[libc-commits] [libc] db5421a - [libc] Implement umask (#222499)
via libc-commits
libc-commits at lists.llvm.org
Thu Sep 10 12:51:57 PDT 2026
Author: ThePo1es
Date: 2026-09-10T12:51:51-07:00
New Revision: db5421adfa1d8984bf0015ded33d12f9bbfbe80f
URL: https://github.com/llvm/llvm-project/commit/db5421adfa1d8984bf0015ded33d12f9bbfbe80f
DIFF: https://github.com/llvm/llvm-project/commit/db5421adfa1d8984bf0015ded33d12f9bbfbe80f.diff
LOG: [libc] Implement umask (#222499)
Implement the POSIX umask() entrypoint for Linux and register it for
aarch64, riscv and x86_64. umask cannot fail, so the syscall wrapper
returns mode_t directly and the entrypoint does not touch errno.
Fixes #220759
Assisted-by: Claude Code
---------
Co-authored-by: Claude Opus 5 (1M context) <noreply at anthropic.com>
Added:
libc/src/__support/OSUtil/linux/syscall_wrappers/umask.h
libc/src/sys/stat/linux/umask.cpp
libc/src/sys/stat/umask.h
libc/test/src/sys/stat/umask_test.cpp
Modified:
libc/config/linux/aarch64/entrypoints.txt
libc/config/linux/riscv/entrypoints.txt
libc/config/linux/x86_64/entrypoints.txt
libc/include/sys/stat.yaml
libc/src/__support/OSUtil/linux/syscall_wrappers/CMakeLists.txt
libc/src/sys/stat/CMakeLists.txt
libc/src/sys/stat/linux/CMakeLists.txt
libc/test/src/sys/stat/CMakeLists.txt
Removed:
################################################################################
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 77610d6d06057..57210e3c79208 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -350,6 +350,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.sys.stat.mkdir
libc.src.sys.stat.mkdirat
libc.src.sys.stat.stat
+ libc.src.sys.stat.umask
libc.src.sys.stat.utimensat
# sys/statfs.h entrypoints
diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
index 71a4d4f5ec5c4..ff3500e272d82 100644
--- a/libc/config/linux/riscv/entrypoints.txt
+++ b/libc/config/linux/riscv/entrypoints.txt
@@ -381,6 +381,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.sys.stat.mkdir
libc.src.sys.stat.mkdirat
libc.src.sys.stat.stat
+ libc.src.sys.stat.umask
libc.src.sys.stat.utimensat
# sys/statfs.h entrypoints
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 65b820e551be6..0175b97b326d4 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -386,6 +386,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.sys.stat.mkdir
libc.src.sys.stat.mkdirat
libc.src.sys.stat.stat
+ libc.src.sys.stat.umask
libc.src.sys.stat.utimensat
# sys/statfs.h entrypoints
diff --git a/libc/include/sys/stat.yaml b/libc/include/sys/stat.yaml
index 6c4fc8c5d93e0..b12e2ac620a4f 100644
--- a/libc/include/sys/stat.yaml
+++ b/libc/include/sys/stat.yaml
@@ -63,6 +63,10 @@ functions:
arguments:
- type: const char *__restrict
- type: struct stat *__restrict
+ - name: umask
+ return_type: mode_t
+ arguments:
+ - type: mode_t
- name: utimensat
return_type: int
arguments:
diff --git a/libc/src/__support/OSUtil/linux/syscall_wrappers/CMakeLists.txt b/libc/src/__support/OSUtil/linux/syscall_wrappers/CMakeLists.txt
index 9512528e9e5e2..9c1690f7a27cf 100644
--- a/libc/src/__support/OSUtil/linux/syscall_wrappers/CMakeLists.txt
+++ b/libc/src/__support/OSUtil/linux/syscall_wrappers/CMakeLists.txt
@@ -1251,3 +1251,15 @@ add_header_library(
libc.src.__support.macros.config
libc.include.sys_syscall
)
+
+add_header_library(
+ umask
+ HDRS
+ umask.h
+ DEPENDS
+ libc.hdr.types.mode_t
+ libc.include.sys_syscall
+ libc.src.__support.common
+ libc.src.__support.macros.config
+ libc.src.__support.OSUtil.osutil
+)
diff --git a/libc/src/__support/OSUtil/linux/syscall_wrappers/umask.h b/libc/src/__support/OSUtil/linux/syscall_wrappers/umask.h
new file mode 100644
index 0000000000000..9544d5b340a52
--- /dev/null
+++ b/libc/src/__support/OSUtil/linux/syscall_wrappers/umask.h
@@ -0,0 +1,34 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 umask.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_UMASK_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_UMASK_H
+
+#include "hdr/types/mode_t.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 mode_t umask(mode_t cmask) {
+ // umask is expected to always succeed, thus no error checking here.
+ return syscall_impl<mode_t>(SYS_umask, cmask);
+}
+
+} // namespace linux_syscalls
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_UMASK_H
diff --git a/libc/src/sys/stat/CMakeLists.txt b/libc/src/sys/stat/CMakeLists.txt
index c873814a6f9f0..7338fac02bc29 100644
--- a/libc/src/sys/stat/CMakeLists.txt
+++ b/libc/src/sys/stat/CMakeLists.txt
@@ -58,6 +58,13 @@ add_entrypoint_object(
.${LIBC_TARGET_OS}.stat
)
+add_entrypoint_object(
+ umask
+ ALIAS
+ DEPENDS
+ .${LIBC_TARGET_OS}.umask
+)
+
add_entrypoint_object(
utimensat
ALIAS
diff --git a/libc/src/sys/stat/linux/CMakeLists.txt b/libc/src/sys/stat/linux/CMakeLists.txt
index 152a34946ae4f..52ae4566a2b87 100644
--- a/libc/src/sys/stat/linux/CMakeLists.txt
+++ b/libc/src/sys/stat/linux/CMakeLists.txt
@@ -127,3 +127,15 @@ add_entrypoint_object(
libc.src.__support.common
libc.src.errno.errno
)
+
+add_entrypoint_object(
+ umask
+ SRCS
+ umask.cpp
+ HDRS
+ ../umask.h
+ DEPENDS
+ libc.hdr.types.mode_t
+ libc.src.__support.OSUtil.linux.syscall_wrappers.umask
+ libc.src.__support.common
+)
diff --git a/libc/src/sys/stat/linux/umask.cpp b/libc/src/sys/stat/linux/umask.cpp
new file mode 100644
index 0000000000000..c68a745fb9da9
--- /dev/null
+++ b/libc/src/sys/stat/linux/umask.cpp
@@ -0,0 +1,27 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// ile
+/// Linux implementation of umask.
+///
+//===----------------------------------------------------------------------===//
+
+#include "src/sys/stat/umask.h"
+
+#include "hdr/types/mode_t.h"
+#include "src/__support/OSUtil/linux/syscall_wrappers/umask.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(mode_t, umask, (mode_t cmask)) {
+ return linux_syscalls::umask(cmask);
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/sys/stat/umask.h b/libc/src/sys/stat/umask.h
new file mode 100644
index 0000000000000..4d32d23d24400
--- /dev/null
+++ b/libc/src/sys/stat/umask.h
@@ -0,0 +1,26 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// ile
+/// Implementation header for umask.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_SYS_STAT_UMASK_H
+#define LLVM_LIBC_SRC_SYS_STAT_UMASK_H
+
+#include "hdr/types/mode_t.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+mode_t umask(mode_t cmask);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_SYS_STAT_UMASK_H
diff --git a/libc/test/src/sys/stat/CMakeLists.txt b/libc/test/src/sys/stat/CMakeLists.txt
index 85568f4b8d049..3e87a11b05e6e 100644
--- a/libc/test/src/sys/stat/CMakeLists.txt
+++ b/libc/test/src/sys/stat/CMakeLists.txt
@@ -176,3 +176,17 @@ add_libc_test(
libc.test.UnitTest.ErrnoCheckingTest
libc.test.UnitTest.ErrnoSetterMatcher
)
+
+add_libc_test(
+ umask_test
+ SUITE
+ libc_sys_stat_unittests
+ SRCS
+ umask_test.cpp
+ DEPENDS
+ libc.hdr.sys_stat_macros
+ libc.hdr.types.mode_t
+ libc.src.errno.errno
+ libc.src.sys.stat.umask
+ libc.test.UnitTest.ErrnoCheckingTest
+)
diff --git a/libc/test/src/sys/stat/umask_test.cpp b/libc/test/src/sys/stat/umask_test.cpp
new file mode 100644
index 0000000000000..c7145689203d8
--- /dev/null
+++ b/libc/test/src/sys/stat/umask_test.cpp
@@ -0,0 +1,28 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+/// Unittests for umask.
+///
+//===----------------------------------------------------------------------===//
+
+#include "hdr/sys_stat_macros.h"
+#include "hdr/types/mode_t.h"
+#include "src/sys/stat/umask.h"
+#include "test/UnitTest/ErrnoCheckingTest.h"
+#include "test/UnitTest/Test.h"
+
+using LlvmLibcUmaskTest = LIBC_NAMESPACE::testing::ErrnoCheckingTest;
+
+TEST_F(LlvmLibcUmaskTest, SmokeTest) {
+ // umask() always succeeds and returns the previous mask. Set a mask, then
+ // restore the original one and check that the mask we set is handed back.
+ mode_t old_mask = LIBC_NAMESPACE::umask(S_IRWXG | S_IRWXO);
+ EXPECT_EQ(LIBC_NAMESPACE::umask(old_mask),
+ static_cast<mode_t>(S_IRWXG | S_IRWXO));
+}
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