[libc] [unistd] implement pipe2 syscall wrapper (#114474)

Closes #85289

Co-authored-by: Michael Jones <michaelrj@google.com>

libc/config/linux/aarch64/entrypoints.txt

@@ -330,6 +330,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.unistd.lseek
     libc.src.unistd.pathconf
     libc.src.unistd.pipe
+    libc.src.unistd.pipe2
     libc.src.unistd.pread
     libc.src.unistd.pwrite
     libc.src.unistd.read

libc/config/linux/riscv/entrypoints.txt

@@ -329,6 +329,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.unistd.lseek
     libc.src.unistd.pathconf
     libc.src.unistd.pipe
+    libc.src.unistd.pipe2
     libc.src.unistd.pread
     libc.src.unistd.pwrite
     libc.src.unistd.read

libc/config/linux/x86_64/entrypoints.txt

@@ -329,6 +329,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.unistd.lseek
     libc.src.unistd.pathconf
     libc.src.unistd.pipe
+    libc.src.unistd.pipe2
     libc.src.unistd.pread
     libc.src.unistd.pwrite
     libc.src.unistd.read

libc/newhdrgen/yaml/unistd.yaml

@@ -204,6 +204,13 @@ functions:
     return_type: int
     arguments:
       - type: int *
+  - name: pipe2
+    standards:
+      - Linux
+    return_type: int
+    arguments:
+      - type: int *
+      - type: int
   - name: pread
     standards:
       - POSIX

libc/spec/linux.td

@@ -287,6 +287,23 @@ def Linux : StandardSpec<"Linux"> {
       ]
   >;
 
+
+  HeaderSpec UniStd = HeaderSpec<
+    "unistd.h",
+    [], // Macros
+    [],
+    [], // Enumerations
+    [
+        FunctionSpec<
+          "pipe2",
+          RetValSpec<IntType>,
+          [ArgSpec<IntPtr>, ArgSpec<IntType>] //TODO: make this int[2]
+        >,
+    ],
+    []
+  >;
+  
+
   let Headers = [
     Errno,
     SysEpoll,
@@ -295,5 +312,6 @@ def Linux : StandardSpec<"Linux"> {
     SysRandom,
     SysTime,
     Signal,
+    UniStd,
   ];
 }

libc/src/unistd/CMakeLists.txt

@@ -182,6 +182,13 @@ add_entrypoint_object(
     .${LIBC_TARGET_OS}.pipe
 )
 
+add_entrypoint_object(
+  pipe2
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.pipe2
+)
+
 add_entrypoint_object(
   pread
   ALIAS

libc/src/unistd/linux/CMakeLists.txt

@@ -329,6 +329,19 @@ add_entrypoint_object(
     libc.src.errno.errno
 )
 
+add_entrypoint_object(
+  pipe2
+  SRCS
+    pipe2.cpp
+  HDRS
+    ../pipe2.h
+  DEPENDS
+    libc.include.unistd
+    libc.include.sys_syscall
+    libc.src.__support.OSUtil.osutil
+    libc.src.errno.errno
+)
+
 add_entrypoint_object(
   pread
   SRCS

libc/src/unistd/linux/pipe2.cpp

@@ -0,0 +1,30 @@
+//===-- Linux implementation of pipe --------------------------------------===//
+//
+// 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/pipe2.h"
+
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/errno/libc_errno.h"
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(int, pipe2, (int pipefd[2], int flags)) {
+  int ret = LIBC_NAMESPACE::syscall_impl<int>(
+      SYS_pipe2, reinterpret_cast<long>(pipefd), flags);
+  if (ret < 0) {
+    libc_errno = -ret;
+    return -1;
+  }
+  MSAN_UNPOISON(pipefd, sizeof(int) * 2);
+  return ret;
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/unistd/pipe2.h

@@ -0,0 +1,20 @@
+//===-- Implementation header for pipe2 -------------------------*- 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_PIPE2_H
+#define LLVM_LIBC_SRC_UNISTD_PIPE2_H
+
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+int pipe2(int pipefd[2], int flags);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_UNISTD_PIPE2_H

libc/test/src/unistd/CMakeLists.txt

@@ -217,6 +217,20 @@ add_libc_unittest(
     libc.test.UnitTest.ErrnoSetterMatcher
 )
 
+add_libc_unittest(
+  pipe2_test
+  SUITE
+    libc_unistd_unittests
+  SRCS
+    pipe2_test.cpp
+  DEPENDS
+    libc.include.unistd
+    libc.src.errno.errno
+    libc.src.unistd.close
+    libc.src.unistd.pipe2
+    libc.test.UnitTest.ErrnoSetterMatcher
+)
+
 add_libc_unittest(
   rmdir_test
   SUITE

libc/test/src/unistd/pipe2_test.cpp

@@ -0,0 +1,28 @@
+//===-- Unittests for pipe2 -----------------------------------------------===//
+//
+// 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/errno/libc_errno.h"
+#include "src/unistd/close.h"
+#include "src/unistd/pipe2.h"
+
+#include "test/UnitTest/ErrnoSetterMatcher.h"
+#include "test/UnitTest/Test.h"
+
+using namespace LIBC_NAMESPACE::testing::ErrnoSetterMatcher;
+
+TEST(LlvmLibcPipe2Test, SmokeTest) {
+  int pipefd[2];
+  ASSERT_THAT(LIBC_NAMESPACE::pipe2(pipefd, 0), Succeeds());
+  ASSERT_THAT(LIBC_NAMESPACE::close(pipefd[0]), Succeeds());
+  ASSERT_THAT(LIBC_NAMESPACE::close(pipefd[1]), Succeeds());
+}
+
+TEST(LlvmLibcPipe2ErrTest, SmokeTest) {
+  int pipefd[2];
+  ASSERT_THAT(LIBC_NAMESPACE::pipe2(pipefd, -1), Fails(EINVAL));
+  ASSERT_THAT(LIBC_NAMESPACE::pipe2(nullptr, 0), Fails(EFAULT));
+}