Fixed NULL_RETURNS issues introduced by remote images code.

Signed-off-by: rodrigo-bruno <rbruno@gsd.inesc-id.pt>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

criu/image.c

@@ -327,14 +327,20 @@ static int img_write_magic(struct cr_img *img, int oflags, int type)
 int do_open_remote_image(int dfd, char *path, int flags)
 {
 	char *snapshot_id = NULL;
-	int ret;
+	int ret, save;
 
 	/* When using namespaces, the current dir is changed so we need to
 	 * change to previous working dir and back to correctly open the image
 	 * proxy and cache sockets. */
-	int save = dirfd(opendir("."));
+	save = open(".", O_RDONLY);
+	if (save < 0) {
+		pr_perror("unable to open current working directory");
+		return -1;
+	}
+
 	if (fchdir(get_service_fd(IMG_FD_OFF)) < 0) {
-		pr_debug("fchdir to dfd failed!\n");
+		pr_perror("fchdir to dfd failed!\n");
+		close(save);
 		return -1;
 	}
 
@@ -353,7 +359,8 @@ int do_open_remote_image(int dfd, char *path, int flags)
 	}
 
 	if (fchdir(save) < 0) {
-		pr_debug("fchdir to save failed!\n");
+		pr_perror("fchdir to save failed");
+		close(save);
 		return -1;
 	}
 	close(save);

criu/util.c

@@ -564,9 +564,15 @@ int copy_file(int fd_in, int fd_out, size_t bytes)
 {
 	ssize_t written = 0;
 	size_t chunk = bytes ? bytes : 4096;
-	char *buffer = (char*) malloc(chunk);
+	char *buffer;
 	ssize_t ret;
 
+	buffer = xmalloc(chunk);
+	if (buffer == NULL) {
+		pr_perror("failed to allocate buffer to copy file");
+		return -1;
+	}
+
 	while (1) {
 		if (opts.remote) {
 			ret = read(fd_in, buffer, chunk);
@@ -602,7 +608,7 @@ int copy_file(int fd_in, int fd_out, size_t bytes)
 		written += ret;
 	}
 err:
-	free(buffer);
+	xfree(buffer);
 	return ret;
 }