llvm/llvm/lib/Support/FileOutputBuffer.cpp

//===- FileOutputBuffer.cpp - File Output Buffer ----------------*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// Utility for creating a in-memory buffer that will be written to a file.
//
//===----------------------------------------------------------------------===//

#include "llvm/Support/FileOutputBuffer.h"
#include "llvm/Support/Errc.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Memory.h"
#include "llvm/Support/TimeProfiler.h"
#include <system_error>

#if !defined(_MSC_VER) && !defined(__MINGW32__)
#include <unistd.h>
#else
#include <io.h>
#endif

usingnamespacellvm;
usingnamespacellvm::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 { … };

// 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 { … };
} // namespace

static Expected<std::unique_ptr<InMemoryBuffer>>
createInMemoryBuffer(StringRef Path, size_t Size, unsigned Mode) { … }

static Expected<std::unique_ptr<FileOutputBuffer>>
createOnDiskBuffer(StringRef Path, size_t Size, unsigned Mode) { … }

// Create an instance of FileOutputBuffer.
Expected<std::unique_ptr<FileOutputBuffer>>
FileOutputBuffer::create(StringRef Path, size_t Size, unsigned Flags) { … }