/* This function can not fail. */
static int dup_cloexec(libxl__gc *gc, int fd, const char *what)
{
int dup_fd = fd;
if (fd <= 2) {
dup_fd = dup(fd);
if (dup_fd < 0) {
LOGE(ERROR,"dup %s", what);
exit(-1);
}
}
libxl_fd_set_cloexec(CTX, dup_fd, 0);
return dup_fd;
}
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);;
}