1 files changed, 139 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Support/FileOutputBuffer.cpp b/contrib/llvm/lib/Support/FileOutputBuffer.cpp
new file mode 100644
index 000000000000..57e5a8d7871c
--- /dev/null
+++ b/contrib/llvm/lib/Support/FileOutputBuffer.cpp
@@ -0,0 +1,139 @@
+//===- FileOutputBuffer.cpp - File Output Buffer ----------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Utility for creating a in-memory buffer that will be written to a file.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/FileOutputBuffer.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/Support/Errc.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/Signals.h"
+#include <system_error>
+
+#if !defined(_MSC_VER) && !defined(__MINGW32__)
+#include <unistd.h>
+#else
+#include <io.h>
+#endif
+
+using llvm::sys::fs::mapped_file_region;
+
+namespace llvm {
+FileOutputBuffer::FileOutputBuffer(std::unique_ptr<mapped_file_region> R,
+                                   StringRef Path, StringRef TmpPath,
+                                   bool IsRegular)
+    : Region(std::move(R)), FinalPath(Path), TempPath(TmpPath),
+      IsRegular(IsRegular) {}
+
+FileOutputBuffer::~FileOutputBuffer() {
+  // Close the mapping before deleting the temp file, so that the removal
+  // succeeds.
+  Region.reset();
+  sys::fs::remove(Twine(TempPath));
+}
+
+ErrorOr<std::unique_ptr<FileOutputBuffer>>
+FileOutputBuffer::create(StringRef FilePath, size_t Size, unsigned Flags) {
+  // Check file is not a regular file, in which case we cannot remove it.
+  sys::fs::file_status Stat;
+  std::error_code EC = sys::fs::status(FilePath, Stat);
+  bool IsRegular = true;
+  switch (Stat.type()) {
+    case sys::fs::file_type::file_not_found:
+      // If file does not exist, we'll create one.
+      break;
+    case sys::fs::file_type::regular_file: {
+        // If file is not currently writable, error out.
+        // FIXME: There is no sys::fs:: api for checking this.
+        // FIXME: In posix, you use the access() call to check this.
+      }
+      break;
+    default:
+      if (EC)
+        return EC;
+      IsRegular = false;
+  }
+
+  if (IsRegular) {
+    // Delete target file.
+    EC = sys::fs::remove(FilePath);
+    if (EC)
+      return EC;
+  }
+
+  SmallString<128> TempFilePath;
+  int FD;
+  if (IsRegular) {
+    unsigned Mode = sys::fs::all_read | sys::fs::all_write;
+    // If requested, make the output file executable.
+    if (Flags & F_executable)
+      Mode |= sys::fs::all_exe;
+    // Create new file in same directory but with random name.
+    EC = sys::fs::createUniqueFile(Twine(FilePath) + ".tmp%%%%%%%", FD,
+                                   TempFilePath, Mode);
+  } else {
+    // Create a temporary file. Since this is a special file, we will not move
+    // it and the new file can be in another filesystem. This avoids trying to
+    // create a temporary file in /dev when outputting to /dev/null for example.
+    EC = sys::fs::createTemporaryFile(sys::path::filename(FilePath), "", FD,
+                                      TempFilePath);
+  }
+
+  if (EC)
+    return EC;
+
+  sys::RemoveFileOnSignal(TempFilePath);
+
+#ifndef LLVM_ON_WIN32
+  // On Windows, CreateFileMapping (the mmap function on Windows)
+  // automatically extends the underlying file. We don't need to
+  // extend the file beforehand. _chsize (ftruncate on Windows) is
+  // pretty slow just like it writes specified amount of bytes,
+  // so we should avoid calling that.
+  EC = sys::fs::resize_file(FD, Size);
+  if (EC)
+    return EC;
+#endif
+
+  auto MappedFile = llvm::make_unique<mapped_file_region>(
+      FD, mapped_file_region::readwrite, Size, 0, EC);
+  int Ret = close(FD);
+  if (EC)
+    return EC;
+  if (Ret)
+    return std::error_code(errno, std::generic_category());
+
+  std::unique_ptr<FileOutputBuffer> Buf(new FileOutputBuffer(
+      std::move(MappedFile), FilePath, TempFilePath, IsRegular));
+  return std::move(Buf);
+}
+
+std::error_code FileOutputBuffer::commit() {
+  // Unmap buffer, letting OS flush dirty pages to file on disk.
+  Region.reset();
+
+  std::error_code EC;
+  if (IsRegular) {
+    // Rename file to final name.
+    EC = sys::fs::rename(Twine(TempPath), Twine(FinalPath));
+    sys::DontRemoveFileOnSignal(TempPath);
+  } else {
+    EC = sys::fs::copy_file(TempPath, FinalPath);
+    std::error_code RMEC = sys::fs::remove(TempPath);
+    sys::DontRemoveFileOnSignal(TempPath);
+    if (RMEC)
+      return RMEC;
+  }
+
+  return EC;
+}
+} // namespace