forked from cyrillos/criu
/
cr-restore.c
2539 lines (2031 loc) · 54.5 KB
/
cr-restore.c
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#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 <grp.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/vfs.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <sys/file.h>
#include <sys/shm.h>
#include <sys/mount.h>
#include <sys/prctl.h>
#include <sched.h>
#include <sys/sendfile.h>
#include "compiler.h"
#include "asm/types.h"
#include "asm/restorer.h"
#include "cr_options.h"
#include "servicefd.h"
#include "image.h"
#include "util.h"
#include "util-pie.h"
#include "log.h"
#include "syscall.h"
#include "restorer.h"
#include "sockets.h"
#include "sk-packet.h"
#include "lock.h"
#include "files.h"
#include "files-reg.h"
#include "pipes.h"
#include "fifo.h"
#include "sk-inet.h"
#include "eventfd.h"
#include "eventpoll.h"
#include "signalfd.h"
#include "proc_parse.h"
#include "restorer-blob.h"
#include "crtools.h"
#include "namespaces.h"
#include "shmem.h"
#include "mount.h"
#include "fsnotify.h"
#include "pstree.h"
#include "net.h"
#include "tty.h"
#include "cpu.h"
#include "file-lock.h"
#include "page-read.h"
#include "vdso.h"
#include "stats.h"
#include "tun.h"
#include "vma.h"
#include "kerndat.h"
#include "rst-malloc.h"
#include "parasite-syscall.h"
#include "protobuf.h"
#include "protobuf/sa.pb-c.h"
#include "protobuf/timer.pb-c.h"
#include "protobuf/vma.pb-c.h"
#include "protobuf/rlimit.pb-c.h"
#include "protobuf/pagemap.pb-c.h"
#include "protobuf/siginfo.pb-c.h"
#include "asm/restore.h"
static struct pstree_item *current;
static int restore_task_with_children(void *);
static int sigreturn_restore(pid_t pid, CoreEntry *core);
static int prepare_restorer_blob(void);
static int prepare_rlimits(int pid);
static int prepare_posix_timers(int pid);
static int prepare_signals(int pid);
static VM_AREA_LIST(rst_vmas); /* XXX .longest is NOT tracked for this guy */
static int shmem_remap(void *old_addr, void *new_addr, unsigned long size)
{
void *ret;
ret = mremap(old_addr, size, size,
MREMAP_FIXED | MREMAP_MAYMOVE, new_addr);
if (new_addr != ret) {
pr_perror("mremap failed");
return -1;
}
return 0;
}
static int crtools_prepare_shared(void)
{
if (prepare_shared_fdinfo())
return -1;
/* Connections are unlocked from criu */
if (collect_inet_sockets())
return -1;
if (tty_prep_fds())
return -1;
return 0;
}
static struct collect_image_info *cinfos[] = {
®_file_cinfo,
&remap_cinfo,
&nsfile_cinfo,
&pipe_cinfo,
&fifo_cinfo,
&unix_sk_cinfo,
&packet_sk_cinfo,
&netlink_sk_cinfo,
&eventfd_cinfo,
&epoll_tfd_cinfo,
&epoll_cinfo,
&signalfd_cinfo,
&inotify_cinfo,
&inotify_mark_cinfo,
&fanotify_cinfo,
&fanotify_mark_cinfo,
&tty_info_cinfo,
&tty_cinfo,
&tunfile_cinfo,
};
static int root_prepare_shared(void)
{
int ret = 0, i;
struct pstree_item *pi;
pr_info("Preparing info about shared resources\n");
if (prepare_shared_tty())
return -1;
if (prepare_shared_reg_files())
return -1;
for (i = 0; i < ARRAY_SIZE(cinfos); i++) {
ret = collect_image(cinfos[i]);
if (ret)
return -1;
}
if (collect_pipes())
return -1;
if (collect_fifo())
return -1;
if (collect_unix_sockets())
return -1;
if (tty_verify_active_pairs())
return -1;
for_each_pstree_item(pi) {
if (pi->state == TASK_HELPER)
continue;
ret = prepare_shmem_pid(pi->pid.virt);
if (ret < 0)
break;
ret = prepare_fd_pid(pi);
if (ret < 0)
break;
}
if (ret < 0)
goto err;
mark_pipe_master();
ret = tty_setup_slavery();
if (ret)
goto err;
ret = resolve_unix_peers();
if (ret)
goto err;
ret = prepare_restorer_blob();
if (ret)
goto err;
show_saved_shmems();
show_saved_files();
err:
return ret;
}
/* Map a private vma, if it is not mapped by a parent yet */
static int map_private_vma(pid_t pid, struct vma_area *vma, void *tgt_addr,
struct vma_area **pvma, struct list_head *pvma_list)
{
int ret;
void *addr, *paddr = NULL;
unsigned long nr_pages, size;
struct vma_area *p = *pvma;
if (vma_entry_is(&vma->vma, VMA_FILE_PRIVATE)) {
ret = get_filemap_fd(pid, &vma->vma);
if (ret < 0) {
pr_err("Can't fixup VMA's fd\n");
return -1;
}
vma->vma.fd = ret;
}
nr_pages = vma_entry_len(&vma->vma) / PAGE_SIZE;
vma->page_bitmap = xzalloc(BITS_TO_LONGS(nr_pages) * sizeof(long));
if (vma->page_bitmap == NULL)
return -1;
list_for_each_entry_continue(p, pvma_list, list) {
if (p->vma.start > vma->vma.start)
break;
if (!vma_priv(&p->vma))
continue;
if (p->vma.end != vma->vma.end ||
p->vma.start != vma->vma.start)
continue;
/* Check flags, which must be identical for both vma-s */
if ((vma->vma.flags ^ p->vma.flags) & (MAP_GROWSDOWN | MAP_ANONYMOUS))
break;
if (!(vma->vma.flags & MAP_ANONYMOUS) &&
vma->vma.shmid != p->vma.shmid)
break;
pr_info("COW 0x%016"PRIx64"-0x%016"PRIx64" 0x%016"PRIx64" vma\n",
vma->vma.start, vma->vma.end, vma->vma.pgoff);
paddr = decode_pointer(vma->premmaped_addr);
}
*pvma = p;
/*
* A grow-down VMA has a guard page, which protect a VMA below it.
* So one more page is mapped here to restore content of the first page
*/
if (vma->vma.flags & MAP_GROWSDOWN) {
vma->vma.start -= PAGE_SIZE;
if (paddr)
paddr -= PAGE_SIZE;
}
size = vma_entry_len(&vma->vma);
if (paddr == NULL) {
/*
* The respective memory area was NOT found in the parent.
* Map a new one.
*/
pr_info("Map 0x%016"PRIx64"-0x%016"PRIx64" 0x%016"PRIx64" vma\n",
vma->vma.start, vma->vma.end, vma->vma.pgoff);
addr = mmap(tgt_addr, size,
vma->vma.prot | PROT_WRITE,
vma->vma.flags | MAP_FIXED,
vma->vma.fd, vma->vma.pgoff);
if (addr == MAP_FAILED) {
pr_perror("Unable to map ANON_VMA");
return -1;
}
} else {
/*
* This region was found in parent -- remap it to inherit physical
* pages (if any) from it (and COW them later if required).
*/
vma->ppage_bitmap = p->page_bitmap;
addr = mremap(paddr, size, size,
MREMAP_FIXED | MREMAP_MAYMOVE, tgt_addr);
if (addr != tgt_addr) {
pr_perror("Unable to remap a private vma");
return -1;
}
}
vma->premmaped_addr = (unsigned long) addr;
pr_debug("\tpremap 0x%016"PRIx64"-0x%016"PRIx64" -> %016lx\n",
vma->vma.start, vma->vma.end, (unsigned long)addr);
if (vma->vma.flags & MAP_GROWSDOWN) { /* Skip gurad page */
vma->vma.start += PAGE_SIZE;
vma->premmaped_addr += PAGE_SIZE;
}
if (vma_entry_is(&vma->vma, VMA_FILE_PRIVATE))
close(vma->vma.fd);
return size;
}
static int restore_priv_vma_content(pid_t pid)
{
struct vma_area *vma;
int ret = 0;
unsigned int nr_restored = 0;
unsigned int nr_shared = 0;
unsigned int nr_droped = 0;
unsigned long va;
struct page_read pr;
vma = list_first_entry(&rst_vmas.h, struct vma_area, list);
ret = open_page_read(pid, &pr);
if (ret)
return -1;
/*
* Read page contents.
*/
while (1) {
unsigned long off, i, nr_pages;;
struct iovec iov;
ret = pr.get_pagemap(&pr, &iov);
if (ret <= 0)
break;
va = (unsigned long)iov.iov_base;
nr_pages = iov.iov_len / PAGE_SIZE;
for (i = 0; i < nr_pages; i++) {
unsigned char buf[PAGE_SIZE];
void *p;
/*
* The lookup is over *all* possible VMAs
* read from image file.
*/
while (va >= vma->vma.end) {
if (vma->list.next == &rst_vmas.h)
goto err_addr;
vma = list_entry(vma->list.next, struct vma_area, list);
}
/*
* Make sure the page address is inside existing VMA
* and the VMA it refers to still private one, since
* there is no guarantee that the data from pagemap is
* valid.
*/
if (va < vma->vma.start)
goto err_addr;
else if (unlikely(!vma_priv(&vma->vma))) {
pr_err("Trying to restore page for non-private VMA\n");
goto err_addr;
}
off = (va - vma->vma.start) / PAGE_SIZE;
p = decode_pointer((off) * PAGE_SIZE +
vma->premmaped_addr);
set_bit(off, vma->page_bitmap);
if (vma->ppage_bitmap) { /* inherited vma */
clear_bit(off, vma->ppage_bitmap);
ret = pr.read_page(&pr, va, buf);
if (ret < 0)
break;
va += PAGE_SIZE;
if (memcmp(p, buf, PAGE_SIZE) == 0) {
nr_shared++; /* the page is cowed */
continue;
}
memcpy(p, buf, PAGE_SIZE);
} else {
ret = pr.read_page(&pr, va, p);
if (ret < 0)
break;
va += PAGE_SIZE;
}
nr_restored++;
}
if (pr.put_pagemap)
pr.put_pagemap(&pr);
}
pr.close(&pr);
if (ret < 0)
return ret;
/* Remove pages, which were not shared with a child */
list_for_each_entry(vma, &rst_vmas.h, list) {
unsigned long size, i = 0;
void *addr = decode_pointer(vma->premmaped_addr);
if (vma->ppage_bitmap == NULL)
continue;
size = vma_entry_len(&vma->vma) / PAGE_SIZE;
while (1) {
/* Find all pages, which are not shared with this child */
i = find_next_bit(vma->ppage_bitmap, size, i);
if ( i >= size)
break;
ret = madvise(addr + PAGE_SIZE * i,
PAGE_SIZE, MADV_DONTNEED);
if (ret < 0) {
pr_perror("madvise failed");
return -1;
}
i++;
nr_droped++;
}
}
cnt_add(CNT_PAGES_COMPARED, nr_restored + nr_shared);
cnt_add(CNT_PAGES_SKIPPED_COW, nr_shared);
pr_info("nr_restored_pages: %d\n", nr_restored);
pr_info("nr_shared_pages: %d\n", nr_shared);
pr_info("nr_droped_pages: %d\n", nr_droped);
return 0;
err_addr:
pr_err("Page entry address %lx outside of VMA %lx-%lx\n",
va, (long)vma->vma.start, (long)vma->vma.end);
return -1;
}
static int prepare_mappings(int pid)
{
int fd, ret = 0;
LIST_HEAD(parent_vmas);
struct vma_area *pvma, *vma;
void *addr;
void *old_premmapped_addr = NULL;
unsigned long old_premmapped_len, pstart = 0;
rst_vmas.nr = 0;
rst_vmas.priv_size = 0;
/*
* Keep parent vmas at hands to check whether we can "inherit" them.
* See comments in map_private_vma.
*/
list_replace_init(&rst_vmas.h, &parent_vmas);
/* Skip errors, because a zombie doesn't have an image of vmas */
fd = open_image(CR_FD_VMAS, O_RSTR, pid);
if (fd < 0) {
if (errno != ENOENT)
ret = fd;
goto out;
}
while (1) {
struct vma_area *vma;
VmaEntry *e;
ret = -1;
vma = alloc_vma_area();
if (!vma)
break;
ret = pb_read_one_eof(fd, &e, PB_VMA);
if (ret <= 0) {
xfree(vma);
break;
}
rst_vmas.nr++;
list_add_tail(&vma->list, &rst_vmas.h);
vma->vma = *e;
vma_entry__free_unpacked(e, NULL);
if (vma->vma.fd != -1) {
ret = -1;
pr_err("Error in vma->fd setting (%Ld)\n",
(unsigned long long)vma->vma.fd);
break;
}
if (vma_priv(&vma->vma)) {
rst_vmas.priv_size += vma_area_len(vma);
if (vma->vma.flags & MAP_GROWSDOWN)
rst_vmas.priv_size += PAGE_SIZE;
}
}
close(fd);
if (ret < 0)
goto out;
/* Reserve a place for mapping private vma-s one by one */
addr = mmap(NULL, rst_vmas.priv_size, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
if (addr == MAP_FAILED) {
pr_perror("Unable to reserve memory (%lu bytes)", rst_vmas.priv_size);
return -1;
}
old_premmapped_addr = current->rst->premmapped_addr;
old_premmapped_len = current->rst->premmapped_len;
current->rst->premmapped_addr = addr;
current->rst->premmapped_len = rst_vmas.priv_size;
pvma = list_entry(&parent_vmas, struct vma_area, list);
list_for_each_entry(vma, &rst_vmas.h, list) {
if (pstart > vma->vma.start) {
ret = -1;
pr_err("VMA-s are not sorted in the image file\n");
break;
}
pstart = vma->vma.start;
if (!vma_priv(&vma->vma))
continue;
ret = map_private_vma(pid, vma, addr, &pvma, &parent_vmas);
if (ret < 0)
break;
addr += ret;
}
if (ret >= 0)
ret = restore_priv_vma_content(pid);
out:
while (!list_empty(&parent_vmas)) {
vma = list_first_entry(&parent_vmas, struct vma_area, list);
list_del(&vma->list);
xfree(vma);
}
if (old_premmapped_addr &&
munmap(old_premmapped_addr, old_premmapped_len)) {
pr_perror("Unable to unmap %p(%lx)",
old_premmapped_addr, old_premmapped_len);
return -1;
}
return ret;
}
/*
* A gard page must be unmapped after restoring content and
* forking children to restore COW memory.
*/
static int unmap_guard_pages()
{
struct vma_area *vma;
list_for_each_entry(vma, &rst_vmas.h, list) {
if (!vma_priv(&vma->vma))
continue;
if (vma->vma.flags & MAP_GROWSDOWN) {
void *addr = decode_pointer(vma->premmaped_addr);
if (munmap(addr - PAGE_SIZE, PAGE_SIZE)) {
pr_perror("Can't unmap guard page\n");
return -1;
}
}
}
return 0;
}
static int open_vmas(int pid)
{
struct vma_area *vma;
int ret = 0;
list_for_each_entry(vma, &rst_vmas.h, list) {
if (!(vma_entry_is(&vma->vma, VMA_AREA_REGULAR)))
continue;
pr_info("Opening 0x%016"PRIx64"-0x%016"PRIx64" 0x%016"PRIx64" (%x) vma\n",
vma->vma.start, vma->vma.end,
vma->vma.pgoff, vma->vma.status);
if (vma_entry_is(&vma->vma, VMA_AREA_SYSVIPC))
ret = vma->vma.shmid;
else if (vma_entry_is(&vma->vma, VMA_ANON_SHARED))
ret = get_shmem_fd(pid, &vma->vma);
else if (vma_entry_is(&vma->vma, VMA_FILE_SHARED))
ret = get_filemap_fd(pid, &vma->vma);
else if (vma_entry_is(&vma->vma, VMA_AREA_SOCKET))
ret = get_socket_fd(pid, &vma->vma);
else
continue;
if (ret < 0) {
pr_err("Can't fixup fd\n");
break;
}
pr_info("\t`- setting %d as mapping fd\n", ret);
vma->vma.fd = ret;
}
return ret < 0 ? -1 : 0;
}
static rt_sigaction_t sigchld_act;
static int prepare_sigactions(int pid)
{
rt_sigaction_t act, oact;
int fd_sigact;
SaEntry *e;
int sig;
int ret = -1;
fd_sigact = open_image(CR_FD_SIGACT, O_RSTR, pid);
if (fd_sigact < 0)
return -1;
for (sig = 1; sig <= SIGMAX; sig++) {
if (sig == SIGKILL || sig == SIGSTOP)
continue;
ret = pb_read_one_eof(fd_sigact, &e, PB_SIGACT);
if (ret == 0) {
if (sig != SIGMAX_OLD + 1) { /* backward compatibility */
pr_err("Unexpected EOF %d\n", sig);
ret = -1;
break;
}
pr_warn("This format of sigacts-%d.img is deprecated\n", pid);
break;
}
if (ret < 0)
break;
ASSIGN_TYPED(act.rt_sa_handler, decode_pointer(e->sigaction));
ASSIGN_TYPED(act.rt_sa_flags, e->flags);
ASSIGN_TYPED(act.rt_sa_restorer, decode_pointer(e->restorer));
ASSIGN_TYPED(act.rt_sa_mask.sig[0], e->mask);
sa_entry__free_unpacked(e, NULL);
if (sig == SIGCHLD) {
sigchld_act = act;
continue;
}
/*
* A pure syscall is used, because glibc
* sigaction overwrites se_restorer.
*/
ret = sys_sigaction(sig, &act, &oact, sizeof(k_rtsigset_t));
if (ret == -1) {
pr_err("%d: Can't restore sigaction: %m\n", pid);
goto err;
}
}
err:
close_safe(&fd_sigact);
return ret;
}
static int pstree_wait_helpers()
{
struct pstree_item *pi;
list_for_each_entry(pi, ¤t->children, sibling) {
int status, ret;
if (pi->state != TASK_HELPER)
continue;
/* Check, that a helper completed. */
ret = waitpid(pi->pid.virt, &status, 0);
if (ret == -1) {
if (errno == ECHILD)
continue; /* It has been waited in sigchld_handler */
pr_err("waitpid(%d) failed\n", pi->pid.virt);
return -1;
}
if (!WIFEXITED(status) || WEXITSTATUS(status)) {
pr_err("%d exited with non-zero code (%d,%d)\n", pi->pid.virt,
WEXITSTATUS(status), WTERMSIG(status));
return -1;
}
}
return 0;
}
static int restore_one_alive_task(int pid, CoreEntry *core)
{
pr_info("Restoring resources\n");
rst_mem_switch_to_private();
if (pstree_wait_helpers())
return -1;
if (prepare_fds(current))
return -1;
if (prepare_file_locks(pid))
return -1;
if (prepare_sigactions(pid))
return -1;
if (open_vmas(pid))
return -1;
if (prepare_signals(pid))
return -1;
if (prepare_posix_timers(pid))
return -1;
if (prepare_rlimits(pid) < 0)
return -1;
return sigreturn_restore(pid, core);
}
static void zombie_prepare_signals(void)
{
sigset_t blockmask;
int sig;
struct sigaction act;
sigfillset(&blockmask);
sigprocmask(SIG_UNBLOCK, &blockmask, NULL);
memset(&act, 0, sizeof(act));
act.sa_handler = SIG_DFL;
for (sig = 1; sig <= SIGMAX; sig++)
sigaction(sig, &act, NULL);
}
#define SIG_FATAL_MASK ( \
(1 << SIGHUP) |\
(1 << SIGINT) |\
(1 << SIGQUIT) |\
(1 << SIGILL) |\
(1 << SIGTRAP) |\
(1 << SIGABRT) |\
(1 << SIGIOT) |\
(1 << SIGBUS) |\
(1 << SIGFPE) |\
(1 << SIGKILL) |\
(1 << SIGUSR1) |\
(1 << SIGSEGV) |\
(1 << SIGUSR2) |\
(1 << SIGPIPE) |\
(1 << SIGALRM) |\
(1 << SIGTERM) |\
(1 << SIGXCPU) |\
(1 << SIGXFSZ) |\
(1 << SIGVTALRM)|\
(1 << SIGPROF) |\
(1 << SIGPOLL) |\
(1 << SIGIO) |\
(1 << SIGSYS) |\
(1 << SIGUNUSED)|\
(1 << SIGSTKFLT)|\
(1 << SIGPWR) \
)
static inline int sig_fatal(int sig)
{
return (sig > 0) && (sig < SIGMAX) && (SIG_FATAL_MASK & (1UL << sig));
}
struct task_entries *task_entries;
static int restore_one_zombie(int pid, CoreEntry *core)
{
int exit_code = core->tc->exit_code;
pr_info("Restoring zombie with %d code\n", exit_code);
sys_prctl(PR_SET_NAME, (long)(void *)core->tc->comm, 0, 0, 0);
if (task_entries != NULL) {
restore_finish_stage(CR_STATE_RESTORE);
zombie_prepare_signals();
mutex_lock(&task_entries->zombie_lock);
}
if (exit_code & 0x7f) {
int signr;
/* prevent generating core files */
if (prctl(PR_SET_DUMPABLE, 0, 0, 0, 0))
pr_perror("Can't drop the dumpable flag");
signr = exit_code & 0x7F;
if (!sig_fatal(signr)) {
pr_warn("Exit with non fatal signal ignored\n");
signr = SIGABRT;
}
if (kill(pid, signr) < 0)
pr_perror("Can't kill myself, will just exit");
exit_code = 0;
}
exit((exit_code >> 8) & 0x7f);
/* never reached */
BUG_ON(1);
return -1;
}
static int check_core(CoreEntry *core, struct pstree_item *me)
{
int ret = -1;
if (core->mtype != CORE_ENTRY__MARCH) {
pr_err("Core march mismatch %d\n", (int)core->mtype);
goto out;
}
if (!core->tc) {
pr_err("Core task state data missed\n");
goto out;
}
if (core->tc->task_state != TASK_DEAD) {
if (!core->ids && !me->ids) {
pr_err("Core IDS data missed for non-zombie\n");
goto out;
}
if (!CORE_THREAD_ARCH_INFO(core)) {
pr_err("Core info data missed for non-zombie\n");
goto out;
}
}
ret = 0;
out:
return ret;
}
static int restore_one_task(int pid, CoreEntry *core)
{
int ret;
/* No more fork()-s => no more per-pid logs */
switch ((int)core->tc->task_state) {
case TASK_ALIVE:
case TASK_STOPPED:
ret = restore_one_alive_task(pid, core);
break;
case TASK_DEAD:
ret = restore_one_zombie(pid, core);
break;
default:
pr_err("Unknown state in code %d\n", (int)core->tc->task_state);
ret = -1;
break;
}
core_entry__free_unpacked(core, NULL);
return ret;
}
/* All arguments should be above stack, because it grows down */
struct cr_clone_arg {
char stack[PAGE_SIZE] __attribute__((aligned (8)));
char stack_ptr[0];
struct pstree_item *item;
unsigned long clone_flags;
int fd;
CoreEntry *core;
};
static inline int fork_with_pid(struct pstree_item *item)
{
int ret = -1, fd;
struct cr_clone_arg ca;
pid_t pid = item->pid.virt;
if (item->state != TASK_HELPER) {
fd = open_image(CR_FD_CORE, O_RSTR, pid);
if (fd < 0)
return -1;
ret = pb_read_one(fd, &ca.core, PB_CORE);
close(fd);
if (ret < 0)
return -1;
if (check_core(ca.core, item))
return -1;
item->state = ca.core->tc->task_state;
switch (item->state) {
case TASK_ALIVE:
case TASK_STOPPED:
break;
case TASK_DEAD:
item->parent->rst->nr_zombies++;
break;
default:
pr_err("Unknown task state %d\n", item->state);
return -1;
}
} else
ca.core = NULL;
ca.item = item;
ca.clone_flags = item->rst->clone_flags;
pr_info("Forking task with %d pid (flags 0x%lx)\n", pid, ca.clone_flags);
if (!(ca.clone_flags & CLONE_NEWPID)) {
char buf[32];
ca.fd = open(LAST_PID_PATH, O_RDWR);
if (ca.fd < 0) {
pr_perror("%d: Can't open %s", pid, LAST_PID_PATH);
goto err;
}
if (flock(ca.fd, LOCK_EX)) {
close(ca.fd);
pr_perror("%d: Can't lock %s", pid, LAST_PID_PATH);
goto err;
}
snprintf(buf, sizeof(buf), "%d", pid - 1);
if (write_img_buf(ca.fd, buf, strlen(buf)))
goto err_unlock;
} else {
ca.fd = -1;
BUG_ON(pid != INIT_PID);
}
if (ca.clone_flags & CLONE_NEWNET)
/*
* When restoring a net namespace we need to communicate
* with the original (i.e. -- init) one. Thus, prepare for
* that before we leave the existing namespaces.
*/
if (netns_pre_create())
goto err_unlock;
ret = clone(restore_task_with_children, ca.stack_ptr,
ca.clone_flags | SIGCHLD, &ca);
if (ret < 0)
pr_perror("Can't fork for %d", pid);
if (item == root_item)
item->pid.real = ret;
if (opts.pidfile && root_item == item) {
int pid;
pid = ret;
ret = write_pidfile(pid);
if (ret < 0) {
pr_perror("Can't write pidfile");