1 //===--- MemoryBuffer.cpp - Memory Buffer implementation ------------------===//
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 implements the MemoryBuffer interface.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "llvm/Support/MemoryBuffer.h"
14 #include "llvm/ADT/SmallString.h"
15 #include "llvm/Config/config.h"
16 #include "llvm/Support/Errc.h"
17 #include "llvm/Support/Errno.h"
18 #include "llvm/Support/FileSystem.h"
19 #include "llvm/Support/MathExtras.h"
20 #include "llvm/Support/Path.h"
21 #include "llvm/Support/Process.h"
22 #include "llvm/Support/Program.h"
23 #include "llvm/Support/SmallVectorMemoryBuffer.h"
24 #include <cassert>
25 #include <cerrno>
26 #include <cstring>
27 #include <new>
28 #include <sys/types.h>
29 #include <system_error>
30 #if !defined(_MSC_VER) && !defined(__MINGW32__)
31 #include <unistd.h>
32 #else
33 #include <io.h>
34 #endif
35 using namespace llvm;
36
37 //===----------------------------------------------------------------------===//
38 // MemoryBuffer implementation itself.
39 //===----------------------------------------------------------------------===//
40
~MemoryBuffer()41 MemoryBuffer::~MemoryBuffer() { }
42
43 /// init - Initialize this MemoryBuffer as a reference to externally allocated
44 /// memory, memory that we know is already null terminated.
init(const char * BufStart,const char * BufEnd,bool RequiresNullTerminator)45 void MemoryBuffer::init(const char *BufStart, const char *BufEnd,
46 bool RequiresNullTerminator) {
47 assert((!RequiresNullTerminator || BufEnd[0] == 0) &&
48 "Buffer is not null terminated!");
49 BufferStart = BufStart;
50 BufferEnd = BufEnd;
51 }
52
53 //===----------------------------------------------------------------------===//
54 // MemoryBufferMem implementation.
55 //===----------------------------------------------------------------------===//
56
57 /// CopyStringRef - Copies contents of a StringRef into a block of memory and
58 /// null-terminates it.
CopyStringRef(char * Memory,StringRef Data)59 static void CopyStringRef(char *Memory, StringRef Data) {
60 if (!Data.empty())
61 memcpy(Memory, Data.data(), Data.size());
62 Memory[Data.size()] = 0; // Null terminate string.
63 }
64
65 namespace {
66 struct NamedBufferAlloc {
67 const Twine &Name;
NamedBufferAlloc__anona069d85d0111::NamedBufferAlloc68 NamedBufferAlloc(const Twine &Name) : Name(Name) {}
69 };
70 }
71
operator new(size_t N,const NamedBufferAlloc & Alloc)72 void *operator new(size_t N, const NamedBufferAlloc &Alloc) {
73 SmallString<256> NameBuf;
74 StringRef NameRef = Alloc.Name.toStringRef(NameBuf);
75
76 char *Mem = static_cast<char *>(operator new(N + NameRef.size() + 1));
77 CopyStringRef(Mem + N, NameRef);
78 return Mem;
79 }
80
81 namespace {
82 /// MemoryBufferMem - Named MemoryBuffer pointing to a block of memory.
83 template<typename MB>
84 class MemoryBufferMem : public MB {
85 public:
MemoryBufferMem(StringRef InputData,bool RequiresNullTerminator)86 MemoryBufferMem(StringRef InputData, bool RequiresNullTerminator) {
87 MemoryBuffer::init(InputData.begin(), InputData.end(),
88 RequiresNullTerminator);
89 }
90
91 /// Disable sized deallocation for MemoryBufferMem, because it has
92 /// tail-allocated data.
operator delete(void * p)93 void operator delete(void *p) { ::operator delete(p); }
94
getBufferIdentifier() const95 StringRef getBufferIdentifier() const override {
96 // The name is stored after the class itself.
97 return StringRef(reinterpret_cast<const char *>(this + 1));
98 }
99
getBufferKind() const100 MemoryBuffer::BufferKind getBufferKind() const override {
101 return MemoryBuffer::MemoryBuffer_Malloc;
102 }
103 };
104 }
105
106 template <typename MB>
107 static ErrorOr<std::unique_ptr<MB>>
108 getFileAux(const Twine &Filename, int64_t FileSize, uint64_t MapSize,
109 uint64_t Offset, bool RequiresNullTerminator, bool IsVolatile);
110
111 std::unique_ptr<MemoryBuffer>
getMemBuffer(StringRef InputData,StringRef BufferName,bool RequiresNullTerminator)112 MemoryBuffer::getMemBuffer(StringRef InputData, StringRef BufferName,
113 bool RequiresNullTerminator) {
114 auto *Ret = new (NamedBufferAlloc(BufferName))
115 MemoryBufferMem<MemoryBuffer>(InputData, RequiresNullTerminator);
116 return std::unique_ptr<MemoryBuffer>(Ret);
117 }
118
119 std::unique_ptr<MemoryBuffer>
getMemBuffer(MemoryBufferRef Ref,bool RequiresNullTerminator)120 MemoryBuffer::getMemBuffer(MemoryBufferRef Ref, bool RequiresNullTerminator) {
121 return std::unique_ptr<MemoryBuffer>(getMemBuffer(
122 Ref.getBuffer(), Ref.getBufferIdentifier(), RequiresNullTerminator));
123 }
124
125 static ErrorOr<std::unique_ptr<WritableMemoryBuffer>>
getMemBufferCopyImpl(StringRef InputData,const Twine & BufferName)126 getMemBufferCopyImpl(StringRef InputData, const Twine &BufferName) {
127 auto Buf = WritableMemoryBuffer::getNewUninitMemBuffer(InputData.size(), BufferName);
128 if (!Buf)
129 return make_error_code(errc::not_enough_memory);
130 memcpy(Buf->getBufferStart(), InputData.data(), InputData.size());
131 return std::move(Buf);
132 }
133
134 std::unique_ptr<MemoryBuffer>
getMemBufferCopy(StringRef InputData,const Twine & BufferName)135 MemoryBuffer::getMemBufferCopy(StringRef InputData, const Twine &BufferName) {
136 auto Buf = getMemBufferCopyImpl(InputData, BufferName);
137 if (Buf)
138 return std::move(*Buf);
139 return nullptr;
140 }
141
142 ErrorOr<std::unique_ptr<MemoryBuffer>>
getFileOrSTDIN(const Twine & Filename,int64_t FileSize,bool RequiresNullTerminator)143 MemoryBuffer::getFileOrSTDIN(const Twine &Filename, int64_t FileSize,
144 bool RequiresNullTerminator) {
145 SmallString<256> NameBuf;
146 StringRef NameRef = Filename.toStringRef(NameBuf);
147
148 if (NameRef == "-")
149 return getSTDIN();
150 return getFile(Filename, FileSize, RequiresNullTerminator);
151 }
152
153 ErrorOr<std::unique_ptr<MemoryBuffer>>
getFileSlice(const Twine & FilePath,uint64_t MapSize,uint64_t Offset,bool IsVolatile)154 MemoryBuffer::getFileSlice(const Twine &FilePath, uint64_t MapSize,
155 uint64_t Offset, bool IsVolatile) {
156 return getFileAux<MemoryBuffer>(FilePath, -1, MapSize, Offset, false,
157 IsVolatile);
158 }
159
160 //===----------------------------------------------------------------------===//
161 // MemoryBuffer::getFile implementation.
162 //===----------------------------------------------------------------------===//
163
164 namespace {
165
166 template <typename MB>
167 constexpr sys::fs::mapped_file_region::mapmode Mapmode =
168 sys::fs::mapped_file_region::readonly;
169 template <>
170 constexpr sys::fs::mapped_file_region::mapmode Mapmode<MemoryBuffer> =
171 sys::fs::mapped_file_region::readonly;
172 template <>
173 constexpr sys::fs::mapped_file_region::mapmode Mapmode<WritableMemoryBuffer> =
174 sys::fs::mapped_file_region::priv;
175 template <>
176 constexpr sys::fs::mapped_file_region::mapmode
177 Mapmode<WriteThroughMemoryBuffer> = sys::fs::mapped_file_region::readwrite;
178
179 /// Memory maps a file descriptor using sys::fs::mapped_file_region.
180 ///
181 /// This handles converting the offset into a legal offset on the platform.
182 template<typename MB>
183 class MemoryBufferMMapFile : public MB {
184 sys::fs::mapped_file_region MFR;
185
getLegalMapOffset(uint64_t Offset)186 static uint64_t getLegalMapOffset(uint64_t Offset) {
187 return Offset & ~(sys::fs::mapped_file_region::alignment() - 1);
188 }
189
getLegalMapSize(uint64_t Len,uint64_t Offset)190 static uint64_t getLegalMapSize(uint64_t Len, uint64_t Offset) {
191 return Len + (Offset - getLegalMapOffset(Offset));
192 }
193
getStart(uint64_t Len,uint64_t Offset)194 const char *getStart(uint64_t Len, uint64_t Offset) {
195 return MFR.const_data() + (Offset - getLegalMapOffset(Offset));
196 }
197
198 public:
MemoryBufferMMapFile(bool RequiresNullTerminator,sys::fs::file_t FD,uint64_t Len,uint64_t Offset,std::error_code & EC)199 MemoryBufferMMapFile(bool RequiresNullTerminator, sys::fs::file_t FD, uint64_t Len,
200 uint64_t Offset, std::error_code &EC)
201 : MFR(FD, Mapmode<MB>, getLegalMapSize(Len, Offset),
202 getLegalMapOffset(Offset), EC) {
203 if (!EC) {
204 const char *Start = getStart(Len, Offset);
205 MemoryBuffer::init(Start, Start + Len, RequiresNullTerminator);
206 }
207 }
208
209 /// Disable sized deallocation for MemoryBufferMMapFile, because it has
210 /// tail-allocated data.
operator delete(void * p)211 void operator delete(void *p) { ::operator delete(p); }
212
getBufferIdentifier() const213 StringRef getBufferIdentifier() const override {
214 // The name is stored after the class itself.
215 return StringRef(reinterpret_cast<const char *>(this + 1));
216 }
217
getBufferKind() const218 MemoryBuffer::BufferKind getBufferKind() const override {
219 return MemoryBuffer::MemoryBuffer_MMap;
220 }
221 };
222 }
223
224 static ErrorOr<std::unique_ptr<WritableMemoryBuffer>>
getMemoryBufferForStream(sys::fs::file_t FD,const Twine & BufferName)225 getMemoryBufferForStream(sys::fs::file_t FD, const Twine &BufferName) {
226 const ssize_t ChunkSize = 4096*4;
227 SmallString<ChunkSize> Buffer;
228 // Read into Buffer until we hit EOF.
229 for (;;) {
230 Buffer.reserve(Buffer.size() + ChunkSize);
231 Expected<size_t> ReadBytes = sys::fs::readNativeFile(
232 FD, makeMutableArrayRef(Buffer.end(), ChunkSize));
233 if (!ReadBytes)
234 return errorToErrorCode(ReadBytes.takeError());
235 if (*ReadBytes == 0)
236 break;
237 Buffer.set_size(Buffer.size() + *ReadBytes);
238 }
239
240 return getMemBufferCopyImpl(Buffer, BufferName);
241 }
242
243
244 ErrorOr<std::unique_ptr<MemoryBuffer>>
getFile(const Twine & Filename,int64_t FileSize,bool RequiresNullTerminator,bool IsVolatile)245 MemoryBuffer::getFile(const Twine &Filename, int64_t FileSize,
246 bool RequiresNullTerminator, bool IsVolatile) {
247 return getFileAux<MemoryBuffer>(Filename, FileSize, FileSize, 0,
248 RequiresNullTerminator, IsVolatile);
249 }
250
251 template <typename MB>
252 static ErrorOr<std::unique_ptr<MB>>
253 getOpenFileImpl(sys::fs::file_t FD, const Twine &Filename, uint64_t FileSize,
254 uint64_t MapSize, int64_t Offset, bool RequiresNullTerminator,
255 bool IsVolatile);
256
257 template <typename MB>
258 static ErrorOr<std::unique_ptr<MB>>
getFileAux(const Twine & Filename,int64_t FileSize,uint64_t MapSize,uint64_t Offset,bool RequiresNullTerminator,bool IsVolatile)259 getFileAux(const Twine &Filename, int64_t FileSize, uint64_t MapSize,
260 uint64_t Offset, bool RequiresNullTerminator, bool IsVolatile) {
261 Expected<sys::fs::file_t> FDOrErr =
262 sys::fs::openNativeFileForRead(Filename, sys::fs::OF_None);
263 if (!FDOrErr)
264 return errorToErrorCode(FDOrErr.takeError());
265 sys::fs::file_t FD = *FDOrErr;
266 auto Ret = getOpenFileImpl<MB>(FD, Filename, FileSize, MapSize, Offset,
267 RequiresNullTerminator, IsVolatile);
268 sys::fs::closeFile(FD);
269 return Ret;
270 }
271
272 ErrorOr<std::unique_ptr<WritableMemoryBuffer>>
getFile(const Twine & Filename,int64_t FileSize,bool IsVolatile)273 WritableMemoryBuffer::getFile(const Twine &Filename, int64_t FileSize,
274 bool IsVolatile) {
275 return getFileAux<WritableMemoryBuffer>(Filename, FileSize, FileSize, 0,
276 /*RequiresNullTerminator*/ false,
277 IsVolatile);
278 }
279
280 ErrorOr<std::unique_ptr<WritableMemoryBuffer>>
getFileSlice(const Twine & Filename,uint64_t MapSize,uint64_t Offset,bool IsVolatile)281 WritableMemoryBuffer::getFileSlice(const Twine &Filename, uint64_t MapSize,
282 uint64_t Offset, bool IsVolatile) {
283 return getFileAux<WritableMemoryBuffer>(Filename, -1, MapSize, Offset, false,
284 IsVolatile);
285 }
286
287 std::unique_ptr<WritableMemoryBuffer>
getNewUninitMemBuffer(size_t Size,const Twine & BufferName)288 WritableMemoryBuffer::getNewUninitMemBuffer(size_t Size, const Twine &BufferName) {
289 using MemBuffer = MemoryBufferMem<WritableMemoryBuffer>;
290 // Allocate space for the MemoryBuffer, the data and the name. It is important
291 // that MemoryBuffer and data are aligned so PointerIntPair works with them.
292 // TODO: Is 16-byte alignment enough? We copy small object files with large
293 // alignment expectations into this buffer.
294 SmallString<256> NameBuf;
295 StringRef NameRef = BufferName.toStringRef(NameBuf);
296 size_t AlignedStringLen = alignTo(sizeof(MemBuffer) + NameRef.size() + 1, 16);
297 size_t RealLen = AlignedStringLen + Size + 1;
298 char *Mem = static_cast<char*>(operator new(RealLen, std::nothrow));
299 if (!Mem)
300 return nullptr;
301
302 // The name is stored after the class itself.
303 CopyStringRef(Mem + sizeof(MemBuffer), NameRef);
304
305 // The buffer begins after the name and must be aligned.
306 char *Buf = Mem + AlignedStringLen;
307 Buf[Size] = 0; // Null terminate buffer.
308
309 auto *Ret = new (Mem) MemBuffer(StringRef(Buf, Size), true);
310 return std::unique_ptr<WritableMemoryBuffer>(Ret);
311 }
312
313 std::unique_ptr<WritableMemoryBuffer>
getNewMemBuffer(size_t Size,const Twine & BufferName)314 WritableMemoryBuffer::getNewMemBuffer(size_t Size, const Twine &BufferName) {
315 auto SB = WritableMemoryBuffer::getNewUninitMemBuffer(Size, BufferName);
316 if (!SB)
317 return nullptr;
318 memset(SB->getBufferStart(), 0, Size);
319 return SB;
320 }
321
shouldUseMmap(sys::fs::file_t FD,size_t FileSize,size_t MapSize,off_t Offset,bool RequiresNullTerminator,int PageSize,bool IsVolatile)322 static bool shouldUseMmap(sys::fs::file_t FD,
323 size_t FileSize,
324 size_t MapSize,
325 off_t Offset,
326 bool RequiresNullTerminator,
327 int PageSize,
328 bool IsVolatile) {
329 // mmap may leave the buffer without null terminator if the file size changed
330 // by the time the last page is mapped in, so avoid it if the file size is
331 // likely to change.
332 if (IsVolatile && RequiresNullTerminator)
333 return false;
334
335 // We don't use mmap for small files because this can severely fragment our
336 // address space.
337 if (MapSize < 4 * 4096 || MapSize < (unsigned)PageSize)
338 return false;
339
340 if (!RequiresNullTerminator)
341 return true;
342
343 // If we don't know the file size, use fstat to find out. fstat on an open
344 // file descriptor is cheaper than stat on a random path.
345 // FIXME: this chunk of code is duplicated, but it avoids a fstat when
346 // RequiresNullTerminator = false and MapSize != -1.
347 if (FileSize == size_t(-1)) {
348 sys::fs::file_status Status;
349 if (sys::fs::status(FD, Status))
350 return false;
351 FileSize = Status.getSize();
352 }
353
354 // If we need a null terminator and the end of the map is inside the file,
355 // we cannot use mmap.
356 size_t End = Offset + MapSize;
357 assert(End <= FileSize);
358 if (End != FileSize)
359 return false;
360
361 // Don't try to map files that are exactly a multiple of the system page size
362 // if we need a null terminator.
363 if ((FileSize & (PageSize -1)) == 0)
364 return false;
365
366 #if defined(__CYGWIN__)
367 // Don't try to map files that are exactly a multiple of the physical page size
368 // if we need a null terminator.
369 // FIXME: We should reorganize again getPageSize() on Win32.
370 if ((FileSize & (4096 - 1)) == 0)
371 return false;
372 #endif
373
374 return true;
375 }
376
377 static ErrorOr<std::unique_ptr<WriteThroughMemoryBuffer>>
getReadWriteFile(const Twine & Filename,uint64_t FileSize,uint64_t MapSize,uint64_t Offset)378 getReadWriteFile(const Twine &Filename, uint64_t FileSize, uint64_t MapSize,
379 uint64_t Offset) {
380 Expected<sys::fs::file_t> FDOrErr = sys::fs::openNativeFileForReadWrite(
381 Filename, sys::fs::CD_OpenExisting, sys::fs::OF_None);
382 if (!FDOrErr)
383 return errorToErrorCode(FDOrErr.takeError());
384 sys::fs::file_t FD = *FDOrErr;
385
386 // Default is to map the full file.
387 if (MapSize == uint64_t(-1)) {
388 // If we don't know the file size, use fstat to find out. fstat on an open
389 // file descriptor is cheaper than stat on a random path.
390 if (FileSize == uint64_t(-1)) {
391 sys::fs::file_status Status;
392 std::error_code EC = sys::fs::status(FD, Status);
393 if (EC)
394 return EC;
395
396 // If this not a file or a block device (e.g. it's a named pipe
397 // or character device), we can't mmap it, so error out.
398 sys::fs::file_type Type = Status.type();
399 if (Type != sys::fs::file_type::regular_file &&
400 Type != sys::fs::file_type::block_file)
401 return make_error_code(errc::invalid_argument);
402
403 FileSize = Status.getSize();
404 }
405 MapSize = FileSize;
406 }
407
408 std::error_code EC;
409 std::unique_ptr<WriteThroughMemoryBuffer> Result(
410 new (NamedBufferAlloc(Filename))
411 MemoryBufferMMapFile<WriteThroughMemoryBuffer>(false, FD, MapSize,
412 Offset, EC));
413 if (EC)
414 return EC;
415 return std::move(Result);
416 }
417
418 ErrorOr<std::unique_ptr<WriteThroughMemoryBuffer>>
getFile(const Twine & Filename,int64_t FileSize)419 WriteThroughMemoryBuffer::getFile(const Twine &Filename, int64_t FileSize) {
420 return getReadWriteFile(Filename, FileSize, FileSize, 0);
421 }
422
423 /// Map a subrange of the specified file as a WritableMemoryBuffer.
424 ErrorOr<std::unique_ptr<WriteThroughMemoryBuffer>>
getFileSlice(const Twine & Filename,uint64_t MapSize,uint64_t Offset)425 WriteThroughMemoryBuffer::getFileSlice(const Twine &Filename, uint64_t MapSize,
426 uint64_t Offset) {
427 return getReadWriteFile(Filename, -1, MapSize, Offset);
428 }
429
430 template <typename MB>
431 static ErrorOr<std::unique_ptr<MB>>
getOpenFileImpl(sys::fs::file_t FD,const Twine & Filename,uint64_t FileSize,uint64_t MapSize,int64_t Offset,bool RequiresNullTerminator,bool IsVolatile)432 getOpenFileImpl(sys::fs::file_t FD, const Twine &Filename, uint64_t FileSize,
433 uint64_t MapSize, int64_t Offset, bool RequiresNullTerminator,
434 bool IsVolatile) {
435 static int PageSize = sys::Process::getPageSizeEstimate();
436
437 // Default is to map the full file.
438 if (MapSize == uint64_t(-1)) {
439 // If we don't know the file size, use fstat to find out. fstat on an open
440 // file descriptor is cheaper than stat on a random path.
441 if (FileSize == uint64_t(-1)) {
442 sys::fs::file_status Status;
443 std::error_code EC = sys::fs::status(FD, Status);
444 if (EC)
445 return EC;
446
447 // If this not a file or a block device (e.g. it's a named pipe
448 // or character device), we can't trust the size. Create the memory
449 // buffer by copying off the stream.
450 sys::fs::file_type Type = Status.type();
451 if (Type != sys::fs::file_type::regular_file &&
452 Type != sys::fs::file_type::block_file)
453 return getMemoryBufferForStream(FD, Filename);
454
455 FileSize = Status.getSize();
456 }
457 MapSize = FileSize;
458 }
459
460 if (shouldUseMmap(FD, FileSize, MapSize, Offset, RequiresNullTerminator,
461 PageSize, IsVolatile)) {
462 std::error_code EC;
463 std::unique_ptr<MB> Result(
464 new (NamedBufferAlloc(Filename)) MemoryBufferMMapFile<MB>(
465 RequiresNullTerminator, FD, MapSize, Offset, EC));
466 if (!EC)
467 return std::move(Result);
468 }
469
470 auto Buf = WritableMemoryBuffer::getNewUninitMemBuffer(MapSize, Filename);
471 if (!Buf) {
472 // Failed to create a buffer. The only way it can fail is if
473 // new(std::nothrow) returns 0.
474 return make_error_code(errc::not_enough_memory);
475 }
476
477 // Read until EOF, zero-initialize the rest.
478 MutableArrayRef<char> ToRead = Buf->getBuffer();
479 while (!ToRead.empty()) {
480 Expected<size_t> ReadBytes =
481 sys::fs::readNativeFileSlice(FD, ToRead, Offset);
482 if (!ReadBytes)
483 return errorToErrorCode(ReadBytes.takeError());
484 if (*ReadBytes == 0) {
485 std::memset(ToRead.data(), 0, ToRead.size());
486 break;
487 }
488 ToRead = ToRead.drop_front(*ReadBytes);
489 Offset += *ReadBytes;
490 }
491
492 return std::move(Buf);
493 }
494
495 ErrorOr<std::unique_ptr<MemoryBuffer>>
getOpenFile(sys::fs::file_t FD,const Twine & Filename,uint64_t FileSize,bool RequiresNullTerminator,bool IsVolatile)496 MemoryBuffer::getOpenFile(sys::fs::file_t FD, const Twine &Filename, uint64_t FileSize,
497 bool RequiresNullTerminator, bool IsVolatile) {
498 return getOpenFileImpl<MemoryBuffer>(FD, Filename, FileSize, FileSize, 0,
499 RequiresNullTerminator, IsVolatile);
500 }
501
502 ErrorOr<std::unique_ptr<MemoryBuffer>>
getOpenFileSlice(sys::fs::file_t FD,const Twine & Filename,uint64_t MapSize,int64_t Offset,bool IsVolatile)503 MemoryBuffer::getOpenFileSlice(sys::fs::file_t FD, const Twine &Filename, uint64_t MapSize,
504 int64_t Offset, bool IsVolatile) {
505 assert(MapSize != uint64_t(-1));
506 return getOpenFileImpl<MemoryBuffer>(FD, Filename, -1, MapSize, Offset, false,
507 IsVolatile);
508 }
509
getSTDIN()510 ErrorOr<std::unique_ptr<MemoryBuffer>> MemoryBuffer::getSTDIN() {
511 // Read in all of the data from stdin, we cannot mmap stdin.
512 //
513 // FIXME: That isn't necessarily true, we should try to mmap stdin and
514 // fallback if it fails.
515 sys::ChangeStdinToBinary();
516
517 return getMemoryBufferForStream(sys::fs::getStdinHandle(), "<stdin>");
518 }
519
520 ErrorOr<std::unique_ptr<MemoryBuffer>>
getFileAsStream(const Twine & Filename)521 MemoryBuffer::getFileAsStream(const Twine &Filename) {
522 Expected<sys::fs::file_t> FDOrErr =
523 sys::fs::openNativeFileForRead(Filename, sys::fs::OF_None);
524 if (!FDOrErr)
525 return errorToErrorCode(FDOrErr.takeError());
526 sys::fs::file_t FD = *FDOrErr;
527 ErrorOr<std::unique_ptr<MemoryBuffer>> Ret =
528 getMemoryBufferForStream(FD, Filename);
529 sys::fs::closeFile(FD);
530 return Ret;
531 }
532
getMemBufferRef() const533 MemoryBufferRef MemoryBuffer::getMemBufferRef() const {
534 StringRef Data = getBuffer();
535 StringRef Identifier = getBufferIdentifier();
536 return MemoryBufferRef(Data, Identifier);
537 }
538
~SmallVectorMemoryBuffer()539 SmallVectorMemoryBuffer::~SmallVectorMemoryBuffer() {}
540