[CRIU] [PATCH 2/5] util: clone service descriptors, if fd tables are shared for tasks

[Pavel Emelyanov]

On 12/25/2012 05:10 PM, Andrey Vagin wrote:
> It looks like a namespace for service descriptors.
> It will be used for restoring tasks with shared fd tables.
> Service descriptors should be its for each process.

The implementation looks horrible. Why do we need per service fd
type explicit helper to clone it?

> Signed-off-by: Andrey Vagin <avagin at openvz.org>
> ---
>  image.c           | 22 +++++++++++++++++
>  include/crtools.h |  2 ++
>  include/log.h     |  1 +
>  log.c             | 11 +++++++++
>  util.c            | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  5 files changed, 109 insertions(+), 1 deletion(-)
> 
> diff --git a/image.c b/image.c
> index f1f93a0..70ababe 100644
> --- a/image.c
> +++ b/image.c
> @@ -276,6 +276,28 @@ err:
>  	return -1;
>  }
>  
> +int clone_image_dir(void)
> +{
> +	int fd;
> +
> +	if (image_dir_fd < 0)
> +		return 0;
> +
> +	fd = get_service_fd(IMG_FD_OFF);
> +	if (fd < 0) {
> +		pr_perror("Can't get image fd");
> +		return -1;
> +	}
> +
> +	image_dir_fd = dup2(image_dir_fd, fd);
> +	if (image_dir_fd < 0) {
> +		pr_perror("Unable to duplicate an image directory descriptor");
> +		return -1;
> +	}
> +
> +	return 0;
> +}
> +
>  int open_image_dir(void)
>  {
>  	int fd;
> diff --git a/include/crtools.h b/include/crtools.h
> index 1155341..9d94fd7 100644
> --- a/include/crtools.h
> +++ b/include/crtools.h
> @@ -121,6 +121,7 @@ enum sfd_type {
>  	SERVICE_FD_MAX
>  };
>  
> +extern int clone_service_fd(bool to_init);
>  extern int init_service_fd(void);
>  extern int get_service_fd(enum sfd_type type);
>  extern bool is_service_fd(int fd, enum sfd_type type);
> @@ -163,6 +164,7 @@ extern void print_image_data(int fd, unsigned int length, int show);
>  extern struct cr_fd_desc_tmpl fdset_template[CR_FD_MAX];
>  
>  extern int open_image_dir(void);
> +extern int clone_image_dir(void);
>  extern void close_image_dir(void);
>  
>  int open_image(int type, unsigned long flags, ...);
> diff --git a/include/log.h b/include/log.h
> index 8fa7dc6..148359e 100644
> --- a/include/log.h
> +++ b/include/log.h
> @@ -10,6 +10,7 @@ extern void log_closedir(void);
>  
>  extern void log_set_fd(int fd);
>  extern int log_get_fd(void);
> +extern int log_clone_fd(void);
>  
>  extern void log_set_loglevel(unsigned int loglevel);
>  extern unsigned int log_get_loglevel(void);
> diff --git a/log.c b/log.c
> index 5fa1c6b..24c3ff5 100644
> --- a/log.c
> +++ b/log.c
> @@ -55,7 +55,18 @@ static void print_ts(void)
>  	buffer[TS_BUF_OFF - 1] = ' '; /* kill the '\0' produced by snprintf */
>  }
>  
> +int log_clone_fd(void)
> +{
> +	current_logfd = dup2(current_logfd, get_service_fd(LOG_FD_OFF));
> +	if (current_logfd < 0)
> +		return -1;
> +
> +	logdir = dup2(logdir, get_service_fd(LOG_DIR_FD_OFF));
> +	if (logdir < 0)
> +		return -1;
>  
> +	return 0;
> +}
>  
>  int log_get_fd(void)
>  {
> diff --git a/util.c b/util.c
> index 59ed831..f4339de 100644
> --- a/util.c
> +++ b/util.c
> @@ -33,6 +33,7 @@
>  #include "types.h"
>  #include "list.h"
>  #include "util.h"
> +#include "lock.h"
>  
>  #include "crtools.h"
>  
> @@ -188,6 +189,22 @@ int close_pid_proc(void)
>  	return ret;
>  }
>  
> +static int clone_proc(void)
> +{
> +	close_pid_proc();
> +
> +	if (proc_dir_fd <= 0)
> +		return 0;
> +
> +	proc_dir_fd = dup2(proc_dir_fd, get_service_fd(PROC_FD_OFF));
> +	if (proc_dir_fd < 0) {
> +		pr_perror("Unable to duplicate a proc descriptor");
> +		return -1;
> +	}
> +
> +	return 0;
> +}
> +
>  void close_proc()
>  {
>  	close_pid_proc();
> @@ -280,6 +297,8 @@ int do_open_proc(pid_t pid, int flags, const char *fmt, ...)
>  }
>  
>  static int service_fd_rlim_cur;
> +static int service_fd_id = 0;
> +static mutex_t *service_fd_lock;
>  
>  int init_service_fd(void)
>  {
> @@ -298,12 +317,65 @@ int init_service_fd(void)
>  	service_fd_rlim_cur = (int)rlimit.rlim_cur;
>  	BUG_ON(service_fd_rlim_cur < SERVICE_FD_MAX);
>  
> +	service_fd_lock = shmalloc(sizeof(mutex_t));
> +	if (service_fd_lock == NULL)
> +		return -1;
> +
> +	mutex_init(service_fd_lock);
> +
>  	return 0;
>  }
>  
> +int clone_service_fd(bool to_init)
> +{
> +	int ret = -1;
> +
> +	if (to_init && service_fd_id == 0)
> +		return 0;
> +
> +	mutex_lock(service_fd_lock);
> +
> +	if (to_init)
> +		service_fd_id = 0;
> +	else {
> +		/*
> +		 * Find a free service fd namespace. We suppose,
> +		 * that LOG_FD_OFF should be opened all time, so
> +		 * if LOG_FD_OFF isn't busy, a service fd namespace is free.
> +		 */
> +		while (1) {
> +			service_fd_id++;
> +
> +			if (fcntl(get_service_fd(LOG_FD_OFF), F_GETFD) != -1)
> +				continue;
> +
> +			if (errno == EBADF)
> +				break;
> +
> +			pr_perror("fcntl failed\n");
> +			goto out;
> +		}
> +	}
> +
> +	if (log_clone_fd())
> +		goto out;
> +
> +	if (clone_proc())
> +		goto out;
> +
> +	if (clone_image_dir())
> +		goto out;
> +
> +	ret = 0;
> +out:
> +	mutex_unlock(service_fd_lock);
> +
> +	return ret;
> +}
> +
>  static int __get_service_fd(enum sfd_type type)
>  {
> -	return service_fd_rlim_cur - type;
> +	return service_fd_rlim_cur - type - SERVICE_FD_MAX * service_fd_id;
>  }
>  
>  int get_service_fd(enum sfd_type type)
>