[SystemZ][z/OS] Fix filesystem testing

[muiez]

Summary

This patch resolves many of the failures in the filesystems/ buckets in the libc++ tests. It adds the correct flag to fopen and marks a test case as unsupported. In particular, that test assumes time is stored as a 64 bit value when on MVS it is stored as 32 bit.

[muiez]

Ping :)

[ldionne]

libcxx/test/support/filesystem_test_helper.h

198–200

While we're at it, let's format them correctly.

[muiez]

better format

libcxx/test/libcxx/input.output/filesystems/class.directory_entry/directory_entry.mods/last_write_time.pass.cpp

 // ADDITIONAL_COMPILE_FLAGS: -I %S/../../../../../../src/filesystem
 
 // This test relies on calling functions from the libcxx internal header
 // filesystem_common.h; the Windows implementation uses different
 // internals and doesn't provide the same set_file_times function as for
 // other platforms.
 // UNSUPPORTED: windows
 
+// This test assumes that time is stored as a 64 bit value when on MVS it is stored as 32 bit
+// UNSUPPORTED: target={{.+}}-zos{{.*}}
+
 // TODO(ldionne): This test fails on Ubuntu Focal on our CI nodes (and only there), in 32 bit mode.
 // UNSUPPORTED: linux && 32bits-on-64bits
 
 // <filesystem>
 
 // class directory_entry
 
 #include "filesystem_include.h"

libcxx/test/support/filesystem_test_helper.h

#endif
         if (size >
             static_cast<typename std::make_unsigned<large_file_offset_t>::type>(
                 std::numeric_limits<large_file_offset_t>::max())) {
             fprintf(stderr, "create_file(%s, %ju) too large\n",
                     filename.c_str(), size);
             abort();
         }
 
-#ifndef _WIN32
-#define FOPEN_CLOEXEC_FLAG "e"
-#else
-#define FOPEN_CLOEXEC_FLAG ""
+#if defined(_WIN32) || defined(__MVS__)
+#  define FOPEN_CLOEXEC_FLAG ""
+#else
+#  define FOPEN_CLOEXEC_FLAG "e"
 #endif
         FILE* file = large_file_fopen(filename.c_str(), "w" FOPEN_CLOEXEC_FLAG);
         if (file == nullptr) {
             fprintf(stderr, "fopen %s failed: %s\n", filename.c_str(),
                     strerror(errno));
             abort();
         }
 
         if (large_file_ftruncate(