[libc-commits] [libc] [libc] Implement sync in unistd (PR #230908)
Aman Maurya via libc-commits
libc-commits at lists.llvm.org
Sat Oct 10 23:58:57 PDT 2026
https://github.com/amanmaurya92 created https://github.com/llvm/llvm-project/pull/230908
Implement the standard POSIX function `void sync(void);` in `<unistd.h>`.
Fixes #230854
>From 3f5d94a33ff6567cec1e33b2d4d6d4c5e197cfb4 Mon Sep 17 00:00:00 2001
From: amanmaurya92 <amanmaurya9209 at gmail.com>
Date: Sun, 11 Oct 2026 03:33:35 +0530
Subject: [PATCH] [libc] Implement sync in unistd (#230854)
Implement the standard POSIX function sync(void) in <unistd.h>.
Fixes #230854
---
libc/config/linux/aarch64/entrypoints.txt | 1 +
libc/config/linux/arm/entrypoints.txt | 1 +
libc/config/linux/riscv/entrypoints.txt | 1 +
libc/config/linux/x86_64/entrypoints.txt | 1 +
libc/include/unistd.yaml | 6 ++++
.../linux/syscall_wrappers/CMakeLists.txt | 11 +++++++
.../OSUtil/linux/syscall_wrappers/sync.h | 30 +++++++++++++++++++
libc/src/unistd/CMakeLists.txt | 7 +++++
libc/src/unistd/linux/CMakeLists.txt | 12 ++++++++
libc/src/unistd/linux/sync.cpp | 19 ++++++++++++
libc/src/unistd/sync.h | 20 +++++++++++++
libc/test/src/unistd/CMakeLists.txt | 10 +++++++
libc/test/src/unistd/sync_test.cpp | 15 ++++++++++
13 files changed, 134 insertions(+)
create mode 100644 libc/src/__support/OSUtil/linux/syscall_wrappers/sync.h
create mode 100644 libc/src/unistd/linux/sync.cpp
create mode 100644 libc/src/unistd/sync.h
create mode 100644 libc/test/src/unistd/sync_test.cpp
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index b8a9a5cff2040..2df6bbd07a722 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -507,6 +507,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.unistd.sleep
libc.src.unistd.symlink
libc.src.unistd.symlinkat
+ libc.src.unistd.sync
libc.src.unistd.tcgetpgrp
libc.src.unistd.tcsetpgrp
libc.src.unistd.truncate
diff --git a/libc/config/linux/arm/entrypoints.txt b/libc/config/linux/arm/entrypoints.txt
index ac66f1f518484..4e535fe5111d6 100644
--- a/libc/config/linux/arm/entrypoints.txt
+++ b/libc/config/linux/arm/entrypoints.txt
@@ -299,6 +299,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.unistd.setuid
libc.src.unistd.symlink
libc.src.unistd.symlinkat
+ libc.src.unistd.sync
libc.src.unistd.tcgetpgrp
libc.src.unistd.tcsetpgrp
libc.src.unistd.truncate
diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
index 0728bd41a40f9..06068b75ab8bf 100644
--- a/libc/config/linux/riscv/entrypoints.txt
+++ b/libc/config/linux/riscv/entrypoints.txt
@@ -527,6 +527,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.unistd.sleep
libc.src.unistd.symlink
libc.src.unistd.symlinkat
+ libc.src.unistd.sync
libc.src.unistd.tcgetpgrp
libc.src.unistd.tcsetpgrp
libc.src.unistd.truncate
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 2df3fb0dfb363..40727d821bcfb 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -547,6 +547,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.unistd.sleep
libc.src.unistd.symlink
libc.src.unistd.symlinkat
+ libc.src.unistd.sync
libc.src.unistd.tcgetpgrp
libc.src.unistd.tcsetpgrp
libc.src.unistd.truncate
diff --git a/libc/include/unistd.yaml b/libc/include/unistd.yaml
index 92951152b7ca7..160b909f3af7b 100644
--- a/libc/include/unistd.yaml
+++ b/libc/include/unistd.yaml
@@ -571,6 +571,12 @@ functions:
- type: const char *
- type: int
- type: const char *
+ - name: sync
+ standards:
+ - posix
+ return_type: void
+ arguments:
+ - type: void
- name: sysconf
standards:
- posix
diff --git a/libc/src/__support/OSUtil/linux/syscall_wrappers/CMakeLists.txt b/libc/src/__support/OSUtil/linux/syscall_wrappers/CMakeLists.txt
index a3f56b1117c2b..978a29a3384d0 100644
--- a/libc/src/__support/OSUtil/linux/syscall_wrappers/CMakeLists.txt
+++ b/libc/src/__support/OSUtil/linux/syscall_wrappers/CMakeLists.txt
@@ -1061,6 +1061,17 @@ add_header_library(
libc.include.sys_syscall
)
+add_header_library(
+ sync
+ HDRS
+ sync.h
+ DEPENDS
+ libc.src.__support.OSUtil.osutil
+ libc.src.__support.common
+ libc.src.__support.macros.config
+ libc.include.sys_syscall
+)
+
add_header_library(
dup
HDRS
diff --git a/libc/src/__support/OSUtil/linux/syscall_wrappers/sync.h b/libc/src/__support/OSUtil/linux/syscall_wrappers/sync.h
new file mode 100644
index 0000000000000..aea7faeca1c14
--- /dev/null
+++ b/libc/src/__support/OSUtil/linux/syscall_wrappers/sync.h
@@ -0,0 +1,30 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Syscall wrapper for sync.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_SYNC_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_SYNC_H
+
+#include "src/__support/OSUtil/linux/syscall.h" // syscall_impl
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include <sys/syscall.h> // For syscall numbers
+
+namespace LIBC_NAMESPACE_DECL {
+namespace linux_syscalls {
+
+LIBC_INLINE void sync() { syscall_impl<int>(SYS_sync); }
+
+} // namespace linux_syscalls
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_SYNC_H
diff --git a/libc/src/unistd/CMakeLists.txt b/libc/src/unistd/CMakeLists.txt
index a9228513c0312..795224f0e9df4 100644
--- a/libc/src/unistd/CMakeLists.txt
+++ b/libc/src/unistd/CMakeLists.txt
@@ -448,6 +448,13 @@ add_entrypoint_object(
.${LIBC_TARGET_OS}.__llvm_libc_syscall
)
+add_entrypoint_object(
+ sync
+ ALIAS
+ DEPENDS
+ .${LIBC_TARGET_OS}.sync
+)
+
add_entrypoint_object(
sysconf
ALIAS
diff --git a/libc/src/unistd/linux/CMakeLists.txt b/libc/src/unistd/linux/CMakeLists.txt
index 2555c9b700982..3624f4e1891f2 100644
--- a/libc/src/unistd/linux/CMakeLists.txt
+++ b/libc/src/unistd/linux/CMakeLists.txt
@@ -794,6 +794,18 @@ add_entrypoint_object(
libc.src.errno.errno
)
+add_entrypoint_object(
+ sync
+ SRCS
+ sync.cpp
+ HDRS
+ ../sync.h
+ DEPENDS
+ libc.src.__support.OSUtil.linux.syscall_wrappers.sync
+ libc.src.__support.common
+ libc.src.__support.macros.config
+)
+
add_entrypoint_object(
sysconf
SRCS
diff --git a/libc/src/unistd/linux/sync.cpp b/libc/src/unistd/linux/sync.cpp
new file mode 100644
index 0000000000000..0ed28984ae57f
--- /dev/null
+++ b/libc/src/unistd/linux/sync.cpp
@@ -0,0 +1,19 @@
+//===-- Linux implementation of sync -------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/unistd/sync.h"
+
+#include "src/__support/OSUtil/linux/syscall_wrappers/sync.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(void, sync, ()) { linux_syscalls::sync(); }
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/unistd/sync.h b/libc/src/unistd/sync.h
new file mode 100644
index 0000000000000..aa276afb936c2
--- /dev/null
+++ b/libc/src/unistd/sync.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for sync --------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_UNISTD_SYNC_H
+#define LLVM_LIBC_SRC_UNISTD_SYNC_H
+
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+void sync();
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_UNISTD_SYNC_H
diff --git a/libc/test/src/unistd/CMakeLists.txt b/libc/test/src/unistd/CMakeLists.txt
index 7588440c3d8df..89d6dcece5e10 100644
--- a/libc/test/src/unistd/CMakeLists.txt
+++ b/libc/test/src/unistd/CMakeLists.txt
@@ -591,6 +591,16 @@ add_libc_test(
libc.test.UnitTest.ErrnoSetterMatcher
)
+add_libc_test(
+ sync_test
+ SUITE
+ libc_unistd_unittests
+ SRCS
+ sync_test.cpp
+ DEPENDS
+ libc.src.unistd.sync
+)
+
add_libc_test(
tcgetpgrp_test
SUITE
diff --git a/libc/test/src/unistd/sync_test.cpp b/libc/test/src/unistd/sync_test.cpp
new file mode 100644
index 0000000000000..ac5d1649736d5
--- /dev/null
+++ b/libc/test/src/unistd/sync_test.cpp
@@ -0,0 +1,15 @@
+//===-- Unittests for sync ------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/unistd/sync.h"
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcSyncTest, SmokeTest) {
+ // sync always succeeds. So, we just call it as a smoke test.
+ LIBC_NAMESPACE::sync();
+}
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