Function gzfwrite 

pub unsafe extern "C" fn gzfwrite(
    buf: *const c_void,
    size: size_t,
    nitems: size_t,
    file: gzFile,
) -> size_t

Available on crate feature gz only.

Compress and write nitems items of size size from buf to file, duplicating the interface of C stdio’s fwrite, with size_t request and return types.

Returns

• The number of full items written of size size on success.
• Zero on error.

Note: If the multiplication of size and nitems overflows, i.e. the product does not fit in a size_t, then nothing is written, zero is returned, and the error state is set to Z_STREAM_ERROR.

Safety

• file, if non-null, must be an open file handle obtained from gzopen or gzdopen.
• The caller must ensure that buf points to at least size * nitems readable bytes.