[libc-commits] [libc] [libc] Implement close_range in unistd (PR #236913)

[Pavel Labath via libc-commits]

================
@@ -0,0 +1,106 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 close_range.
+///
+//===----------------------------------------------------------------------===//
+
+#include "hdr/errno_macros.h"
+#include "hdr/fcntl_macros.h"
+#include "hdr/unistd_macros.h"
+#include "src/__support/CPP/scope.h"
+#include "src/fcntl/fcntl.h"
+#include "src/unistd/close.h"
+#include "src/unistd/close_range.h"
+#include "src/unistd/pipe.h"
+#include "test/UnitTest/ErrnoCheckingTest.h"
+#include "test/UnitTest/ErrnoSetterMatcher.h"
+#include "test/UnitTest/Test.h"
+
+using namespace LIBC_NAMESPACE::testing::ErrnoSetterMatcher;
+using LlvmLibcCloseRangeTest = LIBC_NAMESPACE::testing::ErrnoCheckingTest;
+
+namespace {
+
+bool create_adjacent_fds(int fds[2]) {
+  if (LIBC_NAMESPACE::pipe(fds) != 0)
+    return false;
+  if (fds[0] > fds[1]) {
+    int tmp = fds[0];
+    fds[0] = fds[1];
+    fds[1] = tmp;
+  }
+  while (fds[0] + 1 != fds[1]) {
+    int new_fd = LIBC_NAMESPACE::fcntl(fds[0], F_DUPFD, fds[1]);
+    if (new_fd < 0) {
+      LIBC_NAMESPACE::close(fds[0]);
+      LIBC_NAMESPACE::close(fds[1]);
+      return false;
+    }
+    if (LIBC_NAMESPACE::close(fds[0]) != 0) {
+      LIBC_NAMESPACE::close(fds[1]);
+      LIBC_NAMESPACE::close(new_fd);
+      return false;
+    }
+    fds[0] = fds[1];
+    fds[1] = new_fd;
+  }
+  return true;
+}
+
+} // namespace
+
+TEST_F(LlvmLibcCloseRangeTest, InvalidArgs) {
+  // first > last should fail with EINVAL.
+  ASSERT_THAT(LIBC_NAMESPACE::close_range(10, 5, 0), Fails(EINVAL));
+
+  // Unsupported or invalid flags should fail with EINVAL.
+  ASSERT_THAT(LIBC_NAMESPACE::close_range(10, 10, ~0U), Fails(EINVAL));
+}
+
+TEST_F(LlvmLibcCloseRangeTest, ClosePipes) {
+  int fds[2];
+  ASSERT_TRUE(create_adjacent_fds(fds));
+
+  ASSERT_THAT(LIBC_NAMESPACE::close_range(static_cast<unsigned int>(fds[0]),
+                                          static_cast<unsigned int>(fds[1]), 0),
+              Succeeds(0));
+
+  // Both should now be closed.
+  // Using fcntl(F_GETFD) is safer than close() as it does not risk closing an
+  // unrelated FD.
+  ASSERT_THAT(LIBC_NAMESPACE::fcntl(fds[0], F_GETFD), Fails(EBADF));
+  ASSERT_THAT(LIBC_NAMESPACE::fcntl(fds[1], F_GETFD), Fails(EBADF));
+}
+
+// CLOSE_RANGE_CLOEXEC was introduced in Linux kernel 5.11.
+TEST_F(LlvmLibcCloseRangeTest, CloexecFlag) {
+#ifdef CLOSE_RANGE_CLOEXEC
----------------
labath wrote:

Let's change the order here as well. No point in running an empty test.

```suggestion
#ifdef CLOSE_RANGE_CLOEXEC
TEST_F(LlvmLibcCloseRangeTest, CloexecFlag) {
```

https://github.com/llvm/llvm-project/pull/236913