[libc-commits] [libc] [libc] Remove faccessat entrypoint if facessat2 syscall is not available (PR #164936)

[Marcell Leleszi via libc-commits]

https://github.com/mleleszi created https://github.com/llvm/llvm-project/pull/164936

[#163091](https://github.com/llvm/llvm-project/issues/163091)

>From 61dd0da059016a4562c3d47112574d8ae01a3fdf Mon Sep 17 00:00:00 2001
From: Marcell Leleszi <mleleszi at google.com>
Date: Fri, 24 Oct 2025 07:17:26 +0000
Subject: [PATCH] Remove faccessat entrypoint if facessat2 syscall not
 available

---
 libc/CMakeLists.txt                  | 2 +-
 libc/config/linux/x86_64/exclude.txt | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/libc/CMakeLists.txt b/libc/CMakeLists.txt
index 14718e2090bde..ae555a256ba66 100644
--- a/libc/CMakeLists.txt
+++ b/libc/CMakeLists.txt
@@ -363,7 +363,7 @@ elseif(LLVM_LIBC_FULL_BUILD)
   message(FATAL_ERROR "${LIBC_CONFIG_PATH}/headers.txt file not found and fullbuild requested.")
 endif()
 
-# Check exclude.txt that appends to LIBC_EXCLUDE_ENTRYPOINTS list
+# Check exclude.txt that appends to TARGET_LLVMLIBC_REMOVED_ENTRYPOINTS list
 if(EXISTS "${LIBC_CONFIG_PATH}/exclude.txt")
     include("${LIBC_CONFIG_PATH}/exclude.txt")
 endif()
diff --git a/libc/config/linux/x86_64/exclude.txt b/libc/config/linux/x86_64/exclude.txt
index 2c218b753b176..a0686310d21ac 100644
--- a/libc/config/linux/x86_64/exclude.txt
+++ b/libc/config/linux/x86_64/exclude.txt
@@ -19,3 +19,11 @@ if(NOT has_sys_random)
     )
   endif()
 endif()
+
+include(CheckSymbolExists)
+check_symbol_exists(SYS_faccessat2 "sys/syscall.h" HAVE_SYS_FACCESSAT2)
+if(NOT HAVE_SYS_FACCESSAT2)
+  list(APPEND TARGET_LLVMLIBC_REMOVED_ENTRYPOINTS
+    libc.src.unistd.faccessat
+  )
+endif()