I am working on a class to wrap the libcurl dll functions. This class will be able to work with secure FTP servers.

I have to set up some callback functions for libcurl, for that I am using the vfp2c32.fll

This is the code that is working fine, the libcurl function prototypes are copy/pasted from libcurl.h:

*!*	typedef size_t (*curl_read_callback)(char *buffer,
*!*	                                      size_t size,
*!*	                                      size_t nitems,
*!*	                                      void *instream)
This._CurlReadCallBackAddress  = CreateCallBackFunc("CurlReadCallBack", "INTEGER","INTEGER,INTEGER,INTEGER,INTEGER", This, 1)

*!*	typedef size_t (*curl_write_callback)(char *buffer,
*!*	                                      size_t size,
*!*	                                      size_t nitems,
*!*	                                      void *outstream)
This._CurlWriteCallBackAddress = CreateCallBackFunc("CurlWriteCallBack","INTEGER","INTEGER,INTEGER,INTEGER,INTEGER", This, 1)

*!*	typedef int (*curl_debug_callback)
*!*	       (CURL *handle,      /* the handle/transfer this concerns */
*!*	        curl_infotype type, /* what kind of data */
*!*	        char *data,        /* points to the data */
*!*	        size_t size,       /* size of the data pointed to */
*!*	        void *userptr);    /* whatever the user please */
This._CurlDebugCallBackAddress = CreateCallBackFunc("CurlDebugCallBack","INTEGER","INTEGER,INTEGER,INTEGER,INTEGER,INTEGER", This, 1)

And the following code causes an error "Declare dll caused an exception", when curl_easy_perform is called. It seems that the callback functions are called just once, and then the error fires.

*!*	typedef int (*curl_progress_callback)(void *clientp,
*!*	                                      double dltotal,
*!*	                                      double dlnow,
*!*	                                      double ultotal,
*!*	                                      double ulnow)
This._CurlProgressCallBackAddress = CreateCallBackFunc("CurlProgressCallBack","INTEGER", "INTEGER,DOUBLE,DOUBLE,DOUBLE,DOUBLE", This, 1)

*!*	typedef int (*curl_seek_callback)(void *instream,
*!*	                                  curl_off_t offset,
*!*	                                  int origin); /* 'whence' */
This._CurlSeekCallBackAddress  = CreateCallBackFunc("CurlSeekCallBack", "INTEGER","INTEGER,INTEGER,INTEGER", This, 1)

I guess there is a problem matching the C data types to the vfp2c32.fll data types used in CreateCallBackFunc. Also, I don´t know what a curl_off_t is.

I can only go so far with this, if anyone is willing to take a look, here is what you need:

http://www.ctl32.com.ar/ctl32_curl.asp

It would be great if this could work properly, it will make possible to use FTPS from VFP easily, and best of all, free.

Carlos Alloatti