[libc-commits] [libc] [libc] Add `shm_open/shm_unlink` (PR #84974)

[Nick Desaulniers via libc-commits]

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@@ -0,0 +1,79 @@
+//===-- Unittests for shm_open/shm_unlink ---------------------------------===//
+//
+// 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/__support/OSUtil/syscall.h"
+#include "src/sys/mman/mmap.h"
+#include "src/sys/mman/munmap.h"
+#include "src/sys/mman/shm_open.h"
+#include "src/sys/mman/shm_unlink.h"
+#include "src/unistd/close.h"
+#include "src/unistd/ftruncate.h"
+#include "test/UnitTest/ErrnoSetterMatcher.h"
+#include "test/UnitTest/LibcTest.h"
+#include <asm-generic/fcntl.h>
+#include <sys/syscall.h>
+
+using namespace LIBC_NAMESPACE::testing::ErrnoSetterMatcher;
+// since shm_open/shm_unlink are wrappers around open/unlink, we only focus on
+// testing basic cases and name conversions.
+
+TEST(LlvmLibcShmTest, Basic) {
+  const char *name = "/test_shm_open";
+  int fd;
+  ASSERT_THAT(fd = LIBC_NAMESPACE::shm_open(name, O_CREAT | O_RDWR, 0666),
+              returns(GE(0)).with_errno(EQ(0)));
+
+  // check that FD_CLOEXEC is set by default.
+  // TODO: use fcntl when implemented.
+  // https://github.com/llvm/llvm-project/issues/84968
+  long flag = LIBC_NAMESPACE::syscall_impl(SYS_fcntl, fd, F_GETFD);
+  ASSERT_GE(static_cast<int>(flag), 0);
+  EXPECT_NE(static_cast<int>(flag) & FD_CLOEXEC, 0);
+
+  // allocate space using ftruncate
+  ASSERT_THAT(LIBC_NAMESPACE::ftruncate(fd, 4096), Succeeds());
+  // map the shared memory
+  void *addr = LIBC_NAMESPACE::mmap(nullptr, 4096, PROT_READ | PROT_WRITE,
+                                    MAP_SHARED, fd, 0);
+  ASSERT_NE(addr, MAP_FAILED);
+  // just write random data to the shared memory
+  char data[] = "Despite its name, LLVM has little to do with traditional "
+                "virtual machines.";
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nickdesaulniers wrote:

Well said. +1

https://github.com/llvm/llvm-project/pull/84974