Re: [Libguestfs] [PATCH libnbd 2/2] examples: copy-libev.c: Fix error handling

This example failed to check the *error parameter to the completion and extent callbacks. - If the source NBD server failed a read, we wrote stale data from the request buffer to the destination image, corrupting the image. - If the destination NBD server failed a write or zero command, we ignored the error, leaving previous content on the destination image, corrupting the image. - Error in the extents callbacks were ignored. I'm not sure if this was a real problem, but it is a very bad example. In all cases, the copy would end with zero exit code creating a corrupted image.