static void write_emulator_blob(libxl__egc *egc,
libxl__stream_read_state *stream,
libxl__sr_record_buf *rec)
{
libxl__domain_create_state *dcs = stream->dcs;
libxl__datacopier_state *dc = &stream->emu_dc;
libxl__sr_emulator_hdr *emu_hdr;
STATE_AO_GC(stream->ao);
char path[256];
int rc = 0, writefd;
if (rec->hdr.length < sizeof(*emu_hdr)) {
rc = ERROR_FAIL;
LOG(ERROR, "Emulator record too short to contain header");
goto err;
}
emu_hdr = rec->body;
sprintf(path, LIBXL_DEVICE_MODEL_RESTORE_FILE".%u", dcs->guest_domid);
assert(stream->emu_carefd == NULL);
libxl__carefd_begin();
writefd = open(path, O_WRONLY | O_CREAT | O_TRUNC, 0600);
stream->emu_carefd = libxl__carefd_opened(CTX, writefd);
if (writefd == -1) {
rc = ERROR_FAIL;
LOGE(ERROR, "unable to open %s", path);
goto err;
}
FILLZERO(*dc);
dc->ao = stream->ao;
dc->writewhat = "qemu save file";
dc->copywhat = "restore v2 stream";
dc->writefd = writefd;
dc->readfd = -1;
dc->maxsz = -1;
dc->callback = write_emulator_done;
rc = libxl__datacopier_start(dc);
if (rc)
goto err;
libxl__datacopier_prefixdata(egc, dc,
rec->body + sizeof(*emu_hdr),
rec->hdr.length - sizeof(*emu_hdr));
return;
err:
assert(rc);
stream_complete(egc, stream, rc);
}
int libxl__openptys(libxl__openpty_state *op,
struct termios *termp,
struct winsize *winp) {
/*
* This is completely crazy. openpty calls grantpt which the spec
* says may fork, and may not be called with a SIGCHLD handler.
* Now our application may have a SIGCHLD handler so that's bad.
* We could perhaps block it but we'd need to block it on all
* threads. This is just Too Hard.
*
* So instead, we run openpty in a child process. That child
* process then of course has only our own thread and our own
* signal handlers. We pass the fds back.
*
* Since our only current caller actually wants two ptys, we
* support calling openpty multiple times for a single fork.
*/
STATE_AO_GC(op->ao);
int count = op->count;
int r, i, rc, sockets[2], ptyfds[count][2];
libxl__carefd *for_child = 0;
pid_t pid = -1;
for (i=0; i<count; i++) {
ptyfds[i][0] = ptyfds[i][1] = -1;
libxl__openpty_result *res = &op->results[i];
assert(!res->master);
assert(!res->slave);
}
sockets[0] = sockets[1] = -1; /* 0 is for us, 1 for our child */
libxl__carefd_begin();
r = socketpair(AF_UNIX, SOCK_STREAM, 0, sockets);
if (r) { sockets[0] = sockets[1] = -1; }
for_child = libxl__carefd_opened(CTX, sockets[1]);
if (r) { LOGE(ERROR,"socketpair failed"); rc = ERROR_FAIL; goto out; }
pid = libxl__ev_child_fork(gc, &op->child, openpty_exited);
if (pid == -1) {
rc = ERROR_FAIL;
goto out;
}
if (!pid) {
/* child */
close(sockets[0]);
signal(SIGCHLD, SIG_DFL);
for (i=0; i<count; i++) {
r = openpty(&ptyfds[i][0], &ptyfds[i][1], NULL, termp, winp);
if (r) { LOGE(ERROR,"openpty failed"); _exit(-1); }
}
rc = libxl__sendmsg_fds(gc, sockets[1], "",1,
2*count, &ptyfds[0][0], "ptys");
if (rc) { LOGE(ERROR,"sendmsg to parent failed"); _exit(-1); }
_exit(0);
}
libxl__carefd_close(for_child);
for_child = 0;
/* this should be fast so do it synchronously */
libxl__carefd_begin();
char buf[1];
rc = libxl__recvmsg_fds(gc, sockets[0], buf,1,
2*count, &ptyfds[0][0], "ptys");
if (!rc) {
for (i=0; i<count; i++) {
libxl__openpty_result *res = &op->results[i];
res->master = libxl__carefd_record(CTX, ptyfds[i][0]);
res->slave = libxl__carefd_record(CTX, ptyfds[i][1]);
}
}
/* now the pty fds are in the carefds, if they were ever open */
libxl__carefd_unlock();
if (rc)
goto out;
rc = 0;
out:
if (sockets[0] >= 0) close(sockets[0]);
libxl__carefd_close(for_child);
if (libxl__ev_child_inuse(&op->child)) {
op->rc = rc;
/* we will get a callback when the child dies */
return 0;
}
assert(rc);
openpty_cleanup(op);
return rc;
}
/* Portability note: this lock utilises flock(2) so a proper implementation of
* flock(2) is required.
*/
libxl__domain_userdata_lock *libxl__lock_domain_userdata(libxl__gc *gc,
uint32_t domid)
{
libxl__domain_userdata_lock *lock = NULL;
const char *lockfile;
int fd;
struct stat stab, fstab;
lockfile = libxl__userdata_path(gc, domid, "domain-userdata-lock", "l");
if (!lockfile) goto out;
lock = libxl__zalloc(NOGC, sizeof(libxl__domain_userdata_lock));
lock->path = libxl__strdup(NOGC, lockfile);
while (true) {
libxl__carefd_begin();
fd = open(lockfile, O_RDWR|O_CREAT, 0666);
if (fd < 0)
LOGE(ERROR, "cannot open lockfile %s, errno=%d", lockfile, errno);
lock->lock_carefd = libxl__carefd_opened(CTX, fd);
if (fd < 0) goto out;
/* Lock the file in exclusive mode, wait indefinitely to
* acquire the lock
*/
while (flock(fd, LOCK_EX)) {
switch (errno) {
case EINTR:
/* Signal received, retry */
continue;
default:
/* All other errno: EBADF, EINVAL, ENOLCK, EWOULDBLOCK */
LOGE(ERROR,
"unexpected error while trying to lock %s, fd=%d, errno=%d",
lockfile, fd, errno);
goto out;
}
}
if (fstat(fd, &fstab)) {
LOGE(ERROR, "cannot fstat %s, fd=%d, errno=%d",
lockfile, fd, errno);
goto out;
}
if (stat(lockfile, &stab)) {
if (errno != ENOENT) {
LOGE(ERROR, "cannot stat %s, errno=%d", lockfile, errno);
goto out;
}
} else {
if (stab.st_dev == fstab.st_dev && stab.st_ino == fstab.st_ino)
break;
}
libxl__carefd_close(lock->lock_carefd);
}
/* Check the domain is still there, if not we should release the
* lock and clean up.
*/
if (libxl_domain_info(CTX, NULL, domid))
goto out;
return lock;
out:
if (lock) libxl__unlock_domain_userdata(lock);
return NULL;
}
static void run_helper(libxl__egc *egc, libxl__save_helper_state *shs,
const char *mode_arg, int stream_fd,
const int *preserve_fds, int num_preserve_fds,
const unsigned long *argnums, int num_argnums)
{
STATE_AO_GC(shs->ao);
const char *args[4 + num_argnums];
const char **arg = args;
int i, rc;
/* Resources we must free */
libxl__carefd *childs_pipes[2] = { 0,0 };
/* Convenience aliases */
const uint32_t domid = shs->domid;
shs->rc = 0;
shs->completed = 0;
shs->pipes[0] = shs->pipes[1] = 0;
libxl__ev_fd_init(&shs->readable);
libxl__ev_child_init(&shs->child);
shs->stdin_what = GCSPRINTF("domain %"PRIu32" save/restore helper"
" stdin pipe", domid);
shs->stdout_what = GCSPRINTF("domain %"PRIu32" save/restore helper"
" stdout pipe", domid);
*arg++ = getenv("LIBXL_SAVE_HELPER") ?: PRIVATE_BINDIR "/" "libxl-save-helper";
*arg++ = mode_arg;
const char **stream_fd_arg = arg++;
for (i=0; i<num_argnums; i++)
*arg++ = GCSPRINTF("%lu", argnums[i]);
*arg++ = 0;
assert(arg == args + ARRAY_SIZE(args));
libxl__carefd_begin();
int childfd;
for (childfd=0; childfd<2; childfd++) {
/* Setting up the pipe for the child's fd childfd */
int fds[2];
if (libxl_pipe(CTX,fds)) {
rc = ERROR_FAIL;
libxl__carefd_unlock();
goto out;
}
int childs_end = childfd==0 ? 0 /*read*/ : 1 /*write*/;
int our_end = childfd==0 ? 1 /*write*/ : 0 /*read*/;
childs_pipes[childfd] = libxl__carefd_record(CTX, fds[childs_end]);
shs->pipes[childfd] = libxl__carefd_record(CTX, fds[our_end]);
}
libxl__carefd_unlock();
pid_t pid = libxl__ev_child_fork(gc, &shs->child, helper_exited);
if (!pid) {
if (stream_fd <= 2) {
stream_fd = dup(stream_fd);
if (stream_fd < 0) {
LOGE(ERROR,"dup migration stream fd");
exit(-1);
}
}
libxl_fd_set_cloexec(CTX, stream_fd, 0);
*stream_fd_arg = GCSPRINTF("%d", stream_fd);
for (i=0; i<num_preserve_fds; i++)
if (preserve_fds[i] >= 0) {
assert(preserve_fds[i] > 2);
libxl_fd_set_cloexec(CTX, preserve_fds[i], 0);
}
libxl__exec(gc,
libxl__carefd_fd(childs_pipes[0]),
libxl__carefd_fd(childs_pipes[1]),
-1,
args[0], (char**)args, 0);
}
libxl__carefd_close(childs_pipes[0]);
libxl__carefd_close(childs_pipes[1]);
rc = libxl__ev_fd_register(gc, &shs->readable, helper_stdout_readable,
libxl__carefd_fd(shs->pipes[1]), POLLIN|POLLPRI);
if (rc) goto out;
return;
out:
libxl__carefd_close(childs_pipes[0]);
libxl__carefd_close(childs_pipes[1]);
helper_failed(egc, shs, rc);;
}
