStorage expects to pass an
> argument to readline().

I haven't been keeping up on the issues this has caused wrt WSGI, but note that 
the reason that cgi.FieldStorage passes a size argument to readline is in order 
to prevent memory exhaustion when reading files that don't have any linebreaks 
(denial of service).  See http://bugs.python.org/issue1112549 .

> 
> So, although this is linked in the issues list for possible amendments
> to WSGI specification, there hasn't that I recall been a discussion on
> how readline() would be defined in any amendment or future version.
> 
> In particular, would the specification be changed to either:
> 
> 1. readline(size) where size argument is mandatory, or:
> 
> 2. readline(size=-1) where size argument is optional.
> 
> If the size argument is made mandatory, then it would parallel how
> read() function is defined, but this in itself would mean
> cgi.FieldStorage would break.
> 
> This is because cgi.FieldStorage actually calls readline() with no
> argument as well as an argument in different places in the code.

cgi.FieldStorage doesn't call readline() without an argument. 
cgi.parse_multipart does, but this function is not used by cgi.FieldStorage.  I 
don't know if this changes anything.

- C