/* Returns either the pid of the child process we run or -E* on failure. */
int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv)
{
struct helper_data data;
unsigned long stack, sp;
int pid, fds[2], ret, n;
stack = alloc_stack(0, __cant_sleep());
if (stack == 0)
return -ENOMEM;
ret = socketpair(AF_UNIX, SOCK_STREAM, 0, fds);
if (ret < 0) {
ret = -errno;
printk(UM_KERN_ERR "run_helper : pipe failed, errno = %d\n",
errno);
goto out_free;
}
ret = os_set_exec_close(fds[1]);
if (ret < 0) {
printk(UM_KERN_ERR "run_helper : setting FD_CLOEXEC failed, "
"ret = %d\n", -ret);
goto out_close;
}
sp = stack + UM_KERN_PAGE_SIZE - sizeof(void *);
data.pre_exec = pre_exec;
data.pre_data = pre_data;
data.argv = argv;
data.fd = fds[1];
data.buf = __cant_sleep() ? uml_kmalloc(PATH_MAX, UM_GFP_ATOMIC) :
uml_kmalloc(PATH_MAX, UM_GFP_KERNEL);
pid = clone(helper_child, (void *) sp, CLONE_VM, &data);
if (pid < 0) {
ret = -errno;
printk(UM_KERN_ERR "run_helper : clone failed, errno = %d\n",
errno);
goto out_free2;
}
close(fds[1]);
fds[1] = -1;
/*
* Read the errno value from the child, if the exec failed, or get 0 if
* the exec succeeded because the pipe fd was set as close-on-exec.
*/
n = read(fds[0], &ret, sizeof(ret));
if (n == 0) {
ret = pid;
} else {
if (n < 0) {
n = -errno;
printk(UM_KERN_ERR "run_helper : read on pipe failed, "
"ret = %d\n", -n);
ret = n;
}
CATCH_EINTR(waitpid(pid, NULL, __WCLONE));
}
out_free2:
kfree(data.buf);
out_close:
if (fds[1] != -1)
close(fds[1]);
close(fds[0]);
out_free:
free_stack(stack, 0);
return ret;
}
int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv,
unsigned long *stack_out)
{
struct helper_data data;
unsigned long stack, sp;
int pid, fds[2], err, n;
if((stack_out != NULL) && (*stack_out != 0))
stack = *stack_out;
else stack = alloc_stack(0, um_in_interrupt());
if(stack == 0)
return(-ENOMEM);
err = os_pipe(fds, 1, 0);
if(err < 0){
printk("run_helper : pipe failed, err = %d\n", -err);
goto out_free;
}
err = os_set_exec_close(fds[1], 1);
if(err < 0){
printk("run_helper : setting FD_CLOEXEC failed, err = %d\n",
-err);
goto out_close;
}
sp = stack + page_size() - sizeof(void *);
data.pre_exec = pre_exec;
data.pre_data = pre_data;
data.argv = argv;
data.fd = fds[1];
pid = clone(helper_child, (void *) sp, CLONE_VM | SIGCHLD, &data);
if(pid < 0){
printk("run_helper : clone failed, errno = %d\n", errno);
err = -errno;
goto out_close;
}
os_close_file(fds[1]);
n = os_read_file(fds[0], &err, sizeof(err));
if(n < 0){
printk("run_helper : read on pipe failed, err = %d\n", -n);
err = n;
goto out_kill;
}
else if(n != 0){
CATCH_EINTR(n = waitpid(pid, NULL, 0));
pid = -errno;
}
if(stack_out == NULL) free_stack(stack, 0);
else *stack_out = stack;
return(pid);
out_kill:
os_kill_process(pid, 1);
out_close:
os_close_file(fds[0]);
os_close_file(fds[1]);
out_free:
free_stack(stack, 0);
return(err);
}
