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| Rev | Author | Line No. | Line |
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| 14 | pmbaty | 1 | //=== FileOutputBuffer.h - File Output Buffer -------------------*- C++ -*-===// |
| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | // |
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| 9 | // Utility for creating a in-memory buffer that will be written to a file. |
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| 10 | // |
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| 11 | //===----------------------------------------------------------------------===// |
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| 12 | |||
| 13 | #ifndef LLVM_SUPPORT_FILEOUTPUTBUFFER_H |
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| 14 | #define LLVM_SUPPORT_FILEOUTPUTBUFFER_H |
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| 15 | |||
| 16 | #include "llvm/ADT/StringRef.h" |
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| 17 | #include "llvm/Support/DataTypes.h" |
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| 18 | #include "llvm/Support/Error.h" |
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| 19 | |||
| 20 | namespace llvm { |
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| 21 | /// FileOutputBuffer - This interface provides simple way to create an in-memory |
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| 22 | /// buffer which will be written to a file. During the lifetime of these |
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| 23 | /// objects, the content or existence of the specified file is undefined. That |
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| 24 | /// is, creating an OutputBuffer for a file may immediately remove the file. |
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| 25 | /// If the FileOutputBuffer is committed, the target file's content will become |
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| 26 | /// the buffer content at the time of the commit. If the FileOutputBuffer is |
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| 27 | /// not committed, the file will be deleted in the FileOutputBuffer destructor. |
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| 28 | class FileOutputBuffer { |
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| 29 | public: |
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| 30 | enum { |
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| 31 | /// Set the 'x' bit on the resulting file. |
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| 32 | F_executable = 1, |
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| 33 | |||
| 34 | /// Don't use mmap and instead write an in-memory buffer to a file when this |
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| 35 | /// buffer is closed. |
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| 36 | F_no_mmap = 2, |
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| 37 | }; |
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| 38 | |||
| 39 | /// Factory method to create an OutputBuffer object which manages a read/write |
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| 40 | /// buffer of the specified size. When committed, the buffer will be written |
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| 41 | /// to the file at the specified path. |
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| 42 | /// |
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| 43 | /// When F_modify is specified and \p FilePath refers to an existing on-disk |
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| 44 | /// file \p Size may be set to -1, in which case the entire file is used. |
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| 45 | /// Otherwise, the file shrinks or grows as necessary based on the value of |
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| 46 | /// \p Size. It is an error to specify F_modify and Size=-1 if \p FilePath |
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| 47 | /// does not exist. |
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| 48 | static Expected<std::unique_ptr<FileOutputBuffer>> |
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| 49 | create(StringRef FilePath, size_t Size, unsigned Flags = 0); |
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| 50 | |||
| 51 | /// Returns a pointer to the start of the buffer. |
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| 52 | virtual uint8_t *getBufferStart() const = 0; |
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| 53 | |||
| 54 | /// Returns a pointer to the end of the buffer. |
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| 55 | virtual uint8_t *getBufferEnd() const = 0; |
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| 56 | |||
| 57 | /// Returns size of the buffer. |
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| 58 | virtual size_t getBufferSize() const = 0; |
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| 59 | |||
| 60 | /// Returns path where file will show up if buffer is committed. |
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| 61 | StringRef getPath() const { return FinalPath; } |
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| 62 | |||
| 63 | /// Flushes the content of the buffer to its file and deallocates the |
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| 64 | /// buffer. If commit() is not called before this object's destructor |
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| 65 | /// is called, the file is deleted in the destructor. The optional parameter |
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| 66 | /// is used if it turns out you want the file size to be smaller than |
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| 67 | /// initially requested. |
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| 68 | virtual Error commit() = 0; |
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| 69 | |||
| 70 | /// If this object was previously committed, the destructor just deletes |
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| 71 | /// this object. If this object was not committed, the destructor |
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| 72 | /// deallocates the buffer and the target file is never written. |
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| 73 | virtual ~FileOutputBuffer() = default; |
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| 74 | |||
| 75 | /// This removes the temporary file (unless it already was committed) |
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| 76 | /// but keeps the memory mapping alive. |
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| 77 | virtual void discard() {} |
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| 78 | |||
| 79 | protected: |
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| 80 | FileOutputBuffer(StringRef Path) : FinalPath(Path) {} |
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| 81 | |||
| 82 | std::string FinalPath; |
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| 83 | }; |
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| 84 | } // end namespace llvm |
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| 85 | |||
| 86 | #endif |