cURL / Mailing Lists / curl-library / Single Mail


Re: Crash in the DLL

From: Daniel Stenberg <>
Date: Sun, 26 Aug 2001 18:28:18 +0200 (MET DST)

On Sun, 26 Aug 2001, Steve Lhomme wrote:

> I've build the DLL with Visual C++ 6, and with the simple FTP example, it
> crashes when writing into the file ! So I've tried to debug it, and it's
> on the data->fwrite. So I tried a static build and it worked !
> I really didn't understand what happened. I've tried calling the standard
> fwrite in the DLL and out of the DLL with exactly the same parameters
> (same string, length, stream). And it crashes in the DLL and not inside !
> (in the same program/run)

I think the answer can be found in the FAQ, item 5.5:

  5.5 Does CURLOPT_FILE and CURLOPT_INFILE work on win32 ?

  Yes, but you cannot open a FILE * and pass the pointer to a DLL and have
  that DLL use the FILE *. If you set CURLOPT_FILE you must also use
  CURLOPT_WRITEFUNCTION as well to set a function that writes the file, even
  if that simply writes the data to the specified FILE*. Similarly, if you
  use CURLOPT_INFILE you must also specify CURLOPT_READFUNCTION.

  (Provided by Joel DeYoung and Bob Schader)

... and in fact in the man page for curl_easy_setopt() in the CURLOPT_FILE
there's also this text:

  NOTE: If you're using libcurl as a win32 DLL, you MUST use the
  CURLOPT_WRITEFUNCTION if you set this option.

Of course, I should correct that example so that it'll work on windows too
from the start.

    Daniel Stenberg -- curl groks URLs --
Received on 2001-08-26