missing unztell() function

Forwarding from https://bugzilla.redhat.com/show_bug.cgi?id=1632206 :

Jason Tibbitts 2018-09-24 18:39:22 CEST wrote:

Seems the new minizip lacks the unztell() function so more than a rebuild is required. I could conceivably do a port to the new minizip or to some other library, but this would all be to avoid the use of a single unzip.c source file that's already part of the source.

So I've just reverted to using the bundled bit. It's not called on untrusted data so it shouldn't be particularly problematic.

That was me. The code that calls this is pretty old and part of a game engine. For more than a decade, Fedora has been unbundling the built-in unzip.c file and instead calling into minizip but the new minizip library doesn't have that unztell() function as far as I could tell. This obviously isn't a huge deal, but this ticket was filed.

The only code which calls this function in the relevant program is:

int U4FILE_zip::seek(long offset, int whence) {
    char *buf;
    long pos;

    ASSERT(whence != SEEK_END, "seeking with whence == SEEK_END not allowed with zipfiles");
    pos = unztell(zfile);
    if (whence == SEEK_CUR)
        offset = pos + offset;
    if (offset == pos)
        return 0;
    if (offset < pos) {
        unzCloseCurrentFile(zfile);
        unzOpenCurrentFile(zfile);
        pos = 0;
    }
    ASSERT(offset - pos > 0, "error in U4FILE_zip::seek");
    buf = new char[offset - pos];
    unzReadCurrentFile(zfile, buf, offset - pos);
    delete [] buf;
    return 0;
}

long U4FILE_zip::tell() {
    return unztell(zfile);
}

The implementation of that function in the bundled unzip.c file (which we were previously replacing with minizip):

/*
  Give the current position in uncompressed data
*/
extern z_off_t ZEXPORT unztell (unzFile file)
{
    unz_s* s;
    file_in_zip_read_info_s* pfile_in_zip_read_info;
    if (file==NULL)
        return UNZ_PARAMERROR;
    s=(unz_s*)file;
    pfile_in_zip_read_info=s->pfile_in_zip_read;

    if (pfile_in_zip_read_info==NULL)
        return UNZ_PARAMERROR;

    return (z_off_t)pfile_in_zip_read_info->stream.total_out;
}

Added missing unzip compatibility functions. #319

I have added the missing functions. Let me know if you have any problems.

Added compat definition for unztell. #319

Thanks! Once a release with this hits Fedora I'll see about switching back to the previous setup.

The function upstream is unztell, but it's been added as unzTell here, which is causing compatibility issues for programs that expect the symbol name to match.

unztell has been exported since version 2.8.3.

So it has, but unztell64 is still missing, which is what was causing the issue for me.

It appears to be resolved in #529

Ah, thanks. I missed that when I was searching the repo before.

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missing unztell() function #319

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jasontibbitts commented on Sep 25, 2018

nmoinvaz commented on Sep 25, 2018

jasontibbitts commented on Sep 27, 2018

endrift commented on Nov 4, 2020

nmoinvaz commented on Nov 4, 2020

endrift commented on Nov 4, 2020

nmoinvaz commented on Nov 4, 2020

endrift commented on Nov 4, 2020

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