This is a bit ugly, but in the next patch we will move to using
kselftest_harness.h -- which doesn't play well with being included in
multiple compilation units due to duplicate function definitions.

Not including kselftest_harness.h would let us avoid this patch, but the
helpers will need include kselftest_harness.h in order to switch to
TH_LOG.

Signed-off-by: Aleksa Sarai <aleksa@amutable.com>
---
 .../testing/selftests/filesystems/openat2/Makefile |   2 -
 .../selftests/filesystems/openat2/helpers.c        | 109 ------------------
 .../selftests/filesystems/openat2/helpers.h        | 125 ++++++++++++++++++---
 3 files changed, 107 insertions(+), 129 deletions(-)

diff --git a/tools/testing/selftests/filesystems/openat2/Makefile b/tools/testing/selftests/filesystems/openat2/Makefile
index f36dedccedb6..7736e37b7986 100644
--- a/tools/testing/selftests/filesystems/openat2/Makefile
+++ b/tools/testing/selftests/filesystems/openat2/Makefile
@@ -15,5 +15,3 @@ endif
 LOCAL_HDRS += helpers.h
 
 include ../../lib.mk
-
-$(TEST_GEN_PROGS): helpers.c
diff --git a/tools/testing/selftests/filesystems/openat2/helpers.c b/tools/testing/selftests/filesystems/openat2/helpers.c
deleted file mode 100644
index 5074681ffdc9..000000000000
--- a/tools/testing/selftests/filesystems/openat2/helpers.c
+++ /dev/null
@@ -1,109 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * Author: Aleksa Sarai <cyphar@cyphar.com>
- * Copyright (C) 2018-2019 SUSE LLC.
- */
-
-#define _GNU_SOURCE
-#include <errno.h>
-#include <fcntl.h>
-#include <stdbool.h>
-#include <string.h>
-#include <syscall.h>
-#include <limits.h>
-
-#include "helpers.h"
-
-bool needs_openat2(const struct open_how *how)
-{
-	return how->resolve != 0;
-}
-
-int raw_openat2(int dfd, const char *path, void *how, size_t size)
-{
-	int ret = syscall(__NR_openat2, dfd, path, how, size);
-	return ret >= 0 ? ret : -errno;
-}
-
-int sys_openat2(int dfd, const char *path, struct open_how *how)
-{
-	return raw_openat2(dfd, path, how, sizeof(*how));
-}
-
-int sys_openat(int dfd, const char *path, struct open_how *how)
-{
-	int ret = openat(dfd, path, how->flags, how->mode);
-	return ret >= 0 ? ret : -errno;
-}
-
-int sys_renameat2(int olddirfd, const char *oldpath,
-		  int newdirfd, const char *newpath, unsigned int flags)
-{
-	int ret = syscall(__NR_renameat2, olddirfd, oldpath,
-					  newdirfd, newpath, flags);
-	return ret >= 0 ? ret : -errno;
-}
-
-int touchat(int dfd, const char *path)
-{
-	int fd = openat(dfd, path, O_CREAT, 0700);
-	if (fd >= 0)
-		close(fd);
-	return fd;
-}
-
-char *fdreadlink(int fd)
-{
-	char *target, *tmp;
-
-	E_asprintf(&tmp, "/proc/self/fd/%d", fd);
-
-	target = malloc(PATH_MAX);
-	if (!target)
-		ksft_exit_fail_msg("fdreadlink: malloc failed\n");
-	memset(target, 0, PATH_MAX);
-
-	E_readlink(tmp, target, PATH_MAX);
-	free(tmp);
-	return target;
-}
-
-bool fdequal(int fd, int dfd, const char *path)
-{
-	char *fdpath, *dfdpath, *other;
-	bool cmp;
-
-	fdpath = fdreadlink(fd);
-	dfdpath = fdreadlink(dfd);
-
-	if (!path)
-		E_asprintf(&other, "%s", dfdpath);
-	else if (*path == '/')
-		E_asprintf(&other, "%s", path);
-	else
-		E_asprintf(&other, "%s/%s", dfdpath, path);
-
-	cmp = !strcmp(fdpath, other);
-
-	free(fdpath);
-	free(dfdpath);
-	free(other);
-	return cmp;
-}
-
-bool openat2_supported = false;
-
-void __attribute__((constructor)) init(void)
-{
-	struct open_how how = {};
-	int fd;
-
-	BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_VER0);
-
-	/* Check openat2(2) support. */
-	fd = sys_openat2(AT_FDCWD, ".", &how);
-	openat2_supported = (fd >= 0);
-
-	if (fd >= 0)
-		close(fd);
-}
diff --git a/tools/testing/selftests/filesystems/openat2/helpers.h b/tools/testing/selftests/filesystems/openat2/helpers.h
index 510e60602511..975de513af86 100644
--- a/tools/testing/selftests/filesystems/openat2/helpers.h
+++ b/tools/testing/selftests/filesystems/openat2/helpers.h
@@ -2,6 +2,7 @@
 /*
  * Author: Aleksa Sarai <cyphar@cyphar.com>
  * Copyright (C) 2018-2019 SUSE LLC.
+ * Copyright (C) 2026 Amutable GmbH
  */
 
 #ifndef __RESOLVEAT_H__
@@ -11,19 +12,14 @@
 #include <stdint.h>
 #include <stdbool.h>
 #include <errno.h>
+#include <limits.h>
 #include <linux/types.h>
+#include <linux/unistd.h>
 #include "kselftest.h"
 
 #define ARRAY_LEN(X) (sizeof (X) / sizeof (*(X)))
 #define BUILD_BUG_ON(e) ((void)(sizeof(struct { int:(-!!(e)); })))
 
-#ifndef SYS_openat2
-#ifndef __NR_openat2
-#define __NR_openat2 437
-#endif /* __NR_openat2 */
-#define SYS_openat2 __NR_openat2
-#endif /* SYS_openat2 */
-
 /*
  * Arguments for how openat2(2) should open the target path. If @resolve is
  * zero, then openat2(2) operates very similarly to openat(2).
@@ -45,8 +41,6 @@ struct open_how {
 #define OPEN_HOW_SIZE_VER0	24 /* sizeof first published struct */
 #define OPEN_HOW_SIZE_LATEST	OPEN_HOW_SIZE_VER0
 
-bool needs_openat2(const struct open_how *how);
-
 #ifndef RESOLVE_IN_ROOT
 /* how->resolve flags for openat2(2). */
 #define RESOLVE_NO_XDEV		0x01 /* Block mount-point crossings
@@ -93,16 +87,111 @@ bool needs_openat2(const struct open_how *how);
 					   __FILE__, __LINE__, #expr, ##__VA_ARGS__); \
 	} while (0)
 
-int raw_openat2(int dfd, const char *path, void *how, size_t size);
-int sys_openat2(int dfd, const char *path, struct open_how *how);
-int sys_openat(int dfd, const char *path, struct open_how *how);
-int sys_renameat2(int olddirfd, const char *oldpath,
-		  int newdirfd, const char *newpath, unsigned int flags);
+__maybe_unused
+static bool needs_openat2(const struct open_how *how)
+{
+	return how->resolve != 0;
+}
+
+__maybe_unused
+static int raw_openat2(int dfd, const char *path, void *how, size_t size)
+{
+	int ret = syscall(__NR_openat2, dfd, path, how, size);
+
+	return ret >= 0 ? ret : -errno;
+}
+
+__maybe_unused
+static int sys_openat2(int dfd, const char *path, struct open_how *how)
+{
+	return raw_openat2(dfd, path, how, sizeof(*how));
+}
+
+__maybe_unused
+static int sys_openat(int dfd, const char *path, struct open_how *how)
+{
+	int ret = openat(dfd, path, how->flags, how->mode);
+
+	return ret >= 0 ? ret : -errno;
+}
+
+__maybe_unused
+static int sys_renameat2(int olddirfd, const char *oldpath,
+			 int newdirfd, const char *newpath, unsigned int flags)
+{
+	int ret = syscall(__NR_renameat2, olddirfd, oldpath,
+					  newdirfd, newpath, flags);
+
+	return ret >= 0 ? ret : -errno;
+}
+
+__maybe_unused
+static int touchat(int dfd, const char *path)
+{
+	int fd = openat(dfd, path, O_CREAT, 0700);
+
+	if (fd >= 0)
+		close(fd);
+	return fd;
+}
+
+__maybe_unused
+static char *fdreadlink(int fd)
+{
+	char *target, *tmp;
+
+	E_asprintf(&tmp, "/proc/self/fd/%d", fd);
+
+	target = malloc(PATH_MAX);
+	if (!target)
+		ksft_exit_fail_msg("fdreadlink: malloc failed\n");
+	memset(target, 0, PATH_MAX);
+
+	E_readlink(tmp, target, PATH_MAX);
+	free(tmp);
+	return target;
+}
+
+__maybe_unused
+static bool fdequal(int fd, int dfd, const char *path)
+{
+	char *fdpath, *dfdpath, *other;
+	bool cmp;
+
+	fdpath = fdreadlink(fd);
+	dfdpath = fdreadlink(dfd);
+
+	if (!path)
+		E_asprintf(&other, "%s", dfdpath);
+	else if (*path == '/')
+		E_asprintf(&other, "%s", path);
+	else
+		E_asprintf(&other, "%s/%s", dfdpath, path);
+
+	cmp = !strcmp(fdpath, other);
+
+	free(fdpath);
+	free(dfdpath);
+	free(other);
+	return cmp;
+}
+
+static bool openat2_supported = false;
+
+__attribute__((constructor))
+static void __detect_openat2_supported(void)
+{
+	struct open_how how = {};
+	int fd;
+
+	BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_VER0);
 
-int touchat(int dfd, const char *path);
-char *fdreadlink(int fd);
-bool fdequal(int fd, int dfd, const char *path);
+	/* Check openat2(2) support. */
+	fd = sys_openat2(AT_FDCWD, ".", &how);
+	openat2_supported = (fd >= 0);
 
-extern bool openat2_supported;
+	if (fd >= 0)
+		close(fd);
+}
 
 #endif /* __RESOLVEAT_H__ */

-- 
2.53.0