Learning XS dmake problem

Herkum has asked for the wisdom of the Perl Monks concerning the following question:

I am trying to learn XS and I am trying to do Example 5 from PerlXSut on a Windows 7 machine using dmake, The example is,

        SV * paths
    INIT:
        AV * results;
        I32 numpaths = 0;
        int i, n;
        struct statfs buf;

        if ((!SvROK(paths))
            || (SvTYPE(SvRV(paths)) != SVt_PVAV)
            || ((numpaths = av_len((AV *)SvRV(paths))) < 0))
        {
            XSRETURN_UNDEF;
        }
        results = (AV *)sv_2mortal((SV *)newAV());
    CODE:
        for (n = 0; n <= numpaths; n++) {
            HV * rh;
            STRLEN l;
            char * fn = SvPV(*av_fetch((AV *)SvRV(paths), n, 0), l);

            i = statfs(fn, &buf);
            if (i != 0) {
                av_push(results, newSVnv(errno));
                continue;
            }

            rh = (HV *)sv_2mortal((SV *)newHV());

            hv_store(rh, "f_bavail", 8, newSVnv(buf.f_bavail), 0);
            hv_store(rh, "f_bfree",  7, newSVnv(buf.f_bfree),  0);
            hv_store(rh, "f_blocks", 8, newSVnv(buf.f_blocks), 0);
            hv_store(rh, "f_bsize",  7, newSVnv(buf.f_bsize),  0);
            hv_store(rh, "f_ffree",  7, newSVnv(buf.f_ffree),  0);
            hv_store(rh, "f_files",  7, newSVnv(buf.f_files),  0);
            hv_store(rh, "f_type",   6, newSVnv(buf.f_type),   0);

            av_push(results, newRV((SV *)rh));
        }
        RETVAL = newRV((SV *)results);
    OUTPUT:
        RETVAL
[download]

The problem is when I run 'dmake' I keep seeing this error, I am unsure what to do, any suggestions?

MyTest.xs:45: error: storage size of 'buf' isn't known
[download]

Comment on Learning XS dmake problem Select or Download Code

Replies are listed 'Best First'.
Re: Learning XS dmake problem by almut (Canon) on Sep 25, 2009 at 22:22 UTC
As noted in perlxstut, this particular example would only work on Unix as is: `This extension is very Unix-oriented (struct statfs and the statfs +system call). If you are not running on a Unix system, you can substitute for statfs any other f +unction that returns multiple values, you can hard-code values to be returned to the caller (alth +ough this will be a bit harder to test the error case), or you can simply not do this example.` [download] In other words, the storage size of `buf` cannot be determined because the `struct statfs` is not known on Windows (it's defined in `sys/vfs.h` on Unix).	[reply] [d/l] [select]
Re^2: Learning XS dmake problem by Herkum (Parson) on Sep 25, 2009 at 22:29 UTC
Ah, I figured the examples would be general enough to work on most systems without problem. I guess part of the problem is I am not very familiar with C and the syntax for XS is specialized as well. So it makes it easy to miss details, especially when I am just trying to make progress on learning something.	[reply]
Re^3: Learning XS dmake problem by Anonymous Monk on Sep 26, 2009 at 00:42 UTC
Try the source code from the book Extending and Embedding Perl	[reply]