Re: [libvirt] [PATCH] Fix error report from nl_recvmsg

On Thu, Feb 28, 2013 at 04:16:37PM +0000, Daniel P. Berrange wrote:

Oh joy, it is worse than you could possibly imagine. On libnl1 the return value is a valid -errno, while in libnl3 the return value is an error code of its own invention. Further in libnl1 we can';t rely on the global errno, because other calls libnl does may have overritten it with garbage. We must use the return value from the function. For yet more fun, libnl1's error handling is not threadsafe. Whenever it hits an error with a syscall, it internally runs __nl_error() which mallocs/frees a static global variable containing the contents of strerror() which is itself also not threadsafe :-( Did I mention we should just throw out all versions of libnl entirely and talk to the kernel ourselves..... It has caused us no end of pain in all its versions.