[PATCH v5 01/14] tools/nolibc: sys.h: add a syscall return helper

From: Zhangjin Wu
Date: Wed Jun 28 2023 - 09:11:01 EST


Most of the library routines share the same syscall return logic:

In general, a 0 return value indicates success. A -1 return value
indicates an error, and an error number is stored in errno. [1]

Let's add a __sysret() helper for the above logic to simplify the coding
and shrink the code lines too.

Thomas suggested to use inline function instead of macro for __sysret().

Willy suggested to make __sysret() be always inline.

[1]: https://man7.org/linux/man-pages/man2/syscall.2.html

Suggested-by: Willy Tarreau <w@xxxxxx>
Link: https://lore.kernel.org/linux-riscv/ZH1+hkhiA2+ItSvX@xxxxxx/
Suggested-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/linux-riscv/ea4e7442-7223-4211-ba29-70821e907888@xxxxxxxx/
Reviewed-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
Signed-off-by: Zhangjin Wu <falcon@xxxxxxxxxxx>
---
tools/include/nolibc/sys.h | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h
index 5464f93e863e..097eef88cf7e 100644
--- a/tools/include/nolibc/sys.h
+++ b/tools/include/nolibc/sys.h
@@ -28,6 +28,16 @@
#include "errno.h"
#include "types.h"

+/* Syscall return helper, set errno as -ret when ret < 0 */
+static __inline__ __attribute__((unused, always_inline))
+long __sysret(long ret)
+{
+ if (ret < 0) {
+ SET_ERRNO(-ret);
+ ret = -1;
+ }
+ return ret;
+}

/* Functions in this file only describe syscalls. They're declared static so
* that the compiler usually decides to inline them while still being allowed
--
2.25.1