diff --git a/libc/test/src/__support/CPP/stringview_test.cpp b/libc/test/src/__support/CPP/stringview_test.cpp
@@ -174,3 +174,111 @@ TEST(LlvmLibcStringViewTest, FindLastOf) {
   ASSERT_EQ(Empty1.find_last_of('a', 0), string_view::npos);
   ASSERT_EQ(Empty1.find_last_of('a', 123), string_view::npos);
 }
+
+TEST(LlvmLibcStringViewTest, FindFirstNotOf) {
+  string_view Tmp("abada");
+
+  EXPECT_EQ(Tmp.find_first_not_of('a'), size_t(1));
+  EXPECT_EQ(Tmp.find_first_not_of('a', 123), string_view::npos);
+  EXPECT_EQ(Tmp.find_first_not_of('a', 5), string_view::npos);
+  EXPECT_EQ(Tmp.find_first_not_of('a', 4), string_view::npos);
+  EXPECT_EQ(Tmp.find_first_not_of('a', 3), size_t(3));
+  EXPECT_EQ(Tmp.find_first_not_of('a', 2), size_t(3));
+  EXPECT_EQ(Tmp.find_first_not_of('a', 1), size_t(1));
+  EXPECT_EQ(Tmp.find_first_not_of('a', 0), size_t(1));
+
+  EXPECT_EQ(Tmp.find_first_not_of('b'), size_t(0));
+  EXPECT_EQ(Tmp.find_first_not_of('b', 123), string_view::npos);
+  EXPECT_EQ(Tmp.find_first_not_of('b', 5), string_view::npos);
+  EXPECT_EQ(Tmp.find_first_not_of('b', 4), size_t(4));
+  EXPECT_EQ(Tmp.find_first_not_of('b', 3), size_t(3));
+  EXPECT_EQ(Tmp.find_first_not_of('b', 2), size_t(2));
+  EXPECT_EQ(Tmp.find_first_not_of('b', 1), size_t(2));
+  EXPECT_EQ(Tmp.find_first_not_of('b', 0), size_t(0));
+
+  EXPECT_EQ(Tmp.find_first_not_of('d'), size_t(0));
+  EXPECT_EQ(Tmp.find_first_not_of('d', 123), string_view::npos);
+  EXPECT_EQ(Tmp.find_first_not_of('d', 5), string_view::npos);
+  EXPECT_EQ(Tmp.find_first_not_of('d', 4), size_t(4));
+  EXPECT_EQ(Tmp.find_first_not_of('d', 3), size_t(4));
+  EXPECT_EQ(Tmp.find_first_not_of('d', 2), size_t(2));
+  EXPECT_EQ(Tmp.find_first_not_of('d', 1), size_t(1));
+  EXPECT_EQ(Tmp.find_first_not_of('d', 0), size_t(0));
+
+  EXPECT_EQ(Tmp.find_first_not_of('e'), size_t(0));
+  EXPECT_EQ(Tmp.find_first_not_of('e', 123), string_view::npos);
+  EXPECT_EQ(Tmp.find_first_not_of('e', 5), string_view::npos);
+  EXPECT_EQ(Tmp.find_first_not_of('e', 4), size_t(4));
+  EXPECT_EQ(Tmp.find_first_not_of('e', 3), size_t(3));
+  EXPECT_EQ(Tmp.find_first_not_of('e', 2), size_t(2));
+  EXPECT_EQ(Tmp.find_first_not_of('e', 1), size_t(1));
+  EXPECT_EQ(Tmp.find_first_not_of('e', 0), size_t(0));
+
+  string_view Empty;
+  EXPECT_EQ(Empty.find_first_not_of('a'), string_view::npos);
+  EXPECT_EQ(Empty.find_first_not_of('a', 0), string_view::npos);
+  EXPECT_EQ(Empty.find_first_not_of('a', 123), string_view::npos);
+
+  string_view Empty1("");
+  EXPECT_EQ(Empty1.find_first_not_of('a'), string_view::npos);
+  EXPECT_EQ(Empty1.find_first_not_of('a', 0), string_view::npos);
+  EXPECT_EQ(Empty1.find_first_not_of('a', 123), string_view::npos);
+
+  string_view Full("aaaaaaa");
+  EXPECT_EQ(Full.find_first_not_of('a'), string_view::npos);
+  EXPECT_EQ(Full.find_first_not_of('a', 0), string_view::npos);
+  EXPECT_EQ(Full.find_first_not_of('a', 123), string_view::npos);
+
+  EXPECT_EQ(Full.find_first_not_of('b'), size_t(0));
+  EXPECT_EQ(Full.find_first_not_of('b', 0), size_t(0));
+  EXPECT_EQ(Full.find_first_not_of('b', 123), string_view::npos);
+}
+
+TEST(LlvmLibcStringViewTest, Contains) {
+  string_view Empty;
+  for (char c = 'a'; c < 'z'; ++c)
+    EXPECT_FALSE(Empty.contains(c));
+
+  string_view Tmp("abada");
+  EXPECT_TRUE(Tmp.contains('a'));
+  EXPECT_TRUE(Tmp.contains('b'));
+  EXPECT_FALSE(Tmp.contains('c'));
+  EXPECT_TRUE(Tmp.contains('d'));
+  EXPECT_FALSE(Tmp.contains('e'));
+
+  EXPECT_TRUE(Tmp.substr(1).contains('a'));
+  EXPECT_TRUE(Tmp.substr(1).contains('b'));
+  EXPECT_FALSE(Tmp.substr(1).contains('c'));
+  EXPECT_TRUE(Tmp.substr(1).contains('d'));
+  EXPECT_FALSE(Tmp.substr(1).contains('e'));
+
+  EXPECT_TRUE(Tmp.substr(2).contains('a'));
+  EXPECT_FALSE(Tmp.substr(2).contains('b'));
+  EXPECT_FALSE(Tmp.substr(2).contains('c'));
+  EXPECT_TRUE(Tmp.substr(2).contains('d'));
+  EXPECT_FALSE(Tmp.substr(2).contains('e'));
+
+  EXPECT_TRUE(Tmp.substr(3).contains('a'));
+  EXPECT_FALSE(Tmp.substr(3).contains('b'));
+  EXPECT_FALSE(Tmp.substr(3).contains('c'));
+  EXPECT_TRUE(Tmp.substr(3).contains('d'));
+  EXPECT_FALSE(Tmp.substr(3).contains('e'));
+
+  EXPECT_TRUE(Tmp.substr(4).contains('a'));
+  EXPECT_FALSE(Tmp.substr(4).contains('b'));
+  EXPECT_FALSE(Tmp.substr(4).contains('c'));
+  EXPECT_FALSE(Tmp.substr(4).contains('d'));
+  EXPECT_FALSE(Tmp.substr(4).contains('e'));
+
+  EXPECT_FALSE(Tmp.substr(5).contains('a'));
+  EXPECT_FALSE(Tmp.substr(5).contains('b'));
+  EXPECT_FALSE(Tmp.substr(5).contains('c'));
+  EXPECT_FALSE(Tmp.substr(5).contains('d'));
+  EXPECT_FALSE(Tmp.substr(5).contains('e'));
+
+  EXPECT_FALSE(Tmp.substr(6).contains('a'));
+  EXPECT_FALSE(Tmp.substr(6).contains('b'));
+  EXPECT_FALSE(Tmp.substr(6).contains('c'));
+  EXPECT_FALSE(Tmp.substr(6).contains('d'));
+  EXPECT_FALSE(Tmp.substr(6).contains('e'));
+}
diff --git a/libc/test/src/sys/mman/linux/CMakeLists.txt b/libc/test/src/sys/mman/linux/CMakeLists.txt
@@ -127,3 +127,23 @@ add_libc_unittest(
     libc.src.unistd.sysconf
     libc.test.UnitTest.ErrnoSetterMatcher
 )
+
+add_libc_unittest(
+  shm_test
+  SUITE
+    libc_sys_mman_unittests
+  SRCS
+    shm_test.cpp
+  DEPENDS
+    libc.include.sys_mman
+    libc.include.sys_syscall
+    libc.src.errno.errno
+    libc.src.sys.mman.shm_open
+    libc.src.sys.mman.shm_unlink
+    libc.src.sys.mman.mmap
+    libc.src.sys.mman.munmap
+    libc.src.unistd.ftruncate
+    libc.src.unistd.close
+    libc.src.__support.OSUtil.osutil
+    libc.test.UnitTest.ErrnoSetterMatcher
+)
diff --git a/libc/test/src/sys/mman/linux/shm_test.cpp b/libc/test/src/sys/mman/linux/shm_test.cpp
@@ -0,0 +1,77 @@
+//===-- 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.";
+  for (size_t i = 0; i < sizeof(data); ++i)
+    static_cast<char *>(addr)[i] = data[i];
+
+  // close fd does not affect the mapping
+  ASSERT_THAT(LIBC_NAMESPACE::close(fd), Succeeds());
+  for (size_t i = 0; i < sizeof(data); ++i)
+    EXPECT_EQ(static_cast<char *>(addr)[i], data[i]);
+
+  // unmap the shared memory
+  ASSERT_THAT(LIBC_NAMESPACE::munmap(addr, 4096), Succeeds());
+  // remove the shared memory
+  ASSERT_THAT(LIBC_NAMESPACE::shm_unlink(name), Succeeds());
+}
+
+TEST(LlvmLibcShmTest, NameConversion) {
+  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)));
+  ASSERT_THAT(LIBC_NAMESPACE::close(fd), Succeeds());
+  ASSERT_THAT(LIBC_NAMESPACE::shm_unlink(name), Succeeds());
+
+  ASSERT_THAT(LIBC_NAMESPACE::shm_open("/123/123", O_CREAT | O_RDWR, 0666),
+              Fails(EINVAL));
+
+  ASSERT_THAT(LIBC_NAMESPACE::shm_open("/.", O_CREAT | O_RDWR, 0666),
+              Fails(EINVAL));
+
+  ASSERT_THAT(LIBC_NAMESPACE::shm_open("/..", O_CREAT | O_RDWR, 0666),
+              Fails(EINVAL));
+}