Use GetAbsoluteTestTmpdir() rather than hard-code "/tmp"

This change makes these tests easier to run on systems that have their temp
directory in another location.

PiperOrigin-RevId: 388601202

test/syscalls/linux/lseek.cc

@@ -121,7 +121,8 @@ TEST(LseekTest, InvalidFD) {
 }
 
 TEST(LseekTest, DirCurEnd) {
-  const FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(Open("/tmp", O_RDONLY));
+  const FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(
+      Open(GetAbsoluteTestTmpdir().c_str(), O_RDONLY));
   ASSERT_THAT(lseek(fd.get(), 0, SEEK_CUR), SyscallSucceedsWithValue(0));
 }
 

test/syscalls/linux/memfd.cc

@@ -445,9 +445,10 @@ TEST(MemfdTest, SealsAreInodeLevelProperties) {
 
 // Tmpfs files also support seals, but are created with F_SEAL_SEAL.
 TEST(MemfdTest, TmpfsFilesHaveSealSeal) {
-  SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(IsTmpfs("/tmp")));
+  std::string tmpdir = GetAbsoluteTestTmpdir();
+  SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(IsTmpfs(tmpdir.c_str())));
   const TempPath tmpfs_file =
-      ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileIn("/tmp"));
+      ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileIn(tmpdir.c_str()));
   const FileDescriptor fd =
       ASSERT_NO_ERRNO_AND_VALUE(Open(tmpfs_file.path(), O_RDWR, 0644));
   EXPECT_THAT(fcntl(fd.get(), F_GET_SEALS),

test/syscalls/linux/stat.cc

@@ -765,7 +765,7 @@ TEST_F(StatTest, StatxSymlink) {
   SKIP_IF(!IsRunningOnGvisor() && statx(-1, nullptr, 0, 0, nullptr) < 0 &&
           errno == ENOSYS);
 
-  std::string parent_dir = "/tmp";
+  std::string parent_dir = GetAbsoluteTestTmpdir();
   TempPath link = ASSERT_NO_ERRNO_AND_VALUE(
       TempPath::CreateSymlinkTo(parent_dir, test_file_name_));
   std::string p = link.path();

test/syscalls/linux/statfs.cc

@@ -28,7 +28,7 @@ namespace testing {
 namespace {
 
 TEST(StatfsTest, CannotStatBadPath) {
-  auto temp_file = NewTempAbsPathInDir("/tmp");
+  auto temp_file = NewTempAbsPath();
 
   struct statfs st;
   EXPECT_THAT(statfs(temp_file.c_str(), &st), SyscallFailsWithErrno(ENOENT));