criu/cr-restore.c

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <limits.h>
#include <unistd.h>
#include <errno.h>
#include <dirent.h>
#include <string.h>

#include <fcntl.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/vfs.h>
#include <sys/ptrace.h>
#include <sys/user.h>
#include <sys/wait.h>
#include <sys/file.h>

#include <sched.h>

#include <sys/sendfile.h>

#include "compiler.h"
#include "types.h"

#include "image.h"
#include "util.h"
#include "log.h"
#include "syscall.h"
#include "restorer.h"
#include "sockets.h"
#include "lock.h"
#include "files.h"
#include "proc_parse.h"
#include "restorer-blob.h"
#include "crtools.h"

/*
 * real_pid member formerly served cases when
 * no fork-with-pid functionality were in kernel,
 * so now it is being kept here just in case if
 * we need it again.
 */

#define PIPE_NONE	(0 << 0)
#define PIPE_RDONLY	(1 << 1)
#define PIPE_WRONLY	(1 << 2)
#define PIPE_RDWR	(PIPE_RDONLY | PIPE_WRONLY)
#define PIPE_MODE_MASK	(0x7)
#define PIPE_CREATED	(1 << 3)

#define pipe_is_rw(p)	(((p)->status & PIPE_MODE_MASK) == PIPE_RDWR)

struct pipe_info {
	unsigned int	pipeid;
	int		pid;
	u32		real_pid;	/* futex */
	int		read_fd;
	int		write_fd;
	int		status;
	u32		users;		/* futex */
};

struct shmem_id {
	struct shmem_id *next;
	unsigned long	addr;
	unsigned long	end;
	unsigned long	shmid;
};

struct pipe_list_entry {
	struct list_head	list;
	struct pipe_entry	e;
	off_t			offset;
};

static struct task_entries *task_entries;

static void task_add_entry(int pid)
{
	int *nr = &task_entries->nr;
	struct task_entry *e = &task_entries->entries[*nr];

	(*nr)++;

	BUG_ON((*nr) * sizeof(struct task_entry) +
		sizeof(struct task_entries) > TASK_ENTRIES_SIZE);

	e->pid = pid;
	e->done = 0;
}

static struct shmem_id *shmem_ids;

static struct shmems *shmems;

static struct pipe_info *pipes;
static int nr_pipes;

static pid_t pstree_pid;

static int restore_task_with_children(int pid);
static void sigreturn_restore(pid_t pstree_pid, pid_t pid);

static void show_saved_shmems(void)
{
	int i;

	pr_info("\tSaved shmems:\n");

	for (i = 0; i < shmems->nr_shmems; i++)
		pr_info("\t\tstart: %016lx shmid: %lx pid: %d\n",
			shmems->entries[i].start,
			shmems->entries[i].shmid,
			shmems->entries[i].pid);
}

static void show_saved_pipes(void)
{
	int i;

	pr_info("\tSaved pipes:\n");
	for (i = 0; i < nr_pipes; i++)
		pr_info("\t\tpipeid %x pid %d users %d status %d\n",
			pipes[i].pipeid, pipes[i].pid,
			pipes[i].users, pipes[i].status);
}

static struct pipe_info *find_pipe(unsigned int pipeid)
{
	struct pipe_info *pi;
	int i;

	for (i = 0; i < nr_pipes; i++) {
		pi = pipes + i;
		if (pi->pipeid == pipeid)
			return pi;
	}

	return NULL;
}

static int shmem_wait_and_open(int pid, struct shmem_info *si)
{
	unsigned long time = 1;
	char path[128];
	int ret;

	sprintf(path, "/proc/%d/map_files/%lx-%lx",
		si->pid, si->start, si->end);

	pr_info("%d: Waiting for [%s] to appear\n", pid, path);
	cr_wait_until(&si->lock, 1);

	pr_info("%d: Opening shmem [%s] \n", pid, path);
	ret = open(path, O_RDWR);
	if (ret >= 0)
		return ret;
	else if (ret < 0)
		pr_perror("     %d: Can't stat shmem at %s\n",
			  si->pid, path);
	return ret;
}

static int collect_shmem(int pid, struct shmem_entry *e)
{
	int i;
	struct shmem_info *entries = shmems->entries;
	int nr_shmems = shmems->nr_shmems;

	for (i = 0; i < nr_shmems; i++) {
		if (entries[i].start != e->start ||
		    entries[i].shmid != e->shmid)
			continue;

		if (entries[i].end != e->end) {
			pr_err("Bogus shmem\n");
			return -1;
		}

		/*
		 * Only the shared mapping with a lowest
		 * pid will be created in real, other processes
		 * will wait until the kernel propagate this mapping
		 * into /proc
		 */
		if (entries[i].pid > pid)
			entries[i].pid = pid;

		return 0;
	}

	if ((nr_shmems + 1) * sizeof(struct shmem_info) +
					sizeof (struct shmems) >= SHMEMS_SIZE) {
		pr_panic("OOM storing shmems\n");
		return -1;
	}

	memset(&shmems->entries[nr_shmems], 0, sizeof(shmems->entries[0]));

	entries[nr_shmems].start	= e->start;
	entries[nr_shmems].end		= e->end;
	entries[nr_shmems].shmid	= e->shmid;
	entries[nr_shmems].pid		= pid;

	cr_wait_init(&entries[nr_shmems].lock);

	shmems->nr_shmems++;

	return 0;
}

static int collect_pipe(int pid, struct pipe_entry *e, int p_fd)
{
	int i;

	/*
	 * All pipes get collected into the one array,
	 * note the highest PID is the sign of which
	 * process pipe should be really created, all other
	 * processes (if they have pipes with pipeid matched)
	 * will be attached.
	 */
	for (i = 0; i < nr_pipes; i++) {
		if (pipes[i].pipeid != e->pipeid)
			continue;

		if (pipes[i].pid > pid && !pipe_is_rw(&pipes[i])) {
			pipes[i].pid = pid;
			pipes[i].status = 0;
			pipes[i].read_fd = -1;
			pipes[i].write_fd = -1;
		}

		if (pipes[i].pid == pid) {
			switch (e->flags & O_ACCMODE) {
			case O_RDONLY:
				pipes[i].status |= PIPE_RDONLY;
				pipes[i].read_fd = e->fd;
				break;
			case O_WRONLY:
				pipes[i].status |= PIPE_WRONLY;
				pipes[i].write_fd = e->fd;
				break;
			}
		} else
			pipes[i].users++;

		return 0;
	}

	if ((nr_pipes + 1) * sizeof(struct pipe_info) >= 4096) {
		pr_panic("OOM storing pipes\n");
		return -1;
	}

	memset(&pipes[nr_pipes], 0, sizeof(pipes[nr_pipes]));

	pipes[nr_pipes].pipeid	= e->pipeid;
	pipes[nr_pipes].pid	= pid;
	pipes[nr_pipes].users	= 0;
	pipes[nr_pipes].read_fd = -1;
	pipes[nr_pipes].write_fd = -1;

	switch (e->flags & O_ACCMODE) {
	case O_RDONLY:
		pipes[nr_pipes].status = PIPE_RDONLY;
		pipes[i].read_fd = e->fd;
		break;
	case O_WRONLY:
		pipes[nr_pipes].status = PIPE_WRONLY;
		pipes[i].write_fd = e->fd;
		break;
	}

	nr_pipes++;

	return 0;
}

static int prepare_shmem_pid(int pid)
{
	int sh_fd;

	sh_fd = open_image_ro(CR_FD_SHMEM, pid);
	if (sh_fd < 0)
		return -1;

	while (1) {
		struct shmem_entry e;
		int ret;

		ret = read(sh_fd, &e, sizeof(e));
		if (ret == 0)
			break;

		if (ret != sizeof(e)) {
			pr_perror("%d: Can't read shmem entry\n", pid);
			return -1;
		}

		if (collect_shmem(pid, &e))
			return -1;
	}

	close(sh_fd);
	return 0;
}

static int prepare_pipes_pid(int pid)
{
	int p_fd;

	p_fd = open_image_ro(CR_FD_PIPES, pid);
	if (p_fd < 0)
		return -1;

	while (1) {
		struct pipe_entry e;
		int ret;

		ret = read(p_fd, &e, sizeof(e));
		if (ret == 0)
			break;
		if (ret != sizeof(e)) {
			pr_perror("%d: Read pipes failed %d (expected %li)\n",
				  pid, ret, sizeof(e));
			return -1;
		}

		if (collect_pipe(pid, &e, p_fd))
			return -1;

		if (e.bytes)
			lseek(p_fd, e.bytes, SEEK_CUR);
	}

	close(p_fd);
	return 0;
}

static int shmem_remap(void *old_addr, void *new_addr, unsigned long size)
{
	char path[PATH_MAX];
	int fd;
	void *ret;

	sprintf(path, "/proc/self/map_files/%p-%p",
		old_addr, (void *)old_addr + size);

	fd = open(path, O_RDWR);
	if (fd < 0) {
		pr_perror("open(%s) failed\n", path);
		return -1;
	}

	ret = mmap(new_addr, size, PROT_READ | PROT_WRITE,
		   MAP_SHARED | MAP_FIXED, fd, 0);
	if (ret != new_addr) {
		pr_perror("mmap failed\n");
		return -1;
	}

	close(fd);
	return 0;
}

static int prepare_shared(int ps_fd)
{
	pr_info("Preparing info about shared resources\n");

	shmems = mmap(NULL, SHMEMS_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, 0, 0);
	if (shmems == MAP_FAILED) {
		pr_perror("Can't map shmem\n");
		return -1;
	}

	shmems->nr_shmems = 0;

	task_entries = mmap(NULL, TASK_ENTRIES_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, 0, 0);
	if (task_entries == MAP_FAILED) {
		pr_perror("Can't map shmem\n");
		return -1;
	}
	task_entries->nr = 0;
	task_entries->start = CR_STATE_RESTORE;

	pipes = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, 0, 0);
	if (pipes == MAP_FAILED) {
		pr_perror("Can't map pipes\n");
		return -1;
	}

	if (prepare_fdinfo_global())
		return -1;

	while (1) {
		struct pstree_entry e;
		int ret;

		ret = read(ps_fd, &e, sizeof(e));
		if (ret == 0)
			break;

		if (ret != sizeof(e)) {
			pr_perror("Can't read pstree_entry\n");
			return -1;
		}

		if (prepare_shmem_pid(e.pid))
			return -1;

		if (prepare_pipes_pid(e.pid))
			return -1;

		if (prepare_fd_pid(e.pid))
			return -1;

		task_add_entry(e.pid);

		lseek(ps_fd, e.nr_children * sizeof(u32) + e.nr_threads * sizeof(u32), SEEK_CUR);
	}

	task_entries->nr_in_progress = task_entries->nr;

	lseek(ps_fd, sizeof(u32), SEEK_SET);

	show_saved_shmems();
	show_saved_pipes();

	return 0;
}

static unsigned long find_shmem_id(unsigned long addr)
{
	struct shmem_id *si;

	for (si = shmem_ids; si; si = si->next)
		if (si->addr <= addr && si->end >= addr)
			return si->shmid;

	return 0;
}

static int save_shmem_id(struct shmem_entry *e)
{
	struct shmem_id *si;

	si = xmalloc(sizeof(*si));
	if (!si)
		return -1;

	si->addr	= e->start;
	si->end		= e->end;
	si->shmid	= e->shmid;
	si->next	= shmem_ids;

	shmem_ids	= si;

	return 0;
}

static int prepare_shmem(int pid)
{
	int sh_fd;

	sh_fd = open_image_ro(CR_FD_SHMEM, pid);
	if (sh_fd < 0)
		return -1;

	while (1) {
		struct shmem_entry e;
		int ret;

		ret = read(sh_fd, &e, sizeof(e));
		if (ret == 0)
			break;
		if (ret != sizeof(e)) {
			pr_perror("%d: Can't read shmem entry\n", pid);
			return -1;
		}

		if (save_shmem_id(&e))
			return -1;
	}

	close(sh_fd);
	return 0;
}

static struct shmem_info *
find_shmem(struct shmems *shms, unsigned long start, unsigned long shmid)
{
	struct shmem_info *si;
	int i;

	for (i = 0; i < shms->nr_shmems; i++) {
		si = &shms->entries[i];
		if (si->start == start	&&
		    si->end > start	&&
		    si->shmid == shmid)
			return si;
	}

	return NULL;
}

static struct shmem_info *
find_shmem_page(struct shmems *shms, unsigned long addr, unsigned long shmid)
{
	struct shmem_info *si;
	int i;

	for (i = 0; i < shms->nr_shmems; i++) {
		si = &shms->entries[i];
		if (si->start <= addr	&&
		    si->end > addr	&&
		    si->shmid == shmid)
			return si;
	}

	return NULL;
}

static int try_fixup_shared_map(int pid, struct vma_entry *vi, int fd)
{
	struct shmem_info *si;
	unsigned long shmid;

	shmid = find_shmem_id(vi->start);
	if (!shmid)
		return 0;

	si = find_shmem(shmems, vi->start, shmid);
	pr_info("%d: Search for %016lx shmem %p/%d\n", pid, vi->start, si, si ? si->pid : -1);

	if (!si) {
		pr_err("Can't find my shmem %016lx\n", vi->start);
		return -1;
	}

	if (si->pid != pid) {
		int sh_fd;

		sh_fd = shmem_wait_and_open(pid, si);
		pr_info("%d: Fixing %lx vma to %lx/%d shmem -> %d\n",
			pid, vi->start, si->shmid, si->pid, sh_fd);
		if (sh_fd < 0) {
			pr_perror("%d: Can't open shmem\n", pid);
			return -1;
		}

		lseek(fd, -sizeof(*vi), SEEK_CUR);
		vi->fd = sh_fd;
		pr_info("%d: Fixed %lx vma %lx/%d shmem -> %d\n",
			pid, vi->start, si->shmid, si->pid, sh_fd);
		if (write(fd, vi, sizeof(*vi)) != sizeof(*vi)) {
			pr_perror("%d: Can't write img\n", pid);
			return -1;
		}
	}

	return 0;
}

static int fixup_vma_fds(int pid, int fd)
{
	int offset = GET_FILE_OFF_AFTER(struct core_entry);

	lseek(fd, offset, SEEK_SET);

	while (1) {
		struct vma_entry vi;
		int ret = 0;

		ret = read(fd, &vi, sizeof(vi));
		if (ret < 0) {
			pr_perror("%d: Can't read vma_entry\n", pid);
		} else if (ret != sizeof(vi)) {
			pr_err("%d: Incomplete vma_entry (%d != %d)\n",
			       pid, ret, sizeof(vi));
			return -1;
		}

		if (final_vma_entry(&vi))
			return 0;

		if (!(vma_entry_is(&vi, VMA_AREA_REGULAR)))
			continue;

		if (vma_entry_is(&vi, VMA_FILE_PRIVATE)	||
		    vma_entry_is(&vi, VMA_FILE_SHARED)	||
		    vma_entry_is(&vi, VMA_ANON_SHARED)) {

			pr_info("%d: Fixing %016lx-%016lx %016lx vma\n",
				pid, vi.start, vi.end, vi.pgoff);
			if (try_fixup_file_map(pid, &vi, fd))
				return -1;

			if (try_fixup_shared_map(pid, &vi, fd))
				return -1;
		}
	}
}

static inline bool should_restore_page(int pid, unsigned long va)
{
	struct shmem_info *si;
	unsigned long shmid;

	/*
	 * If this is not a shmem virtual address
	 * we should restore such page.
	 */
	shmid = find_shmem_id(va);
	if (!shmid)
		return true;

	si = find_shmem_page(shmems, va, shmid);
	return si->pid == pid;
}

static char zpage[PAGE_SIZE];

static int fixup_pages_data(int pid, int fd)
{
	int shfd;
	u64 va;

	pr_info("%d: Reading shmem pages img\n", pid);

	shfd = open_image_ro(CR_FD_PAGES_SHMEM, pid);
	if (shfd < 0)
		return -1;

	/*
	 * Find out the last page, which must be a zero page.
	 */
	lseek(fd, -sizeof(struct page_entry), SEEK_END);
	read(fd, &va, sizeof(va));
	if (va) {
		pr_panic("Zero-page expected but got %lx\n", (unsigned long)va);
		return -1;
	}

	/*
	 * Since we're to update pages we suppress old zero-page
	 * and will write new one at the end.
	 */
	lseek(fd, -sizeof(struct page_entry), SEEK_END);

	while (1) {
		int ret;

		ret = read(shfd, &va, sizeof(va));
		if (ret == 0)
			break;

		if (ret < 0 || ret != sizeof(va)) {
			pr_perror("%d: Can't read virtual address\n", pid);
			return -1;
		}

		if (va == 0)
			break;

		if (!should_restore_page(pid, va)) {
			lseek(shfd, PAGE_SIZE, SEEK_CUR);
			continue;
		}

		pr_info("%d: Restoring shared page: %16lx\n",
			pid, va);

		write(fd, &va, sizeof(va));
		sendfile(fd, shfd, NULL, PAGE_SIZE);
	}

	close(shfd);
	va = 0;
	write(fd, &va, sizeof(va));
	write(fd, zpage, sizeof(zpage));

	return 0;
}

static int prepare_image_maps(int fd, int pid)
{
	pr_info("%d: Fixing maps\n", pid);

	if (fixup_vma_fds(pid, fd))
		return -1;

	if (fixup_pages_data(pid, fd))
		return -1;

	return 0;
}

static int prepare_and_sigreturn(int pid)
{
	char path[PATH_MAX];
	int fd, fd_new;
	struct stat buf;

	fd = open_image_ro_nocheck(FMT_FNAME_CORE, pid);
	if (fd < 0)
		return -1;

	if (fstat(fd, &buf)) {
		pr_perror("%d: Can't stat\n", pid);
		return -1;
	}

	if (get_image_path(path, sizeof(path), FMT_FNAME_CORE_OUT, pid))
		return -1;

	fd_new = open(path, O_RDWR | O_CREAT | O_TRUNC, CR_FD_PERM);
	if (fd_new < 0) {
		pr_perror("%d: Can't open new image\n", pid);
		return -1;
	}

	pr_info("%d: Preparing restore image %s (%li bytes)\n", pid, path, buf.st_size);
	if (sendfile(fd_new, fd, NULL, buf.st_size) != buf.st_size) {
		pr_perror("%d: sendfile failed\n", pid);
		return -1;
	}
	close(fd);

	if (fstat(fd_new, &buf)) {
		pr_perror("%d: Can't stat\n", pid);
		return -1;
	}

	pr_info("fd_new: %li bytes\n", buf.st_size);

	if (prepare_image_maps(fd_new, pid))
		return -1;

	close(fd_new);
	sigreturn_restore(pstree_pid, pid);

	return 0;
}

#define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME)

static int set_fd_flags(int fd, int flags)
{
	int old;

	old = fcntl(fd, F_GETFL, 0);
	if (old < 0)
		return old;

	flags = (SETFL_MASK & flags) | (old & ~SETFL_MASK);

	return fcntl(fd, F_SETFL, flags);
}

static int reopen_pipe(int src, int *dst, int *other, int *pipes_fd)
{
	int tmp;

	if (*dst != -1) {
		if (move_img_fd(other, *dst))
			return -1;

		if (move_img_fd(pipes_fd, *dst))
			return -1;

		return reopen_fd_as(*dst, src);
	}

	*dst = src;
	return 0;
}

static int restore_pipe_data(struct pipe_entry *e, int wfd, int pipes_fd)
{
	int ret, size = 0;

	pr_info("\t%x: Splicing data to %d\n", e->pipeid, wfd);

	while (size != e->bytes) {
		ret = splice(pipes_fd, NULL, wfd, NULL, e->bytes, 0);
		if (ret < 0) {
			pr_perror("\t%x: Error splicing data\n", e->pipeid);
			return -1;
		}
		if (ret == 0) {
			pr_err("\t%x: Wanted to restore %d bytes, but got %d\n",
			       e->pipeid, e->bytes, size);
			return -1;
		}

		size =+ ret;
	}

	return 0;
}

static int create_pipe(int pid, struct pipe_entry *e, struct pipe_info *pi, int *pipes_fd)
{
	unsigned long time = 1000;
	int pfd[2], tmp;

	pr_info("\t%d: Creating pipe %x%s\n", pid, e->pipeid, pipe_is_rw(pi) ? "(rw)" : "");

	if (pipe(pfd) < 0) {
		pr_perror("%d: Can't create pipe\n", pid);
		return -1;
	}

	if (restore_pipe_data(e, pfd[1], *pipes_fd))
		return -1;

	if (reopen_pipe(pfd[0], &pi->read_fd, &pfd[1], pipes_fd))
		return -1;
	if (reopen_pipe(pfd[1], &pi->write_fd, &pi->read_fd, pipes_fd))
		return -1;

	cr_wait_set(&pi->real_pid, pid);

	pi->status |= PIPE_CREATED;

	pr_info("\t%d: Done, waiting for others (users %d) on %d pid with r:%d w:%d\n",
		pid, pi->users, pi->real_pid, pi->read_fd, pi->write_fd);

	if (!pipe_is_rw(pi)) {
		pr_info("\t%d: Waiting for %x pipe to attach (%d users left)\n",
				pid, e->pipeid, pi->users);

		cr_wait_until(&pi->users, 0);

		if ((e->flags & O_ACCMODE) == O_WRONLY)
			close_safe(&pi->read_fd);
		else
			close_safe(&pi->write_fd);
	}

	tmp = 0;
	if (pi->write_fd != e->fd && pi->read_fd != e->fd) {
		if (move_img_fd(pipes_fd, e->fd))
			return -1;

		switch (e->flags & O_ACCMODE) {
		case O_WRONLY:
			tmp = dup2(pi->write_fd, e->fd);
			break;
		case O_RDONLY:
			tmp = dup2(pi->read_fd, e->fd);
			break;
		}
	}
	if (tmp < 0)
		return -1;

	tmp = set_fd_flags(e->fd, e->flags);
	if (tmp < 0)
		return -1;

	pr_info("\t%d: All is ok - reopening pipe for %d\n", pid, e->fd);

	return 0;
}

static int attach_pipe(int pid, struct pipe_entry *e, struct pipe_info *pi, int *pipes_fd)
{
	char path[128];
	int tmp, fd;

	pr_info("\t%d: Wating for pipe %x to appear\n",
		pid, e->pipeid);

	cr_wait_while(&pi->real_pid, 0);

	if (move_img_fd(pipes_fd, e->fd))
			return -1;

	if ((e->flags & O_ACCMODE) == O_WRONLY)
		tmp = pi->write_fd;
	else
		tmp = pi->read_fd;

	if (pid == pi->pid) {
		if (tmp != e->fd)
			tmp = dup2(tmp, e->fd);

		if (tmp < 0) {
			pr_perror("%d: Can't duplicate %d->%d\n",
					pid, tmp, e->fd);
			return -1;
		}

		goto out;
	}

	sprintf(path, "/proc/%d/fd/%d", pi->real_pid, tmp);
	pr_info("\t%d: Attaching pipe %s (%d users left)\n",
		pid, path, pi->users - 1);

	fd = open(path, e->flags);
	if (fd < 0) {
		pr_perror("%d: Can't attach pipe\n", pid);
		return -1;
	}

	pr_info("\t%d: Done, reopening for %d\n", pid, e->fd);
	if (reopen_fd_as(e->fd, fd))
		return -1;

	cr_wait_dec(&pi->users);
out:
	tmp = set_fd_flags(e->fd, e->flags);
	if (tmp < 0)
		return -1;

	return 0;

}

static int open_pipe(int pid, struct pipe_entry *e, int *pipes_fd)
{
	struct pipe_info *pi;

	pr_info("\t%d: Opening pipe %x on fd %d\n", pid, e->pipeid, e->fd);

	pi = find_pipe(e->pipeid);
	if (!pi) {
		pr_err("BUG: can't find my pipe %x\n", e->pipeid);
		return -1;
	}

	/*
	 * This is somewhat tricky -- in case if a process uses
	 * both pipe ends the pipe should be created but only one
	 * pipe end get connected immediately in create_pipe the
	 * other pipe end should be connected via pipe attaching.
	 */
	if (pi->pid == pid && !(pi->status & PIPE_CREATED))
		return create_pipe(pid, e, pi, pipes_fd);
	else
		return attach_pipe(pid, e, pi, pipes_fd);
}

static rt_sigaction_t sigchld_act;
static int prepare_sigactions(int pid)
{
	rt_sigaction_t act, oact;
	int fd_sigact, ret;
	struct sa_entry e;
	int sig, i;

	fd_sigact = open_image_ro(CR_FD_SIGACT, pid);
	if (fd_sigact < 0)
		return -1;

	for (sig = 1; sig < SIGMAX; sig++) {
		if (sig == SIGKILL || sig == SIGSTOP)
			continue;

		ret = read(fd_sigact, &e, sizeof(e));
		if (ret != sizeof(e)) {
			pr_err("%d: Bad sigaction entry: %d (%m)\n", pid, ret);
			ret = -1;
			goto err;
		}

		ASSIGN_TYPED(act.rt_sa_handler, e.sigaction);
		ASSIGN_TYPED(act.rt_sa_flags, e.flags);
		ASSIGN_TYPED(act.rt_sa_restorer, e.restorer);
		ASSIGN_TYPED(act.rt_sa_mask.sig[0], e.mask);

		if (sig == SIGCHLD) {
			sigchld_act = act;
			continue;
		}
		/*
		 * A pure syscall is used, because glibc
		 * sigaction overwrites se_restorer.
		 */
		ret = sys_sigaction(sig, &act, &oact);
		if (ret == -1) {
			pr_err("%d: Can't restore sigaction: %m\n", pid);
			goto err;
		}
	}

err:
	close(fd_sigact);
	return ret;
}

static int prepare_pipes(int pid)
{
	u32 err = -1, ret;
	int pipes_fd;

	struct pipe_list_entry *le, *buf;
	int buf_size = PAGE_SIZE;
	int nr = 0;

	LIST_HEAD(head);

	pr_info("%d: Opening pipes\n", pid);

	pipes_fd = open_image_ro(CR_FD_PIPES, pid);
	if (pipes_fd < 0)
		return -1;

	buf = xmalloc(buf_size);
	if (!buf) {
		close(pipes_fd);
		return -1;
	}

	while (1) {
		struct list_head *cur;
		struct pipe_list_entry *cur_entry;

		le = &buf[nr];

		ret = read(pipes_fd, &le->e, sizeof(le->e));
		if (ret == 0)
			break;

		if (ret != sizeof(le->e)) {
			pr_perror("%d: Bad pipes entry\n", pid);
			goto err_free;
		}

		list_for_each(cur, &head) {
			cur_entry = list_entry(cur, struct pipe_list_entry, list);
			if (cur_entry->e.pipeid > le->e.pipeid)
				break;
		}

		list_add_tail(&le->list, cur);

		le->offset = lseek(pipes_fd, 0, SEEK_CUR);
		lseek(pipes_fd, le->e.bytes, SEEK_CUR);

		nr++;
		if (nr > buf_size / sizeof(*le)) {
			pr_err("OOM storing pipes");
			goto err_free;
		}
	}

	list_for_each_entry(le, &head, list) {
		lseek(pipes_fd, le->offset, SEEK_SET);
		if (open_pipe(pid, &le->e, &pipes_fd))
			goto err_free;
	}

	err = 0;
err_free:
	free(buf);
	close(pipes_fd);
	return err;
}

static int restore_one_task(int pid)
{
	pr_info("%d: Restoring resources\n", pid);

	if (prepare_pipes(pid))
		return -1;

	if (prepare_sockets(pid))
		return -1;

	if (prepare_fds(pid))
		return -1;

	if (prepare_shmem(pid))
		return -1;

	if (prepare_sigactions(pid))
		return -1;

	return prepare_and_sigreturn(pid);
}

static inline int fork_with_pid(int pid)
{
	int ret = -1, fd = -1;
	char buf[32];

	snprintf(buf, sizeof(buf), "%d", pid - 1);

	fd = open(LAST_PID_PATH, O_RDWR);
	if (fd < 0) {
		pr_perror("%d: Can't open %s\n", pid, LAST_PID_PATH);
		goto err;
	}

	if (flock(fd, LOCK_EX)) {
		pr_perror("%d: Can't lock %s\n", pid, LAST_PID_PATH);
		goto err;
	}

	write_safe(fd, buf, strlen(buf), err_unlock);

	ret = fork();
	if (ret < 0) {
		pr_perror("Can't fork for %d\n", pid);
		goto err_unlock;
	} else if (!ret) {
		int my_pid = getpid();

		close_safe(&fd);

		if (my_pid != pid) {
			pr_err("%d: Pids do not match got %d but expected %d\n",
			       my_pid, my_pid, pid);
			return -1;
		}

		/*
		 * We should never return here.
		 */
		ret = restore_task_with_children(pid);

		pr_err("%d: Something failed with code %d\n", pid, ret);
		exit(1);
	}

err_unlock:
	if (flock(fd, LOCK_UN))
		pr_perror("%d: Can't unlock %s\n", pid, LAST_PID_PATH);

err:
	close_safe(&fd);
	return ret;
}

static void sigchld_handler(int signal, siginfo_t *siginfo, void *data)
{
	int status, pid;

	if (siginfo->si_code & CLD_EXITED)
		pr_err("%d exited, status=%d\n",
			siginfo->si_pid, siginfo->si_status);
	else if (siginfo->si_code & CLD_KILLED)
		pr_err("%d killed by signal %d\n",
			siginfo->si_pid, siginfo->si_status);

	cr_wait_set(&task_entries->nr_in_progress, -1);
}

static int restore_task_with_children(int pid)
{
	int *pids;
	int fd, ret, i;
	struct pstree_entry e;
	sigset_t blockmask;

	/*
	 * The block mask will be restored in sigresturn.
	 *
	 * TODO: This code should be removed, when a freezer will be added.
	 */
	sigfillset(&blockmask);
	sigdelset(&blockmask, SIGCHLD);
	ret = sigprocmask(SIG_BLOCK, &blockmask, NULL);
	if (ret) {
		pr_perror("%d: Can't block signals\n", pid);
		exit(1);
	}

	pr_info("%d: Starting restore\n", pid);

	fd = open_image_ro_nocheck(FMT_FNAME_PSTREE, pstree_pid);
	if (fd < 0) {
		pr_perror("%d: Can't reopen pstree image\n", pid);
		exit(1);
	}

	lseek(fd, sizeof(u32), SEEK_SET);
	while (1) {
		ret = read(fd, &e, sizeof(e));
		if (ret == 0)
			break;

		if (ret != sizeof(e)) {
			pr_err("%d: Read returned %d\n", pid, ret);
			if (ret < 0)
				pr_perror("%d: Can't read pstree\n", pid);
			exit(1);
		}

		if (e.pid != pid) {
			lseek(fd, e.nr_children * sizeof(u32) + e.nr_threads * sizeof(u32), SEEK_CUR);
			continue;
		}

		break;
	}

	if (e.nr_children > 0) {
		i = e.nr_children * sizeof(int);
		pids = xmalloc(i);
		if (!pids)
			exit(1);

		ret = read(fd, pids, i);
		if (ret != i) {
			pr_perror("%d: Can't read children pids\n", pid);
			exit(1);
		}

		close(fd);

		pr_info("%d: Restoring %d children:\n", pid, e.nr_children);
		for (i = 0; i < e.nr_children; i++) {
			pr_info("\tFork %d from %d\n", pids[i], pid);
			ret = fork_with_pid(pids[i]);
			if (ret < 0)
				exit(1);
		}
	} else
		close(fd);

	return restore_one_task(pid);
}

static int restore_root_task(int fd, bool detach)
{
	struct pstree_entry e;
	int ret, i;
	struct sigaction act;

	ret = read(fd, &e, sizeof(e));
	if (ret != sizeof(e)) {
		pr_perror("Can't read root pstree entry\n");
		return -1;
	}

	close(fd);

	ret = sigaction(SIGCHLD, NULL, &act);
	if (ret < 0) {
		perror("sigaction() failed\n");
		return -1;
	}

	act.sa_flags |= SA_NOCLDWAIT | SA_NOCLDSTOP | SA_SIGINFO | SA_RESTART;
	act.sa_sigaction = sigchld_handler;
	ret = sigaction(SIGCHLD, &act, NULL);
	if (ret < 0) {
		perror("sigaction() failed\n");
		return -1;
	}

	pr_info("Forking root with %d pid\n", e.pid);
	ret = fork_with_pid(e.pid);
	if (ret < 0)
		return -1;

	pr_info("Wait until all tasks are restored");
	ret = cr_wait_until_greater(&task_entries->nr_in_progress, 0);
	if (ret < 0) {
		pr_err("Someone can't be restored\n");
		for (i = 0; i < task_entries->nr; i++)
			kill(task_entries->entries[i].pid, SIGKILL);
		return 1;
	}

	for (i = 0; i < task_entries->nr; i++) {
		pr_info("Wait while the task %d restored\n",
				task_entries->entries[i].pid);
		cr_wait_while(&task_entries->entries[i].done, 0);
	}

	cr_wait_set(&task_entries->nr_in_progress, task_entries->nr);
	cr_wait_set(&task_entries->start, CR_STATE_RESTORE_SIGCHLD);
	cr_wait_until(&task_entries->nr_in_progress, 0);
	pr_info("Go on!!!\n");
	cr_wait_set(&task_entries->start, CR_STATE_COMPLETE);

	if (!detach)
		wait(NULL);
	return 0;
}

static int restore_all_tasks(pid_t pid, bool detach)
{
	int pstree_fd;
	u32 type = 0;

	pstree_fd = open_image_ro(CR_FD_PSTREE, pstree_pid);
	if (pstree_fd < 0)
		return -1;

	if (prepare_shared(pstree_fd))
		return -1;

	return restore_root_task(pstree_fd, detach);
}

static long restorer_get_vma_hint(pid_t pid, struct list_head *self_vma_list, long vma_len)
{
	struct vma_area *vma_area;
	long prev_vma_end, hint;
	struct vma_entry vma;
	int fd = -1, ret;

	hint = -1;

	/*
	 * Here we need some heuristics -- the VMA which restorer will
	 * belong to should not be unmapped, so we need to gueess out
	 * where to put it in.
	 *
	 * Yes, I know it's an O(n^2) algorithm, but usually there are
	 * not that many VMAs presented so instead of consuming memory
	 * better to stick with it.
	 */

	fd = open_image_ro_nocheck(FMT_FNAME_CORE, pid);
	if (fd < 0)
		goto err_or_found;

	prev_vma_end = 0;

	lseek(fd, GET_FILE_OFF_AFTER(struct core_entry), SEEK_SET);

	while (1) {
		ret = read(fd, &vma, sizeof(vma));
		if (ret && ret != sizeof(vma)) {
			pr_perror("Can't read vma entry from core-%d\n", pid);
			goto err_or_found;
		}

		if (!prev_vma_end) {
			prev_vma_end = vma.end;
			continue;
		}

		if ((vma.start - prev_vma_end) > vma_len) {
			list_for_each_entry(vma_area, self_vma_list, list) {
				if (vma_area->vma.start <= prev_vma_end &&
				    vma_area->vma.end >= prev_vma_end)
					goto err_or_found;
			}
			hint = prev_vma_end;
			goto err_or_found;
		} else
			prev_vma_end = vma.end;
	}

err_or_found:
	if (fd >= 0)
		close(fd);
	return hint;
}

static void sigreturn_restore(pid_t pstree_pid, pid_t pid)
{
	long restore_code_len, restore_task_vma_len;
	long restore_thread_vma_len;

	void *exec_mem = MAP_FAILED;
	void *restore_thread_exec_start;
	void *restore_task_exec_start;
	void *restore_code_start;
	void *shmems_ref;

	long new_sp, exec_mem_hint;
	long ret;

	struct task_restore_core_args *task_args;
	struct thread_restore_args *thread_args;

	char self_vmas_path[PATH_MAX];

	LIST_HEAD(self_vma_list);
	struct vma_area *vma_area;
	int fd_self_vmas = -1;
	int fd_core = -1;
	int num;

	struct pstree_entry pstree_entry;
	int *fd_core_threads;
	int fd_pstree = -1;
	int pid_dir;

	pr_info("%d: Restore via sigreturn\n", pid);

	restore_code_len	= 0;
	restore_task_vma_len	= 0;
	restore_thread_vma_len	= 0;

	pid_dir = open_pid_proc(pid);
	if (pid_dir < 0)
		goto err;

	ret = parse_maps(pid, pid_dir, &self_vma_list, false);
	close(pid_dir);
	if (ret)
		goto err;

	/* pr_info_vma_list(&self_vma_list); */

	BUILD_BUG_ON(sizeof(struct task_restore_core_args) & 1);
	BUILD_BUG_ON(sizeof(struct thread_restore_args) & 1);
	BUILD_BUG_ON(SHMEMS_SIZE % PAGE_SIZE);
	BUILD_BUG_ON(TASK_ENTRIES_SIZE % PAGE_SIZE);

	fd_pstree = open_image_ro_nocheck(FMT_FNAME_PSTREE, pstree_pid);
	if (fd_pstree < 0)
		goto err;

	fd_core = open_image_ro_nocheck(FMT_FNAME_CORE_OUT, pid);
	if (fd_core < 0)
		pr_perror("Can't open core-out-%d\n", pid);

	if (get_image_path(self_vmas_path, sizeof(self_vmas_path),
			   FMT_FNAME_VMAS, pid))
		goto err;

	fd_self_vmas = open(self_vmas_path, O_CREAT | O_RDWR | O_TRUNC, CR_FD_PERM);

	/*
	 * This is a temporary file used to pass vma info to
	 * restorer code, thus unlink it early to make it disappear
	 * as soon as we close it
	 */
	// unlink(self_vmas_path);

	if (fd_self_vmas < 0) {
		pr_perror("Can't open %s\n", self_vmas_path);
		goto err;
	}

	num = 0;
	list_for_each_entry(vma_area, &self_vma_list, list) {
		ret = write(fd_self_vmas, &vma_area->vma, sizeof(vma_area->vma));
		if (ret != sizeof(vma_area->vma)) {
			pr_perror("\nUnable to write vma entry (%li written)\n", num);
			goto err;
		}
		num++;
	}

	free_mappings(&self_vma_list);

	restore_code_len	= sizeof(restorer_blob);
	restore_code_len	= round_up(restore_code_len, 16);

	restore_task_vma_len	= round_up(restore_code_len + sizeof(*task_args), PAGE_SIZE);

	/*
	 * Thread statistics
	 */
	lseek(fd_pstree, MAGIC_OFFSET, SEEK_SET);
	while (1) {
		ret = read_ptr_safe_eof(fd_pstree, &pstree_entry, err);
		if (!ret) {
			pr_perror("Pid %d not found in process tree\n", pid);
			goto err;
		}

		if (pstree_entry.pid != pid) {
			lseek(fd_pstree,
			      (pstree_entry.nr_children +
			       pstree_entry.nr_threads) *
			      sizeof(u32), SEEK_CUR);
			continue;
		}

		if (!pstree_entry.nr_threads)
			break;

		/*
		 * Compute how many memory we will need
		 * to restore all threads, every thread
		 * requires own stack and heap, it's ~40K
		 * per thread.
		 */

		restore_thread_vma_len = sizeof(*thread_args) * pstree_entry.nr_threads;
		restore_thread_vma_len = round_up(restore_thread_vma_len, 16);

		pr_info("%d: %d threads require %dK of memory\n",
			pid, pstree_entry.nr_threads,
			KBYTES(restore_thread_vma_len));
		break;
	}

	restore_thread_vma_len = round_up(restore_thread_vma_len, PAGE_SIZE);

	exec_mem_hint = restorer_get_vma_hint(pid, &self_vma_list,
					      restore_task_vma_len +
					      restore_thread_vma_len +
					      SHMEMS_SIZE + TASK_ENTRIES_SIZE);
	if (exec_mem_hint == -1) {
		pr_err("No suitable area for task_restore bootstrap (%dK)\n",
		       restore_task_vma_len + restore_thread_vma_len);
		goto err;
	} else {
		pr_info("Found bootstrap VMA hint at: %lx (needs ~%dK)\n",
			exec_mem_hint,
			KBYTES(restore_task_vma_len + restore_thread_vma_len));
	}

	/* VMA we need to run task_restore code */
	exec_mem = mmap((void *)exec_mem_hint,
			restore_task_vma_len + restore_thread_vma_len,
			PROT_READ | PROT_WRITE | PROT_EXEC,
			MAP_PRIVATE | MAP_ANON, 0, 0);
	if (exec_mem == MAP_FAILED) {
		pr_err("Can't mmap section for restore code\n");
		goto err;
	}

	/*
	 * Prepare a memory map for restorer. Note a thread space
	 * might be completely unused so it's here just for convenience.
	 */
	restore_code_start		= exec_mem;
	restore_thread_exec_start	= restore_code_start + restorer_blob_offset__restore_thread;
	restore_task_exec_start		= restore_code_start + restorer_blob_offset__restore_task;
	task_args			= restore_code_start + restore_code_len;
	thread_args			= restore_thread_exec_start;

	memzero_p(task_args);
	memzero_p(thread_args);

	/*
	 * Code at a new place.
	 */
	memcpy(restore_code_start, &restorer_blob, sizeof(restorer_blob));

	/*
	 * Adjust stack.
	 */
	new_sp = RESTORE_ALIGN_STACK((long)task_args->mem_zone.stack, sizeof(task_args->mem_zone.stack));

	/*
	 * Get a reference to shared memory area which is
	 * used to signal if shmem restoration complete
	 * from low-level restore code.
	 *
	 * This shmem area is mapped right after the whole area of
	 * sigreturn rt code. Note we didn't allocated it before
	 * but this area is taken into account for 'hint' memory
	 * address.
	 */
	shmems_ref = (struct shmems *)(exec_mem_hint +
				       restore_task_vma_len +
				       restore_thread_vma_len);
	ret = shmem_remap(shmems, shmems_ref, SHMEMS_SIZE);
	if (ret < 0)
		goto err;
	task_args->shmems	= shmems_ref;

	shmems_ref = (struct shmems *)(exec_mem_hint +
				       restore_task_vma_len +
				       restore_thread_vma_len +
				       SHMEMS_SIZE);
	ret = shmem_remap(task_entries, shmems_ref, TASK_ENTRIES_SIZE);
	if (ret < 0)
		goto err;
	task_args->task_entries = shmems_ref;

	/*
	 * Arguments for task restoration.
	 */
	task_args->pid		= pid;
	task_args->fd_core	= fd_core;
	task_args->fd_self_vmas	= fd_self_vmas;
	task_args->logfd	= get_logfd();
	task_args->sigchld_act	= sigchld_act;

	cr_mutex_init(&task_args->rst_lock);

	if (pstree_entry.nr_threads) {
		int i;

		/*
		 * Now prepare run-time data for threads restore.
		 */
		task_args->nr_threads		= pstree_entry.nr_threads;
		task_args->clone_restore_fn	= (void *)restore_thread_exec_start;
		task_args->thread_args		= thread_args;

		/*
		 * Fill up per-thread data.
		 */
		lseek(fd_pstree, sizeof(u32) * pstree_entry.nr_children, SEEK_CUR);
		for (i = 0; i < pstree_entry.nr_threads; i++) {
			read_ptr_safe(fd_pstree, &thread_args[i].pid, err);

			/* skip self */
			if (thread_args[i].pid == pid)
				continue;

			/* Core files are to be opened */
			thread_args[i].fd_core = open_image_ro_nocheck(FMT_FNAME_CORE, thread_args[i].pid);
			if (thread_args[i].fd_core < 0)
				goto err;

			thread_args[i].rst_lock = &task_args->rst_lock;

			pr_info("Thread %4d stack %8p heap %8p rt_sigframe %8p\n",
				i, (long)thread_args[i].mem_zone.stack,
				thread_args[i].mem_zone.heap,
				thread_args[i].mem_zone.rt_sigframe);

		}
	}

	pr_info("task_args: %p\n"
		"task_args->pid: %d\n"
		"task_args->fd_core: %d\n"
		"task_args->fd_self_vmas: %d\n"
		"task_args->nr_threads: %d\n"
		"task_args->clone_restore_fn: %p\n"
		"task_args->thread_args: %p\n",
		task_args, task_args->pid,
		task_args->fd_core, task_args->fd_self_vmas,
		task_args->nr_threads, task_args->clone_restore_fn,
		task_args->thread_args);

	close_safe(&fd_pstree);

	/*
	 * An indirect call to task_restore, note it never resturns
	 * and restoreing core is extremely destructive.
	 */
	asm volatile(
		"movq %0, %%rbx						\n"
		"movq %1, %%rax						\n"
		"movq %2, %%rdi						\n"
		"movq %%rbx, %%rsp					\n"
		"callq *%%rax						\n"
		:
		: "g"(new_sp),
		  "g"(restore_task_exec_start),
		  "g"(task_args)
		: "rsp", "rdi", "rsi", "rbx", "rax", "memory");

err:
	free_mappings(&self_vma_list);
	close_safe(&fd_pstree);
	close_safe(&fd_core);
	close_safe(&fd_self_vmas);

	if (exec_mem != MAP_FAILED)
		munmap(exec_mem, restore_task_vma_len + restore_thread_vma_len);

	/* Just to be sure */
	exit(1);
}

int cr_restore_tasks(pid_t pid, struct cr_options *opts)
{
	pstree_pid = pid;

	if (opts->leader_only)
		return restore_one_task(pid);
	return restore_all_tasks(pid, opts->restore_detach);
}