1 //=== FileOutputBuffer.h - File Output Buffer -------------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // Utility for creating a in-memory buffer that will be written to a file. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_SUPPORT_FILEOUTPUTBUFFER_H 15 #define LLVM_SUPPORT_FILEOUTPUTBUFFER_H 16 17 #include "llvm/ADT/SmallString.h" 18 #include "llvm/ADT/StringRef.h" 19 #include "llvm/Support/DataTypes.h" 20 #include "llvm/Support/ErrorOr.h" 21 #include "llvm/Support/FileSystem.h" 22 23 namespace llvm { 24 /// FileOutputBuffer - This interface provides simple way to create an in-memory 25 /// buffer which will be written to a file. During the lifetime of these 26 /// objects, the content or existence of the specified file is undefined. That 27 /// is, creating an OutputBuffer for a file may immediately remove the file. 28 /// If the FileOutputBuffer is committed, the target file's content will become 29 /// the buffer content at the time of the commit. If the FileOutputBuffer is 30 /// not committed, the file will be deleted in the FileOutputBuffer destructor. 31 class FileOutputBuffer { 32 public: 33 34 enum { 35 F_executable = 1 /// set the 'x' bit on the resulting file 36 }; 37 38 /// Factory method to create an OutputBuffer object which manages a read/write 39 /// buffer of the specified size. When committed, the buffer will be written 40 /// to the file at the specified path. 41 static ErrorOr<std::unique_ptr<FileOutputBuffer>> 42 create(StringRef FilePath, size_t Size, unsigned Flags = 0); 43 44 /// Returns a pointer to the start of the buffer. 45 uint8_t *getBufferStart() { 46 return (uint8_t*)Region->data(); 47 } 48 49 /// Returns a pointer to the end of the buffer. 50 uint8_t *getBufferEnd() { 51 return (uint8_t*)Region->data() + Region->size(); 52 } 53 54 /// Returns size of the buffer. 55 size_t getBufferSize() const { 56 return Region->size(); 57 } 58 59 /// Returns path where file will show up if buffer is committed. 60 StringRef getPath() const { 61 return FinalPath; 62 } 63 64 /// Flushes the content of the buffer to its file and deallocates the 65 /// buffer. If commit() is not called before this object's destructor 66 /// is called, the file is deleted in the destructor. The optional parameter 67 /// is used if it turns out you want the file size to be smaller than 68 /// initially requested. 69 std::error_code commit(); 70 71 /// If this object was previously committed, the destructor just deletes 72 /// this object. If this object was not committed, the destructor 73 /// deallocates the buffer and the target file is never written. 74 ~FileOutputBuffer(); 75 76 private: 77 FileOutputBuffer(const FileOutputBuffer &) = delete; 78 FileOutputBuffer &operator=(const FileOutputBuffer &) = delete; 79 80 FileOutputBuffer(std::unique_ptr<llvm::sys::fs::mapped_file_region> R, 81 StringRef Path, StringRef TempPath, bool IsRegular); 82 83 std::unique_ptr<llvm::sys::fs::mapped_file_region> Region; 84 SmallString<128> FinalPath; 85 SmallString<128> TempPath; 86 bool IsRegular; 87 }; 88 } // end namespace llvm 89 90 #endif 91
