1//===- Buffer.cpp ---------------------------------------------------------===// 2// 3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4// See https://llvm.org/LICENSE.txt for license information. 5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6// 7//===----------------------------------------------------------------------===// 8 9#include "Buffer.h" 10#include "llvm/Support/FileOutputBuffer.h" 11#include "llvm/Support/FileSystem.h" 12#include "llvm/Support/MemoryBuffer.h" 13#include "llvm/Support/Process.h" 14#include <memory> 15 16namespace llvm { 17namespace objcopy { 18 19Buffer::~Buffer() {} 20 21static Error createEmptyFile(StringRef FileName) { 22 // Create an empty tempfile and atomically swap it in place with the desired 23 // output file. 24 Expected<sys::fs::TempFile> Temp = 25 sys::fs::TempFile::create(FileName + ".temp-empty-%%%%%%%"); 26 return Temp ? Temp->keep(FileName) : Temp.takeError(); 27} 28 29Error FileBuffer::allocate(size_t Size) { 30 // When a 0-sized file is requested, skip allocation but defer file 31 // creation/truncation until commit() to avoid side effects if something 32 // happens between allocate() and commit(). 33 if (Size == 0) { 34 EmptyFile = true; 35 return Error::success(); 36 } 37 38 Expected<std::unique_ptr<FileOutputBuffer>> BufferOrErr = 39 FileOutputBuffer::create(getName(), Size, FileOutputBuffer::F_executable); 40 // FileOutputBuffer::create() returns an Error that is just a wrapper around 41 // std::error_code. Wrap it in FileError to include the actual filename. 42 if (!BufferOrErr) 43 return createFileError(getName(), BufferOrErr.takeError()); 44 Buf = std::move(*BufferOrErr); 45 return Error::success(); 46} 47 48Error FileBuffer::commit() { 49 if (EmptyFile) 50 return createEmptyFile(getName()); 51 52 assert(Buf && "allocate() not called before commit()!"); 53 Error Err = Buf->commit(); 54 // FileOutputBuffer::commit() returns an Error that is just a wrapper around 55 // std::error_code. Wrap it in FileError to include the actual filename. 56 return Err ? createFileError(getName(), std::move(Err)) : std::move(Err); 57} 58 59uint8_t *FileBuffer::getBufferStart() { 60 return reinterpret_cast<uint8_t *>(Buf->getBufferStart()); 61} 62 63Error MemBuffer::allocate(size_t Size) { 64 Buf = WritableMemoryBuffer::getNewMemBuffer(Size, getName()); 65 return Error::success(); 66} 67 68Error MemBuffer::commit() { return Error::success(); } 69 70uint8_t *MemBuffer::getBufferStart() { 71 return reinterpret_cast<uint8_t *>(Buf->getBufferStart()); 72} 73 74std::unique_ptr<WritableMemoryBuffer> MemBuffer::releaseMemoryBuffer() { 75 return std::move(Buf); 76} 77 78} // end namespace objcopy 79} // end namespace llvm 80