Imported Upstream version 5.18.0.234

Former-commit-id: 8071ec1a8c5eaa9be24b41745add19297608001f

external/llvm/lib/Support/FileOutputBuffer.cpp

@@ -1,170 +0,0 @@
-//===- 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/Memory.h"
-#include "llvm/Support/Path.h"
-#include <system_error>
-
-#if !defined(_MSC_VER) && !defined(__MINGW32__)
-#include <unistd.h>
-#else
-#include <io.h>
-#endif
-
-using namespace llvm;
-using namespace llvm::sys;
-
-namespace {
-// A FileOutputBuffer which creates a temporary file in the same directory
-// as the final output file. The final output file is atomically replaced
-// with the temporary file on commit().
-class OnDiskBuffer : public FileOutputBuffer {
-public:
-  OnDiskBuffer(StringRef Path, fs::TempFile Temp,
-               std::unique_ptr<fs::mapped_file_region> Buf)
-      : FileOutputBuffer(Path), Buffer(std::move(Buf)), Temp(std::move(Temp)) {}
-
-  uint8_t *getBufferStart() const override { return (uint8_t *)Buffer->data(); }
-
-  uint8_t *getBufferEnd() const override {
-    return (uint8_t *)Buffer->data() + Buffer->size();
-  }
-
-  size_t getBufferSize() const override { return Buffer->size(); }
-
-  Error commit() override {
-    // Unmap buffer, letting OS flush dirty pages to file on disk.
-    Buffer.reset();
-
-    // Atomically replace the existing file with the new one.
-    return Temp.keep(FinalPath);
-  }
-
-  ~OnDiskBuffer() override {
-    // Close the mapping before deleting the temp file, so that the removal
-    // succeeds.
-    Buffer.reset();
-    consumeError(Temp.discard());
-  }
-
-private:
-  std::unique_ptr<fs::mapped_file_region> Buffer;
-  fs::TempFile Temp;
-};
-
-// A FileOutputBuffer which keeps data in memory and writes to the final
-// output file on commit(). This is used only when we cannot use OnDiskBuffer.
-class InMemoryBuffer : public FileOutputBuffer {
-public:
-  InMemoryBuffer(StringRef Path, MemoryBlock Buf, unsigned Mode)
-      : FileOutputBuffer(Path), Buffer(Buf), Mode(Mode) {}
-
-  uint8_t *getBufferStart() const override { return (uint8_t *)Buffer.base(); }
-
-  uint8_t *getBufferEnd() const override {
-    return (uint8_t *)Buffer.base() + Buffer.size();
-  }
-
-  size_t getBufferSize() const override { return Buffer.size(); }
-
-  Error commit() override {
-    int FD;
-    std::error_code EC;
-    if (auto EC = openFileForWrite(FinalPath, FD, fs::F_None, Mode))
-      return errorCodeToError(EC);
-    raw_fd_ostream OS(FD, /*shouldClose=*/true, /*unbuffered=*/true);
-    OS << StringRef((const char *)Buffer.base(), Buffer.size());
-    return Error::success();
-  }
-
-private:
-  OwningMemoryBlock Buffer;
-  unsigned Mode;
-};
-} // namespace
-
-static Expected<std::unique_ptr<InMemoryBuffer>>
-createInMemoryBuffer(StringRef Path, size_t Size, unsigned Mode) {
-  std::error_code EC;
-  MemoryBlock MB = Memory::allocateMappedMemory(
-      Size, nullptr, sys::Memory::MF_READ | sys::Memory::MF_WRITE, EC);
-  if (EC)
-    return errorCodeToError(EC);
-  return llvm::make_unique<InMemoryBuffer>(Path, MB, Mode);
-}
-
-static Expected<std::unique_ptr<OnDiskBuffer>>
-createOnDiskBuffer(StringRef Path, size_t Size, unsigned Mode) {
-  Expected<fs::TempFile> FileOrErr =
-      fs::TempFile::create(Path + ".tmp%%%%%%%", Mode);
-  if (!FileOrErr)
-    return FileOrErr.takeError();
-  fs::TempFile File = std::move(*FileOrErr);
-
-#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 function.
-  if (auto EC = fs::resize_file(File.FD, Size)) {
-    consumeError(File.discard());
-    return errorCodeToError(EC);
-  }
-#endif
-
-  // Mmap it.
-  std::error_code EC;
-  auto MappedFile = llvm::make_unique<fs::mapped_file_region>(
-      File.FD, fs::mapped_file_region::readwrite, Size, 0, EC);
-  if (EC) {
-    consumeError(File.discard());
-    return errorCodeToError(EC);
-  }
-  return llvm::make_unique<OnDiskBuffer>(Path, std::move(File),
-                                         std::move(MappedFile));
-}
-
-// Create an instance of FileOutputBuffer.
-Expected<std::unique_ptr<FileOutputBuffer>>
-FileOutputBuffer::create(StringRef Path, size_t Size, unsigned Flags) {
-  unsigned Mode = fs::all_read | fs::all_write;
-  if (Flags & F_executable)
-    Mode |= fs::all_exe;
-
-  fs::file_status Stat;
-  fs::status(Path, Stat);
-
-  // Usually, we want to create OnDiskBuffer to create a temporary file in
-  // the same directory as the destination file and atomically replaces it
-  // by rename(2).
-  //
-  // However, if the destination file is a special file, we don't want to
-  // use rename (e.g. we don't want to replace /dev/null with a regular
-  // file.) If that's the case, we create an in-memory buffer, open the
-  // destination file and write to it on commit().
-  switch (Stat.type()) {
-  case fs::file_type::directory_file:
-    return errorCodeToError(errc::is_a_directory);
-  case fs::file_type::regular_file:
-  case fs::file_type::file_not_found:
-  case fs::file_type::status_error:
-    return createOnDiskBuffer(Path, Size, Mode);
-  default:
-    return createInMemoryBuffer(Path, Size, Mode);
-  }
-}