First, I want to thank everyone for your great replies! I really learned a lot from reading what was written here.

Okay, so I've tried to absorb what I read, and now my XS code looks something like this:

SV *
my_xs_func(p_struct, len)
        void *p_struct;
        IV len
    PREINIT:
        int bytes_read;
        char *tmp_buffer;
    PPCODE:
        tmp_buffer = (char *)malloc(len + 1); // + 1 for NULL
        if (tmp_buffer == NULL)
            XSRETURN_UNDEF;

        bytes_read = my_func(p_struct, tmp_buffer, len);
 
        // need to NULL-terminate the buffer
        tmp_buffer[bytes_read] = '\0';

        XPUSHs(sv_2mortal(newSVpv(tmp_buffer, bytes_read)));

        free(tmp_buffer);

[download]

I have incorporated the advice of Elian here, tye here, and pg here.

I am manipulating the return stack myself, only returning the buffer (the caller can call length), and I'm checking the malloc() return value, and returning undef if it fails. my_func() returns the number of bytes written to tmp_buffer, which is guaranteed to be less than len, so the line that NULL-terminates the buffer should be safe, unless my_func() seriously misbehaves. And I'm using that value for the second argument to newSVpv() instead of zero...

Any new critiques or comments? Does it look better?

Thanks,

3dan

In reply to Re: Perl XS: garbage-collecting my malloc'd buffer by edan
in thread Perl XS: garbage-collecting my malloc'd buffer by edan

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