//===--- MemoryBuffer.h - Memory Buffer Interface ---------------*- C++ -*-===// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// // // This file defines the MemoryBuffer interface. // //===----------------------------------------------------------------------===// #ifndef LLVM_SUPPORT_MEMORYBUFFER_H #define LLVM_SUPPORT_MEMORYBUFFER_H #include "llvm-c/Types.h" #include "llvm/ADT/ArrayRef.h" #include "llvm/ADT/StringRef.h" #include "llvm/ADT/Twine.h" #include "llvm/Support/CBindingWrapping.h" #include "llvm/Support/ErrorOr.h" #include "llvm/Support/FileSystem.h" #include #include #include namespace llvm { class MemoryBufferRef; /// This interface provides simple read-only access to a block of memory, and /// provides simple methods for reading files and standard input into a memory /// buffer. In addition to basic access to the characters in the file, this /// interface guarantees you can read one character past the end of the file, /// and that this character will read as '\0'. /// /// The '\0' guarantee is needed to support an optimization -- it's intended to /// be more efficient for clients which are reading all the data to stop /// reading when they encounter a '\0' than to continually check the file /// position to see if it has reached the end of the file. class MemoryBuffer { const char *BufferStart; // Start of the buffer. const char *BufferEnd; // End of the buffer. protected: MemoryBuffer() = default; void init(const char *BufStart, const char *BufEnd, bool RequiresNullTerminator); static constexpr sys::fs::mapped_file_region::mapmode Mapmode = sys::fs::mapped_file_region::readonly; public: MemoryBuffer(const MemoryBuffer &) = delete; MemoryBuffer &operator=(const MemoryBuffer &) = delete; virtual ~MemoryBuffer(); const char *getBufferStart() const { return BufferStart; } const char *getBufferEnd() const { return BufferEnd; } size_t getBufferSize() const { return BufferEnd-BufferStart; } StringRef getBuffer() const { return StringRef(BufferStart, getBufferSize()); } /// Return an identifier for this buffer, typically the filename it was read /// from. virtual StringRef getBufferIdentifier() const { return "Unknown buffer"; } /// Open the specified file as a MemoryBuffer, returning a new MemoryBuffer /// if successful, otherwise returning null. If FileSize is specified, this /// means that the client knows that the file exists and that it has the /// specified size. /// /// \param IsVolatile Set to true to indicate that the contents of the file /// can change outside the user's control, e.g. when libclang tries to parse /// while the user is editing/updating the file or if the file is on an NFS. static ErrorOr> getFile(const Twine &Filename, int64_t FileSize = -1, bool RequiresNullTerminator = true, bool IsVolatile = false); /// Read all of the specified file into a MemoryBuffer as a stream /// (i.e. until EOF reached). This is useful for special files that /// look like a regular file but have 0 size (e.g. /proc/cpuinfo on Linux). static ErrorOr> getFileAsStream(const Twine &Filename); /// Given an already-open file descriptor, map some slice of it into a /// MemoryBuffer. The slice is specified by an \p Offset and \p MapSize. /// Since this is in the middle of a file, the buffer is not null terminated. static ErrorOr> getOpenFileSlice(sys::fs::file_t FD, const Twine &Filename, uint64_t MapSize, int64_t Offset, bool IsVolatile = false); /// Given an already-open file descriptor, read the file and return a /// MemoryBuffer. /// /// \param IsVolatile Set to true to indicate that the contents of the file /// can change outside the user's control, e.g. when libclang tries to parse /// while the user is editing/updating the file or if the file is on an NFS. static ErrorOr> getOpenFile(sys::fs::file_t FD, const Twine &Filename, uint64_t FileSize, bool RequiresNullTerminator = true, bool IsVolatile = false); /// Open the specified memory range as a MemoryBuffer. Note that InputData /// must be null terminated if RequiresNullTerminator is true. static std::unique_ptr getMemBuffer(StringRef InputData, StringRef BufferName = "", bool RequiresNullTerminator = true); static std::unique_ptr getMemBuffer(MemoryBufferRef Ref, bool RequiresNullTerminator = true); /// Open the specified memory range as a MemoryBuffer, copying the contents /// and taking ownership of it. InputData does not have to be null terminated. static std::unique_ptr getMemBufferCopy(StringRef InputData, const Twine &BufferName = ""); /// Read all of stdin into a file buffer, and return it. static ErrorOr> getSTDIN(); /// Open the specified file as a MemoryBuffer, or open stdin if the Filename /// is "-". static ErrorOr> getFileOrSTDIN(const Twine &Filename, int64_t FileSize = -1, bool RequiresNullTerminator = true); /// Map a subrange of the specified file as a MemoryBuffer. static ErrorOr> getFileSlice(const Twine &Filename, uint64_t MapSize, uint64_t Offset, bool IsVolatile = false); //===--------------------------------------------------------------------===// // Provided for performance analysis. //===--------------------------------------------------------------------===// /// The kind of memory backing used to support the MemoryBuffer. enum BufferKind { MemoryBuffer_Malloc, MemoryBuffer_MMap }; /// Return information on the memory mechanism used to support the /// MemoryBuffer. virtual BufferKind getBufferKind() const = 0; MemoryBufferRef getMemBufferRef() const; }; /// This class is an extension of MemoryBuffer, which allows copy-on-write /// access to the underlying contents. It only supports creation methods that /// are guaranteed to produce a writable buffer. For example, mapping a file /// read-only is not supported. class WritableMemoryBuffer : public MemoryBuffer { protected: WritableMemoryBuffer() = default; static constexpr sys::fs::mapped_file_region::mapmode Mapmode = sys::fs::mapped_file_region::priv; public: using MemoryBuffer::getBuffer; using MemoryBuffer::getBufferEnd; using MemoryBuffer::getBufferStart; // const_cast is well-defined here, because the underlying buffer is // guaranteed to have been initialized with a mutable buffer. char *getBufferStart() { return const_cast(MemoryBuffer::getBufferStart()); } char *getBufferEnd() { return const_cast(MemoryBuffer::getBufferEnd()); } MutableArrayRef getBuffer() { return {getBufferStart(), getBufferEnd()}; } static ErrorOr> getFile(const Twine &Filename, int64_t FileSize = -1, bool IsVolatile = false); /// Map a subrange of the specified file as a WritableMemoryBuffer. static ErrorOr> getFileSlice(const Twine &Filename, uint64_t MapSize, uint64_t Offset, bool IsVolatile = false); /// Allocate a new MemoryBuffer of the specified size that is not initialized. /// Note that the caller should initialize the memory allocated by this /// method. The memory is owned by the MemoryBuffer object. static std::unique_ptr getNewUninitMemBuffer(size_t Size, const Twine &BufferName = ""); /// Allocate a new zero-initialized MemoryBuffer of the specified size. Note /// that the caller need not initialize the memory allocated by this method. /// The memory is owned by the MemoryBuffer object. static std::unique_ptr getNewMemBuffer(size_t Size, const Twine &BufferName = ""); private: // Hide these base class factory function so one can't write // WritableMemoryBuffer::getXXX() // and be surprised that he got a read-only Buffer. using MemoryBuffer::getFileAsStream; using MemoryBuffer::getFileOrSTDIN; using MemoryBuffer::getMemBuffer; using MemoryBuffer::getMemBufferCopy; using MemoryBuffer::getOpenFile; using MemoryBuffer::getOpenFileSlice; using MemoryBuffer::getSTDIN; }; /// This class is an extension of MemoryBuffer, which allows write access to /// the underlying contents and committing those changes to the original source. /// It only supports creation methods that are guaranteed to produce a writable /// buffer. For example, mapping a file read-only is not supported. class WriteThroughMemoryBuffer : public MemoryBuffer { protected: WriteThroughMemoryBuffer() = default; static constexpr sys::fs::mapped_file_region::mapmode Mapmode = sys::fs::mapped_file_region::readwrite; public: using MemoryBuffer::getBuffer; using MemoryBuffer::getBufferEnd; using MemoryBuffer::getBufferStart; // const_cast is well-defined here, because the underlying buffer is // guaranteed to have been initialized with a mutable buffer. char *getBufferStart() { return const_cast(MemoryBuffer::getBufferStart()); } char *getBufferEnd() { return const_cast(MemoryBuffer::getBufferEnd()); } MutableArrayRef getBuffer() { return {getBufferStart(), getBufferEnd()}; } static ErrorOr> getFile(const Twine &Filename, int64_t FileSize = -1); /// Map a subrange of the specified file as a ReadWriteMemoryBuffer. static ErrorOr> getFileSlice(const Twine &Filename, uint64_t MapSize, uint64_t Offset); private: // Hide these base class factory function so one can't write // WritableMemoryBuffer::getXXX() // and be surprised that he got a read-only Buffer. using MemoryBuffer::getFileAsStream; using MemoryBuffer::getFileOrSTDIN; using MemoryBuffer::getMemBuffer; using MemoryBuffer::getMemBufferCopy; using MemoryBuffer::getOpenFile; using MemoryBuffer::getOpenFileSlice; using MemoryBuffer::getSTDIN; }; class MemoryBufferRef { StringRef Buffer; StringRef Identifier; public: MemoryBufferRef() = default; MemoryBufferRef(const MemoryBuffer& Buffer) : Buffer(Buffer.getBuffer()), Identifier(Buffer.getBufferIdentifier()) {} MemoryBufferRef(StringRef Buffer, StringRef Identifier) : Buffer(Buffer), Identifier(Identifier) {} StringRef getBuffer() const { return Buffer; } StringRef getBufferIdentifier() const { return Identifier; } const char *getBufferStart() const { return Buffer.begin(); } const char *getBufferEnd() const { return Buffer.end(); } size_t getBufferSize() const { return Buffer.size(); } }; // Create wrappers for C Binding types (see CBindingWrapping.h). DEFINE_SIMPLE_CONVERSION_FUNCTIONS(MemoryBuffer, LLVMMemoryBufferRef) } // end namespace llvm #endif // LLVM_SUPPORT_MEMORYBUFFER_H