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mach-o supports "fat" files which are a header/table-of-contents followed by a concatenation of mach-o files built for different architectures. Currently, MemoryBuffer has no easy way to map a subrange (slice) of a file which lld will need to select a mach-o slice of a fat file. The new function provides an easy way to map a slice of a file into a MemoryBuffer. Test case included. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219260 91177308-0d34-0410-b5e6-96231b3b80d8
174 lines
6.7 KiB
C++
174 lines
6.7 KiB
C++
//===--- MemoryBuffer.h - Memory Buffer Interface ---------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the MemoryBuffer interface.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_MEMORYBUFFER_H
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#define LLVM_SUPPORT_MEMORYBUFFER_H
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#include "llvm-c/Support.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/Support/CBindingWrapping.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/DataTypes.h"
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#include "llvm/Support/ErrorOr.h"
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#include <memory>
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#include <system_error>
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namespace llvm {
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class MemoryBufferRef;
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/// This interface provides simple read-only access to a block of memory, and
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/// provides simple methods for reading files and standard input into a memory
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/// buffer. In addition to basic access to the characters in the file, this
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/// interface guarantees you can read one character past the end of the file,
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/// and that this character will read as '\0'.
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///
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/// The '\0' guarantee is needed to support an optimization -- it's intended to
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/// be more efficient for clients which are reading all the data to stop
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/// reading when they encounter a '\0' than to continually check the file
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/// position to see if it has reached the end of the file.
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class MemoryBuffer {
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const char *BufferStart; // Start of the buffer.
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const char *BufferEnd; // End of the buffer.
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MemoryBuffer(const MemoryBuffer &) LLVM_DELETED_FUNCTION;
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MemoryBuffer &operator=(const MemoryBuffer &) LLVM_DELETED_FUNCTION;
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protected:
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MemoryBuffer() {}
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void init(const char *BufStart, const char *BufEnd,
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bool RequiresNullTerminator);
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public:
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virtual ~MemoryBuffer();
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const char *getBufferStart() const { return BufferStart; }
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const char *getBufferEnd() const { return BufferEnd; }
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size_t getBufferSize() const { return BufferEnd-BufferStart; }
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StringRef getBuffer() const {
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return StringRef(BufferStart, getBufferSize());
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}
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/// Return an identifier for this buffer, typically the filename it was read
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/// from.
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virtual const char *getBufferIdentifier() const {
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return "Unknown buffer";
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}
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/// Open the specified file as a MemoryBuffer, returning a new MemoryBuffer
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/// if successful, otherwise returning null. If FileSize is specified, this
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/// means that the client knows that the file exists and that it has the
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/// specified size.
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///
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/// \param IsVolatileSize Set to true to indicate that the file size may be
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/// changing, e.g. when libclang tries to parse while the user is
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/// editing/updating the file.
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static ErrorOr<std::unique_ptr<MemoryBuffer>>
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getFile(const Twine &Filename, int64_t FileSize = -1,
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bool RequiresNullTerminator = true, bool IsVolatileSize = false);
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/// Given an already-open file descriptor, map some slice of it into a
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/// MemoryBuffer. The slice is specified by an \p Offset and \p MapSize.
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/// Since this is in the middle of a file, the buffer is not null terminated.
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static ErrorOr<std::unique_ptr<MemoryBuffer>>
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getOpenFileSlice(int FD, const Twine &Filename, uint64_t MapSize,
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int64_t Offset);
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/// Given an already-open file descriptor, read the file and return a
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/// MemoryBuffer.
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///
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/// \param IsVolatileSize Set to true to indicate that the file size may be
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/// changing, e.g. when libclang tries to parse while the user is
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/// editing/updating the file.
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static ErrorOr<std::unique_ptr<MemoryBuffer>>
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getOpenFile(int FD, const Twine &Filename, uint64_t FileSize,
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bool RequiresNullTerminator = true, bool IsVolatileSize = false);
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/// Open the specified memory range as a MemoryBuffer. Note that InputData
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/// must be null terminated if RequiresNullTerminator is true.
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static std::unique_ptr<MemoryBuffer>
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getMemBuffer(StringRef InputData, StringRef BufferName = "",
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bool RequiresNullTerminator = true);
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static std::unique_ptr<MemoryBuffer>
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getMemBuffer(MemoryBufferRef Ref, bool RequiresNullTerminator = true);
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/// Open the specified memory range as a MemoryBuffer, copying the contents
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/// and taking ownership of it. InputData does not have to be null terminated.
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static std::unique_ptr<MemoryBuffer>
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getMemBufferCopy(StringRef InputData, const Twine &BufferName = "");
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/// Allocate a new zero-initialized MemoryBuffer of the specified size. Note
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/// that the caller need not initialize the memory allocated by this method.
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/// The memory is owned by the MemoryBuffer object.
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static std::unique_ptr<MemoryBuffer>
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getNewMemBuffer(size_t Size, StringRef BufferName = "");
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/// Allocate a new MemoryBuffer of the specified size that is not initialized.
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/// Note that the caller should initialize the memory allocated by this
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/// method. The memory is owned by the MemoryBuffer object.
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static std::unique_ptr<MemoryBuffer>
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getNewUninitMemBuffer(size_t Size, const Twine &BufferName = "");
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/// Read all of stdin into a file buffer, and return it.
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static ErrorOr<std::unique_ptr<MemoryBuffer>> getSTDIN();
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/// Open the specified file as a MemoryBuffer, or open stdin if the Filename
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/// is "-".
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static ErrorOr<std::unique_ptr<MemoryBuffer>>
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getFileOrSTDIN(const Twine &Filename, int64_t FileSize = -1);
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/// Map a subrange of the the specified file as a MemoryBuffer.
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static ErrorOr<std::unique_ptr<MemoryBuffer>>
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getFileSlice(const Twine &Filename, uint64_t MapSize, uint64_t Offset);
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//===--------------------------------------------------------------------===//
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// Provided for performance analysis.
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//===--------------------------------------------------------------------===//
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/// The kind of memory backing used to support the MemoryBuffer.
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enum BufferKind {
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MemoryBuffer_Malloc,
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MemoryBuffer_MMap
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};
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/// Return information on the memory mechanism used to support the
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/// MemoryBuffer.
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virtual BufferKind getBufferKind() const = 0;
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MemoryBufferRef getMemBufferRef() const;
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};
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class MemoryBufferRef {
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StringRef Buffer;
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StringRef Identifier;
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public:
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MemoryBufferRef() {}
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MemoryBufferRef(StringRef Buffer, StringRef Identifier)
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: Buffer(Buffer), Identifier(Identifier) {}
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StringRef getBuffer() const { return Buffer; }
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StringRef getBufferIdentifier() const { return Identifier; }
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const char *getBufferStart() const { return Buffer.begin(); }
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const char *getBufferEnd() const { return Buffer.end(); }
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size_t getBufferSize() const { return Buffer.size(); }
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};
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// Create wrappers for C Binding types (see CBindingWrapping.h).
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DEFINE_SIMPLE_CONVERSION_FUNCTIONS(MemoryBuffer, LLVMMemoryBufferRef)
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} // end namespace llvm
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#endif
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