[PATCH RESEND] UAPI: move RENAME_* definitions to separated file

[PATCH RESEND] UAPI: move RENAME_* definitions to separated file

[Yury Norov]

Discussion:
https://lore.kernel.org/lkml/20180702084622.GA15274@yury-thinkpad/

Although RENAME_* macros are exposed in kernel headers, they are not
used by glibc. That's because linux/fs.h which hosts RENAME_* is
considered unsuitable by glibc developers:

As Florian Weimer wrote:

> <linux/fs.h> undefines and defines macros not mentioned in the standards
> (and it even contains a few unrelated structs), so we cannot include it
> without _GNU_SOURCE.
>
> It might be possible to include it only for _GNU_SOURCE, but there are a
> lot of things in <linux/fs.h>, so that does not seem to be particularly
> advisable.

In this patch RENAME_* is removed to separated header file that
conforms standards and therefore is suitable for inclusion by glibc.

Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
---
 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 53a22e8e0408..dbf58bbf5bad 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 */
-- 
2.17.1

Re: [PATCH RESEND] UAPI: move RENAME_* definitions to separated file

[Florian Weimer]

* Yury Norov:

> diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
> index 53a22e8e0408..dbf58bbf5bad 100644
> --- a/include/uapi/linux/fs.h
> +++ b/include/uapi/linux/fs.h

Could you move it to a dedicated <linux/rename-flags.h> header?  Or add
a comment that the header is only for rename flags?

Then we can change glibc to include it if it is present and when
compiling under _GNU_SOURCE.

Thanks,
Florian