criu: image: add img_raw_size helper

Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/image.c

 #include <unistd.h>
 #include <stdarg.h>
 #include <fcntl.h>
+#include <sys/stat.h>
 #include "crtools.h"
 #include "cr_options.h"
 #include "imgset.h"
@@ -563,3 +564,14 @@ int read_img_str(struct cr_img *img, char **pstr, int size)
 	return 0;
 }
 
+off_t img_raw_size(struct cr_img *img)
+{
+	struct stat stat;
+
+	if (fstat(img->_x.fd, &stat)) {
+		pr_perror("Failed to get image stats\n");
+		return -1;
+	}
+
+	return stat.st_size;
+}

criu/include/image.h

@@ -142,6 +142,8 @@ static inline int img_raw_fd(struct cr_img *img)
 	return img->_x.fd;
 }
 
+extern off_t img_raw_size(struct cr_img *img);
+
 extern int open_image_dir(char *dir);
 extern void close_image_dir(void);