• Maxim Fomin (26/26) Nov 05 2011 Hello. I use curl library and need to overwrite default behavior of
• Jonas Drewsen (4/9) Nov 05 2011 You can use this working curl wrapper (from phobos review 2) as inspirat...
• Jonas Drewsen (3/13) Nov 05 2011 And the link ;)
• Benjamin Thaut (21/47) Nov 07 2011 If you cast the void* to a INet when recieving it you should also cast

Maxim Fomin <maxim maxim-fomin.ru> writes:

Hello. I use curl library and need to overwrite default behavior of
data/headers writing.
I use

   curl_easy_setopt(curl, CurlOption.headerfunction, &header_func);
   curl_easy_setopt(curl, CurlOption.writeheader, &this);

where "this" is a class Inet instance, and header_func is a static
function of the class
(should be a callback of fwrite() args semantics). The class has
buffer for header_func
which should copy data from char *ptr to the buffer.
In
   private static size_t header_func(char *ptr, size_t size, size_t
nmemb, void *userdata)
object is casted back:
   Inet *net = cast(Inet*)userdata;
However, I receive segfault at the beginning of header_func().
I don't know how dmd compiler treats object references.
I tried to pass just "this" (without taking address) and cast without
* and all 4 combinations
of &this/this, cast(Inet*)/cast(Inet); none of them works (segfault on
access to Inet class).

So, how can I pass an object through void* or may be there is another
way to tell
header_func() which object should be used?

Thanks.

P.S. D is a nice language, it's a pleasant to work with)

Jonas Drewsen <jdrewsen nospam.com> writes:

Den 05-11-2011 09:38, Maxim Fomin skrev:
 Hello. I use curl library and need to overwrite default behavior of
 data/headers writing.

<snip>

 So, how can I pass an object through void* or may be there is another
 way to tell
 header_func() which object should be used?

You can use this working curl wrapper (from phobos review 2) as inspiration.

/Jonas

Jonas Drewsen <jdrewsen nospam.com> writes:

Den 05-11-2011 21:00, Jonas Drewsen skrev:
 Den 05-11-2011 09:38, Maxim Fomin skrev:
 Hello. I use curl library and need to overwrite default behavior of
 data/headers writing.

 <snip>

 So, how can I pass an object through void* or may be there is another
 way to tell
 header_func() which object should be used?

 You can use this working curl wrapper (from phobos review 2) as
 inspiration.

 /Jonas

And the link ;)

https://github.com/jcd/phobos/blob/curl-wrapper/etc/curl.d

Benjamin Thaut <code benjamin-thaut.de> writes:

Am 05.11.2011 09:38, schrieb Maxim Fomin:
 Hello. I use curl library and need to overwrite default behavior of
 data/headers writing.
 I use

     curl_easy_setopt(curl, CurlOption.headerfunction,&header_func);
     curl_easy_setopt(curl, CurlOption.writeheader,&this);

 where "this" is a class Inet instance, and header_func is a static
 function of the class
 (should be a callback of fwrite() args semantics). The class has
 buffer for header_func
 which should copy data from char *ptr to the buffer.
 In
     private static size_t header_func(char *ptr, size_t size, size_t
 nmemb, void *userdata)
 object is casted back:
     Inet *net = cast(Inet*)userdata;
 However, I receive segfault at the beginning of header_func().
 I don't know how dmd compiler treats object references.
 I tried to pass just "this" (without taking address) and cast without
 * and all 4 combinations
 of&this/this, cast(Inet*)/cast(Inet); none of them works (segfault on
 access to Inet class).

 So, how can I pass an object through void* or may be there is another
 way to tell
 header_func() which object should be used?

 Thanks.

 P.S. D is a nice language, it's a pleasant to work with)

If you cast the void* to a INet when recieving it you should also cast 
it to a INet when passing it to curl. Pointers to classes point at the 
same address as any parent class they inherit from. Interfaces however 
might point into the middle of a class, thus the address of a interface 
reference is different then the address of a class reference. Classes 
and interfaces are references types in D so there is no need to use the 
address operator.

Correct would be something like:

INet callback = this;
curl_easy_setopt(curl, CurlOption.headerfunction, &header_func);
curl_easy_setopt(curl, CurlOption.writeheader, callback);

...

void header_func(...)
{
  INet callback = cast(INet)userdata;
  ...
}

-- 
Kind Regards
Benjamin Thaut