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/Compiler.h" 21 #include "llvm/Support/DataTypes.h" 22 #include "llvm/Support/ErrorOr.h" 23 #include <memory> 24 #include <system_error> 25 26 namespace llvm { 27 /// MemoryBuffer - This interface provides simple read-only access to a block 28 /// of memory, and provides simple methods for reading files and standard input 29 /// into a memory buffer. In addition to basic access to the characters in the 30 /// file, this interface guarantees you can read one character past the end of 31 /// the file, 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 &) LLVM_DELETED_FUNCTION; 42 MemoryBuffer &operator=(const MemoryBuffer &) LLVM_DELETED_FUNCTION; 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 /// getBufferIdentifier - Return an identifier for this buffer, typically the 59 /// filename it was read 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(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 /// 80 /// \param IsVolatileSize Set to true to indicate that the file size may be 81 /// changing, e.g. when libclang tries to parse while the user is 82 /// editing/updating the file. 83 static ErrorOr<std::unique_ptr<MemoryBuffer>> 84 getOpenFileSlice(int FD, const char *Filename, uint64_t MapSize, 85 int64_t Offset, bool IsVolatileSize = false); 86 87 /// Given an already-open file descriptor, read the file and return a 88 /// MemoryBuffer. 89 /// 90 /// \param IsVolatileSize Set to true to indicate that the file size may be 91 /// changing, e.g. when libclang tries to parse while the user is 92 /// editing/updating the file. 93 static ErrorOr<std::unique_ptr<MemoryBuffer>> 94 getOpenFile(int FD, const char *Filename, uint64_t FileSize, 95 bool RequiresNullTerminator = true, bool IsVolatileSize = false); 96 97 /// getMemBuffer - Open the specified memory range as a MemoryBuffer. Note 98 /// that InputData must be null terminated if RequiresNullTerminator is true. 99 static MemoryBuffer *getMemBuffer(StringRef InputData, 100 StringRef BufferName = "", 101 bool RequiresNullTerminator = true); 102 103 /// getMemBufferCopy - Open the specified memory range as a MemoryBuffer, 104 /// copying the contents and taking ownership of it. InputData does not 105 /// have to be null terminated. 106 static MemoryBuffer *getMemBufferCopy(StringRef InputData, 107 StringRef BufferName = ""); 108 109 /// getNewMemBuffer - Allocate a new MemoryBuffer of the specified size that 110 /// is completely initialized to zeros. Note that the caller should 111 /// initialize the memory allocated by this method. The memory is owned by 112 /// the MemoryBuffer object. 113 static MemoryBuffer *getNewMemBuffer(size_t Size, StringRef BufferName = ""); 114 115 /// getNewUninitMemBuffer - Allocate a new MemoryBuffer of the specified size 116 /// that is not initialized. Note that the caller should initialize the 117 /// memory allocated by this method. The memory is owned by the MemoryBuffer 118 /// object. 119 static MemoryBuffer *getNewUninitMemBuffer(size_t Size, 120 StringRef BufferName = ""); 121 122 /// Read all of stdin into a file buffer, and return it. 123 static ErrorOr<std::unique_ptr<MemoryBuffer>> getSTDIN(); 124 125 /// Open the specified file as a MemoryBuffer, or open stdin if the Filename 126 /// is "-". 127 static ErrorOr<std::unique_ptr<MemoryBuffer>> 128 getFileOrSTDIN(StringRef Filename, int64_t FileSize = -1); 129 130 //===--------------------------------------------------------------------===// 131 // Provided for performance analysis. 132 //===--------------------------------------------------------------------===// 133 134 /// The kind of memory backing used to support the MemoryBuffer. 135 enum BufferKind { 136 MemoryBuffer_Malloc, 137 MemoryBuffer_MMap 138 }; 139 140 /// Return information on the memory mechanism used to support the 141 /// MemoryBuffer. 142 virtual BufferKind getBufferKind() const = 0; 143 }; 144 145 // Create wrappers for C Binding types (see CBindingWrapping.h). 146 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(MemoryBuffer, LLVMMemoryBufferRef) 147 148 } // end namespace llvm 149 150 #endif 151
