Helper for moving image fd

When opening an fd at a position where the current image fd sits
the latter one should be moved.

Introduce a helper for this.

Signed-off-by; Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>

cr-restore.c

@@ -506,15 +506,8 @@ static int open_fd(int pid, struct fdinfo_entry *fe, int *cfd)
 {
 	int fd, tmp;
 
-	if (*cfd == (int)fe->addr) {
-		tmp = dup(*cfd);
-		if (tmp < 0) {
-			pr_perror("Can't dup file\n");
-			return -1;
-		}
-
-		*cfd = tmp;
-	}
+	if (move_img_fd(cfd, (int)fe->addr))
+		return -1;
 
 	if (fe->addr == ~0L)
 		return restore_cwd(fe, *cfd);
@@ -940,15 +933,8 @@ static int reopen_pipe(int src, int *dst, int *other)
 	int tmp;
 
 	if (*dst != -1) {
-		if (*other == *dst) {
-			tmp = dup(*other);
-			if (tmp < 0) {
-				pr_perror("dup failed\n");
-				return -1;
-			}
-			close_safe(other);
-			*other = tmp;
-		}
+		if (move_img_fd(other, *dst))
+			return -1;
 
 		return reopen_fd_as(*dst, src);
 	}
@@ -1107,17 +1093,8 @@ static int open_pipe(int pid, struct pipe_entry *e, int *pipes_fd)
 	struct pipe_info *pi;
 
 	pr_info("\t%d: Opening pipe %x on fd %d\n", pid, e->pipeid, e->fd);
-	if (e->fd == *pipes_fd) {
-		int tmp;
-
-		tmp = dup(*pipes_fd);
-		if (tmp < 0) {
-			pr_perror("%d: Can't dup file\n", pid);
-			return -1;
-		}
-
-		*pipes_fd = tmp;
-	}
+	if (move_img_fd(pipes_fd, e->fd))
+		return -1;
 
 	pi = find_pipe(e->pipeid);
 	if (!pi) {

include/util.h

@@ -167,6 +167,7 @@ extern void printk_vma(struct vma_area *vma_area);
 #define pr_info_siginfo(siginfo)	printk_siginfo(siginfo)
 
 extern int reopen_fd_as(int new_fd, int old_fd);
+extern int move_img_fd(int *img_fd, int want_fd);
 extern int parse_maps(pid_t pid, struct list_head *vma_area_list, bool use_map_files);
 extern int close_safe(int *fd);
 

util.c

@@ -144,6 +144,23 @@ int reopen_fd_as(int new_fd, int old_fd)
 	return 0;
 }
 
+int move_img_fd(int *img_fd, int want_fd)
+{
+	if (*img_fd == want_fd) {
+		int tmp;
+
+		tmp = dup(*img_fd);
+		if (tmp < 0) {
+			pr_perror("Can't dup file\n");
+			return -1;
+		}
+
+		*img_fd = tmp;
+	}
+
+	return 0;
+}
+
 int parse_maps(pid_t pid, struct list_head *vma_area_list, bool use_map_files)
 {
 	struct vma_area *vma_area = NULL;