1 files changed, 112 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Support/FileOutputBuffer.cpp b/contrib/llvm/lib/Support/FileOutputBuffer.cpp
new file mode 100644
index 0000000..307ff09
--- /dev/null
+++ b/contrib/llvm/lib/Support/FileOutputBuffer.cpp
@@ -0,0 +1,112 @@
+//===- 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 <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)
+    : Region(std::move(R)), FinalPath(Path), TempPath(TmpPath) {}
+
+FileOutputBuffer::~FileOutputBuffer() {
+  sys::fs::remove(Twine(TempPath));
+}
+
+std::error_code
+FileOutputBuffer::create(StringRef FilePath, size_t Size,
+                         std::unique_ptr<FileOutputBuffer> &Result,
+                         unsigned Flags) {
+  // If file already exists, it must be a regular file (to be mappable).
+  sys::fs::file_status Stat;
+  std::error_code EC = sys::fs::status(FilePath, Stat);
+  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;
+      else
+        return make_error_code(errc::operation_not_permitted);
+  }
+
+  // Delete target file.
+  EC = sys::fs::remove(FilePath);
+  if (EC)
+    return EC;
+
+  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.
+  SmallString<128> TempFilePath;
+  int FD;
+  EC = sys::fs::createUniqueFile(Twine(FilePath) + ".tmp%%%%%%%", FD,
+                                 TempFilePath, Mode);
+  if (EC)
+    return EC;
+
+#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());
+
+  Result.reset(
+      new FileOutputBuffer(std::move(MappedFile), FilePath, TempFilePath));
+
+  return std::error_code();
+}
+
+std::error_code FileOutputBuffer::commit() {
+  // Unmap buffer, letting OS flush dirty pages to file on disk.
+  Region.reset();
+
+
+  // Rename file to final name.
+  return sys::fs::rename(Twine(TempPath), Twine(FinalPath));
+}
+} // namespace