[libc-commits] [libc] [libc] Swap order of syscall on chmod (PR #138427)

[Mikhail R. Gadelha via libc-commits]

https://github.com/mikhailramalho created https://github.com/llvm/llvm-project/pull/138427

We define SYS_fchmodat2 on libc but the syscall is not available on old kernels, so prefer the SYS_fchmodat version when possible.

>From 264b48b92873e87bf96703fa0cfe13320c81f02b Mon Sep 17 00:00:00 2001
From: "Mikhail R. Gadelha" <mikhail at igalia.com>
Date: Sat, 3 May 2025 19:20:01 -0300
Subject: [PATCH] [libc] Swap order of syscall on chmod

We define SYS_fchmodat2 on libc but the syscall is not available on
old kernels, so prefer the SYS_fchmodat version when possible.
---
 libc/src/sys/stat/linux/chmod.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/libc/src/sys/stat/linux/chmod.cpp b/libc/src/sys/stat/linux/chmod.cpp
index 57d5bae6b8191..1b787e47e7c68 100644
--- a/libc/src/sys/stat/linux/chmod.cpp
+++ b/libc/src/sys/stat/linux/chmod.cpp
@@ -23,12 +23,12 @@ namespace LIBC_NAMESPACE_DECL {
 LLVM_LIBC_FUNCTION(int, chmod, (const char *path, mode_t mode)) {
 #ifdef SYS_chmod
   int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_chmod, path, mode);
-#elif defined(SYS_fchmodat2)
-  int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_fchmodat2, AT_FDCWD, path,
-                                              mode, 0, AT_SYMLINK_NOFOLLOW);
 #elif defined(SYS_fchmodat)
   int ret =
       LIBC_NAMESPACE::syscall_impl<int>(SYS_fchmodat, AT_FDCWD, path, mode, 0);
+#elif defined(SYS_fchmodat2)
+  int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_fchmodat2, AT_FDCWD, path,
+                                              mode, 0, AT_SYMLINK_NOFOLLOW);
 #else
 #error "chmod, fchmodat and fchmodat2 syscalls not available."
 #endif