`sizeof(of.size)` is not necessarily the bytes taken by `%z`

[duhoobo]

Found several odd lines of code:

        216 str_buffer.data = ngx_palloc(r->pool,
        217     3 + r->uri.len + sizeof(of.size) + sizeof(of.mtime)  
        218     );

        225 str_buffer.len = ngx_sprintf(str_buffer.data, "%V_%T_%z",&r->uri,of.mtime,of.size) - str_buffer.data;

sizeof(of.size) and sizeof(of.mtime) will only return the bytes occupied by integer representation of these two fields. But the converted strings may need more.