Re: [PATCH] Add renameat2 function [BZ #17662]

From: Florian Weimer
Date: Mon Jul 02 2018 - 05:33:04 EST


On 07/02/2018 10:46 AM, Yury Norov wrote:

Is my understanding correct that glibc community finds <linux/fs.h>
inappropriate for their use, and prefer to re-introduce (duplicate)
its functionality locally? I think it's wrong. The right way to go
is to make kernel headers comfortable for users instead of ignoring
it.

In some cases, we already use UAPI headers (<linux/falloc.h> is an example), but it is not always possible.

Are you OK to switch to kernel RENAME_* definitions if they will be
located in separated small file? Like in the patch below.

Signed-off-by: Yury Norov <ynorov@xxxxxxxxxxxxxxxxxx>
---
include/uapi/linux/fs.h | 4 +---
include/uapi/linux/rename.h | 12 ++++++++++++
2 files changed, 13 insertions(+), 3 deletions(-)
create mode 100644 include/uapi/linux/rename.h

diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index c27576d471c2..46c03ea31a76 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -44,9 +44,7 @@
#define SEEK_HOLE 4 /* seek to the next hole */
#define SEEK_MAX SEEK_HOLE
-#define RENAME_NOREPLACE (1 << 0) /* Don't overwrite target */
-#define RENAME_EXCHANGE (1 << 1) /* Exchange source and dest */
-#define RENAME_WHITEOUT (1 << 2) /* Whiteout source */
+#include <linux/rename.h>
struct file_clone_range {
__s64 src_fd;
diff --git a/include/uapi/linux/rename.h b/include/uapi/linux/rename.h
new file mode 100644
index 000000000000..7178f0565657
--- /dev/null
+++ b/include/uapi/linux/rename.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI_LINUX_RENAME_H
+#define _UAPI_LINUX_RENAME_H
+
+/*
+ * Definitions for rename syscall family.
+ */
+#define RENAME_NOREPLACE (1 << 0) /* Don't overwrite target */
+#define RENAME_EXCHANGE (1 << 1) /* Exchange source and dest */
+#define RENAME_WHITEOUT (1 << 2) /* Whiteout source */
+
+#endif /* _UAPI_LINUX_RENAME_H */

This would help.

We would need to provide definitions for compatibility with older kernel headers locally, but on newer kernels, we could use the UAPI header file.

Thanks,
Florian