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mirror of https://github.com/checkpoint-restore/criu synced 2025-08-22 09:58:09 +00:00
criu/fifo.c
Pavel Emelyanov 8a07349388 files: Fix open_path() to provide mntns root fd to callbacks
This fixes the support for fifo-s in mount namespaces and
makes it easier to control the correct open_path() usage in
the future.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
2014-06-06 12:20:02 +04:00

169 lines
3.9 KiB
C

#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include "fdset.h"
#include "image.h"
#include "files.h"
#include "files-reg.h"
#include "pipes.h"
#include "fifo.h"
#include "protobuf.h"
#include "protobuf/regfile.pb-c.h"
#include "protobuf/fifo.pb-c.h"
/*
* FIFO checkpoint and restore is done in a bit unusual manner.
* We use files-reg.c engine to save fifo path and flags,
* thus regular files image will contain fifo descriptors which
* are useless for reg-files engine itself but needed for our fifo
* engine.
*
* In particular we dump fifo-entry automatically and appropriate
* reg-file entry manually, thus on restore we need to ask reg-file
* engine to restore fifo path and flags via direct call.
*/
struct fifo_info {
struct list_head list;
struct file_desc d;
FifoEntry *fe;
bool restore_data;
struct file_desc *reg_d;
};
static LIST_HEAD(fifo_head);
static struct pipe_data_dump pd_fifo = { .img_type = CR_FD_FIFO_DATA, };
static int dump_one_fifo(int lfd, u32 id, const struct fd_parms *p)
{
int img = fdset_fd(glob_fdset, CR_FD_FIFO);
FifoEntry e = FIFO_ENTRY__INIT;
/*
* It's a trick here, we use regular files dumping
* code to save path to a fifo, then we reuse it
* on restore.
*/
if (dump_one_reg_file(lfd, id, p))
return -1;
pr_info("Dumping fifo %d with id %#x pipe_id %#x\n",
lfd, id, pipe_id(p));
e.id = id;
e.pipe_id = pipe_id(p);
if (pb_write_one(img, &e, PB_FIFO))
return -1;
return dump_one_pipe_data(&pd_fifo, lfd, p);
}
const struct fdtype_ops fifo_dump_ops = {
.type = FD_TYPES__FIFO,
.dump = dump_one_fifo,
};
static struct pipe_data_rst *pd_hash_fifo[PIPE_DATA_HASH_SIZE];
static int do_open_fifo(int ns_root_fd, struct reg_file_info *rfi, void *arg)
{
struct fifo_info *info = arg;
int new_fifo, fake_fifo = -1;
/*
* The fifos (except read-write fifos) do wait until
* another pipe-end get connected, so to be able to
* proceed the restoration procedure we open a fake
* fifo here.
*/
fake_fifo = openat(ns_root_fd, rfi->path, O_RDWR);
if (fake_fifo < 0) {
pr_perror("Can't open fake fifo %#x [%s]", info->fe->id, rfi->path);
return -1;
}
new_fifo = openat(ns_root_fd, rfi->path, rfi->rfe->flags);
if (new_fifo < 0) {
pr_perror("Can't open fifo %#x [%s]", info->fe->id, rfi->path);
goto out;
}
if (info->restore_data)
if (restore_pipe_data(CR_FD_FIFO_DATA, fake_fifo,
info->fe->pipe_id, pd_hash_fifo)) {
close(new_fifo);
new_fifo = -1;
}
out:
close(fake_fifo);
return new_fifo;
}
static int open_fifo_fd(struct file_desc *d)
{
struct fifo_info *info = container_of(d, struct fifo_info, d);
return open_path(info->reg_d, do_open_fifo, info);
}
static void collect_fifo_fd(struct file_desc *d,
struct fdinfo_list_entry *fle, struct rst_info *ri)
{
struct fifo_info *info;
info = container_of(d, struct fifo_info, d);
info->reg_d = collect_special_file(info->fe->id);
BUG_ON(info->reg_d == NULL);
collect_gen_fd(fle, ri);
}
static struct file_desc_ops fifo_desc_ops = {
.type = FD_TYPES__FIFO,
.open = open_fifo_fd,
.collect_fd = collect_fifo_fd,
};
static int collect_one_fifo(void *o, ProtobufCMessage *base)
{
struct fifo_info *info = o, *f;
info->fe = pb_msg(base, FifoEntry);
pr_info("Collected fifo entry ID %#x PIPE ID %#x\n",
info->fe->id, info->fe->pipe_id);
/* check who will restore the fifo data */
list_for_each_entry(f, &fifo_head, list)
if (f->fe->pipe_id == info->fe->pipe_id)
break;
if (&f->list == &fifo_head) {
list_add(&info->list, &fifo_head);
info->restore_data = true;
} else {
INIT_LIST_HEAD(&info->list);
info->restore_data = false;
}
return file_desc_add(&info->d, info->fe->id, &fifo_desc_ops);
}
struct collect_image_info fifo_cinfo = {
.fd_type = CR_FD_FIFO,
.pb_type = PB_FIFO,
.priv_size = sizeof(struct fifo_info),
.collect = collect_one_fifo,
};
int collect_fifo(void)
{
return collect_pipe_data(CR_FD_FIFO_DATA, pd_hash_fifo);
}