util: move open_proc_fd to service_fd

We need this to avoid conflicts with file descriptors,
which has to be restored.

Currently open_proc_pid() doesn't used during restoring
file descriptors, but we are going to use it to restore
sockets in proper network namespaces.
Acked-by: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

criu/include/servicefd.h

@@ -9,6 +9,7 @@ enum sfd_type {
 	LOG_FD_OFF,
 	IMG_FD_OFF,
 	PROC_FD_OFF,	/* fd with /proc for all proc_ calls */
+	PROC_PID_FD_OFF,
 	CTL_TTY_OFF,
 	SELF_STDIN_OFF,
 	CR_PROC_FD_OFF, /* some other's proc fd.

criu/util.c

@@ -291,7 +291,6 @@ int move_fd_from(int *img_fd, int want_fd)
  */
 
 static pid_t open_proc_pid = PROC_NONE;
-static int open_proc_fd = -1;
 static pid_t open_proc_self_pid;
 static int open_proc_self_fd = -1;
 
@@ -304,13 +303,18 @@ static inline void set_proc_self_fd(int fd)
 	open_proc_self_pid = getpid();
 }
 
-static inline void set_proc_pid_fd(int pid, int fd)
+static inline int set_proc_pid_fd(int pid, int fd)
 {
-	if (open_proc_fd >= 0)
-		close(open_proc_fd);
+	int ret;
+
+	if (fd < 0)
+		return close_service_fd(PROC_PID_FD_OFF);
 
 	open_proc_pid = pid;
-	open_proc_fd = fd;
+	ret = install_service_fd(PROC_PID_FD_OFF, fd);
+	close(fd);
+
+	return ret;
 }
 
 static inline int get_proc_fd(int pid)
@@ -322,7 +326,7 @@ static inline int get_proc_fd(int pid)
 		}
 		return open_proc_self_fd;
 	} else if (pid == open_proc_pid)
-		return open_proc_fd;
+		return get_service_fd(PROC_PID_FD_OFF);
 	else
 		return -1;
 }
@@ -406,7 +410,7 @@ inline int open_pid_proc(pid_t pid)
 	if (pid == PROC_SELF)
 		set_proc_self_fd(fd);
 	else
-		set_proc_pid_fd(pid, fd);
+		fd = set_proc_pid_fd(pid, fd);
 
 	return fd;
 }