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/Types.h" 18 #include "llvm/ADT/StringRef.h" 19 #include "llvm/ADT/Twine.h" 20 #include "llvm/Support/CBindingWrapping.h" 21 #include "llvm/Support/ErrorOr.h" 22 #include <cstddef> 23 #include <cstdint> 24 #include <memory> 25 26 namespace llvm { 27 28 class MemoryBufferRef; 29 30 /// This interface provides simple read-only access to a block of memory, and 31 /// provides simple methods for reading files and standard input into a memory 32 /// buffer. In addition to basic access to the characters in the file, this 33 /// interface guarantees you can read one character past the end of the file, 34 /// and that this character will read as '\0'. 35 /// 36 /// The '\0' guarantee is needed to support an optimization -- it's intended to 37 /// be more efficient for clients which are reading all the data to stop 38 /// reading when they encounter a '\0' than to continually check the file 39 /// position to see if it has reached the end of the file. 40 class MemoryBuffer { 41 const char *BufferStart; // Start of the buffer. 42 const char *BufferEnd; // End of the buffer. 43 44 45 protected: 46 MemoryBuffer() = default; 47 48 void init(const char *BufStart, const char *BufEnd, 49 bool RequiresNullTerminator); 50 public: 51 MemoryBuffer(const MemoryBuffer &) = delete; 52 MemoryBuffer &operator=(const MemoryBuffer &) = delete; 53 virtual ~MemoryBuffer(); 54 55 const char *getBufferStart() const { return BufferStart; } 56 const char *getBufferEnd() const { return BufferEnd; } 57 size_t getBufferSize() const { return BufferEnd-BufferStart; } 58 59 StringRef getBuffer() const { 60 return StringRef(BufferStart, getBufferSize()); 61 } 62 63 /// Return an identifier for this buffer, typically the filename it was read 64 /// from. 65 virtual StringRef getBufferIdentifier() const { return "Unknown buffer"; } 66 67 /// Open the specified file as a MemoryBuffer, returning a new MemoryBuffer 68 /// if successful, otherwise returning null. If FileSize is specified, this 69 /// means that the client knows that the file exists and that it has the 70 /// specified size. 71 /// 72 /// \param IsVolatile Set to true to indicate that the contents of the file 73 /// can change outside the user's control, e.g. when libclang tries to parse 74 /// while the user is editing/updating the file or if the file is on an NFS. 75 static ErrorOr<std::unique_ptr<MemoryBuffer>> 76 getFile(const Twine &Filename, int64_t FileSize = -1, 77 bool RequiresNullTerminator = true, bool IsVolatile = false); 78 79 /// Read all of the specified file into a MemoryBuffer as a stream 80 /// (i.e. until EOF reached). This is useful for special files that 81 /// look like a regular file but have 0 size (e.g. /proc/cpuinfo on Linux). 82 static ErrorOr<std::unique_ptr<MemoryBuffer>> 83 getFileAsStream(const Twine &Filename); 84 85 /// Given an already-open file descriptor, map some slice of it into a 86 /// MemoryBuffer. The slice is specified by an \p Offset and \p MapSize. 87 /// Since this is in the middle of a file, the buffer is not null terminated. 88 static ErrorOr<std::unique_ptr<MemoryBuffer>> 89 getOpenFileSlice(int FD, const Twine &Filename, uint64_t MapSize, 90 int64_t Offset, bool IsVolatile = false); 91 92 /// Given an already-open file descriptor, read the file and return a 93 /// MemoryBuffer. 94 /// 95 /// \param IsVolatile Set to true to indicate that the contents of the file 96 /// can change outside the user's control, e.g. when libclang tries to parse 97 /// while the user is editing/updating the file or if the file is on an NFS. 98 static ErrorOr<std::unique_ptr<MemoryBuffer>> 99 getOpenFile(int FD, const Twine &Filename, uint64_t FileSize, 100 bool RequiresNullTerminator = true, bool IsVolatile = false); 101 102 /// Open the specified memory range as a MemoryBuffer. Note that InputData 103 /// must be null terminated if RequiresNullTerminator is true. 104 static std::unique_ptr<MemoryBuffer> 105 getMemBuffer(StringRef InputData, StringRef BufferName = "", 106 bool RequiresNullTerminator = true); 107 108 static std::unique_ptr<MemoryBuffer> 109 getMemBuffer(MemoryBufferRef Ref, bool RequiresNullTerminator = true); 110 111 /// Open the specified memory range as a MemoryBuffer, copying the contents 112 /// and taking ownership of it. InputData does not have to be null terminated. 113 static std::unique_ptr<MemoryBuffer> 114 getMemBufferCopy(StringRef InputData, const Twine &BufferName = ""); 115 116 /// Allocate a new zero-initialized MemoryBuffer of the specified size. Note 117 /// that the caller need not initialize the memory allocated by this method. 118 /// The memory is owned by the MemoryBuffer object. 119 static std::unique_ptr<MemoryBuffer> 120 getNewMemBuffer(size_t Size, StringRef BufferName = ""); 121 122 /// Allocate a new MemoryBuffer of the specified size that is not initialized. 123 /// Note that the caller should initialize the memory allocated by this 124 /// method. The memory is owned by the MemoryBuffer object. 125 static std::unique_ptr<MemoryBuffer> 126 getNewUninitMemBuffer(size_t Size, const Twine &BufferName = ""); 127 128 /// Read all of stdin into a file buffer, and return it. 129 static ErrorOr<std::unique_ptr<MemoryBuffer>> getSTDIN(); 130 131 /// Open the specified file as a MemoryBuffer, or open stdin if the Filename 132 /// is "-". 133 static ErrorOr<std::unique_ptr<MemoryBuffer>> 134 getFileOrSTDIN(const Twine &Filename, int64_t FileSize = -1, 135 bool RequiresNullTerminator = true); 136 137 /// Map a subrange of the specified file as a MemoryBuffer. 138 static ErrorOr<std::unique_ptr<MemoryBuffer>> 139 getFileSlice(const Twine &Filename, uint64_t MapSize, uint64_t Offset, bool IsVolatile = false); 140 141 //===--------------------------------------------------------------------===// 142 // Provided for performance analysis. 143 //===--------------------------------------------------------------------===// 144 145 /// The kind of memory backing used to support the MemoryBuffer. 146 enum BufferKind { 147 MemoryBuffer_Malloc, 148 MemoryBuffer_MMap 149 }; 150 151 /// Return information on the memory mechanism used to support the 152 /// MemoryBuffer. 153 virtual BufferKind getBufferKind() const = 0; 154 155 MemoryBufferRef getMemBufferRef() const; 156 }; 157 158 class MemoryBufferRef { 159 StringRef Buffer; 160 StringRef Identifier; 161 162 public: 163 MemoryBufferRef() = default; 164 MemoryBufferRef(MemoryBuffer& Buffer) 165 : Buffer(Buffer.getBuffer()), Identifier(Buffer.getBufferIdentifier()) {} 166 MemoryBufferRef(StringRef Buffer, StringRef Identifier) 167 : Buffer(Buffer), Identifier(Identifier) {} 168 169 StringRef getBuffer() const { return Buffer; } 170 171 StringRef getBufferIdentifier() const { return Identifier; } 172 173 const char *getBufferStart() const { return Buffer.begin(); } 174 const char *getBufferEnd() const { return Buffer.end(); } 175 size_t getBufferSize() const { return Buffer.size(); } 176 }; 177 178 // Create wrappers for C Binding types (see CBindingWrapping.h). 179 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(MemoryBuffer, LLVMMemoryBufferRef) 180 181 } // end namespace llvm 182 183 #endif // LLVM_SUPPORT_MEMORYBUFFER_H 184
