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llvm-mirror/tools/llvm-objcopy/Buffer.h
Jordan Rupprecht 801060bf79 [llvm-objcopy] Fix crash when writing empty binary output
Summary: When using llvm-objcopy -O binary and the resulting file will be empty (e.g. removing the only section that would be written, or using --only-keep with a section that doesn't exist/isn't SHF_ALLOC), we crash because FileOutputBuffer expects Size > 0. Add a regression test, and change Buffer to open/truncate the output file in this case.

Reviewers: alexshap, jhenderson, jakehehrlich, espindola

Reviewed By: alexshap, jhenderson

Subscribers: jfb, llvm-commits, emaste, arichardson

Differential Revision: https://reviews.llvm.org/D56806

llvm-svn: 352371
2019-01-28 15:02:40 +00:00

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2.0 KiB
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//===- Buffer.h -------------------------------------------------*- 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
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TOOLS_OBJCOPY_BUFFER_H
#define LLVM_TOOLS_OBJCOPY_BUFFER_H
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/FileOutputBuffer.h"
#include "llvm/Support/MemoryBuffer.h"
#include <memory>
namespace llvm {
namespace objcopy {
// The class Buffer abstracts out the common interface of FileOutputBuffer and
// WritableMemoryBuffer so that the hierarchy of Writers depends on this
// abstract interface and doesn't depend on a particular implementation.
// TODO: refactor the buffer classes in LLVM to enable us to use them here
// directly.
class Buffer {
StringRef Name;
public:
virtual ~Buffer();
virtual Error allocate(size_t Size) = 0;
virtual uint8_t *getBufferStart() = 0;
virtual Error commit() = 0;
explicit Buffer(StringRef Name) : Name(Name) {}
StringRef getName() const { return Name; }
};
class FileBuffer : public Buffer {
std::unique_ptr<FileOutputBuffer> Buf;
// Indicates that allocate(0) was called, and commit() should create or
// truncate a file instead of using a FileOutputBuffer.
bool EmptyFile = false;
public:
Error allocate(size_t Size) override;
uint8_t *getBufferStart() override;
Error commit() override;
explicit FileBuffer(StringRef FileName) : Buffer(FileName) {}
};
class MemBuffer : public Buffer {
std::unique_ptr<WritableMemoryBuffer> Buf;
public:
Error allocate(size_t Size) override;
uint8_t *getBufferStart() override;
Error commit() override;
explicit MemBuffer(StringRef Name) : Buffer(Name) {}
std::unique_ptr<WritableMemoryBuffer> releaseMemoryBuffer();
};
} // end namespace objcopy
} // end namespace llvm
#endif // LLVM_TOOLS_OBJCOPY_BUFFER_H