[Winpcap-users] pcap_fopen_offline not exported?

Okraszewski, Marcin Marcin.Okraszewski at pl.compuware.com
Wed Jul 23 09:07:37 GMT 2008

Right ... this might be a problem in deed :( But if I recompile winpcap
with the same compiler as rest of the project it seems it should work.

Maybe Winpcap could export an alternative function which would work on
file descriptor? This shouldn't have the CRT compatibility issues. It
could look like this:

pcap_t* pcap_fdopen_offline(int fd, char *errorbuf) {
    FILE *file = _fdopen(fd, "rb");
    if ( file == NULL ) {
        strerror_s(errorbuf, PCAP_ERRBUF_SIZE, errno);
        return NULL;
    return pcap_fopen_offline(file, errorbuf);

Then also it could override pcap_fopen_offline calls with a macro:

#define pcap_fopen_offline(file, errorbuf) \
    pcap_fdopen_offline(_fileno(file), errorbuf)

This together would make it compatible with libpcap.

Thanks a lot for answers!

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From: winpcap-users-bounces at winpcap.org
[mailto:winpcap-users-bounces at winpcap.org] On Behalf Of Gianluca Varenni
Sent: Wednesday, July 23, 2008 7:44 AM
To: winpcap-users at winpcap.org
Subject: Re: [Winpcap-users] pcap_fopen_offline not exported?

Actually, the function has not been exported because as far as I
remember it 
doesn't work on Windows. The reason is the usual one with MS C RunTimes 
(CRTs): you cannot pass FILE* handlers between modules compiled with 
different versions of the CRT.

Have a nice day

----- Original Message ----- 
From: "Guy Harris" <guy at alum.mit.edu>
To: <winpcap-users at winpcap.org>
Sent: Tuesday, July 22, 2008 6:54 PM
Subject: Re: [Winpcap-users] pcap_fopen_offline not exported?

> On Jul 22, 2008, at 8:36 AM, Okraszewski, Marcin wrote:
>> I wanted to use pcap_fopen_offline which is mentioned in
>> as well as available in pcap.h. Unfortunately this  function is not 
>> exported by both 4.0.2 and 4.1 beta 4. Is it on  purpose or some 
>> oversight?
> Probably an oversight.  The .def files weren't updated when the
> base of WinPcap was updated to a version that includes 
> pcap_fopen_offline(); the release notes for libpcap release that first

> included them might not have mentioned that routine.
> (So what exactly *are* the benefits of requiring a .def file when you 
> build a dynamically-linked library?  No UN*X that I know of requires
> the exported functions be explicitly declared when you build a 
> dynamically-linked shared library....)
> _______________________________________________
> Winpcap-users mailing list
> Winpcap-users at winpcap.org
> https://www.winpcap.org/mailman/listinfo/winpcap-users 

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