On 9/30/19 11:32 AM, Richard W.M. Jones wrote: We probably ought to use AC_CACHE_CHECK for our various configure.ac things, to let a user have more control at overriding things if we probed wrong without having to patch configure.ac. But that's a separate problem, not affecting this one. Easy enough to work around. In the parameters: unsigned long v, and the condition here should be: if ((long) v < 0) Do we want to assert that bufsize is large enough? (Or rather, abort() if it is not, since assert() is borderline in fork-safe context) Surprisingly, strlen() is not listed in current POSIX' list of async-signal-safe functions. But I have an open bug to remedy that, and don't see any problem in using it. I think it looks nicer to use STDERR_FILENO instead of 2. Otherwise looks sane. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org

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 --- .gitignore | 2 + TODO | 2 - configure.ac | 4 + generator/Makefile.am | 1 + generator/generator | 53 ++++- generator/states-connect-socket-activation.c | 228 +++++++++++++++++++ interop/Makefile.am | 22 ++ interop/socket-activation.c | 92 ++++++++ lib/connect.c | 28 +++ lib/handle.c | 10 + lib/internal.h | 6 + 11 files changed, 443 insertions(+), 5 deletions(-) diff --git a/.gitignore b/.gitignore index 1720e8f..9254d1a 100644 --- a/.gitignore +++ b/.gitignore @@ -71,6 +71,8 @@ Makefile.in /interop/interop-qemu-nbd /interop/interop-qemu-nbd-tls-certs /interop/interop-qemu-nbd-tls-psk +/interop/socket-activation-nbdkit +/interop/socket-activation-qemu-nbd /interop/structured-read /lib/api.c /lib/libnbd.pc diff --git a/TODO b/TODO index 2f23a34..71d678b 100644 --- a/TODO +++ b/TODO @@ -17,8 +17,6 @@ NBD_INFO_BLOCK_SIZE. TLS should properly shut down the session (calling gnutls_bye). -Implement nbd_connect + systemd socket activation. - Improve function trace output so that: - Long strings are truncated. - Strings with non-printable characters are escaped. diff --git a/configure.ac b/configure.ac index 35a4fed..2ebd47c 100644 --- a/configure.ac +++ b/configure.ac @@ -77,6 +77,10 @@ AC_CHECK_HEADERS([\ stdatomic.h \ sys/endian.h]) +dnl Check for functions, all optional. +AC_CHECK_FUNCS([\ + execvpe]) + dnl Check for sys_errlist (optional). AC_MSG_CHECKING([for sys_errlist]) AC_TRY_LINK([], [extern int sys_errlist; char *p = &sys_errlist;], [ diff --git a/generator/Makefile.am b/generator/Makefile.am index c20184a..dca17de 100644 --- a/generator/Makefile.am +++ b/generator/Makefile.am @@ -24,6 +24,7 @@ DISTCLEANFILES = stamp-generator states_code = \ states.c \ states-connect.c \ + states-connect-socket-activation.c \ states-issue-command.c \ states-magic.c \ states-newstyle-opt-export-name.c \ diff --git a/generator/generator b/generator/generator index 2fd2907..7a6b980 100755 --- a/generator/generator +++ b/generator/generator @@ -95,6 +95,7 @@ type external_event = | CmdConnectUnix (* [nbd_aio_connect_unix] *) | CmdConnectTCP (* [nbd_aio_connect_tcp] *) | CmdConnectCommand (* [nbd_aio_connect_command] *) + | CmdConnectSA (* [nbd_aio_connect_socket_activation] *) | CmdIssue (* issuing an NBD command *) type location = string * int (* source location: file, line number *) @@ -168,13 +169,15 @@ let rec state_machine = [ CmdConnectSockAddr, "CONNECT.START"; CmdConnectUnix, "CONNECT_UNIX.START"; CmdConnectTCP, "CONNECT_TCP.START"; - CmdConnectCommand, "CONNECT_COMMAND.START" ]; + CmdConnectCommand, "CONNECT_COMMAND.START"; + CmdConnectSA, "CONNECT_SA.START" ]; }; Group ("CONNECT", connect_state_machine); Group ("CONNECT_UNIX", connect_unix_state_machine); Group ("CONNECT_TCP", connect_tcp_state_machine); Group ("CONNECT_COMMAND", connect_command_state_machine); + Group ("CONNECT_SA", connect_sa_state_machine); Group ("MAGIC", magic_state_machine); Group ("OLDSTYLE", oldstyle_state_machine); @@ -272,6 +275,16 @@ and connect_command_state_machine = [ }; ] +(* State machine implementing [nbd_aio_connect_socket_activation]. *) +and connect_sa_state_machine = [ + State { + default_state with + name = "START"; + comment = "Connect to a subprocess with systemd socket activation"; + external_events = []; + }; +] + (* Parse initial magic string from the server. *) and magic_state_machine = [ State { @@ -1501,6 +1514,18 @@ behave like inetd clients, such as C<nbdkit --single>."; example = Some "examples/connect-command.c"; }; + "connect_socket_activation", { + default_call with + args = [ StringList "argv" ]; ret = RErr; + permitted_states = [ Created ]; + shortdesc = "connect using systemd socket activation"; + longdesc = "\ +Run the command as a subprocess and connect to it using +systemd socket activation. This is for use with NBD servers +such as C<nbdkit> which understand socket activation."; + see_also = ["L<nbd_kill_subprocess(3)>"]; + }; + "is_read_only", { default_call with args = []; ret = RBool; @@ -2093,6 +2118,22 @@ Run the command as a subprocess and begin connecting to it over stdin/stdout. Parameters behave as documented in L<nbd_connect_command(3)>. +You can check if the connection is still connecting by calling +L<nbd_aio_is_connecting(3)>, or if it has connected to the server +and completed the NBD handshake by calling L<nbd_aio_is_ready(3)>, +on the connection."; + }; + + "aio_connect_socket_activation", { + default_call with + args = [ StringList "argv" ]; ret = RErr; + permitted_states = [ Created ]; + shortdesc = "connect using systemd socket activation"; + longdesc = "\ +Run the command as a subprocess and begin connecting to it using +systemd socket activation. Parameters behave as documented in +L<nbd_connect_socket_activation(3)>. + You can check if the connection is still connecting by calling L<nbd_aio_is_connecting(3)>, or if it has connected to the server and completed the NBD handshake by calling L<nbd_aio_is_ready(3)>, @@ -2678,6 +2719,8 @@ let first_version = [ "get_protocol", (1, 2); "set_handshake_flags", (1, 2); "get_handshake_flags", (1, 2); + "connect_socket_activation", (1, 2); + "aio_connect_socket_activation", (1, 2); (* These calls are proposed for a future version of libnbd, but * have not been added to any released version so far. @@ -3036,7 +3079,8 @@ end = struct let all_external_events = [NotifyRead; NotifyWrite; CmdCreate; - CmdConnectSockAddr; CmdConnectUnix; CmdConnectTCP; CmdConnectCommand; + CmdConnectSockAddr; CmdConnectUnix; CmdConnectTCP; + CmdConnectCommand; CmdConnectSA; CmdIssue] let string_of_external_event = function @@ -3047,6 +3091,7 @@ let string_of_external_event = function | CmdConnectUnix -> "CmdConnectUnix" | CmdConnectTCP -> "CmdConnectTCP" | CmdConnectCommand -> "CmdConnectCommand" + | CmdConnectSA -> "CmdConnectSA" | CmdIssue -> "CmdIssue" let c_string_of_external_event = function @@ -3057,6 +3102,7 @@ let c_string_of_external_event = function | CmdConnectUnix -> "cmd_connect_unix" | CmdConnectTCP -> "cmd_connect_tcp" | CmdConnectCommand -> "cmd_connect_command" + | CmdConnectSA -> "cmd_connect_sa" | CmdIssue -> "cmd_issue" (* Find a state in the state machine hierarchy by path. The [path] @@ -3504,7 +3550,8 @@ let generate_lib_states_run_c () = | NotifyWrite -> pr " r |= LIBNBD_AIO_DIRECTION_WRITE;\n" | CmdCreate | CmdConnectSockAddr - | CmdConnectUnix | CmdConnectTCP | CmdConnectCommand + | CmdConnectUnix | CmdConnectTCP + | CmdConnectCommand | CmdConnectSA | CmdIssue -> () ) events; pr " break;\n"; diff --git a/generator/states-connect-socket-activation.c b/generator/states-connect-socket-activation.c new file mode 100644 index 0000000..67e043a --- /dev/null +++ b/generator/states-connect-socket-activation.c @@ -0,0 +1,228 @@ +/* nbd client library in userspace: state machine + * Copyright (C) 2013-2019 Red Hat Inc. + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +/* State machine related to connecting with systemd socket activation. */ + +#include <config.h> + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <errno.h> +#include <unistd.h> +#include <sys/socket.h> +#include <sys/un.h> + +#include "internal.h" + +/* This is baked into the systemd socket activation API. */ +#define FIRST_SOCKET_ACTIVATION_FD 3 + +/* Prepare environment for calling execvpe when doing systemd socket + * activation. Takes the current environment and copies it. Removes + * any existing LISTEN_PID or LISTEN_FDS and replaces them with new + * variables. env[0] is "LISTEN_PID=..." which is filled in by + * CONNECT_SA.START, and env[1] is "LISTEN_FDS=1". + */ +static char ** +prepare_socket_activation_environment (void) +{ + char **env = NULL; + char *p0 = NULL, *p1 = NULL; + size_t i, len; + void *vp; + + p0 = strdup ("LISTEN_PID=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"); + if (p0 == NULL) + goto err; + p1 = strdup ("LISTEN_FDS=1"); + if (p1 == NULL) + goto err; + + /* Copy the current environment. */ + env = nbd_internal_copy_string_list (environ); + if (env == NULL) + goto err; + + /* Reserve slots env[0] and env[1]. */ + len = nbd_internal_string_list_length (env); + vp = realloc (env, + sizeof (char *) * (len + 3 /* include final NULL entry */)); + if (vp == NULL) + goto err; + env = vp; + memmove (&env[2], &env[0], sizeof (char *) * (len + 1)); + + env[0] = p0; /* Code below assumes env[0] is LISTEN_PID. */ + env[1] = p1; + + /* Remove any existing LISTEN_PID or LISTEN_FDS instances. */ + for (i = 2; env[i] != NULL; ++i) { + if (strncmp (env[i], "LISTEN_PID=", 11) == 0 || + strncmp (env[i], "LISTEN_FDS=", 11) == 0) { + memmove (&env[i], &env[i+1], + sizeof (char *) * (nbd_internal_string_list_length (&env[i]))); + i--; + } + } + + return env; + + err: + set_error (errno, "malloc"); + nbd_internal_free_string_list (env); + free (p0); + free (p1); + return NULL; +} + +STATE_MACHINE { + CONNECT_SA.START: +#ifdef HAVE_EXECVPE + size_t len; + int s; + struct sockaddr_un addr; + char **env; + pid_t pid; + int flags; + + assert (!h->sock); + assert (h->argv); + assert (h->argv[0]); + + /* 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"); + if (h->sa_tmpdir == 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"); + /* Avoid cleanup in nbd_close. */ + free (h->sa_tmpdir); + h->sa_tmpdir = NULL; + return 0; + } + + h->sa_sockpath = strdup ("/tmp/libnbdXXXXXX/sock"); + if (h->sa_sockpath == NULL) { + SET_NEXT_STATE (%.DEAD); + set_error (errno, "strdup"); + 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); + if (bind (s, (struct sockaddr *) &addr, sizeof addr) == -1) { + SET_NEXT_STATE (%.DEAD); + set_error (errno, "bind: %s", h->sa_sockpath); + close (s); + return 0; + } + + if (listen (s, 1) == -1) { + SET_NEXT_STATE (%.DEAD); + set_error (errno, "listen"); + close (s); + return 0; + } + + env = prepare_socket_activation_environment (); + if (!env) { + SET_NEXT_STATE (%.DEAD); + close (s); + return 0; + } + + pid = fork (); + if (pid == -1) { + SET_NEXT_STATE (%.DEAD); + set_error (errno, "fork"); + close (s); + nbd_internal_free_string_list (env); + return 0; + } + if (pid == 0) { /* child - run command */ + if (s != FIRST_SOCKET_ACTIVATION_FD) { + dup2 (s, FIRST_SOCKET_ACTIVATION_FD); + close (s); + } + else { + /* We must unset CLOEXEC on the fd. (dup2 above does this + * implicitly because CLOEXEC is set on the fd, not on the + * socket). + */ + flags = fcntl (s, F_GETFD, 0); + if (flags == -1) { + nbd_internal_fork_safe_perror ("fcntl: F_GETFD"); + _exit (126); + } + if (fcntl (s, F_SETFD, flags & ~FD_CLOEXEC) == -1) { + nbd_internal_fork_safe_perror ("fcntl: F_SETFD"); + _exit (126); + } + } + + char buf[32]; + const char *v = + nbd_internal_fork_safe_itoa ((long) getpid (), buf, sizeof buf); + strcpy (&env[0][11], v); + + /* Restore SIGPIPE back to SIG_DFL. */ + signal (SIGPIPE, SIG_DFL); + + execvpe (h->argv[0], h->argv, env); + nbd_internal_fork_safe_perror (h->argv[0]); + if (errno == ENOENT) + _exit (127); + else + _exit (126); + } + + /* Parent. */ + close (s); + nbd_internal_free_string_list (env); + h->pid = pid; + + h->connaddrlen = sizeof addr; + memcpy (&h->connaddr, &addr, h->connaddrlen); + SET_NEXT_STATE (%^CONNECT.START); + return 0; + +#else /* !HAVE_EXECVPE */ + SET_NEXT_STATE (%.DEAD) + set_error (ENOTSUP, "platform does not support socket activation"); + return 0; +#endif + +} /* END STATE MACHINE */ diff --git a/interop/Makefile.am b/interop/Makefile.am index 43350a8..d30cdf1 100644 --- a/interop/Makefile.am +++ b/interop/Makefile.am @@ -48,11 +48,13 @@ if HAVE_QEMU_NBD check_PROGRAMS += \ interop-qemu-nbd \ dirty-bitmap \ + socket-activation-qemu-nbd \ structured-read \ $(NULL) TESTS += \ interop-qemu-nbd \ dirty-bitmap.sh \ + socket-activation-qemu-nbd \ structured-read.sh \ $(NULL) @@ -124,6 +126,15 @@ dirty_bitmap_CPPFLAGS = -I$(top_srcdir)/include dirty_bitmap_CFLAGS = $(WARNINGS_CFLAGS) dirty_bitmap_LDADD = $(top_builddir)/lib/libnbd.la +socket_activation_qemu_nbd_SOURCES = socket-activation.c +socket_activation_qemu_nbd_CPPFLAGS = \ + -I$(top_srcdir)/include \ + -DSERVER=\"$(QEMU_NBD)\" \ + -DSERVER_PARAMS='"-f", "raw", "-x", "", tmpfile' \ + $(NULL) +socket_activation_qemu_nbd_CFLAGS = $(WARNINGS_CFLAGS) +socket_activation_qemu_nbd_LDADD = $(top_builddir)/lib/libnbd.la + structured_read_SOURCES = structured-read.c structured_read_CPPFLAGS = -I$(top_srcdir)/include structured_read_CFLAGS = $(WARNINGS_CFLAGS) @@ -135,9 +146,11 @@ if HAVE_NBDKIT check_PROGRAMS += \ interop-nbdkit \ + socket-activation-nbdkit \ $(NULL) TESTS += \ interop-nbdkit \ + socket-activation-nbdkit \ $(NULL) # See above comment about files in ../tests/Makefile.am @@ -245,6 +258,15 @@ interop_nbdkit_tls_psk_allow_fallback_CPPFLAGS = \ interop_nbdkit_tls_psk_allow_fallback_CFLAGS = $(WARNINGS_CFLAGS) interop_nbdkit_tls_psk_allow_fallback_LDADD = $(top_builddir)/lib/libnbd.la +socket_activation_nbdkit_SOURCES = socket-activation.c +socket_activation_nbdkit_CPPFLAGS = \ + -I$(top_srcdir)/include \ + -DSERVER=\"$(NBDKIT)\" \ + -DSERVER_PARAMS='"file", tmpfile' \ + $(NULL) +socket_activation_nbdkit_CFLAGS = $(WARNINGS_CFLAGS) +socket_activation_nbdkit_LDADD = $(top_builddir)/lib/libnbd.la + endif HAVE_NBDKIT check-valgrind: diff --git a/interop/socket-activation.c b/interop/socket-activation.c new file mode 100644 index 0000000..db6f6ca --- /dev/null +++ b/interop/socket-activation.c @@ -0,0 +1,92 @@ +/* NBD client library in userspace + * Copyright (C) 2019 Red Hat Inc. + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +/* Test interop with nbdkit or qemu-nbd, and systemd socket activation. */ + +#include <config.h> + +#include <stdio.h> +#include <stdlib.h> +#include <stdint.h> +#include <inttypes.h> +#include <unistd.h> + +#include <libnbd.h> + +#define SIZE 1048576 + +int +main (int argc, char *argv[]) +{ + struct nbd_handle *nbd; + char tmpfile[] = "/tmp/nbdXXXXXX"; + int fd; + int64_t actual_size; + char buf[512]; + int r = -1; + + /* Create a large sparse temporary file. */ + fd = mkstemp (tmpfile); + if (fd == -1 || + ftruncate (fd, SIZE) == -1 || + close (fd) == -1) { + perror (tmpfile); + goto out; + } + + nbd = nbd_create (); + if (nbd == NULL) { + fprintf (stderr, "%s\n", nbd_get_error ()); + goto out; + } + + char *args[] = { SERVER, SERVER_PARAMS, NULL }; + if (nbd_connect_socket_activation (nbd, args) == -1) { + fprintf (stderr, "%s\n", nbd_get_error ()); + goto out; + } + + actual_size = nbd_get_size (nbd); + if (actual_size == -1) { + fprintf (stderr, "%s\n", nbd_get_error ()); + goto out; + } + if (actual_size != SIZE) { + fprintf (stderr, "%s: actual size %" PRIi64 " <> expected size %d", + argv[0], actual_size, SIZE); + goto out; + } + + if (nbd_pread (nbd, buf, sizeof buf, 0, 0) == -1) { + fprintf (stderr, "%s\n", nbd_get_error ()); + goto out; + } + + if (nbd_shutdown (nbd, 0) == -1) { + fprintf (stderr, "%s\n", nbd_get_error ()); + goto out; + } + + nbd_close (nbd); + + r = 0; + out: + unlink (tmpfile); + + exit (r == 0 ? EXIT_SUCCESS : EXIT_FAILURE); +} diff --git a/lib/connect.c b/lib/connect.c index f98bcdb..c1cbef7 100644 --- a/lib/connect.c +++ b/lib/connect.c @@ -112,6 +112,16 @@ nbd_unlocked_connect_command (struct nbd_handle *h, char **argv) return wait_until_connected (h); } +/* Connect to a local command, use systemd socket activation. */ +int +nbd_unlocked_connect_socket_activation (struct nbd_handle *h, char **argv) +{ + if (nbd_unlocked_aio_connect_socket_activation (h, argv) == -1) + return -1; + + return wait_until_connected (h); +} + int nbd_unlocked_aio_connect (struct nbd_handle *h, const struct sockaddr *addr, socklen_t len) @@ -405,3 +415,21 @@ nbd_unlocked_aio_connect_command (struct nbd_handle *h, char **argv) return nbd_internal_run (h, cmd_connect_command); } + +int +nbd_unlocked_aio_connect_socket_activation (struct nbd_handle *h, char **argv) +{ + char **copy; + + copy = nbd_internal_copy_string_list (argv); + if (!copy) { + set_error (errno, "copy_string_list"); + return -1; + } + + if (h->argv) + nbd_internal_free_string_list (h->argv); + h->argv = copy; + + return nbd_internal_run (h, cmd_connect_sa); +} diff --git a/lib/handle.c b/lib/handle.c index 2af25fe..a7f2c79 100644 --- a/lib/handle.c +++ b/lib/handle.c @@ -129,6 +129,16 @@ nbd_close (struct nbd_handle *h) free_cmd_list (h->cmds_in_flight); free_cmd_list (h->cmds_done); nbd_internal_free_string_list (h->argv); + if (h->sa_sockpath) { + if (h->pid > 0) + kill (h->pid, SIGTERM); + unlink (h->sa_sockpath); + free (h->sa_sockpath); + } + if (h->sa_tmpdir) { + rmdir (h->sa_tmpdir); + free (h->sa_tmpdir); + } free (h->unixsocket); free (h->hostname); free (h->port); diff --git a/lib/internal.h b/lib/internal.h index 31bc3d4..6433183 100644 --- a/lib/internal.h +++ b/lib/internal.h @@ -188,6 +188,12 @@ struct nbd_handle { char **argv; pid_t pid; + /* When using systemd socket activation, this directory and socket + * must be deleted, and the pid above must be killed. + */ + char *sa_tmpdir; + char *sa_sockpath; + /* When connecting to Unix domain socket. */ char *unixsocket; -- 2.23.0

On Tue, Oct 01, 2019 at 08:24:33AM -0500, Eric Blake wrote: I'm hoping we will find the time to write a replacement execvpe so that we can implement this on all platforms. That way we can avoid having a redundant nbd_supports_socket_activation() call that (in future) always returns true. Probably not right now, but it might happen if we ever implement error recovery for either nbd_connect_socket_activation or nbd_connect_command. At the moment these functions move the handle to the DEAD state if they fail, but that's not really necessary in all cases. I added a note to the documentation of nbd_close to say it can block. However that's unfortunate and we should really provide a way to let callers avoid that behaviour. See: https://github.com/libguestfs/libnbd/commit/b9ed0d56a5e26b1a051f68e7565dd... Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://people.redhat.com/~rjones/virt-df/

On Fri, Nov 15, 2019 at 09:43:28AM -0600, Eric Blake wrote: ACK thanks. Be interesting if the *BSDs support systemd socket activation (in qemu-nbd or elsewhere). I'll have to check later. Of course they don't have systemd, but also socket activation is not really tied to systemd. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-p2v converts physical machines to virtual machines. Boot with a live CD or over the network (PXE) and turn machines into KVM guests. http://libguestfs.org/virt-v2v