Re: [Libguestfs] [PATCH libnbd 2/2] api: Implement local command with systemd socket activation.

This adds new APIs for running a local NBD server and connecting to it using systemd socket activation (instead of stdin/stdout). This includes interop tests against nbdkit and qemu-nbd which I believe are the only NBD servers supporting socket activation. (If we find others then we can add more interop tests in future.) The upstream spec for systemd socket activation is here: http://0pointer.de/blog/projects/socket-activation.html ---

+ + /* Use /tmp instead of TMPDIR because we must ensure the path is + * short enough to store in the sockaddr_un. On some platforms this + * may cause problems so we may need to revisit it. XXX + */ + h->sa_tmpdir = strdup ("/tmp/libnbdXXXXXX"); + h->sa_sockpath = strdup ("/tmp/libnbdXXXXXX/sock"); + if (h->sa_tmpdir == NULL || h->sa_sockpath == NULL) { + SET_NEXT_STATE (%.DEAD); + set_error (errno, "strdup"); + return 0; + } + + if (mkdtemp (h->sa_tmpdir) == NULL) { + SET_NEXT_STATE (%.DEAD); + set_error (errno, "mkdtemp"); + return 0; + } + len = strlen (h->sa_tmpdir); + memcpy (h->sa_sockpath, h->sa_tmpdir, len); + + s = socket (AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0); + if (s == -1) { + SET_NEXT_STATE (%.DEAD); + set_error (errno, "socket"); + return 0; + } + + addr.sun_family = AF_UNIX; + memcpy (addr.sun_path, h->sa_sockpath, strlen (h->sa_sockpath) + 1);