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//===- Buffer.cpp ---------------------------------------------------------===// 
// 
// 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 
// 
//===----------------------------------------------------------------------===// 
 
#include "Buffer.h" 
#include "llvm/Support/FileOutputBuffer.h" 
#include "llvm/Support/FileSystem.h" 
#include "llvm/Support/MemoryBuffer.h" 
#include "llvm/Support/Process.h" 
#include <memory> 
 
namespace llvm { 
namespace objcopy { 
 
Buffer::~Buffer() {} 
 
static Error createEmptyFile(StringRef FileName) { 
  // Create an empty tempfile and atomically swap it in place with the desired 
  // output file. 
  Expected<sys::fs::TempFile> Temp = 
      sys::fs::TempFile::create(FileName + ".temp-empty-%%%%%%%"); 
  return Temp ? Temp->keep(FileName) : Temp.takeError(); 
} 
 
Error FileBuffer::allocate(size_t Size) { 
  // When a 0-sized file is requested, skip allocation but defer file 
  // creation/truncation until commit() to avoid side effects if something 
  // happens between allocate() and commit(). 
  if (Size == 0) { 
    EmptyFile = true; 
    return Error::success(); 
  } 
 
  Expected<std::unique_ptr<FileOutputBuffer>> BufferOrErr = 
      FileOutputBuffer::create(getName(), Size, FileOutputBuffer::F_executable); 
  // FileOutputBuffer::create() returns an Error that is just a wrapper around 
  // std::error_code. Wrap it in FileError to include the actual filename. 
  if (!BufferOrErr) 
    return createFileError(getName(), BufferOrErr.takeError()); 
  Buf = std::move(*BufferOrErr); 
  return Error::success(); 
} 
 
Error FileBuffer::commit() { 
  if (EmptyFile) 
    return createEmptyFile(getName()); 
 
  assert(Buf && "allocate() not called before commit()!"); 
  Error Err = Buf->commit(); 
  // FileOutputBuffer::commit() returns an Error that is just a wrapper around 
  // std::error_code. Wrap it in FileError to include the actual filename. 
  return Err ? createFileError(getName(), std::move(Err)) : std::move(Err); 
} 
 
uint8_t *FileBuffer::getBufferStart() { 
  return reinterpret_cast<uint8_t *>(Buf->getBufferStart()); 
} 
 
Error MemBuffer::allocate(size_t Size) { 
  Buf = WritableMemoryBuffer::getNewMemBuffer(Size, getName()); 
  return Error::success(); 
} 
 
Error MemBuffer::commit() { return Error::success(); } 
 
uint8_t *MemBuffer::getBufferStart() { 
  return reinterpret_cast<uint8_t *>(Buf->getBufferStart()); 
} 
 
std::unique_ptr<WritableMemoryBuffer> MemBuffer::releaseMemoryBuffer() { 
  return std::move(Buf); 
} 
 
} // end namespace objcopy 
} // end namespace llvm