toolchain/musl: add support for renameat2()

Backport an upstream patch to support the renameat2 syscall, added in Linux
3.15 and supported by glibc since 2.28. It is commonly used in filesystem
or security contexts, and needed building upstream kernel bpf selftests.

Link:
https://inbox.vuxu.org/musl/20240421153640.379015-1-Tony.Ambardar@gmail.com/

Signed-off-by: Tony Ambardar <itugrok@yahoo.com>
Link: https://github.com/openwrt/openwrt/pull/15697
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
This commit is contained in:
Tony Ambardar 2024-06-11 22:30:48 -07:00 committed by Christian Marangi
parent 75a76355cb
commit cc6a1e2abc
No known key found for this signature in database
GPG Key ID: AC001D09ADBFEAD7

View File

@ -0,0 +1,61 @@
From dc651fe2e6b16087c519c0bd0bf943cb7c53c807 Mon Sep 17 00:00:00 2001
In-Reply-To: <20240423234355.2414567-1-Tony.Ambardar@gmail.com>
References: <20240423234355.2414567-1-Tony.Ambardar@gmail.com>
From: Tony Ambardar <Tony.Ambardar@gmail.com>
Date: Sat, 20 Apr 2024 21:30:13 -0700
Subject: [PATCH v3] add renameat2 linux syscall wrapper
To: musl@lists.openwall.com
Cc: Rich Felker <dalias@libc.org>
This syscall is available since Linux 3.15 and also implemented in glibc
from version 2.28. It is commonly used in filesystem or security contexts.
Constants RENAME_NOREPLACE, RENAME_EXCHANGE, RENAME_WHITEOUT are guarded by
_GNU_SOURCE as with glibc.
Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com>
---
v2 -> v3:
* call SYS_renameat first if applicable
* drop unneeded error code handling
v1 -> v2:
* align related constants
* drop 'int' from 'unsigned int'
* add fallback to SYS_renameat where applicable
---
include/stdio.h | 7 +++++++
src/linux/renameat2.c | 11 +++++++++++
2 files changed, 18 insertions(+)
create mode 100644 src/linux/renameat2.c
--- a/include/stdio.h
+++ b/include/stdio.h
@@ -158,6 +158,13 @@ char *ctermid(char *);
#define L_ctermid 20
#endif
+#if defined(_GNU_SOURCE)
+#define RENAME_NOREPLACE (1 << 0)
+#define RENAME_EXCHANGE (1 << 1)
+#define RENAME_WHITEOUT (1 << 2)
+
+int renameat2(int, const char *, int, const char *, unsigned);
+#endif
#if defined(_XOPEN_SOURCE) || defined(_GNU_SOURCE) \
|| defined(_BSD_SOURCE)
--- /dev/null
+++ b/src/linux/renameat2.c
@@ -0,0 +1,11 @@
+#define _GNU_SOURCE
+#include <stdio.h>
+#include "syscall.h"
+
+int renameat2(int oldfd, const char *old, int newfd, const char *new, unsigned flags)
+{
+#ifdef SYS_renameat
+ if (!flags) return syscall(SYS_renameat, oldfd, old, newfd, new);
+#endif
+ return syscall(SYS_renameat2, oldfd, old, newfd, new, flags);
+}