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llvm-mirror/include/llvm/Support/FileOutputBuffer.h
Chandler Carruth ae65e281f3 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00

85 lines
3.3 KiB
C++

//=== FileOutputBuffer.h - 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.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_FILEOUTPUTBUFFER_H
#define LLVM_SUPPORT_FILEOUTPUTBUFFER_H
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/DataTypes.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/FileSystem.h"
namespace llvm {
/// FileOutputBuffer - This interface provides simple way to create an in-memory
/// buffer which will be written to a file. During the lifetime of these
/// objects, the content or existence of the specified file is undefined. That
/// is, creating an OutputBuffer for a file may immediately remove the file.
/// If the FileOutputBuffer is committed, the target file's content will become
/// the buffer content at the time of the commit. If the FileOutputBuffer is
/// not committed, the file will be deleted in the FileOutputBuffer destructor.
class FileOutputBuffer {
public:
enum {
/// set the 'x' bit on the resulting file
F_executable = 1,
};
/// Factory method to create an OutputBuffer object which manages a read/write
/// buffer of the specified size. When committed, the buffer will be written
/// to the file at the specified path.
///
/// When F_modify is specified and \p FilePath refers to an existing on-disk
/// file \p Size may be set to -1, in which case the entire file is used.
/// Otherwise, the file shrinks or grows as necessary based on the value of
/// \p Size. It is an error to specify F_modify and Size=-1 if \p FilePath
/// does not exist.
static Expected<std::unique_ptr<FileOutputBuffer>>
create(StringRef FilePath, size_t Size, unsigned Flags = 0);
/// Returns a pointer to the start of the buffer.
virtual uint8_t *getBufferStart() const = 0;
/// Returns a pointer to the end of the buffer.
virtual uint8_t *getBufferEnd() const = 0;
/// Returns size of the buffer.
virtual size_t getBufferSize() const = 0;
/// Returns path where file will show up if buffer is committed.
StringRef getPath() const { return FinalPath; }
/// Flushes the content of the buffer to its file and deallocates the
/// buffer. If commit() is not called before this object's destructor
/// is called, the file is deleted in the destructor. The optional parameter
/// is used if it turns out you want the file size to be smaller than
/// initially requested.
virtual Error commit() = 0;
/// If this object was previously committed, the destructor just deletes
/// this object. If this object was not committed, the destructor
/// deallocates the buffer and the target file is never written.
virtual ~FileOutputBuffer() {}
/// This removes the temporary file (unless it already was committed)
/// but keeps the memory mapping alive.
virtual void discard() {}
protected:
FileOutputBuffer(StringRef Path) : FinalPath(Path) {}
std::string FinalPath;
};
} // end namespace llvm
#endif