1 //===--- MemoryBuffer.h - Memory Buffer Interface ---------------*- 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 // This file defines the MemoryBuffer interface. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_SUPPORT_MEMORYBUFFER_H 15 #define LLVM_SUPPORT_MEMORYBUFFER_H 16 17 #include "llvm-c/Support.h" 18 #include "llvm/ADT/Twine.h" 19 #include "llvm/Support/CBindingWrapping.h" 20 #include "llvm/Support/DataTypes.h" 21 #include "llvm/Support/ErrorOr.h" 22 #include <memory> 23 24 namespace llvm { 25 class MemoryBufferRef; 26 27 /// This interface provides simple read-only access to a block of memory, and 28 /// provides simple methods for reading files and standard input into a memory 29 /// buffer. In addition to basic access to the characters in the file, this 30 /// interface guarantees you can read one character past the end of the file, 31 /// and that this character will read as '\0'. 32 /// 33 /// The '\0' guarantee is needed to support an optimization -- it's intended to 34 /// be more efficient for clients which are reading all the data to stop 35 /// reading when they encounter a '\0' than to continually check the file 36 /// position to see if it has reached the end of the file. 37 class MemoryBuffer { 38 const char *BufferStart; // Start of the buffer. 39 const char *BufferEnd; // End of the buffer. 40 41 MemoryBuffer(const MemoryBuffer &) = delete; 42 MemoryBuffer &operator=(const MemoryBuffer &) = delete; 43 protected: 44 MemoryBuffer() {} 45 void init(const char *BufStart, const char *BufEnd, 46 bool RequiresNullTerminator); 47 public: 48 virtual ~MemoryBuffer(); 49 50 const char *getBufferStart() const { return BufferStart; } 51 const char *getBufferEnd() const { return BufferEnd; } 52 size_t getBufferSize() const { return BufferEnd-BufferStart; } 53 54 StringRef getBuffer() const { 55 return StringRef(BufferStart, getBufferSize()); 56 } 57 58 /// Return an identifier for this buffer, typically the filename it was read 59 /// from. 60 virtual const char *getBufferIdentifier() const { 61 return "Unknown buffer"; 62 } 63 64 /// Open the specified file as a MemoryBuffer, returning a new MemoryBuffer 65 /// if successful, otherwise returning null. If FileSize is specified, this 66 /// means that the client knows that the file exists and that it has the 67 /// specified size. 68 /// 69 /// \param IsVolatileSize Set to true to indicate that the file size may be 70 /// changing, e.g. when libclang tries to parse while the user is 71 /// editing/updating the file. 72 static ErrorOr<std::unique_ptr<MemoryBuffer>> 73 getFile(const Twine &Filename, int64_t FileSize = -1, 74 bool RequiresNullTerminator = true, bool IsVolatileSize = false); 75 76 /// Given an already-open file descriptor, map some slice of it into a 77 /// MemoryBuffer. The slice is specified by an \p Offset and \p MapSize. 78 /// Since this is in the middle of a file, the buffer is not null terminated. 79 static ErrorOr<std::unique_ptr<MemoryBuffer>> 80 getOpenFileSlice(int FD, const Twine &Filename, uint64_t MapSize, 81 int64_t Offset); 82 83 /// Given an already-open file descriptor, read the file and return a 84 /// MemoryBuffer. 85 /// 86 /// \param IsVolatileSize Set to true to indicate that the file size may be 87 /// changing, e.g. when libclang tries to parse while the user is 88 /// editing/updating the file. 89 static ErrorOr<std::unique_ptr<MemoryBuffer>> 90 getOpenFile(int FD, const Twine &Filename, uint64_t FileSize, 91 bool RequiresNullTerminator = true, bool IsVolatileSize = false); 92 93 /// Open the specified memory range as a MemoryBuffer. Note that InputData 94 /// must be null terminated if RequiresNullTerminator is true. 95 static std::unique_ptr<MemoryBuffer> 96 getMemBuffer(StringRef InputData, StringRef BufferName = "", 97 bool RequiresNullTerminator = true); 98 99 static std::unique_ptr<MemoryBuffer> 100 getMemBuffer(MemoryBufferRef Ref, bool RequiresNullTerminator = true); 101 102 /// Open the specified memory range as a MemoryBuffer, copying the contents 103 /// and taking ownership of it. InputData does not have to be null terminated. 104 static std::unique_ptr<MemoryBuffer> 105 getMemBufferCopy(StringRef InputData, const Twine &BufferName = ""); 106 107 /// Allocate a new zero-initialized MemoryBuffer of the specified size. Note 108 /// that the caller need not initialize the memory allocated by this method. 109 /// The memory is owned by the MemoryBuffer object. 110 static std::unique_ptr<MemoryBuffer> 111 getNewMemBuffer(size_t Size, StringRef BufferName = ""); 112 113 /// Allocate a new MemoryBuffer of the specified size that is not initialized. 114 /// Note that the caller should initialize the memory allocated by this 115 /// method. The memory is owned by the MemoryBuffer object. 116 static std::unique_ptr<MemoryBuffer> 117 getNewUninitMemBuffer(size_t Size, const Twine &BufferName = ""); 118 119 /// Read all of stdin into a file buffer, and return it. 120 static ErrorOr<std::unique_ptr<MemoryBuffer>> getSTDIN(); 121 122 /// Open the specified file as a MemoryBuffer, or open stdin if the Filename 123 /// is "-". 124 static ErrorOr<std::unique_ptr<MemoryBuffer>> 125 getFileOrSTDIN(const Twine &Filename, int64_t FileSize = -1); 126 127 /// Map a subrange of the the specified file as a MemoryBuffer. 128 static ErrorOr<std::unique_ptr<MemoryBuffer>> 129 getFileSlice(const Twine &Filename, uint64_t MapSize, uint64_t Offset); 130 131 //===--------------------------------------------------------------------===// 132 // Provided for performance analysis. 133 //===--------------------------------------------------------------------===// 134 135 /// The kind of memory backing used to support the MemoryBuffer. 136 enum BufferKind { 137 MemoryBuffer_Malloc, 138 MemoryBuffer_MMap 139 }; 140 141 /// Return information on the memory mechanism used to support the 142 /// MemoryBuffer. 143 virtual BufferKind getBufferKind() const = 0; 144 145 MemoryBufferRef getMemBufferRef() const; 146 }; 147 148 class MemoryBufferRef { 149 StringRef Buffer; 150 StringRef Identifier; 151 152 public: 153 MemoryBufferRef() {} 154 MemoryBufferRef(StringRef Buffer, StringRef Identifier) 155 : Buffer(Buffer), Identifier(Identifier) {} 156 157 StringRef getBuffer() const { return Buffer; } 158 159 StringRef getBufferIdentifier() const { return Identifier; } 160 161 const char *getBufferStart() const { return Buffer.begin(); } 162 const char *getBufferEnd() const { return Buffer.end(); } 163 size_t getBufferSize() const { return Buffer.size(); } 164 }; 165 166 // Create wrappers for C Binding types (see CBindingWrapping.h). 167 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(MemoryBuffer, LLVMMemoryBufferRef) 168 169 } // end namespace llvm 170 171 #endif 172
