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bdc220866d
When writing to a non regular file we cannot rename to it. Since we have to write, we may as well create a temporary file to avoid trying to create an unique file in /dev when trying to write to /dev/null. llvm-svn: 291485
91 lines
3.2 KiB
C++
91 lines
3.2 KiB
C++
//=== FileOutputBuffer.h - File Output Buffer -------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// Utility for creating a in-memory buffer that will be written to a file.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_FILEOUTPUTBUFFER_H
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#define LLVM_SUPPORT_FILEOUTPUTBUFFER_H
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#include "llvm/ADT/SmallString.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/Support/DataTypes.h"
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#include "llvm/Support/ErrorOr.h"
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#include "llvm/Support/FileSystem.h"
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namespace llvm {
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/// FileOutputBuffer - This interface provides simple way to create an in-memory
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/// buffer which will be written to a file. During the lifetime of these
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/// objects, the content or existence of the specified file is undefined. That
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/// is, creating an OutputBuffer for a file may immediately remove the file.
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/// If the FileOutputBuffer is committed, the target file's content will become
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/// the buffer content at the time of the commit. If the FileOutputBuffer is
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/// not committed, the file will be deleted in the FileOutputBuffer destructor.
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class FileOutputBuffer {
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public:
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enum {
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F_executable = 1 /// set the 'x' bit on the resulting file
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};
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/// Factory method to create an OutputBuffer object which manages a read/write
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/// buffer of the specified size. When committed, the buffer will be written
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/// to the file at the specified path.
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static ErrorOr<std::unique_ptr<FileOutputBuffer>>
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create(StringRef FilePath, size_t Size, unsigned Flags = 0);
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/// Returns a pointer to the start of the buffer.
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uint8_t *getBufferStart() {
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return (uint8_t*)Region->data();
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}
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/// Returns a pointer to the end of the buffer.
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uint8_t *getBufferEnd() {
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return (uint8_t*)Region->data() + Region->size();
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}
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/// Returns size of the buffer.
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size_t getBufferSize() const {
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return Region->size();
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}
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/// Returns path where file will show up if buffer is committed.
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StringRef getPath() const {
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return FinalPath;
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}
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/// Flushes the content of the buffer to its file and deallocates the
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/// buffer. If commit() is not called before this object's destructor
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/// is called, the file is deleted in the destructor. The optional parameter
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/// is used if it turns out you want the file size to be smaller than
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/// initially requested.
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std::error_code commit();
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/// If this object was previously committed, the destructor just deletes
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/// this object. If this object was not committed, the destructor
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/// deallocates the buffer and the target file is never written.
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~FileOutputBuffer();
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private:
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FileOutputBuffer(const FileOutputBuffer &) = delete;
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FileOutputBuffer &operator=(const FileOutputBuffer &) = delete;
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FileOutputBuffer(std::unique_ptr<llvm::sys::fs::mapped_file_region> R,
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StringRef Path, StringRef TempPath, bool IsRegular);
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std::unique_ptr<llvm::sys::fs::mapped_file_region> Region;
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SmallString<128> FinalPath;
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SmallString<128> TempPath;
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bool IsRegular;
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};
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} // end namespace llvm
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#endif
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