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/Alignment.h"
17 #include "llvm/Support/Errc.h"
18 #include "llvm/Support/Error.h"
19 #include "llvm/Support/ErrorHandling.h"
20 #include "llvm/Support/FileSystem.h"
21 #include "llvm/Support/MathExtras.h"
22 #include "llvm/Support/Process.h"
23 #include "llvm/Support/Program.h"
24 #include "llvm/Support/SmallVectorMemoryBuffer.h"
25 #include <cassert>
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
36 #ifdef __MVS__
37 #include "llvm/Support/AutoConvert.h"
38 #endif
39 using namespace llvm;
40
41 //===----------------------------------------------------------------------===//
42 // MemoryBuffer implementation itself.
43 //===----------------------------------------------------------------------===//
44
45 MemoryBuffer::~MemoryBuffer() = default;
46
47 /// init - Initialize this MemoryBuffer as a reference to externally allocated
48 /// memory, memory that we know is already null terminated.
init(const char * BufStart,const char * BufEnd,bool RequiresNullTerminator)49 void MemoryBuffer::init(const char *BufStart, const char *BufEnd,
50 bool RequiresNullTerminator) {
51 assert((!RequiresNullTerminator || BufEnd[0] == 0) &&
52 "Buffer is not null terminated!");
53 BufferStart = BufStart;
54 BufferEnd = BufEnd;
55 }
56
57 //===----------------------------------------------------------------------===//
58 // MemoryBufferMem implementation.
59 //===----------------------------------------------------------------------===//
60
61 /// CopyStringRef - Copies contents of a StringRef into a block of memory and
62 /// null-terminates it.
CopyStringRef(char * Memory,StringRef Data)63 static void CopyStringRef(char *Memory, StringRef Data) {
64 if (!Data.empty())
65 memcpy(Memory, Data.data(), Data.size());
66 Memory[Data.size()] = 0; // Null terminate string.
67 }
68
69 namespace {
70 struct NamedBufferAlloc {
71 const Twine &Name;
NamedBufferAlloc__anon84f27ddc0111::NamedBufferAlloc72 NamedBufferAlloc(const Twine &Name) : Name(Name) {}
73 };
74 } // namespace
75
operator new(size_t N,const NamedBufferAlloc & Alloc)76 void *operator new(size_t N, const NamedBufferAlloc &Alloc) {
77 SmallString<256> NameBuf;
78 StringRef NameRef = Alloc.Name.toStringRef(NameBuf);
79
80 char *Mem = static_cast<char *>(operator new(N + sizeof(size_t) +
81 NameRef.size() + 1));
82 *reinterpret_cast<size_t *>(Mem + N) = NameRef.size();
83 CopyStringRef(Mem + N + sizeof(size_t), NameRef);
84 return Mem;
85 }
86
87 namespace {
88 /// MemoryBufferMem - Named MemoryBuffer pointing to a block of memory.
89 template<typename MB>
90 class MemoryBufferMem : public MB {
91 public:
MemoryBufferMem(StringRef InputData,bool RequiresNullTerminator)92 MemoryBufferMem(StringRef InputData, bool RequiresNullTerminator) {
93 MemoryBuffer::init(InputData.begin(), InputData.end(),
94 RequiresNullTerminator);
95 }
96
97 /// Disable sized deallocation for MemoryBufferMem, because it has
98 /// tail-allocated data.
operator delete(void * p)99 void operator delete(void *p) { ::operator delete(p); }
100
getBufferIdentifier() const101 StringRef getBufferIdentifier() const override {
102 // The name is stored after the class itself.
103 return StringRef(reinterpret_cast<const char *>(this + 1) + sizeof(size_t),
104 *reinterpret_cast<const size_t *>(this + 1));
105 }
106
getBufferKind() const107 MemoryBuffer::BufferKind getBufferKind() const override {
108 return MemoryBuffer::MemoryBuffer_Malloc;
109 }
110 };
111 } // namespace
112
113 template <typename MB>
114 static ErrorOr<std::unique_ptr<MB>>
115 getFileAux(const Twine &Filename, uint64_t MapSize, uint64_t Offset,
116 bool IsText, bool RequiresNullTerminator, bool IsVolatile,
117 std::optional<Align> Alignment);
118
119 std::unique_ptr<MemoryBuffer>
getMemBuffer(StringRef InputData,StringRef BufferName,bool RequiresNullTerminator)120 MemoryBuffer::getMemBuffer(StringRef InputData, StringRef BufferName,
121 bool RequiresNullTerminator) {
122 auto *Ret = new (NamedBufferAlloc(BufferName))
123 MemoryBufferMem<MemoryBuffer>(InputData, RequiresNullTerminator);
124 return std::unique_ptr<MemoryBuffer>(Ret);
125 }
126
127 std::unique_ptr<MemoryBuffer>
getMemBuffer(MemoryBufferRef Ref,bool RequiresNullTerminator)128 MemoryBuffer::getMemBuffer(MemoryBufferRef Ref, bool RequiresNullTerminator) {
129 return std::unique_ptr<MemoryBuffer>(getMemBuffer(
130 Ref.getBuffer(), Ref.getBufferIdentifier(), RequiresNullTerminator));
131 }
132
133 static ErrorOr<std::unique_ptr<WritableMemoryBuffer>>
getMemBufferCopyImpl(StringRef InputData,const Twine & BufferName)134 getMemBufferCopyImpl(StringRef InputData, const Twine &BufferName) {
135 auto Buf = WritableMemoryBuffer::getNewUninitMemBuffer(InputData.size(), BufferName);
136 if (!Buf)
137 return make_error_code(errc::not_enough_memory);
138 memcpy(Buf->getBufferStart(), InputData.data(), InputData.size());
139 return std::move(Buf);
140 }
141
142 std::unique_ptr<MemoryBuffer>
getMemBufferCopy(StringRef InputData,const Twine & BufferName)143 MemoryBuffer::getMemBufferCopy(StringRef InputData, const Twine &BufferName) {
144 auto Buf = getMemBufferCopyImpl(InputData, BufferName);
145 if (Buf)
146 return std::move(*Buf);
147 return nullptr;
148 }
149
150 ErrorOr<std::unique_ptr<MemoryBuffer>>
getFileOrSTDIN(const Twine & Filename,bool IsText,bool RequiresNullTerminator,std::optional<Align> Alignment)151 MemoryBuffer::getFileOrSTDIN(const Twine &Filename, bool IsText,
152 bool RequiresNullTerminator,
153 std::optional<Align> Alignment) {
154 SmallString<256> NameBuf;
155 StringRef NameRef = Filename.toStringRef(NameBuf);
156
157 if (NameRef == "-")
158 return getSTDIN();
159 return getFile(Filename, IsText, RequiresNullTerminator,
160 /*IsVolatile=*/false, Alignment);
161 }
162
163 ErrorOr<std::unique_ptr<MemoryBuffer>>
getFileSlice(const Twine & FilePath,uint64_t MapSize,uint64_t Offset,bool IsVolatile,std::optional<Align> Alignment)164 MemoryBuffer::getFileSlice(const Twine &FilePath, uint64_t MapSize,
165 uint64_t Offset, bool IsVolatile,
166 std::optional<Align> Alignment) {
167 return getFileAux<MemoryBuffer>(FilePath, MapSize, Offset, /*IsText=*/false,
168 /*RequiresNullTerminator=*/false, IsVolatile,
169 Alignment);
170 }
171
172 //===----------------------------------------------------------------------===//
173 // MemoryBuffer::getFile implementation.
174 //===----------------------------------------------------------------------===//
175
176 namespace {
177
178 template <typename MB>
179 constexpr sys::fs::mapped_file_region::mapmode Mapmode =
180 sys::fs::mapped_file_region::readonly;
181 template <>
182 constexpr sys::fs::mapped_file_region::mapmode Mapmode<MemoryBuffer> =
183 sys::fs::mapped_file_region::readonly;
184 template <>
185 constexpr sys::fs::mapped_file_region::mapmode Mapmode<WritableMemoryBuffer> =
186 sys::fs::mapped_file_region::priv;
187 template <>
188 constexpr sys::fs::mapped_file_region::mapmode
189 Mapmode<WriteThroughMemoryBuffer> = sys::fs::mapped_file_region::readwrite;
190
191 /// Memory maps a file descriptor using sys::fs::mapped_file_region.
192 ///
193 /// This handles converting the offset into a legal offset on the platform.
194 template<typename MB>
195 class MemoryBufferMMapFile : public MB {
196 sys::fs::mapped_file_region MFR;
197
getLegalMapOffset(uint64_t Offset)198 static uint64_t getLegalMapOffset(uint64_t Offset) {
199 return Offset & ~(sys::fs::mapped_file_region::alignment() - 1);
200 }
201
getLegalMapSize(uint64_t Len,uint64_t Offset)202 static uint64_t getLegalMapSize(uint64_t Len, uint64_t Offset) {
203 return Len + (Offset - getLegalMapOffset(Offset));
204 }
205
getStart(uint64_t Len,uint64_t Offset)206 const char *getStart(uint64_t Len, uint64_t Offset) {
207 return MFR.const_data() + (Offset - getLegalMapOffset(Offset));
208 }
209
210 public:
MemoryBufferMMapFile(bool RequiresNullTerminator,sys::fs::file_t FD,uint64_t Len,uint64_t Offset,std::error_code & EC)211 MemoryBufferMMapFile(bool RequiresNullTerminator, sys::fs::file_t FD, uint64_t Len,
212 uint64_t Offset, std::error_code &EC)
213 : MFR(FD, Mapmode<MB>, getLegalMapSize(Len, Offset),
214 getLegalMapOffset(Offset), EC) {
215 if (!EC) {
216 const char *Start = getStart(Len, Offset);
217 MemoryBuffer::init(Start, Start + Len, RequiresNullTerminator);
218 }
219 }
220
221 /// Disable sized deallocation for MemoryBufferMMapFile, because it has
222 /// tail-allocated data.
operator delete(void * p)223 void operator delete(void *p) { ::operator delete(p); }
224
getBufferIdentifier() const225 StringRef getBufferIdentifier() const override {
226 // The name is stored after the class itself.
227 return StringRef(reinterpret_cast<const char *>(this + 1) + sizeof(size_t),
228 *reinterpret_cast<const size_t *>(this + 1));
229 }
230
getBufferKind() const231 MemoryBuffer::BufferKind getBufferKind() const override {
232 return MemoryBuffer::MemoryBuffer_MMap;
233 }
234
dontNeedIfMmap()235 void dontNeedIfMmap() override { MFR.dontNeed(); }
236 };
237 } // namespace
238
239 static ErrorOr<std::unique_ptr<WritableMemoryBuffer>>
getMemoryBufferForStream(sys::fs::file_t FD,const Twine & BufferName)240 getMemoryBufferForStream(sys::fs::file_t FD, const Twine &BufferName) {
241 SmallString<sys::fs::DefaultReadChunkSize> Buffer;
242 if (Error E = sys::fs::readNativeFileToEOF(FD, Buffer))
243 return errorToErrorCode(std::move(E));
244 return getMemBufferCopyImpl(Buffer, BufferName);
245 }
246
247 ErrorOr<std::unique_ptr<MemoryBuffer>>
getFile(const Twine & Filename,bool IsText,bool RequiresNullTerminator,bool IsVolatile,std::optional<Align> Alignment)248 MemoryBuffer::getFile(const Twine &Filename, bool IsText,
249 bool RequiresNullTerminator, bool IsVolatile,
250 std::optional<Align> Alignment) {
251 return getFileAux<MemoryBuffer>(Filename, /*MapSize=*/-1, /*Offset=*/0,
252 IsText, RequiresNullTerminator, IsVolatile,
253 Alignment);
254 }
255
256 template <typename MB>
257 static ErrorOr<std::unique_ptr<MB>>
258 getOpenFileImpl(sys::fs::file_t FD, const Twine &Filename, uint64_t FileSize,
259 uint64_t MapSize, int64_t Offset, bool RequiresNullTerminator,
260 bool IsVolatile, std::optional<Align> Alignment);
261
262 template <typename MB>
263 static ErrorOr<std::unique_ptr<MB>>
getFileAux(const Twine & Filename,uint64_t MapSize,uint64_t Offset,bool IsText,bool RequiresNullTerminator,bool IsVolatile,std::optional<Align> Alignment)264 getFileAux(const Twine &Filename, uint64_t MapSize, uint64_t Offset,
265 bool IsText, bool RequiresNullTerminator, bool IsVolatile,
266 std::optional<Align> Alignment) {
267 Expected<sys::fs::file_t> FDOrErr = sys::fs::openNativeFileForRead(
268 Filename, IsText ? sys::fs::OF_TextWithCRLF : sys::fs::OF_None);
269 if (!FDOrErr)
270 return errorToErrorCode(FDOrErr.takeError());
271 sys::fs::file_t FD = *FDOrErr;
272 auto Ret = getOpenFileImpl<MB>(FD, Filename, /*FileSize=*/-1, MapSize, Offset,
273 RequiresNullTerminator, IsVolatile, Alignment);
274 sys::fs::closeFile(FD);
275 return Ret;
276 }
277
278 ErrorOr<std::unique_ptr<WritableMemoryBuffer>>
getFile(const Twine & Filename,bool IsVolatile,std::optional<Align> Alignment)279 WritableMemoryBuffer::getFile(const Twine &Filename, bool IsVolatile,
280 std::optional<Align> Alignment) {
281 return getFileAux<WritableMemoryBuffer>(
282 Filename, /*MapSize=*/-1, /*Offset=*/0, /*IsText=*/false,
283 /*RequiresNullTerminator=*/false, IsVolatile, Alignment);
284 }
285
286 ErrorOr<std::unique_ptr<WritableMemoryBuffer>>
getFileSlice(const Twine & Filename,uint64_t MapSize,uint64_t Offset,bool IsVolatile,std::optional<Align> Alignment)287 WritableMemoryBuffer::getFileSlice(const Twine &Filename, uint64_t MapSize,
288 uint64_t Offset, bool IsVolatile,
289 std::optional<Align> Alignment) {
290 return getFileAux<WritableMemoryBuffer>(
291 Filename, MapSize, Offset, /*IsText=*/false,
292 /*RequiresNullTerminator=*/false, IsVolatile, Alignment);
293 }
294
295 std::unique_ptr<WritableMemoryBuffer>
getNewUninitMemBuffer(size_t Size,const Twine & BufferName,std::optional<Align> Alignment)296 WritableMemoryBuffer::getNewUninitMemBuffer(size_t Size,
297 const Twine &BufferName,
298 std::optional<Align> Alignment) {
299 using MemBuffer = MemoryBufferMem<WritableMemoryBuffer>;
300
301 // Use 16-byte alignment if no alignment is specified.
302 Align BufAlign = Alignment.value_or(Align(16));
303
304 // Allocate space for the MemoryBuffer, the data and the name. It is important
305 // that MemoryBuffer and data are aligned so PointerIntPair works with them.
306 SmallString<256> NameBuf;
307 StringRef NameRef = BufferName.toStringRef(NameBuf);
308
309 size_t StringLen = sizeof(MemBuffer) + sizeof(size_t) + NameRef.size() + 1;
310 size_t RealLen = StringLen + Size + 1 + BufAlign.value();
311 if (RealLen <= Size) // Check for rollover.
312 return nullptr;
313 char *Mem = static_cast<char*>(operator new(RealLen, std::nothrow));
314 if (!Mem)
315 return nullptr;
316
317 // The name is stored after the class itself.
318 *reinterpret_cast<size_t *>(Mem + sizeof(MemBuffer)) = NameRef.size();
319 CopyStringRef(Mem + sizeof(MemBuffer) + sizeof(size_t), NameRef);
320
321 // The buffer begins after the name and must be aligned.
322 char *Buf = (char *)alignAddr(Mem + StringLen, BufAlign);
323 Buf[Size] = 0; // Null terminate buffer.
324
325 auto *Ret = new (Mem) MemBuffer(StringRef(Buf, Size), true);
326 return std::unique_ptr<WritableMemoryBuffer>(Ret);
327 }
328
329 std::unique_ptr<WritableMemoryBuffer>
getNewMemBuffer(size_t Size,const Twine & BufferName)330 WritableMemoryBuffer::getNewMemBuffer(size_t Size, const Twine &BufferName) {
331 auto SB = WritableMemoryBuffer::getNewUninitMemBuffer(Size, BufferName);
332 if (!SB)
333 return nullptr;
334 memset(SB->getBufferStart(), 0, Size);
335 return SB;
336 }
337
shouldUseMmap(sys::fs::file_t FD,size_t FileSize,size_t MapSize,off_t Offset,bool RequiresNullTerminator,int PageSize,bool IsVolatile)338 static bool shouldUseMmap(sys::fs::file_t FD,
339 size_t FileSize,
340 size_t MapSize,
341 off_t Offset,
342 bool RequiresNullTerminator,
343 int PageSize,
344 bool IsVolatile) {
345 // mmap may leave the buffer without null terminator if the file size changed
346 // by the time the last page is mapped in, so avoid it if the file size is
347 // likely to change.
348 if (IsVolatile && RequiresNullTerminator)
349 return false;
350
351 // We don't use mmap for small files because this can severely fragment our
352 // address space.
353 if (MapSize < 4 * 4096 || MapSize < (unsigned)PageSize)
354 return false;
355
356 if (!RequiresNullTerminator)
357 return true;
358
359 // If we don't know the file size, use fstat to find out. fstat on an open
360 // file descriptor is cheaper than stat on a random path.
361 // FIXME: this chunk of code is duplicated, but it avoids a fstat when
362 // RequiresNullTerminator = false and MapSize != -1.
363 if (FileSize == size_t(-1)) {
364 sys::fs::file_status Status;
365 if (sys::fs::status(FD, Status))
366 return false;
367 FileSize = Status.getSize();
368 }
369
370 // If we need a null terminator and the end of the map is inside the file,
371 // we cannot use mmap.
372 size_t End = Offset + MapSize;
373 assert(End <= FileSize);
374 if (End != FileSize)
375 return false;
376
377 // Don't try to map files that are exactly a multiple of the system page size
378 // if we need a null terminator.
379 if ((FileSize & (PageSize -1)) == 0)
380 return false;
381
382 #if defined(__CYGWIN__)
383 // Don't try to map files that are exactly a multiple of the physical page size
384 // if we need a null terminator.
385 // FIXME: We should reorganize again getPageSize() on Win32.
386 if ((FileSize & (4096 - 1)) == 0)
387 return false;
388 #endif
389
390 return true;
391 }
392
393 static ErrorOr<std::unique_ptr<WriteThroughMemoryBuffer>>
getReadWriteFile(const Twine & Filename,uint64_t FileSize,uint64_t MapSize,uint64_t Offset)394 getReadWriteFile(const Twine &Filename, uint64_t FileSize, uint64_t MapSize,
395 uint64_t Offset) {
396 Expected<sys::fs::file_t> FDOrErr = sys::fs::openNativeFileForReadWrite(
397 Filename, sys::fs::CD_OpenExisting, sys::fs::OF_None);
398 if (!FDOrErr)
399 return errorToErrorCode(FDOrErr.takeError());
400 sys::fs::file_t FD = *FDOrErr;
401
402 // Default is to map the full file.
403 if (MapSize == uint64_t(-1)) {
404 // If we don't know the file size, use fstat to find out. fstat on an open
405 // file descriptor is cheaper than stat on a random path.
406 if (FileSize == uint64_t(-1)) {
407 sys::fs::file_status Status;
408 std::error_code EC = sys::fs::status(FD, Status);
409 if (EC)
410 return EC;
411
412 // If this not a file or a block device (e.g. it's a named pipe
413 // or character device), we can't mmap it, so error out.
414 sys::fs::file_type Type = Status.type();
415 if (Type != sys::fs::file_type::regular_file &&
416 Type != sys::fs::file_type::block_file)
417 return make_error_code(errc::invalid_argument);
418
419 FileSize = Status.getSize();
420 }
421 MapSize = FileSize;
422 }
423
424 std::error_code EC;
425 std::unique_ptr<WriteThroughMemoryBuffer> Result(
426 new (NamedBufferAlloc(Filename))
427 MemoryBufferMMapFile<WriteThroughMemoryBuffer>(false, FD, MapSize,
428 Offset, EC));
429 if (EC)
430 return EC;
431 return std::move(Result);
432 }
433
434 ErrorOr<std::unique_ptr<WriteThroughMemoryBuffer>>
getFile(const Twine & Filename,int64_t FileSize)435 WriteThroughMemoryBuffer::getFile(const Twine &Filename, int64_t FileSize) {
436 return getReadWriteFile(Filename, FileSize, FileSize, 0);
437 }
438
439 /// Map a subrange of the specified file as a WritableMemoryBuffer.
440 ErrorOr<std::unique_ptr<WriteThroughMemoryBuffer>>
getFileSlice(const Twine & Filename,uint64_t MapSize,uint64_t Offset)441 WriteThroughMemoryBuffer::getFileSlice(const Twine &Filename, uint64_t MapSize,
442 uint64_t Offset) {
443 return getReadWriteFile(Filename, -1, MapSize, Offset);
444 }
445
446 template <typename MB>
447 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,std::optional<Align> Alignment)448 getOpenFileImpl(sys::fs::file_t FD, const Twine &Filename, uint64_t FileSize,
449 uint64_t MapSize, int64_t Offset, bool RequiresNullTerminator,
450 bool IsVolatile, std::optional<Align> Alignment) {
451 static int PageSize = sys::Process::getPageSizeEstimate();
452
453 // Default is to map the full file.
454 if (MapSize == uint64_t(-1)) {
455 // If we don't know the file size, use fstat to find out. fstat on an open
456 // file descriptor is cheaper than stat on a random path.
457 if (FileSize == uint64_t(-1)) {
458 sys::fs::file_status Status;
459 std::error_code EC = sys::fs::status(FD, Status);
460 if (EC)
461 return EC;
462
463 // If this not a file or a block device (e.g. it's a named pipe
464 // or character device), we can't trust the size. Create the memory
465 // buffer by copying off the stream.
466 sys::fs::file_type Type = Status.type();
467 if (Type != sys::fs::file_type::regular_file &&
468 Type != sys::fs::file_type::block_file)
469 return getMemoryBufferForStream(FD, Filename);
470
471 FileSize = Status.getSize();
472 }
473 MapSize = FileSize;
474 }
475
476 if (shouldUseMmap(FD, FileSize, MapSize, Offset, RequiresNullTerminator,
477 PageSize, IsVolatile)) {
478 std::error_code EC;
479 std::unique_ptr<MB> Result(
480 new (NamedBufferAlloc(Filename)) MemoryBufferMMapFile<MB>(
481 RequiresNullTerminator, FD, MapSize, Offset, EC));
482 if (!EC)
483 return std::move(Result);
484 }
485
486 #ifdef __MVS__
487 // Set codepage auto-conversion for z/OS.
488 if (auto EC = llvm::enableAutoConversion(FD))
489 return EC;
490 #endif
491
492 auto Buf =
493 WritableMemoryBuffer::getNewUninitMemBuffer(MapSize, Filename, Alignment);
494 if (!Buf) {
495 // Failed to create a buffer. The only way it can fail is if
496 // new(std::nothrow) returns 0.
497 return make_error_code(errc::not_enough_memory);
498 }
499
500 // Read until EOF, zero-initialize the rest.
501 MutableArrayRef<char> ToRead = Buf->getBuffer();
502 while (!ToRead.empty()) {
503 Expected<size_t> ReadBytes =
504 sys::fs::readNativeFileSlice(FD, ToRead, Offset);
505 if (!ReadBytes)
506 return errorToErrorCode(ReadBytes.takeError());
507 if (*ReadBytes == 0) {
508 std::memset(ToRead.data(), 0, ToRead.size());
509 break;
510 }
511 ToRead = ToRead.drop_front(*ReadBytes);
512 Offset += *ReadBytes;
513 }
514
515 return std::move(Buf);
516 }
517
518 ErrorOr<std::unique_ptr<MemoryBuffer>>
getOpenFile(sys::fs::file_t FD,const Twine & Filename,uint64_t FileSize,bool RequiresNullTerminator,bool IsVolatile,std::optional<Align> Alignment)519 MemoryBuffer::getOpenFile(sys::fs::file_t FD, const Twine &Filename,
520 uint64_t FileSize, bool RequiresNullTerminator,
521 bool IsVolatile, std::optional<Align> Alignment) {
522 return getOpenFileImpl<MemoryBuffer>(FD, Filename, FileSize, FileSize, 0,
523 RequiresNullTerminator, IsVolatile,
524 Alignment);
525 }
526
getOpenFileSlice(sys::fs::file_t FD,const Twine & Filename,uint64_t MapSize,int64_t Offset,bool IsVolatile,std::optional<Align> Alignment)527 ErrorOr<std::unique_ptr<MemoryBuffer>> MemoryBuffer::getOpenFileSlice(
528 sys::fs::file_t FD, const Twine &Filename, uint64_t MapSize, int64_t Offset,
529 bool IsVolatile, std::optional<Align> Alignment) {
530 assert(MapSize != uint64_t(-1));
531 return getOpenFileImpl<MemoryBuffer>(FD, Filename, -1, MapSize, Offset, false,
532 IsVolatile, Alignment);
533 }
534
getSTDIN()535 ErrorOr<std::unique_ptr<MemoryBuffer>> MemoryBuffer::getSTDIN() {
536 // Read in all of the data from stdin, we cannot mmap stdin.
537 //
538 // FIXME: That isn't necessarily true, we should try to mmap stdin and
539 // fallback if it fails.
540 sys::ChangeStdinMode(sys::fs::OF_Text);
541
542 return getMemoryBufferForStream(sys::fs::getStdinHandle(), "<stdin>");
543 }
544
545 ErrorOr<std::unique_ptr<MemoryBuffer>>
getFileAsStream(const Twine & Filename)546 MemoryBuffer::getFileAsStream(const Twine &Filename) {
547 Expected<sys::fs::file_t> FDOrErr =
548 sys::fs::openNativeFileForRead(Filename, sys::fs::OF_None);
549 if (!FDOrErr)
550 return errorToErrorCode(FDOrErr.takeError());
551 sys::fs::file_t FD = *FDOrErr;
552 ErrorOr<std::unique_ptr<MemoryBuffer>> Ret =
553 getMemoryBufferForStream(FD, Filename);
554 sys::fs::closeFile(FD);
555 return Ret;
556 }
557
getMemBufferRef() const558 MemoryBufferRef MemoryBuffer::getMemBufferRef() const {
559 StringRef Data = getBuffer();
560 StringRef Identifier = getBufferIdentifier();
561 return MemoryBufferRef(Data, Identifier);
562 }
563
564 SmallVectorMemoryBuffer::~SmallVectorMemoryBuffer() = default;
565