linux-kernel - [PATCH 2/5] tools/nolibc: provide a fallback for lseek through llseek

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Message-Id: <20240929-nolibc-csky-v1-2-bb28031a73b0@weissschuh.net>
Date: Sun, 29 Sep 2024 23:47:37 +0200
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Guo Ren <guoren@...nel.org>, Willy Tarreau <w@....eu>, 
 Shuah Khan <shuah@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-csky@...r.kernel.org, 
 linux-kselftest@...r.kernel.org, 
 Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH 2/5] tools/nolibc: provide a fallback for lseek through
 llseek

Not all architectures implement the lseek syscall, for example csky for
which support will be added.
Provide a fallback implementation to the llseek syscall.

Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
---
 tools/include/nolibc/sys.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h
index 7b82bc3cf107439a3f09f98b99d4d540ffb9ba2a..b3b78343647177c9e5ecb7261997b4f5e03fb8f5 100644
--- a/tools/include/nolibc/sys.h
+++ b/tools/include/nolibc/sys.h
@@ -595,6 +595,14 @@ off_t sys_lseek(int fd, off_t offset, int whence)
 {
 #ifdef __NR_lseek
 	return my_syscall3(__NR_lseek, fd, offset, whence);
+#elif defined(__NR_llseek)
+	off_t result;
+	int ret;
+
+	ret = my_syscall5(__NR_llseek, fd,
+			  sizeof(offset) > 4 ? offset >> 32 : 0,
+			  offset, &result, whence);
+	return ret ? ret : result;
 #else
 	return __nolibc_enosys(__func__, fd, offset, whence);
 #endif

-- 
2.46.2