LLVM 17.0.0git
MemoryBuffer.h
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1//===--- MemoryBuffer.h - Memory Buffer Interface ---------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file defines the MemoryBuffer interface.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_SUPPORT_MEMORYBUFFER_H
14#define LLVM_SUPPORT_MEMORYBUFFER_H
15
16#include "llvm-c/Types.h"
17#include "llvm/ADT/ArrayRef.h"
18#include "llvm/ADT/StringRef.h"
19#include "llvm/ADT/Twine.h"
24#include <cstddef>
25#include <cstdint>
26#include <memory>
27
28namespace llvm {
29namespace sys {
30namespace fs {
31// Duplicated from FileSystem.h to avoid a dependency.
32#if defined(_WIN32)
33// A Win32 HANDLE is a typedef of void*
34using file_t = void *;
35#else
36using file_t = int;
37#endif
38} // namespace fs
39} // namespace sys
40
41/// This interface provides simple read-only access to a block of memory, and
42/// provides simple methods for reading files and standard input into a memory
43/// buffer. In addition to basic access to the characters in the file, this
44/// interface guarantees you can read one character past the end of the file,
45/// and that this character will read as '\0'.
46///
47/// The '\0' guarantee is needed to support an optimization -- it's intended to
48/// be more efficient for clients which are reading all the data to stop
49/// reading when they encounter a '\0' than to continually check the file
50/// position to see if it has reached the end of the file.
52 const char *BufferStart; // Start of the buffer.
53 const char *BufferEnd; // End of the buffer.
54
55protected:
56 MemoryBuffer() = default;
57
58 void init(const char *BufStart, const char *BufEnd,
59 bool RequiresNullTerminator);
60
61public:
62 MemoryBuffer(const MemoryBuffer &) = delete;
64 virtual ~MemoryBuffer();
65
66 const char *getBufferStart() const { return BufferStart; }
67 const char *getBufferEnd() const { return BufferEnd; }
68 size_t getBufferSize() const { return BufferEnd-BufferStart; }
69
71 return StringRef(BufferStart, getBufferSize());
72 }
73
74 /// Return an identifier for this buffer, typically the filename it was read
75 /// from.
76 virtual StringRef getBufferIdentifier() const { return "Unknown buffer"; }
77
78 /// For read-only MemoryBuffer_MMap, mark the buffer as unused in the near
79 /// future and the kernel can free resources associated with it. Further
80 /// access is supported but may be expensive. This calls
81 /// madvise(MADV_DONTNEED) on read-only file mappings on *NIX systems. This
82 /// function should not be called on a writable buffer.
83 virtual void dontNeedIfMmap() {}
84
85 /// Open the specified file as a MemoryBuffer, returning a new MemoryBuffer
86 /// if successful, otherwise returning null.
87 ///
88 /// \param IsText Set to true to indicate that the file should be read in
89 /// text mode.
90 ///
91 /// \param IsVolatile Set to true to indicate that the contents of the file
92 /// can change outside the user's control, e.g. when libclang tries to parse
93 /// while the user is editing/updating the file or if the file is on an NFS.
94 ///
95 /// \param Alignment Set to indicate that the buffer should be aligned to at
96 /// least the specified alignment.
98 getFile(const Twine &Filename, bool IsText = false,
99 bool RequiresNullTerminator = true, bool IsVolatile = false,
100 std::optional<Align> Alignment = std::nullopt);
101
102 /// Read all of the specified file into a MemoryBuffer as a stream
103 /// (i.e. until EOF reached). This is useful for special files that
104 /// look like a regular file but have 0 size (e.g. /proc/cpuinfo on Linux).
106 getFileAsStream(const Twine &Filename);
107
108 /// Given an already-open file descriptor, map some slice of it into a
109 /// MemoryBuffer. The slice is specified by an \p Offset and \p MapSize.
110 /// Since this is in the middle of a file, the buffer is not null terminated.
112 getOpenFileSlice(sys::fs::file_t FD, const Twine &Filename, uint64_t MapSize,
113 int64_t Offset, bool IsVolatile = false,
114 std::optional<Align> Alignment = std::nullopt);
115
116 /// Given an already-open file descriptor, read the file and return a
117 /// MemoryBuffer.
118 ///
119 /// \param IsVolatile Set to true to indicate that the contents of the file
120 /// can change outside the user's control, e.g. when libclang tries to parse
121 /// while the user is editing/updating the file or if the file is on an NFS.
122 ///
123 /// \param Alignment Set to indicate that the buffer should be aligned to at
124 /// least the specified alignment.
126 getOpenFile(sys::fs::file_t FD, const Twine &Filename, uint64_t FileSize,
127 bool RequiresNullTerminator = true, bool IsVolatile = false,
128 std::optional<Align> Alignment = std::nullopt);
129
130 /// Open the specified memory range as a MemoryBuffer. Note that InputData
131 /// must be null terminated if RequiresNullTerminator is true.
132 static std::unique_ptr<MemoryBuffer>
133 getMemBuffer(StringRef InputData, StringRef BufferName = "",
134 bool RequiresNullTerminator = true);
135
136 static std::unique_ptr<MemoryBuffer>
137 getMemBuffer(MemoryBufferRef Ref, bool RequiresNullTerminator = true);
138
139 /// Open the specified memory range as a MemoryBuffer, copying the contents
140 /// and taking ownership of it. InputData does not have to be null terminated.
141 static std::unique_ptr<MemoryBuffer>
142 getMemBufferCopy(StringRef InputData, const Twine &BufferName = "");
143
144 /// Read all of stdin into a file buffer, and return it.
146
147 /// Open the specified file as a MemoryBuffer, or open stdin if the Filename
148 /// is "-".
150 getFileOrSTDIN(const Twine &Filename, bool IsText = false,
151 bool RequiresNullTerminator = true,
152 std::optional<Align> Alignment = std::nullopt);
153
154 /// Map a subrange of the specified file as a MemoryBuffer.
156 getFileSlice(const Twine &Filename, uint64_t MapSize, uint64_t Offset,
157 bool IsVolatile = false,
158 std::optional<Align> Alignment = std::nullopt);
159
160 //===--------------------------------------------------------------------===//
161 // Provided for performance analysis.
162 //===--------------------------------------------------------------------===//
163
164 /// The kind of memory backing used to support the MemoryBuffer.
168 };
169
170 /// Return information on the memory mechanism used to support the
171 /// MemoryBuffer.
172 virtual BufferKind getBufferKind() const = 0;
173
175};
176
177/// This class is an extension of MemoryBuffer, which allows copy-on-write
178/// access to the underlying contents. It only supports creation methods that
179/// are guaranteed to produce a writable buffer. For example, mapping a file
180/// read-only is not supported.
182protected:
184
185public:
189
190 // const_cast is well-defined here, because the underlying buffer is
191 // guaranteed to have been initialized with a mutable buffer.
193 return const_cast<char *>(MemoryBuffer::getBufferStart());
194 }
195 char *getBufferEnd() {
196 return const_cast<char *>(MemoryBuffer::getBufferEnd());
197 }
199 return {getBufferStart(), getBufferEnd()};
200 }
201
203 getFile(const Twine &Filename, bool IsVolatile = false,
204 std::optional<Align> Alignment = std::nullopt);
205
206 /// Map a subrange of the specified file as a WritableMemoryBuffer.
208 getFileSlice(const Twine &Filename, uint64_t MapSize, uint64_t Offset,
209 bool IsVolatile = false,
210 std::optional<Align> Alignment = std::nullopt);
211
212 /// Allocate a new MemoryBuffer of the specified size that is not initialized.
213 /// Note that the caller should initialize the memory allocated by this
214 /// method. The memory is owned by the MemoryBuffer object.
215 ///
216 /// \param Alignment Set to indicate that the buffer should be aligned to at
217 /// least the specified alignment.
218 static std::unique_ptr<WritableMemoryBuffer>
219 getNewUninitMemBuffer(size_t Size, const Twine &BufferName = "",
220 std::optional<Align> Alignment = std::nullopt);
221
222 /// Allocate a new zero-initialized MemoryBuffer of the specified size. Note
223 /// that the caller need not initialize the memory allocated by this method.
224 /// The memory is owned by the MemoryBuffer object.
225 static std::unique_ptr<WritableMemoryBuffer>
226 getNewMemBuffer(size_t Size, const Twine &BufferName = "");
227
228private:
229 // Hide these base class factory function so one can't write
230 // WritableMemoryBuffer::getXXX()
231 // and be surprised that he got a read-only Buffer.
239};
240
241/// This class is an extension of MemoryBuffer, which allows write access to
242/// the underlying contents and committing those changes to the original source.
243/// It only supports creation methods that are guaranteed to produce a writable
244/// buffer. For example, mapping a file read-only is not supported.
246protected:
248
249public:
253
254 // const_cast is well-defined here, because the underlying buffer is
255 // guaranteed to have been initialized with a mutable buffer.
257 return const_cast<char *>(MemoryBuffer::getBufferStart());
258 }
259 char *getBufferEnd() {
260 return const_cast<char *>(MemoryBuffer::getBufferEnd());
261 }
263 return {getBufferStart(), getBufferEnd()};
264 }
265
267 getFile(const Twine &Filename, int64_t FileSize = -1);
268
269 /// Map a subrange of the specified file as a ReadWriteMemoryBuffer.
271 getFileSlice(const Twine &Filename, uint64_t MapSize, uint64_t Offset);
272
273private:
274 // Hide these base class factory function so one can't write
275 // WritableMemoryBuffer::getXXX()
276 // and be surprised that he got a read-only Buffer.
284};
285
286// Create wrappers for C Binding types (see CBindingWrapping.h).
288
289} // end namespace llvm
290
291#endif // LLVM_SUPPORT_MEMORYBUFFER_H
#define DEFINE_SIMPLE_CONVERSION_FUNCTIONS(ty, ref)
uint64_t Size
Provides ErrorOr<T> smart pointer.
Represents either an error or a value T.
Definition: ErrorOr.h:56
This interface provides simple read-only access to a block of memory, and provides simple methods for...
Definition: MemoryBuffer.h:51
static ErrorOr< std::unique_ptr< MemoryBuffer > > getOpenFile(sys::fs::file_t FD, const Twine &Filename, uint64_t FileSize, bool RequiresNullTerminator=true, bool IsVolatile=false, std::optional< Align > Alignment=std::nullopt)
Given an already-open file descriptor, read the file and return a MemoryBuffer.
static std::unique_ptr< MemoryBuffer > getMemBuffer(StringRef InputData, StringRef BufferName="", bool RequiresNullTerminator=true)
Open the specified memory range as a MemoryBuffer.
BufferKind
The kind of memory backing used to support the MemoryBuffer.
Definition: MemoryBuffer.h:165
virtual StringRef getBufferIdentifier() const
Return an identifier for this buffer, typically the filename it was read from.
Definition: MemoryBuffer.h:76
size_t getBufferSize() const
Definition: MemoryBuffer.h:68
static std::unique_ptr< MemoryBuffer > getMemBufferCopy(StringRef InputData, const Twine &BufferName="")
Open the specified memory range as a MemoryBuffer, copying the contents and taking ownership of it.
MemoryBuffer(const MemoryBuffer &)=delete
static ErrorOr< std::unique_ptr< MemoryBuffer > > getOpenFileSlice(sys::fs::file_t FD, const Twine &Filename, uint64_t MapSize, int64_t Offset, bool IsVolatile=false, std::optional< Align > Alignment=std::nullopt)
Given an already-open file descriptor, map some slice of it into a MemoryBuffer.
virtual BufferKind getBufferKind() const =0
Return information on the memory mechanism used to support the MemoryBuffer.
void init(const char *BufStart, const char *BufEnd, bool RequiresNullTerminator)
init - Initialize this MemoryBuffer as a reference to externally allocated memory,...
StringRef getBuffer() const
Definition: MemoryBuffer.h:70
static ErrorOr< std::unique_ptr< MemoryBuffer > > getFileAsStream(const Twine &Filename)
Read all of the specified file into a MemoryBuffer as a stream (i.e.
virtual void dontNeedIfMmap()
For read-only MemoryBuffer_MMap, mark the buffer as unused in the near future and the kernel can free...
Definition: MemoryBuffer.h:83
MemoryBufferRef getMemBufferRef() const
virtual ~MemoryBuffer()
static ErrorOr< std::unique_ptr< MemoryBuffer > > getFileOrSTDIN(const Twine &Filename, bool IsText=false, bool RequiresNullTerminator=true, std::optional< Align > Alignment=std::nullopt)
Open the specified file as a MemoryBuffer, or open stdin if the Filename is "-".
MemoryBuffer & operator=(const MemoryBuffer &)=delete
static ErrorOr< std::unique_ptr< MemoryBuffer > > getFileSlice(const Twine &Filename, uint64_t MapSize, uint64_t Offset, bool IsVolatile=false, std::optional< Align > Alignment=std::nullopt)
Map a subrange of the specified file as a MemoryBuffer.
static ErrorOr< std::unique_ptr< MemoryBuffer > > getFile(const Twine &Filename, bool IsText=false, bool RequiresNullTerminator=true, bool IsVolatile=false, std::optional< Align > Alignment=std::nullopt)
Open the specified file as a MemoryBuffer, returning a new MemoryBuffer if successful,...
MemoryBuffer()=default
const char * getBufferEnd() const
Definition: MemoryBuffer.h:67
static ErrorOr< std::unique_ptr< MemoryBuffer > > getSTDIN()
Read all of stdin into a file buffer, and return it.
const char * getBufferStart() const
Definition: MemoryBuffer.h:66
MutableArrayRef - Represent a mutable reference to an array (0 or more elements consecutively in memo...
Definition: ArrayRef.h:305
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:50
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:81
This class is an extension of MemoryBuffer, which allows copy-on-write access to the underlying conte...
Definition: MemoryBuffer.h:181
MutableArrayRef< char > getBuffer()
Definition: MemoryBuffer.h:198
static std::unique_ptr< WritableMemoryBuffer > getNewMemBuffer(size_t Size, const Twine &BufferName="")
Allocate a new zero-initialized MemoryBuffer of the specified size.
static ErrorOr< std::unique_ptr< WritableMemoryBuffer > > getFile(const Twine &Filename, bool IsVolatile=false, std::optional< Align > Alignment=std::nullopt)
static std::unique_ptr< WritableMemoryBuffer > getNewUninitMemBuffer(size_t Size, const Twine &BufferName="", std::optional< Align > Alignment=std::nullopt)
Allocate a new MemoryBuffer of the specified size that is not initialized.
static ErrorOr< std::unique_ptr< WritableMemoryBuffer > > getFileSlice(const Twine &Filename, uint64_t MapSize, uint64_t Offset, bool IsVolatile=false, std::optional< Align > Alignment=std::nullopt)
Map a subrange of the specified file as a WritableMemoryBuffer.
This class is an extension of MemoryBuffer, which allows write access to the underlying contents and ...
Definition: MemoryBuffer.h:245
MutableArrayRef< char > getBuffer()
Definition: MemoryBuffer.h:262
static ErrorOr< std::unique_ptr< WriteThroughMemoryBuffer > > getFile(const Twine &Filename, int64_t FileSize=-1)
static ErrorOr< std::unique_ptr< WriteThroughMemoryBuffer > > getFileSlice(const Twine &Filename, uint64_t MapSize, uint64_t Offset)
Map a subrange of the specified file as a ReadWriteMemoryBuffer.
struct LLVMOpaqueMemoryBuffer * LLVMMemoryBufferRef
LLVM uses a polymorphic type hierarchy which C cannot represent, therefore parameters must be passed ...
Definition: Types.h:48
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
@ Offset
Definition: DWP.cpp:440
@ Ref
The access may reference the value stored in memory.