[libc-commits] [libc] [libc] prefer *at syscalls in sys/stat wrappers (PR #195792)

[Kiriti Ponduri via libc-commits]

https://github.com/udaykiriti updated https://github.com/llvm/llvm-project/pull/195792

>From 5529e876a423002b5e65867992957c775a8bc81d Mon Sep 17 00:00:00 2001
From: udaykiriti <udaykiriti624 at gmail.com>
Date: Tue, 5 May 2026 10:15:43 +0530
Subject: [PATCH] [libc] prefer *at syscalls in sys/stat wrappers

  - so the changes flips the #ifdef order to prefer the *at syscalls over normal ones.
  - In modern architectures, *at system calls are preferred over normal
    system calls.
  - so by checking for "*at" sys calls first, we ensure better
    compatibility with modern systems.
  - then normal syscalls moved to else for support of older ones.

Signed-off-by: udaykiriti <udaykiriti624 at gmail.com>
---
 libc/src/__support/OSUtil/linux/syscall_wrappers/chmod.h | 6 +++---
 libc/src/__support/OSUtil/linux/syscall_wrappers/mkdir.h | 6 +++---
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/libc/src/__support/OSUtil/linux/syscall_wrappers/chmod.h b/libc/src/__support/OSUtil/linux/syscall_wrappers/chmod.h
index 69acf4c5cf1b3..42b0d3db98326 100644
--- a/libc/src/__support/OSUtil/linux/syscall_wrappers/chmod.h
+++ b/libc/src/__support/OSUtil/linux/syscall_wrappers/chmod.h
@@ -26,13 +26,13 @@ namespace LIBC_NAMESPACE_DECL {
 namespace linux_syscalls {
 
 LIBC_INLINE ErrorOr<int> chmod(const char *path, mode_t mode) {
-#ifdef SYS_chmod
-  int ret = syscall_impl<int>(SYS_chmod, path, mode);
-#elif defined(SYS_fchmodat)
+#ifdef SYS_fchmodat
   int ret = syscall_impl<int>(SYS_fchmodat, AT_FDCWD, path, mode, 0);
 #elif defined(SYS_fchmodat2)
   int ret = syscall_impl<int>(SYS_fchmodat2, AT_FDCWD, path, mode, 0,
                               AT_SYMLINK_NOFOLLOW);
+#elif defined(SYS_chmod)
+  int ret = syscall_impl<int>(SYS_chmod, path, mode);
 #else
 #error "chmod, fchmodat and fchmodat2 syscalls not available."
 #endif
diff --git a/libc/src/__support/OSUtil/linux/syscall_wrappers/mkdir.h b/libc/src/__support/OSUtil/linux/syscall_wrappers/mkdir.h
index 6d77894c36b6b..b5002914c5ec0 100644
--- a/libc/src/__support/OSUtil/linux/syscall_wrappers/mkdir.h
+++ b/libc/src/__support/OSUtil/linux/syscall_wrappers/mkdir.h
@@ -26,10 +26,10 @@ namespace LIBC_NAMESPACE_DECL {
 namespace linux_syscalls {
 
 LIBC_INLINE ErrorOr<int> mkdir(const char *path, mode_t mode) {
-#ifdef SYS_mkdir
-  int ret = syscall_impl<int>(SYS_mkdir, path, mode);
-#else
+#ifdef SYS_mkdirat
   int ret = syscall_impl<int>(SYS_mkdirat, AT_FDCWD, path, mode);
+#else
+  int ret = syscall_impl<int>(SYS_mkdir, path, mode);
 #endif
   if (ret < 0)
     return Error(-ret);