InternetGetLastResponseInfo returns strange characters instead of error message

Question

I'm using the following code after a call to FtpOpenFile:

error=GetLastError();
if(error!=0)
{
    if(error==ERROR_INTERNET_EXTENDED_ERROR)
    {
        InternetGetLastResponseInfo(&error,NULL,&bufferLength);
        buffer=malloc(bufferLength);
        InternetGetLastResponseInfo(&error,buffer,NULL);
        printf("FtpOpenFile error : %s.\n",buffer);
    }
    else
    {
        printf("FtpOpenFile error : %d.\n",(int)error);
    }
}

I confirmed that error=ERROR_INTERNET_EXTENDED_ERROR, but instead of printf-ing something like

FtpOpenFile error : The server denied the request due to the fact that it has a personal dislike, or in other words, a subtle hatred, towards you.

It gives me

FtpOpenFile error : x☺?.

Thanks.

Answer 1

Your second call to IntergetGetLastResponseInfo is wrong; you're not passing the length of the buffer as required. The first call you make retrieves the size of the buffer needed, but you still have to tell the function how large the buffer is when you call it the second time. (Also note that the documentation says that the value returned in the first call does not include space for the terminating zero.)

InternetGetLastResponseInfo(&error, NULL, &bufferLength);
buffer = malloc(bufferLength + 1);
InternetGetLastResponseInfo(&error, buffer, &bufferLength);

See the InternetGetLastReponseInfo documentation for more info.