[libcxx-commits] [libcxx] [libc++] use copy_file_range for fs::copy (PR #109211)

[Louis Dionne via libcxx-commits]

Jannik =?utf-8?q?Glückert?= <jannik.glueckert at gmail.com>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/109211 at github.com>


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@@ -0,0 +1,50 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14
+// REQUIRES: linux
+// UNSUPPORTED: no-filesystem
+// UNSUPPORTED: availability-filesystem-missing
+
+// <filesystem>
+
+// bool copy_file(const path& from, const path& to);
+// bool copy_file(const path& from, const path& to, error_code& ec) noexcept;
+// bool copy_file(const path& from, const path& to, copy_options options);
+// bool copy_file(const path& from, const path& to, copy_options options,
+//           error_code& ec) noexcept;
+
+#include <filesystem>
+#include <cassert>
+
+#include "test_macros.h"
+#include "filesystem_test_helper.h"
+
+using namespace std::filesystem;
+
+// Linux has various virtual filesystems such as /proc and /sys
+// where files may have no length (st_size == 0), but still contain data.
+// This is because the to-be-read data is usually generated ad-hoc by the reading syscall
+// These files can not be copied with kernel-side copies like copy_file_range or sendfile,
+// and must instead be copied via a traditional userspace read + write loop.
+int main(int, char**) {
+  const path procfile{"/proc/self/comm"};
+  assert(file_size(procfile) == 0);
+
+  scoped_test_env env;
+  std::error_code ec = GetTestEC();
+
+  const path dest = env.make_env_path("dest");
+
+  assert(copy_file(procfile, dest, ec));
+  assert(!ec);
+
+  // a tad fragile if lit ever changes the output name,
+  // but the easiest way to assert that the correct data was copied.
+  assert(file_size(dest) == sizeof("t.tmp.exe"));
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ldionne wrote:

Could you instead derive something from `argv[0]`?

https://github.com/llvm/llvm-project/pull/109211