Re: Was [Re: [evolution-patches] itip-formatter plugin invocation URI fix.]

[Jeffrey Stedfast <fejj novell com>]

On Fri, 2005-07-08 at 16:35 +0530, Veerapuram Varadhan wrote:
> On Thu, 2005-07-07 at 16:45 -0400, Jeffrey Stedfast wrote:
> > On Fri, 2005-07-08 at 01:45 +0530, Veerapuram Varadhan wrote:
> > > -               slash = uri_string + strcspn (uri_string, "/#");
> > > +               /* 
> > > +                * Play safe. ;-)
> > > +                * If username, password, host, port things are not 
> > > +                * specified in the url, find a way to not crib about
> > > +                * them.  So, check for the "existance" of magic "/"
> > > or 
> > > +                * "#" which will give a clue about the presence of
> > > something
> > > +                * that we are looking for.
> > > +                */
> > > +
> > > +               slash = strchr (uri_string, '/');
> > > +               if (!slash)
> > > +                       slash = strchr (uri_string, '#');
> > > +               if (slash)
> > > +                       slash = uri_string + strcspn (uri_string,
> > > "/#");
> > > +               else
> > > +                       slash = uri_string;
> > > +
> > 
> > read up on what strcspn does. your above code changes duplicate the code
> > you replaced (almost) but does it in a less efficient manner.
> 
> >From the man page of strcspn....
> 
> size_t strcspn(const char *s, const char *reject);
> strcspn() returns the number of characters in the initial segment of s
> which are not  in  the  string reject.
> 
> Here is a sample program to verify strcspn.
> 
> #include <unistd.h>
> #include <stdio.h>
> #include <string.h>
>                                                                                                                              
> int
> main ()
> {
>   int len = 0;
>   char * url =
> "calendar://?startdate=20050601T0000Z&enddate=20050602T0000Z";
>                                                                                                                              
>   len = strcspn (url+11, "/#");
>   printf ("Len: %d\n", len);
>   printf ("url = %s\n", url);
>   printf ("url+len = %s\n", url+len);
>                                                                                                                              
>   return 0;
> }
> 
> So, it does mean that when "/" or "#" is not found in string uri_string,
> it will return the "rest-of-the-string". So, the code
> 
> 	slash = uri_string+strcspn (uri_string, "/#");
> 
> will make slash point to the end-of-the-string, in case of "/" or "#"
> not present in the uri_string.

indeed.

> 
> > instead, the following change is simpler:
> > 
> > if ((slash = uri_string + strcspn (uri_string, "/#"))[0] == 0)
> >    slash = uri_string;
> > 
> I don't think this will ever be "TRUE" unless and otherwise the string
> url string contains just the protocol.
> 
> IMO, the above change will never work.

you realise that "end of the string" is the nul-char right? so how would
it never work?

> 
> > however, looking over the e-url.c code, I fail to see how this actually
> > solves the problem. In fact, I fail to see any problem at all in the
> > original code. Please explain what exactly the problem is...
> > 
> Now lets discuss the problem in detail.
> 
> Consider the url-string passed from the itip-formatter plugin,
> "calendar://?startdate=20050601T0000Z&enddate=20050602T0000Z"
> 
> When it get passed to the e_uri_new (url_string), the function parses
> the url and extracts the individual fields/components of a passed url.
> 
> Right after fetching the protocol correctly, the parser starts to parse
> the "authority" fields, (i.e) username, password, host and port.

ONLY if it finds a '@', which it would not do in your example.

> 
> So, in a normal url, these fields are passed as..
> 
> "ftp://username:password host:port/path/file"
> 
> After parsing through the protocol, (i.e.) "calendar:", the following
> code gets executed.
>         if (strncmp (uri_string, "//", 2) == 0) {
>                 uri_string += 2;
> now the uri_string will be
> "?startdate=20050601T0000Z&enddate=20050602T0000Z"
> 
> Now, when the following gets executed
> (179)  slash = uri_string + strcspn (uri_string, "/#");
> 
> slash points to the "end-of-the-uri-string", because, both "/" and "#"
> are not present in the string and strcspn returns 
> len (?startdate=20050601T0000Z&enddate=20050602T0000Z)
> 
> So, uri_string+len (uri_string) == end-of-string.

right...

> 
> And rest of the conditions for "@" and others fail and the code reaches,
> 
> (221)		 uri_string = slash;
> which makes uri_string to point to the end-of-it.
>
> Thereby the rest of code for finding queries, parameters etc fails and
> uri->query returns NULL for urls that dont have proper "authority"
> fields.

ok, so then just fix that. there's no need for you to rewrite the code
that searches for a '/' or '#', that code worked fine before.

> 
> P.S:-
> Having said/done all these.. i have a question...
> 
> should the url that we are currently using in itip-formatter plugin be 
> "calendar:///?startdate=<date-time>&enddate=<date-time>"?
> 
> because "calendar://" is the protocol and "?" should follow a path,
> isn't it?

I'm not sure, possibly.

> 
> Thanks,
> 
> V. Varadhan
> 
>